SynC™

SynC · Editorial revision

Gypsum Board Assemblies

Revision8
EditedSep 26, 2026
StatusCurrent
Contents

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Current revision. This is editorial revision 8, the current text of this standard. Read it on the standard's page.

SynC Standards Team — Specifier (Platform Standards) ✓ OfficialDiscloses employment SynC (SynC Platform Team)
Remade from scratch under the authoring cheatsheet: the assembly as a system built to its design number, framing and blocking owned for the trades that hang on these walls, finish levels defined, a trade-off note beside every choice

1 Scope

1.1 Work Covered by This Standard

NOTE This standard governs the furnishing, framing, application, finishing, and protection of gypsum board partitions, furred walls, ceilings, soffits, and bulkheads, and of gypsum sheathing on framed exterior walls. (1.1.1)
NOTE A gypsum board assembly is a system rather than a product. Its fire-resistance rating, its sound transmission class, its limiting height, and its abuse resistance each depend together on the board type and thickness, the number of layers, the framing depth, thickness, and spacing, the fastener type and pattern, the cavity fill, the decoupling accessories, and the perimeter treatment, and a change to any one of those variables changes what the assembly is. (1.1.2)
NOTE The board itself carries no rating. Type X is a core formulation defined by the performance it delivers in a tested assembly, and the hourly rating, the sound rating, and the limiting height all belong to the assembly in which the board was tested. (1.1.3)
1.1.4 The gypsum board assemblies included in the work shall be as indicated in the datasheet.
Gypsum Board Assemblies in Scopecheckbox
☐ Interior partitions on nonstructural steel framing
☐ Interior partitions on wood framing
☐ Furred walls over concrete and masonry
☐ Fire-resistance-rated partitions and horizontal membranes
☐ Sound-rated partitions
☐ Suspended gypsum board ceilings
☐ Direct-attached gypsum board ceilings
☐ Soffits and bulkheads
☐ Area separation walls
☐ Wet-area tile backer on framed walls
☐ Gypsum base and veneer plaster
☐ Gypsum sheathing on framed exterior walls
NOTE Several articles of this standard apply only to assemblies selected in this field, and each such article states its own trigger. (1.1.5)
1.1.6 The partition types, their board layers, their framing, their rating, and their locations shall be as indicated on the partition schedule and the floor plans.
1.1.7 The ceiling types, their board, their framing, and their extents shall be as indicated on the reflected ceiling plans.

1.2 Work Not Covered by This Standard

NOTE The following are governed elsewhere and are outside this standard: (1.2.1)
  • load-bearing and wind-bearing cold-formed framing engineered under AISI S100 and AISI S240, which is governed by Cold Formed Metal FramingCold-Formed Metal FramingResolves to the current adopted revision.sync/cold-formed-metal-framing
  • wood light framing, its studs, plates, and headers, which is governed by Wood FramingWood Light FramingResolves to the current adopted revision.sync/wood-framing, and the miscellaneous wood blocking, nailers, and furring that are governed by Rough CarpentryRough CarpentryResolves to the current adopted revision.sync/rough-carpentry
  • single-side-access shaft walls at elevator hoistways, exit stairs, and vertical chases, which are governed by Gypsum Shaft Wall AssembliesGypsum Shaft Wall AssembliesResolves to the current adopted revision.sync/gypsum-shaft-wall-assemblies
  • through-penetration firestop systems and listed joint systems at the head of a partition, at its base, and at penetrations, which are governed by FirestoppingFirestoppingResolves to the current adopted revision.sync/firestopping
  • selection and documentation of the design number for each rated assembly, which is governed by Fire Rated Wall And Floor AssembliesFire-Resistance-Rated AssembliesResolves to the current adopted revision.sync/fire-rated-wall-and-floor-assemblies
  • sound-attenuation cavity fill, which is governed by Acoustic InsulationAcoustic InsulationResolves to the current adopted revision.sync/acoustic-insulation
  • thermal insulation in the envelope and its vapor retarder, which are governed by Building Thermal InsulationBuilding Thermal InsulationResolves to the current adopted revision.sync/building-thermal-insulation
  • sealant materials and their chemistry, which are governed by Joint SealantsJoint SealantsResolves to the current adopted revision.sync/joint-sealants
  • field painting of the finished board, which is governed by Interior PaintingInterior PaintingResolves to the current adopted revision.sync/interior-painting, and wall coverings, which are governed by Wall CoveringsWall CoveringsResolves to the current adopted revision.sync/wall-coverings
  • tile, its setting materials, and the membranes beneath it, which are governed by Ceramic TileCeramic TileResolves to the current adopted revision.sync/ceramic-tile
  • portland cement plaster and stucco, which are governed by Plaster And StuccoPortland Cement Plaster and StuccoResolves to the current adopted revision.sync/plaster-and-stucco
  • acoustical tile ceilings and their suspension grids, which are governed by Suspended Acoustical CeilingsSuspended Acoustical CeilingsResolves to the current adopted revision.sync/suspended-acoustical-ceilings
  • doors, frames, and hardware, which are governed by Doors Frames And HardwareDoors, Frames, and HardwareResolves to the current adopted revision.sync/doors-frames-and-hardware, and access doors and panels themselves, which are governed by Access Doors And PanelsAccess Doors and PanelsResolves to the current adopted revision.sync/access-doors-and-panels
  • spray-applied fireproofing on structure, which is governed by FireproofingApplied FireproofingResolves to the current adopted revision.sync/fireproofing

1.3 Coordination With Adjacent Work

NOTE Gypsum board closes more other trades' work than any other interior finish, and most defects found after occupancy trace to something that was missing, wrong, or displaced when the board went on. (1.3.1)
1.3.2 The Contractor shall coordinate the cavity fill of sound-rated and fire-resistance-rated partitions with Acoustic InsulationAcoustic InsulationResolves to the current adopted revision.sync/acoustic-insulation so that the fill is in place and inspected before the closing face is applied.
1.3.3 The Contractor shall coordinate the envelope insulation, vapor retarder, and air barrier behind furred and framed exterior walls with Building Thermal InsulationBuilding Thermal InsulationResolves to the current adopted revision.sync/building-thermal-insulation and Air BarriersAir BarriersResolves to the current adopted revision.sync/air-barriers before the board is applied.
1.3.4 The Contractor shall coordinate the head-of-wall joint system, the bottom-of-wall joint system, and every penetration firestop in a rated assembly with FirestoppingFirestoppingResolves to the current adopted revision.sync/firestopping before the assembly is closed.
1.3.5 The Contractor shall coordinate frame anchorage, jamb reinforcement, and wall build sequence with Doors Frames And HardwareDoors, Frames, and HardwareResolves to the current adopted revision.sync/doors-frames-and-hardware before frames are delivered.
1.3.6 The Contractor shall coordinate the framing, panel installation, and finishing of access panel openings with Access Doors And PanelsAccess Doors and PanelsResolves to the current adopted revision.sync/access-doors-and-panels.
1.3.7 The Contractor shall coordinate the finish level of each surface with Interior PaintingInterior PaintingResolves to the current adopted revision.sync/interior-painting and Wall CoveringsWall CoveringsResolves to the current adopted revision.sync/wall-coverings against the room finish schedule before joint treatment begins.
1.3.8 The Contractor shall coordinate the backer board, its framing, and its joint treatment at tiled walls with Ceramic TileCeramic TileResolves to the current adopted revision.sync/ceramic-tile.
1.3.9 The Contractor shall coordinate the gypsum board soffits and bulkheads that bound an acoustical ceiling field with Suspended Acoustical CeilingsSuspended Acoustical CeilingsResolves to the current adopted revision.sync/suspended-acoustical-ceilings.
1.3.10 The Contractor shall coordinate the interface between an ordinary partition and a shaft wall, including the corner framing and the face-layer continuity, with Gypsum Shaft Wall AssembliesGypsum Shaft Wall AssembliesResolves to the current adopted revision.sync/gypsum-shaft-wall-assemblies.
1.3.11 The Contractor shall coordinate the header and hard ceiling above an operable partition with Operable PartitionsOperable PartitionsResolves to the current adopted revision.sync/operable-partitions so that the track support is framed before the ceiling is closed.
1.3.12 The Contractor shall coordinate recessed shade pockets and their framing with Window TreatmentsWindow TreatmentsResolves to the current adopted revision.sync/window-treatments.
1.3.13 The Contractor shall coordinate the rated openings for fire-rated glazing with Fire Rated GlazingFire-Rated Glazing and FramingResolves to the current adopted revision.sync/fire-rated-glazing so that the framing and substrate at the opening match the listed assembly.

2 Referenced Standards

2.1 Materials, framing, application, and finishing shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2 Where referenced standards conflict, the more stringent requirement shall govern unless the Architect of Record directs otherwise in writing.
Standard Title
ASTM C1396/C1396M Gypsum Board
ASTM C1177/C1177M Glass Mat Gypsum Substrate for Use as Sheathing
ASTM C1178/C1178M Coated Glass Mat Water-Resistant Gypsum Backing Panel
ASTM C1658/C1658M Glass Mat Gypsum Panels
ASTM C1629/C1629M Abuse-Resistant Nonstructural Gypsum Panel Products and Fiber-Reinforced Cement Panels
ASTM C1278/C1278M Fiber-Reinforced Gypsum Panel
ASTM C1288 Discrete Non-Asbestos Fiber-Cement Interior Substrate Sheets
ASTM C1325 Fiber-Mat Reinforced Cementitious Backer Units
ASTM C1264 Sampling, Inspection, Rejection, Certification, Packaging, Marking, Shipping, Handling, and Storage of Gypsum Panel Products
ASTM C473 Physical Testing of Gypsum Panel Products
ASTM D3273 Resistance to Growth of Mold on the Surface of Interior Coatings in an Environmental Chamber
ASTM C645 Nonstructural Steel Framing Members
ASTM C754 Installation of Steel Framing Members to Receive Screw-Attached Gypsum Panel Products
AISI S220 North American Standard for Cold-Formed Steel Framing, Nonstructural Members
ICC-ES AC86 Acceptance Criteria for Cold-Formed Steel Framing Members, Interior Nonload-Bearing Wall Construction
ASTM A653/A653M Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-Dip Process
ASTM C635/C635M Manufacture, Performance, and Testing of Metal Suspension Systems for Acoustical Tile and Lay-in Panel Ceilings
ASTM C636/C636M Installation of Metal Ceiling Suspension Systems for Acoustical Tile and Lay-in Panels
ASTM C840 Application and Finishing of Gypsum Board
ASTM C1002 Steel Self-Piercing Tapping Screws for Application of Gypsum Panel Products or Metal Plaster Bases to Wood Studs or Steel Studs
ASTM C954 Steel Drill Screws for the Application of Gypsum Panel Products or Metal Plaster Bases to Steel Studs from 0.033 in. to 0.112 in. in Thickness
ASTM C514 Nails for the Application of Gypsum Board
ASTM C557 Adhesives for Fastening Gypsum Wallboard to Wood Framing
ASTM C475/C475M Joint Compound and Joint Tape for Finishing Gypsum Board
ASTM C1047 Accessories for Gypsum Wallboard and Gypsum Veneer Base
ASTM C587 Gypsum Veneer Plaster
ASTM C843 Application of Gypsum Veneer Plaster
ASTM C919 Use of Sealants in Acoustical Applications
ASTM E119 Fire Tests of Building Construction and Materials
UL 263 Fire Tests of Building Construction and Materials
ASTM E84 Surface Burning Characteristics of Building Materials
ASTM E136 Behavior of Materials in a Vertical Tube Furnace at 750°C
ASTM E90 Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements
ASTM E413 Classification for Rating Sound Insulation
ASTM E336 Measurement of Airborne Sound Attenuation Between Rooms in Buildings
GA-216 Application and Finishing of Gypsum Panel Products
GA-214 Recommended Levels of Finish for Gypsum Board, Glass Mat and Fiber-Reinforced Gypsum Panels
GA-234 Control Joints for Fire-Resistance-Rated Systems
GA-238 Guidelines for Prevention of Mold Growth on Gypsum Board
GA-253 Application of Gypsum Sheathing
GA-600 Fire Resistance and Sound Control Design Manual
GA-620 Gypsum Area Separation Walls
UL Fire Resistance Directory Fire-Resistance-Rated Systems and Products
ASCE/SEI 7 Minimum Design Loads and Associated Criteria for Buildings and Other Structures (Chapter 13, Seismic Design Requirements for Nonstructural Components)
IBC International Building Code (Chapter 7, Fire and Smoke Protection Features; Chapter 25, Gypsum Board, Gypsum Panel Products and Plaster; Section 1607, Live Loads; Section 2603, Foam Plastic Insulation)
NOTE GA-216 is the application document the International Building Code adopts by reference for gypsum board, so its provisions are code obligations wherever the IBC is in force, and ASTM C840 covers the same ground as a consensus standard; where the two differ on a detail this standard cites the one that governs that detail. (2.3)

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for review before gypsum board products or framing are procured:
  • Product data for each gypsum panel product, stating the product standard, the type designation, the thickness, the edge profile, the facing, the core treatment, the surface burning classification, and the mold resistance score where the product is furnished as mold resistant
  • Product data for studs, runners, furring channels, resilient channels, sound isolation clips, deflection track, ceiling suspension members, and hangers, stating the member designation, the base steel thickness in mils, the yield strength, the metallic coating, and the evaluation report where a member is qualified by test rather than by thickness
  • Product data for screws, nails, adhesives, joint compound, joint tape, trim accessories, control joints, acoustic sealant, and putty pads
  • A schedule listing every fire-resistance-rated assembly, the design number cited for it, and the board, framing, fastener, and cavity fill proposed to build it
  • A schedule listing every sound-rated assembly, the sound transmission class required, the tested assembly cited for it, and the decoupling accessories proposed to build it
  • Limiting height tables for the studs proposed, marked to show the tallest partition of each type on the project against the deflection limit selected
  • Shop drawings for suspended ceiling framing, showing hanger locations, carrying channel and furring spacing, bracing, perimeter conditions, and the framing at fixtures, air devices, and access panels
  • A blocking and backing schedule listing every wall-mounted item that requires backing, its location, its mounting height, and the backing material and size proposed
  • Samples of each trim accessory and control joint, and a 12 in. by 12 in. sample of each textured finish
Action Submittals Requiredcheckbox
☑ Product data for gypsum panel products
☑ Product data for framing, furring, and suspension members
☑ Product data for fasteners, compound, tape, accessories, and sealants
☑ Fire-resistance-rated assembly schedule
☐ Sound-rated assembly schedule
☐ Limiting height tables marked to the project
☐ Shop drawings for suspended ceiling framing
☑ Blocking and backing schedule
☐ Samples of accessories and textured finishes
3.1.2 Installation of any assembly shall not begin until the submittals covering its products have been reviewed and returned.
3.1.3 The Contractor shall submit a written request before furnishing a board type, thickness, framing member, fastener, or accessory that differs from the reviewed submittal, and the request shall identify each rated or sound-rated assembly the change affects.

3.2 Informational Submittals

3.2.1 The Contractor shall submit the following before the first assembly is closed:
  • Evaluation reports for studs qualified under AISI S220 and ICC-ES AC86 at a base steel thickness below the ASTM C645 minimum
  • Documentation of the installer's experience meeting the qualification stated in this standard
  • Evidence that each product furnished as noncombustible, mold resistant, or abuse resistant carries the classification claimed for it
Informational Submittals Requiredcheckbox
☐ Evaluation reports for equivalent-performance studs
☑ Installer experience documentation
☑ Product classification evidence

3.3 Closeout Submittals

3.3.1 The Contractor shall submit the following before the gypsum board work is accepted:
  • Inspection records for each rated and sound-rated assembly inspected before concealment, identifying the date, the inspecting party, the assemblies inspected, and the disposition of any deficiency
  • A record of every substitution to a design number accepted in writing during construction, with the revised design number or the engineering judgment that supports it
  • Warranty documents for each product that carries a written manufacturer warranty
Closeout Submittals Requiredcheckbox
☑ Inspection records before concealment
☑ Record of accepted design number substitutions
☐ Manufacturer warranty documents

4 Quality Assurance

4.1 Installer Qualifications

4.1.1 Gypsum board and its framing shall be installed by a firm experienced in the partition, ceiling, and rated assembly types required on the project.
4.1.2 The foreman for rated assemblies shall have built fire-resistance-rated gypsum board assemblies to a cited design number on not fewer than three completed projects.
4.1.3 Where the parties disagree whether an installer's experience is comparable in scope to the work of this project, the Architect of Record shall make the initial determination.
NOTE The skill a rated assembly requires is not in the board hanging but in reading the design number: which layer is screwed and which is laminated, which joints are staggered, where the fasteners land, and what happens at the head, and a crew that has never been held to a listing does not know which of its habits the listing forbids. (4.1.4)

4.2 Pre-Installation Conference

4.2.1 Before framing for gypsum board begins, the Contractor shall hold a pre-installation conference attended by the Architect of Record, the gypsum board installer, the cavity insulation installer, the firestopping installer, the electrical installer, and the trades whose work is backed by in-wall blocking.
4.2.2 The conference shall review the rated assembly schedule, the sound-rated assembly schedule, the finish level of each surface, the deflection head details, the blocking and backing schedule, the electrical box offsets in sound-rated partitions, and the sequence by which each rated and sound-rated assembly is filled, sealed, inspected, and closed.
NOTE The trades that follow the framing are the ones that most often defeat it, by filling a deflection gap, running back-to-back boxes in a sound-rated bay, or closing a wall before its backing is in, which is why they attend the conference rather than only the board installer. (4.2.3)

4.3 Mock-Ups

4.3.1 The mock-up requirement for the gypsum board work shall be as indicated in the datasheet.
Mock-Up Requirementradio
● Not required
○ One mock-up of each fire-resistance-rated and sound-rated partition type
○ One mock-up of each finish level and texture in a location the Architect of Record selects
NOTE A partition mock-up finds a systemic error in the layers, the fasteners, or the perimeter at one location instead of across a floor, and a finish mock-up settles what a Level 4 surface or a knockdown texture looks like under the project's lighting before the argument can start; each costs a day of one crew, and neither is worth building on a project with a single unrated partition type and flat paint throughout. (4.3.2)
4.3.3 Where a mock-up is required, the closing face shall not be applied until the framing, cavity fill, blocking, and perimeter sealant of the mock-up have been reviewed.
4.3.4 A mock-up that does not represent the cited assembly or does not pass its review shall be corrected or rebuilt at the Contractor's expense before production assemblies of that type are closed.
4.3.5 An accepted mock-up may remain as part of the work.

4.4 Inspection Before Concealment

4.4.1 The assemblies whose framing, cavity fill, blocking, and perimeter treatment are inspected before the closing face is applied shall be as indicated in the datasheet.
Assemblies Inspected Before Concealmentselect
Every partition and ceiling
Fire-resistance-rated and sound-rated assemblies
Fire-resistance-rated assemblies
None beyond the inspections the adopted code requires
NOTE Inspecting every wall buys certainty at the cost of holding every crew for a walk before each face goes on, and inspecting only rated assemblies leaves the blocking and box offsets in ordinary partitions to the closeout survey; the rated-and-sound-rated selection is the norm because those are the assemblies whose defects cannot be seen or corrected from the finished face. (4.4.2)
4.4.3 The Contractor shall give the inspecting party not less than two working days' notice before the closing face of an assembly selected for inspection is applied.
4.4.4 The Contractor shall not apply the closing face of an assembly selected for inspection until it has been inspected and released, or until the inspecting party has waived the inspection in writing.
4.4.5 An assembly closed without a required inspection shall be reopened at the Contractor's expense to the extent the inspecting party requires.
4.4.6 Special inspection of rated assemblies, where the adopted code requires it, is performed under Special Inspections And TestingSpecial Inspections and Structural TestingResolves to the current adopted revision.sync/special-inspections-and-testing and does not replace the inspection this article requires.

5 Environmental Conditions

5.1 Temperature During Application and Finishing

5.1.1 Gypsum board shall not be mechanically applied when the air temperature in the space is below 40°F.
5.1.2 Joint compound, adhesive, texture, and veneer plaster shall not be applied unless the air temperature in the space has been held at or above 50°F for not less than 48 hours before application and is held there continuously until the material is dry.
5.1.3 Rapid temperature change during drying shall be avoided, and temporary heat shall be distributed so that no surface is heated directly by a flame or a hot-air discharge.
NOTE Drying-type compound cures by evaporation and setting-type compound by hydration, and both are slowed by cold and both crack when a surface dries faster than the material beneath it; the 48-hour lead is what brings the board and framing to temperature so that the compound is not applied to a cold substrate in a warm room. (5.1.4)

5.2 Ventilation and Drying

5.2.1 Ventilation shall be provided to remove moisture from the space during joint treatment and until each coat is dry.
5.2.2 Where natural ventilation does not dry each coat within the manufacturer's stated time, the Contractor shall provide mechanical ventilation or dehumidification.
NOTE Stagnant, humid air over fresh compound produces slow, uneven drying, and the joints that dry last are the ones that blister and ridge. (5.2.3)

5.3 Protection From Moisture

5.3.1 Gypsum board shall not be applied in a space that is not enclosed against weather unless the product is a glass-mat sheathing or an exterior soffit board furnished for that exposure.
5.3.2 Installed board that has been wetted shall be inspected by the Contractor before finishing, and board with face paper separation, a softened core, or visible mold growth shall be removed and replaced.
NOTE Paper-faced gypsum board wetted after installation and dried within a day or two commonly recovers its strength, but the paper feeds mold within about two days of staying wet, and the growth begins on the concealed face where no one sees it; GA-238 is the industry guidance on which wetted board is salvageable. (5.3.3)

6 Tested Assembly Basis

6.1 Fire-Resistance-Rated Assemblies

6.1.1 The design number, the hourly rating, and the assembly classification of each fire-resistance-rated partition, ceiling, and horizontal membrane shall be as indicated on the partition schedule and the floor and ceiling assembly schedule.
NOTE The design number is selected and documented under Fire Rated Wall And Floor AssembliesFire-Resistance-Rated AssembliesResolves to the current adopted revision.sync/fire-rated-wall-and-floor-assemblies, and this standard builds the assembly the design number describes. (6.1.2)
6.1.3 Every fire-resistance-rated assembly shall be built with the board type and thickness, the number of layers, the framing depth, thickness, and spacing, the fastener type, length, and pattern, the joint treatment, the cavity fill, and the perimeter detail that the cited design number states.
6.1.4 Where a design number names a proprietary product, the Contractor shall furnish that product or a product covered by the same listing.
6.1.5 Where a field condition prevents an assembly from being built as the design number states, the Contractor shall report the condition to the Architect of Record before proceeding and shall not build a departure without written acceptance of a substitute design number or an engineering judgment obtained under Fire Rated Wall And Floor AssembliesFire-Resistance-Rated AssembliesResolves to the current adopted revision.sync/fire-rated-wall-and-floor-assemblies.
NOTE The rating an assembly earns in the furnace belongs to the whole configuration tested, and a listing does not permit a project to loosen any variable it fixes; a stud spacing opened up for economy, a screw pattern shortened, or a batt omitted because the acoustic schedule did not need it each produces a wall that was never tested. (6.1.6)
NOTE Gypsum board resists fire by calcination. The core holds about a fifth of its weight as chemically bound water, and driving that water off consumes heat and holds the unexposed face near the boiling point until the calcination front has passed through the thickness; the rating is largely the time that takes, which is why thickness and layer count matter more than any other variable. (6.1.7)

6.2 Sound-Rated Assemblies

6.2.1 The sound transmission class required of each sound-rated partition and floor-ceiling assembly shall be as indicated on the partition schedule and the floor and ceiling assembly schedule.
6.2.2 The sources of tested sound-rated assembly data accepted on the project shall be as indicated in the datasheet.
Accepted Sources of Sound-Rated Assembly Datacheckbox
☑ GA-600 sound-rated designs
☑ Listed fire-resistance designs that carry a published sound transmission class
☑ ASTM E90 laboratory test reports from an independent accredited laboratory
☐ Manufacturer-sponsored ASTM E90 test reports from an accredited laboratory
6.2.3 Each sound-rated assembly shall be built with the board layers, the framing, the decoupling accessories, the cavity fill, and the perimeter treatment of the tested assembly cited for it.
NOTE A sound transmission class is a laboratory rating measured under ASTM E90 and classified under ASTM E413 on a specimen with no flanking paths. A field measurement under ASTM E336 of the same assembly runs several points lower because the structure, the plenum, the doors, and the penetrations carry sound around it, and the adopted building code sets its field minimum for walls between dwelling units five points below the laboratory minimum for that reason. (6.2.4)
NOTE Raising a partition from the mid-40s to the mid-50s is done by decoupling one face on resilient channels or isolation clips, by adding a second layer of board, or by building a double or staggered stud wall, and each step costs cavity depth and floor area as well as money; above the mid-50s the flanking paths, not the partition, set the result. (6.2.5)
NOTE The construction of the flanking paths that limit field performance is addressed in the sound-rated construction articles of this standard, and field acoustic testing of completed assemblies is performed under Acoustic InsulationAcoustic InsulationResolves to the current adopted revision.sync/acoustic-insulation. (6.2.6)

7 Gypsum Panel Products

7.1 Product Standards and Labeling

7.1.1 Gypsum board shall conform to ASTM C1396 for the type designated.
7.1.2 Glass-mat faced interior board shall conform to ASTM C1658, glass-mat water-resistant backing board to ASTM C1178, glass-mat sheathing to ASTM C1177, and abuse-resistant and impact-resistant board to ASTM C1629 in addition to ASTM C1396.
7.1.3 Every panel shall bear the manufacturer's identification, the product standard, the type designation, and the thickness, and panels whose marking is illegible or absent shall not be installed.
7.1.4 Sampling, inspection, and rejection of gypsum panel products shall follow ASTM C1264.
NOTE The gypsum core of every panel product under this standard is noncombustible as tested under ASTM E136, and a paper-faced panel earns a Class A surface burning classification under ASTM E84; a panel's facing, not its core, is what a surface burning or mold test is measuring. (7.1.5)

7.2 Board Type at Non-Rated Assemblies

NOTE Type X board is required wherever a design number calls for it, and the decision this field records is what goes on the partitions and ceilings that carry no rating. (7.2.1)
7.2.2 The board type at non-rated partitions and ceilings shall be as indicated in the datasheet.
Board Type at Non-Rated Assembliesradio
○ Type X board throughout, at rated and non-rated assemblies alike
○ Regular board at non-rated assemblies and Type X only where a design number requires it
NOTE Type X throughout removes the possibility of regular board being hung in a rated wall by a crew that has both on the floor, and 5/8 in. Type X is stiffer and more dent resistant than 1/2 in. regular board at a small premium per square foot; regular board at non-rated assemblies saves that premium and the weight, which is the norm in residential work where most walls are unrated and the framing is at 16 in. on center. (7.2.3)
7.2.4 Where the datasheet selects Type X throughout, regular board shall not be installed in any partition or ceiling.
NOTE Type C board is a Type X formulation with additional glass fiber and a shrinkage-compensating additive that keeps the core intact and in place longer under fire exposure, so that certain listings achieve a rating at fewer layers or a thinner section than Type X allows; it is furnished only where the design number names it, and Type X is not a substitute for it. (7.2.5)
7.2.6 Where a design number names Type C board, Type X board shall not be substituted for it.

7.3 Wall Board Thickness

7.3.1 The thickness of the board on partitions and furred walls, where a design number does not fix it, shall be as indicated in the datasheet.
Wall Board Thicknessrange
in.
0.250.3750.50.6250.751
NOTE The 5/8 in. thickness is the commercial norm because it is the thickness in which Type X is listed for one-hour assemblies, it spans framing at 24 in. on center without sag or fastener telegraphing, and it takes a dent that 1/2 in. board does not; 1/2 in. board is the norm in residential work on 16 in. framing, 1/4 in. and 3/8 in. board are furnished for curved surfaces and for laminating over an existing surface, and 3/4 in. and 1 in. panels are the abuse-resistant and shaftliner products that a listing or a duty rating calls for. (7.3.2)
7.3.3 Where a design number fixes the board thickness, the design number governs.

7.4 Ceiling Board

NOTE A ceiling carries the board on its weak axis, and board that is adequate on a wall sags between supports on a ceiling, especially once a wet texture or a heavy paint has loaded it; sag-resistant ceiling board is a 1/2 in. product formulated to span 24 in. framing without that deflection. (7.4.1)
7.4.2 The board type on ceilings, where a design number does not fix it, shall be as indicated in the datasheet.
Ceiling Board Typeselect
Sag-resistant ceiling board
Regular gypsum board
Type X gypsum board
Type C gypsum board
Glass-mat faced gypsum board
NOTE Sag-resistant ceiling board delivers a flat 1/2 in. ceiling on 24 in. framing at the lowest weight, Type X is required by every rated horizontal membrane and is the choice where the ceiling board is also the wall board, regular board serves ceilings on 16 in. framing that receive no texture, Type C appears only where a design number calls for it, and glass-mat faced board is the product for exterior soffits and for ceilings in humid rooms. (7.4.3)
7.4.4 The thickness of the board on ceilings, where a design number does not fix it, shall be as indicated in the datasheet.
Ceiling Board Thicknessrange
in.
0.3750.50.625
NOTE Regular 1/2 in. board applied perpendicular to framing spans 24 in. on a ceiling only where no water-based texture will follow, and 16 in. where one will; 5/8 in. board and sag-resistant 1/2 in. board span 24 in. under either finish. (7.4.5)
7.4.6 Regular 1/2 in. board shall not be applied to ceiling framing spaced wider than 16 in. on center where a water-based texture or a spray-applied finish will follow.

7.5 Edge Profile

7.5.1 The edge profile of the board shall be as indicated in the datasheet.
Board Edge Profileradio
● Tapered edge
○ Square edge
○ Tapered edge with rounded corner
NOTE A tapered edge recesses the tape and compound below the face so that a flat joint can be finished flush, which is why it is the norm for every surface that will be finished; a square edge is furnished where the board is a base layer, a tile backer, or a sheathing that will never see compound, and the rounded-corner taper is a variant that reduces edge crushing during handling at the same finishing behavior. (7.5.2)
NOTE Butt ends of the board are always square, and the joint between two butt ends is finished with a wider feather than a tapered joint or is back-blocked to form a recess. (7.5.3)

7.6 Board at Intermittently Damp Locations

7.6.1 The board at toilet rooms, locker rooms, janitor closets, kitchens, and other rooms with intermittent moisture and elevated humidity, where the surface will not be tiled, shall be as indicated in the datasheet.
Board at Intermittently Damp Locationsselect
Mold- and moisture-resistant paper-faced gypsum board
Glass-mat faced gypsum board
Regular or Type X gypsum board without moisture treatment
NOTE Mold- and moisture-resistant paper-faced board carries a treated core and a treated face that score 10 under ASTM D3273, at a small premium over regular board and with the same finishing behavior; glass-mat faced board replaces the paper with an inorganic mat that gives mold nothing to feed on and tolerates repeated wetting, at a higher premium and with a face that takes compound differently; untreated board is the choice where the room is conditioned, the moisture is occasional, and the finish is a washable paint. (7.6.2)
7.6.3 The rooms and surfaces that receive the board selected in this field shall be as indicated on the room finish schedule.
7.6.4 Board furnished as mold resistant shall score 10 when tested under ASTM D3273.
7.6.5 No gypsum board of any facing shall be installed where the surface will be continuously wet or in continuous high humidity, including steam rooms, saunas, gang showers, and indoor pool enclosures, and the substrate at those locations shall be as indicated on the room finish schedule.

7.7 Abuse- and Impact-Resistant Board

7.7.1 Requirements in this article apply where abuse-resistant or impact-resistant board is designated on the partition schedule.
NOTE ASTM C1629 classifies a panel in four categories, surface abrasion, indentation, soft-body impact, and hard-body impact, each at Level 1, 2, or 3 with 3 the most resistant; the products sold as abuse resistant carry a dense, fiber-reinforced core and a heavier face and reach the upper levels in abrasion and indentation, and the products sold as impact resistant add an embedded mesh that reaches Level 3 in hard-body impact. (7.7.2)
7.7.3 The enhanced-durability board furnished at designated locations shall be as indicated in the datasheet.
Enhanced-Durability Board at Designated Locationsselect
Abuse-resistant gypsum board
Impact-resistant gypsum board
Impact-resistant gypsum board with embedded reinforcing mesh
Fiber-reinforced gypsum panel conforming to ASTM C1278
NOTE Abuse-resistant board resists the scuffs, gouges, and dents of carts and furniture in a corridor at a modest premium and is finished like standard board; impact-resistant board resists the through-penetration of a hard object, which is what a gymnasium, a psychiatric unit, or a detention corridor needs, at a higher premium and with a face that is harder to cut and fasten; the mesh-reinforced product holds together after the core is broken, and a fiber-reinforced gypsum panel is a homogeneous product without a face paper that resists all four categories and is the heaviest of the group. (7.7.4)
7.7.5 The minimum hard-body impact classification of the board furnished shall be as indicated in the datasheet.
Minimum Hard-Body Impact Classification per ASTM C1629range
level
123
7.7.6 The locations that receive enhanced-durability board, and the height to which it extends, shall be as indicated on the partition schedule and the interior elevations.
NOTE The resistance of a wall to impact is a property of the assembly, and board classified under ASTM C1629 delivers its rating only on framing at the spacing and thickness the manufacturer's classification test used. (7.7.7)
7.7.8 Enhanced-durability board shall be applied to framing at not wider than the spacing, and not thinner than the thickness, that the manufacturer's ASTM C1629 classification was tested on.

7.8 Wet-Area Tile Backer Board

7.8.1 Requirements in this article apply where wet-area tile backer is selected in the datasheet field for the assemblies in scope.
7.8.2 The backer board behind tile at tubs, showers, and other wet walls on framed construction shall be as indicated in the datasheet.
Wet-Area Tile Backer Boardselect
Glass-mat water-resistant gypsum backing board conforming to ASTM C1178
Fiber-mat reinforced cementitious backer unit conforming to ASTM C1325
Fiber-cement backer sheet conforming to ASTM C1288
Fiber-reinforced gypsum backer conforming to ASTM C1278
NOTE A glass-mat gypsum backer is cut and fastened like gypsum board, weighs the least, and is the choice where the crew hanging the walls also hangs the backer; a cementitious backer unit is unaffected by water even at a failed membrane and is the choice where the tile is heavy or the wall will be wet daily, at twice the weight and with a cutting and fastening method of its own; a fiber-cement sheet sits between the two in weight and cost, and a fiber-reinforced gypsum backer has no facing to delaminate but is the least common of the four. (7.8.3)
7.8.4 The wet walls that receive backer board, and the height to which it extends, shall be as indicated on the room finish schedule and the interior elevations.
7.8.5 Paper-faced gypsum board, including moisture-resistant paper-faced board, shall not be installed as the substrate for tile at tubs, showers, or other surfaces that will be wetted in service.
7.8.6 Backer board shall be installed with the fastener type and spacing, the joint tape, and the joint treatment the backer manufacturer publishes for tile, and the joint compound used at painted board shall not be used at backer joints that will be tiled.
7.8.7 Backer board on ceilings shall be applied to framing at not wider than the spacing the backer manufacturer publishes for ceiling application.
NOTE The waterproofing membrane, the setting mortar, and the tile over the backer are furnished under Ceramic TileCeramic TileResolves to the current adopted revision.sync/ceramic-tile. (7.8.8)

7.9 Gypsum Base and Veneer Plaster

7.9.1 Requirements in this article apply where gypsum base and veneer plaster are selected in the datasheet field for the assemblies in scope.
NOTE Veneer plaster is a thin, hard, hand-applied gypsum finish over a gypsum base panel with a face paper made to bond it, and it gives a monolithic surface that is harder and more abrasion resistant than finished gypsum board at about the same installed cost as a Level 5 finish; the base panel is hung and fastened like gypsum board, so the assembly is specified here rather than with lath and plaster. (7.9.2)
7.9.3 The veneer plaster system shall be as indicated in the datasheet.
Veneer Plaster Systemradio
○ One-coat veneer plaster
○ Two-coat veneer plaster with a basecoat and a finish coat
○ Gypsum base finished as gypsum board without veneer plaster
NOTE A one-coat system is a single finish coat of about 1/16 in. troweled over the base and reaches a smooth or textured finish in one pass, at the lowest cost and with the least tolerance for an uneven base; a two-coat system adds a basecoat that fills the joints and levels the surface, which doubles the labor and produces a harder, flatter wall; finishing the base as gypsum board is the fallback where the base was furnished and the veneer plaster is later dropped from the scope. (7.9.4)
7.9.5 Gypsum base for veneer plaster shall conform to ASTM C1396.
7.9.6 Veneer plaster shall conform to ASTM C587 and shall be applied under ASTM C843.
7.9.7 Joints in gypsum base shall be reinforced with the glass fiber mesh tape and the joint treatment ASTM C843 requires, and paper tape and drying-type joint compound shall not be used under veneer plaster.
NOTE The face paper of gypsum base loses its bond to veneer plaster after prolonged exposure to sunlight, and base that has faded before plastering has to be treated with a bonding agent or replaced. (7.9.8)
7.9.9 Gypsum base whose face paper has faded from light exposure shall be treated with the bonding agent the plaster manufacturer specifies before veneer plaster is applied.

8 Gypsum Sheathing

8.1 Sheathing Product

8.1.1 Requirements in this article apply where gypsum sheathing is selected in the datasheet field for the assemblies in scope.
NOTE Gypsum sheathing is the noncombustible substrate on a framed exterior wall that carries the water-resistive barrier and, where the wall is rated, contributes to the listed assembly; the wall's cavity insulation, the air and water barrier over the sheathing, and the cladding attachment through it are each governed by their own standards. (8.1.2)
8.1.3 The gypsum sheathing product shall be as indicated in the datasheet.
Gypsum Sheathing Productradio
● Glass-mat gypsum sheathing conforming to ASTM C1177
○ Paper-faced gypsum sheathing conforming to ASTM C1396
NOTE Glass-mat sheathing is the norm because its inorganic facing tolerates months of weather exposure before the cladding goes on and does not feed mold, while paper-faced sheathing, even with a water-resistant core, loses its face in weeks of exposure and remains a product for walls that are clad within days of sheathing. (8.1.4)
8.1.5 The thickness of the gypsum sheathing shall be as indicated in the datasheet.
Gypsum Sheathing Thicknessrange
in.
0.50.625
Per drawings — the exterior wall types (deferred by default)
NOTE Sheathing thickness follows the wall type, because a rated exterior wall calls for 5/8 in. Type X sheathing as part of its listing and an unrated wall commonly carries 1/2 in., and the exterior wall types carry that answer per wall. (8.1.6)

8.2 Sheathing Application and Exposure

8.2.1 Gypsum sheathing shall be applied under GA-253 and the sheathing manufacturer's published instructions.
8.2.2 Sheathing shall be fastened with corrosion-resistant screws of the type and at the spacing the manufacturer publishes for the framing material and thickness, and where the sheathing is part of a listed assembly, at the spacing the design number states.
8.2.3 Sheathing shall not remain exposed to weather beyond the period the manufacturer publishes for the product before the water-resistive barrier is applied over it.
8.2.4 Sheathing that has been exposed beyond the published period, or that shows a softened core, delaminated facing, or mold growth, shall be removed and replaced before the barrier is applied.
NOTE The water-resistive barrier and the air barrier over the sheathing are furnished under Air BarriersAir BarriersResolves to the current adopted revision.sync/air-barriers, and the flashing at openings through the sheathing under the standard that governs the cladding. (8.2.5)
8.2.6 Where gypsum sheathing is the substrate for an exterior insulation and finish system, its thickness, fastening, and joint treatment shall additionally satisfy Exterior Insulation And Finish SystemsExterior Insulation and Finish Systems (EIFS)Resolves to the current adopted revision.sync/exterior-insulation-and-finish-systems.

9 Nonstructural Steel Framing

9.1 Framing Standards and Loads

9.1.1 Nonstructural steel studs, runners, furring channels, and resilient channels shall conform to ASTM C645 and shall be installed under ASTM C754.
NOTE Nonstructural framing carries the weight of the board and its finishes and resists the lateral load the adopted building code assigns to interior partitions, which IBC Section 1607 sets at 5 psf, and it is selected from the manufacturer's limiting height tables rather than designed member by member. (9.1.2)
9.1.3 Framing that carries gravity load from the structure, resists wind pressure on an exterior wall, or forms part of a shear wall is structural and is furnished under Cold Formed Metal FramingCold-Formed Metal FramingResolves to the current adopted revision.sync/cold-formed-metal-framing regardless of what it supports.
9.1.4 Nonstructural framing shall not be used to support mechanical equipment, plumbing fixtures, casework, or any other item whose weight is not accounted for in the limiting height table used, unless the framing is reinforced under a detail the Architect of Record accepts.
9.1.5 Each stud, runner, and channel shall carry the manufacturer's legible identification of the member designation, the base steel thickness, and the yield strength.

9.2 Stud Thickness Basis

NOTE ASTM C645 sets a minimum base steel thickness of 18 mil for a nonstructural stud. Equivalent-performance studs, sold as EQ studs, are formed from thinner, higher-strength steel with a stiffened profile and are qualified by test under AISI S220 and ICC-ES AC86 to the limiting height of the member they replace; they dominate the market, and a specification that names 18 mil without saying whether EQ studs are accepted is the source of a standing dispute on delivery. (9.2.1)
9.2.2 The basis on which nonstructural studs are accepted shall be as indicated in the datasheet.
Nonstructural Stud Thickness Basisradio
○ Minimum base steel thickness per ASTM C645 without equivalent-performance substitution
○ Equivalent-performance studs qualified under AISI S220 and ICC-ES AC86 accepted at their published limiting heights
9.2.3 Where equivalent-performance studs are accepted, each such member shall be covered by a current evaluation report, and its limiting height at the deflection limit selected shall be taken from that report and not from the tables for the member it replaces.
9.2.4 Where equivalent-performance studs are accepted, screws into them shall be of the type the evaluation report and the fastener manufacturer publish for the reduced thickness.
9.2.5 Equivalent-performance studs shall not be used in a listed assembly unless the design number or the evaluation report covers their use in it.

9.3 Stud Web Depth

9.3.1 The web depth of nonstructural studs shall be as indicated in the datasheet.
Nonstructural Stud Web Depthrange
in.
1.6252.53.625468
Per drawings — the partition schedule (deferred by default)
NOTE Stud depth is set per partition type by the height, the plumbing and conduit the cavity has to pass, the cavity the sound rating needs, and the door frame throat, and a project with chase walls and corridor walls has several answers, which is why the partition schedule carries it. (9.3.2)
9.3.3 Where the datasheet records a depth for the work and the partition schedule states a different depth for a partition type, the partition schedule governs for that type.

9.4 Stud Base Steel Thickness

9.4.1 The base steel thickness of the studs in each partition type shall be as indicated in the datasheet.
Nonstructural Stud Base Steel Thicknessrange
mil
151830334354
Derived — the partition height, the stud web depth and spacing, the 5 psf interior partition load, and the deflection limit selected (by default)
NOTE Stud thickness follows from the limiting height tables once the height, the depth, the spacing, the load, and the deflection limit are known, and the same inputs give the same member on every project, which is why the field is derived rather than chosen; the 15 mil setpoint is the equivalent-performance product and is selectable only where the thickness basis accepts it. (9.4.2)
9.4.3 The Contractor shall select the stud thickness for each partition type from the manufacturer's limiting height table, or from the evaluation report for an equivalent-performance stud, for the tallest partition of that type, at the spacing installed and at the deflection limit selected in this standard.
9.4.4 Where a listed assembly or a door frame anchorage detail requires a thicker stud than the limiting height table, the thicker stud governs.

9.5 Stud Spacing

9.5.1 The spacing of nonstructural studs shall be as indicated in the datasheet.
Nonstructural Stud Spacingrange
in. o.c.
8121624
NOTE Spacing at 16 in. is the norm because it is what most listings, most limiting height tables, and most tile and abuse-resistant board classifications were tested at; 24 in. spacing saves a third of the studs on a plain partition and is admissible wherever the board thickness, the height, and the listing allow it, and 12 in. or 8 in. spacing is the answer at tall partitions, heavy finishes, and shear-loaded gypsum walls. (9.5.2)
9.5.3 Where a listed assembly, a board classification, or a tile backer manufacturer requires a closer spacing than the datasheet value, the closer spacing governs for that assembly.
9.5.4 Studs shall be spaced from a common end of each wall so that board edges land on studs.

9.6 Partition Deflection Limit

9.6.1 The deflection limit under the interior partition load at which limiting heights are read shall be as indicated in the datasheet.
Partition Deflection Limitradio
○ L/120
● L/240
○ L/360
NOTE The adopted building code permits L/120 for a partition with flexible finishes and requires L/240 for one with brittle finishes, and L/240 is the norm for gypsum board because taped joints and paint crack at deflections a flexible finish tolerates; L/360 is selected where the wall carries tile, stone, or a veneer plaster, and it costs a thicker or deeper stud at every height. (9.6.2)
9.6.3 Partitions that carry tile, stone, or veneer plaster shall be framed to a deflection limit of not less than L/360 regardless of the datasheet selection.

9.7 Metallic Coating on Framing

9.7.1 The minimum metallic coating on nonstructural framing members shall be as indicated in the datasheet.
Minimum Metallic Coating on Nonstructural Framingselect
G40 zinc coating conforming to ASTM A653
G60 zinc coating conforming to ASTM A653
G90 zinc coating conforming to ASTM A653
Coating with corrosion resistance equivalent to G40 as ASTM C645 permits
NOTE G40 is the ASTM C645 minimum and the norm for framing that will spend its life in a dry, conditioned cavity; G60 and G90 buy longer life in a cavity that can wet, at a furred exterior wall or a wet room, and the equivalent-coating option admits the proprietary coatings that ASTM C645 accepts at G40 performance and that equivalent-performance studs commonly carry. (9.7.2)
9.7.3 Framing in a furred exterior wall, in a natatorium, or in a room with a floor drain shall carry not less than a G60 coating regardless of the datasheet selection.

9.8 Runners and Anchorage

9.8.1 Runners shall be of the same depth as the studs they receive and of not less than the stud thickness.
9.8.2 Floor runners shall be anchored to the slab at not more than 24 in. on center and within 2 in. of each end of every runner section and each side of every opening.
9.8.3 Runners at concrete shall be anchored with powder-actuated fasteners, pneumatically driven pins, or post-installed anchors whose capacity in the slab is established by a current evaluation report, and driven fasteners shall not be installed where they would strike post-tensioning tendons or embedded conduit.
9.8.4 Studs shall be set into the runners with their flanges in the same direction and shall be fastened to the runner at both flanges where the stud is at a jamb, a corner, an intersection, or the end of a wall.
NOTE Studs in the field of a wall are commonly left unfastened at the runner so that the board fastening squares them, which is admissible under ASTM C754 and is the practice that lets a deflection head work; studs at jambs and corners are fastened because they carry a door or a return that the board alone will not hold square. (9.8.5)

9.9 Head of Partition and Deflection

9.9.1 The head condition of each partition type, whether it stops at the ceiling, extends above the ceiling and is braced, or extends to the underside of the structure, shall be as indicated on the partition schedule.
9.9.2 A partition that extends to the underside of the structure above shall be framed with a deflection head that lets the structure deflect without loading the studs or the board.
9.9.3 The deflection head type at partitions extending to the structure shall be as indicated in the datasheet.
Deflection Head Typeselect
Deep-leg deflection runner with the studs unattached to the runner legs
Slotted deflection runner fastened to each stud through the slots
Nested double runner
Proprietary slide clip at each stud
Fixed runner with a compressible joint and the board held clear of the structure
NOTE A deep-leg runner is the least expensive head and the one most listings show, and it relies on the stud being cut short and left unattached, which a crew defeats by screwing the runner to the stud; a slotted runner keeps the stud positively attached while letting it slide, at a higher cost per foot; a nested double runner and a slide clip each provide larger movement and a firmer lateral hold at a partition that is tall or heavily loaded; and a fixed runner with a compressible joint is the head at a partition where the structure above is stiff enough that the calculated deflection is within what the joint absorbs. (9.9.4)
9.9.5 The vertical movement capacity provided at the head of each full-height partition shall be as indicated in the datasheet.
Vertical Movement Capacity at the Head of Partitionrange
in.
0.50.7511.52
Derived — the calculated deflection of the structure above each partition stated on the structural general notes (by default)
NOTE The movement a head has to absorb is the calculated live-load deflection of the structure above, and the structural general notes state it, so the capacity follows from that number rather than from a choice made here; a capacity of zero is the fixed head at a partition that stops below a stiff slab or at the ceiling. (9.9.6)
9.9.7 Studs at a deflection head shall be cut short of the inside of the runner by not less than the movement capacity provided.
9.9.8 Board shall be held clear of the structure above at a deflection head by the same distance and shall not be fastened to the deflection runner.
9.9.9 The gap at the head of a rated partition shall be closed with the listed joint system that FirestoppingFirestoppingResolves to the current adopted revision.sync/firestopping furnishes for the movement capacity provided, and this standard shall not fill it with board, compound, or unlisted sealant.
NOTE The head of a rated partition is the most frequently cited deficiency in rated construction, and the defect is almost always a trade filling the movement gap with something the listing does not permit, or a stud cut long enough to bear on the runner and turn the partition into a column. (9.9.10)

9.10 Partition Bracing Above Ceilings

9.10.1 Partitions that stop above a suspended ceiling and do not reach the structure shall be braced laterally to the structure at not more than 48 in. on center along the partition and at each end.
9.10.2 Partitions taller than 6 ft, and partitions that a suspended ceiling is attached to, shall be laterally braced to the structure where ASCE 7 Chapter 13 requires it for Seismic Design CategorySeismic Design CategoryParameterEach project supplies its own value.seismic-design-category.
9.10.3 Bracing shall be steel studs or runners, or diagonal steel strap with a stiffener, fastened to the top runner and to the structure, and shall not be fastened to a ceiling suspension system, a duct, or a pipe.
NOTE A partition that leans on the ceiling grid for its lateral support loads the grid with a force it was not designed for, and the grid transmits the partition's movement into every tile and fixture along it. (9.10.4)

9.11 Openings and Jamb Framing

9.11.1 Each side of a door opening, a borrowed light, a rated glazing frame, and an access panel shall be framed with a jamb stud of not less than the field stud thickness, fastened to the floor and head runners at both flanges.
9.11.2 Door frames in nonstructural partitions shall be anchored to jamb studs of the thickness and configuration the frame anchorage under Doors Frames And HardwareDoors, Frames, and HardwareResolves to the current adopted revision.sync/doors-frames-and-hardware requires, and jamb studs shall be doubled, boxed, or increased in thickness where that anchorage requires it.
9.11.3 A header shall be framed above each opening from a runner section cut and bent over the jamb studs, or from a stud, and cripple studs shall continue the field spacing above the header and below any sill.
9.11.4 Openings in rated partitions shall be framed as the design number and the opening protective listing state, and the board around a rated frame shall be fastened at the spacing the listing states.
9.11.5 Openings for access panels in walls and ceilings shall be framed to the panel manufacturer's rough opening, and the panel shall be installed and finished so that its frame is flush with the board and, where the panel is in a rated assembly, so that the listed panel and its framing maintain the rating.
9.11.6 Board joints shall not fall at the corner of an opening, and the board shall be cut so that a joint occurs not less than 8 in. from a jamb.
NOTE A joint at the corner of an opening cracks under the racking a door swing produces, which is why the board is cut around the opening in an L rather than pieced to it. (9.11.7)

9.12 Furring at Concrete and Masonry

9.12.1 Requirements in this article apply where furred walls are selected in the datasheet field for the assemblies in scope.
9.12.2 The furring that carries board on concrete and masonry walls shall be as indicated in the datasheet.
Furring at Concrete and Masonry Wallsselect
Hat-shaped furring channel fastened to the wall
Z-shaped furring channel with rigid insulation between the channels
Nonstructural studs set clear of the wall as a freestanding furred wall
Resilient channel fastened to the wall
NOTE Hat channel is the least expensive furring and holds the board about 7/8 in. off the wall, which is enough to flatten a masonry wall but leaves no room for insulation or services; Z-furring is the product for a wall that receives rigid insulation between the channels and holds the board off by the insulation thickness; a freestanding stud wall clears the masonry entirely, gives a full cavity for insulation and conduit, and breaks the thermal and acoustic bridge that a channel screwed to the wall carries, at the cost of a stud wall's floor area; and resilient channel on masonry is the furring at a sound-rated wall where the mass of the masonry is to be decoupled from the board. (9.12.3)
9.12.4 Furring channels shall be fastened to concrete and masonry at not more than 24 in. on center with fasteners whose capacity in the substrate is established by a current evaluation report.
9.12.5 Furring channels shall be installed at not more than 24 in. on center for 1/2 in. and 5/8 in. board applied perpendicular to them, and at 16 in. on center for board applied parallel.
9.12.6 Where the furred wall is on the interior face of an exterior wall, the insulation and vapor retarder between the furring are furnished under Building Thermal InsulationBuilding Thermal InsulationResolves to the current adopted revision.sync/building-thermal-insulation, and the furring shall be installed so that the insulation is continuous behind it.
9.12.7 Furring on a below-grade or exterior masonry wall shall be isolated from the masonry by the method the wall's moisture control design requires so that moisture in the wall does not reach the board.

9.13 Resilient Channels and Decoupling

NOTE The decoupling method at each sound-rated assembly, whether resilient channel, sound isolation clips with hat channel, a double stud wall, or a staggered stud wall, is fixed by the tested assembly cited for it on the partition schedule, and a method the tested assembly did not use is a different assembly. (9.13.1)
9.13.2 Resilient channels shall be single-leg channels conforming to ASTM C645, installed with the attachment flange down and the open side up unless the tested assembly shows otherwise, at not more than 24 in. on center and within 6 in. of the floor and the ceiling.
9.13.3 Board on resilient channel shall be fastened with screws of a length that engages the channel and does not reach the framing behind it.
9.13.4 Board on resilient channel shall not be fastened at any point where a stud is behind the channel.
NOTE Resilient channel works by letting the board float on the flexible leg of the channel, and a single screw that passes through the channel into the stud, or a channel screwed at a stud where it crosses one, ties the board back to the framing and drops the assembly by ten or more points; it is the most common cause of a sound-rated partition failing its field test. (9.13.5)
9.13.6 Where sound isolation clips are used, the clips and the hat channel they carry shall be the products the tested assembly names, at the spacing it states.
9.13.7 Base trim, casework, and fixtures at a resiliently mounted face shall not be fastened through the board into the framing behind the channel.

9.14 Blocking and Backing

NOTE Wall-mounted items are attached to what is behind the board, not to the board, and the wall closes weeks before most of them arrive; the backing has to be located from the mounting heights and anchor patterns of the items themselves, so this article is executed against the blocking and backing schedule rather than against the framing plan. (9.14.1)
9.14.2 The Contractor shall install blocking or backing behind the board at every location where a wall-mounted item is shown on the interior elevations and the equipment and accessory schedules.
9.14.3 Blocking and backing shall be located from the reviewed shop drawings and mounting heights of the supported work and shall extend not less than 6 in. beyond the anchor pattern of the item in each direction.
9.14.4 The material of the in-wall backing shall be as indicated in the datasheet.
In-Wall Backing Materialselect
Flat steel backing plate screwed across the stud flanges
Proprietary steel backing bracket or channel clipped to the studs
Fire-retardant-treated wood blocking let into the studs
Untreated wood blocking let into the studs
Plywood backing screwed to the stud faces
NOTE A flat steel plate is the norm in steel-framed partitions because it is cut and screwed by the framing crew and does not depend on a wood product in a noncombustible building; a proprietary bracket sets faster where the backing is standardized across many rooms; fire-retardant-treated wood is admissible in a noncombustible building where the adopted code permits it in a nonbearing partition and gives a fastener the withdrawal grip that a thin plate does not; untreated wood is the choice in a combustible building; and plywood backing gives a continuous field of anchorage behind a wall that carries a run of casework or a display system. (9.14.5)
9.14.6 Where Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code limits combustible material in the partitions of the building's type of construction, wood blocking shall be fire-retardant-treated and shall be furnished under Rough CarpentryRough CarpentryResolves to the current adopted revision.sync/rough-carpentry.
9.14.7 Steel backing plates shall be of the thickness the anchorage of the supported item requires and shall be fastened to each stud flange they cross with not fewer than two screws.
9.14.8 Grab bars, handrails, and other items whose anchorage carries a code-required load shall be backed with material and fastening that develop that load, and a backing plate thinner than the anchorage of the item requires shall not be used for them.
9.14.9 Blocking and backing shall be installed and inspected before the board is applied, and a wall closed before its scheduled backing is in shall be reopened at the Contractor's expense.
9.14.10 The Contractor shall mark the location of each concealed backing on the floor or the ceiling, or record it on the as-built framing drawings, so that the installing trade can find it after the wall is finished.
NOTE The trades whose work depends on this backing include the wall stops and holders under Door HardwareDoor HardwareResolves to the current adopted revision.sync/door-hardware, the grab bars and accessories under Toilet AccessoriesToilet and Bath AccessoriesResolves to the current adopted revision.sync/toilet-accessories, the compartments under Toilet CompartmentsToilet CompartmentsResolves to the current adopted revision.sync/toilet-compartments, the crash rails and corner guards under Wall And Corner ProtectionWall and Corner ProtectionResolves to the current adopted revision.sync/wall-and-corner-protection, the dimensional signs under SignageSignageResolves to the current adopted revision.sync/signage, the shade brackets under Window TreatmentsWindow TreatmentsResolves to the current adopted revision.sync/window-treatments, the markerboards under Visual Display UnitsVisual Display UnitsResolves to the current adopted revision.sync/visual-display-units, the lockers under Metal LockersMetal LockersResolves to the current adopted revision.sync/metal-lockers, and the casework, trim, and paneling under Wood And Laminate CaseworkWood and Laminate CaseworkResolves to the current adopted revision.sync/wood-and-laminate-casework, Architectural Wood Trim And PanelingArchitectural Wood Trim and PanelingResolves to the current adopted revision.sync/architectural-wood-trim-and-paneling, and Interior Architectural WoodworkInterior Architectural WoodworkResolves to the current adopted revision.sync/interior-architectural-woodwork. (9.14.11)
9.14.12 Recessed accessories, fire extinguisher cabinets, and recessed units shall be framed with a rough opening to the unit's published dimensions, with a jamb stud on each side and a header and sill between them.

10 Ceiling Framing

10.1 Ceiling Framing System

10.1.1 Requirements in this article apply where suspended or direct-attached gypsum board ceilings are selected in the datasheet field for the assemblies in scope.
10.1.2 The framing that carries gypsum board ceilings shall be as indicated in the datasheet.
Gypsum Board Ceiling Framing Systemselect
Cold-rolled carrying channels and hat furring channels suspended on hanger wire under ASTM C754
Proprietary drywall suspension grid conforming to ASTM C635 and installed under ASTM C636
Hat furring channels attached directly to the structure or to joists
Nonstructural steel studs or joists spanning between walls or beams
NOTE The channel-and-wire system is the traditional suspension, is what most rated horizontal membranes were tested on, and is built from stock members by any framing crew; a drywall grid installs faster, holds a flatter plane, and carries its own listings for rated membranes and seismic bracing, at a higher material cost; direct-attached furring is the ceiling on a wood or steel joist floor above or on a concrete deck where no plenum is needed; and studs or joists spanning wall to wall carry a soffit or a small ceiling where hangers cannot be placed. (10.1.3)
10.1.4 The ceiling framing system at a rated horizontal membrane shall be the system the design number was tested with.
10.1.5 Where the framing spans wall to wall, the members shall be selected from the manufacturer's span tables for the ceiling load at a deflection limit of L/240.

10.2 Suspension Members and Spacing

10.2.1 Hangers, carrying channels, furring channels, and their spacing and attachment shall comply with ASTM C754 for the board thickness and orientation installed.
10.2.2 Hangers shall be attached to the structure with an anchorage established for the hanger load, and hangers shall not be attached to ducts, pipes, conduit, or the deck flutes of a steel deck.
10.2.3 Hangers shall be plumb and shall be placed within 6 in. of the end of each carrying channel and at each side of every opening in the ceiling that interrupts a channel.
10.2.4 Where a hanger cannot be placed at the spacing required because of an obstruction, a trapeze or a supplemental carrying member shall be installed to carry the interrupted hanger load, and the hanger spacing shall not be opened up.
10.2.5 Furring channels shall be attached to carrying channels with the clips or saddle ties ASTM C754 permits and shall be lapped at splices by not less than 8 in. with the lap tied at both ends.
10.2.6 Recessed luminaires, air devices, and access panels shall be framed with supplemental furring on all sides of the opening and shall be supported independently of the board.

10.3 Ceiling Bracing and Perimeter

10.3.1 Suspended gypsum board ceilings shall be laterally braced to the structure where ASCE 7 Chapter 13 requires it for Seismic Design CategorySeismic Design CategoryParameterEach project supplies its own value.seismic-design-category.
NOTE A screw-attached gypsum board ceiling on a single level that extends from wall to wall is exempt from the seismic bracing provisions of ASCE 7 for suspended ceilings, and a gypsum board ceiling with a step, a free edge, or a large opening is not; the exemption is what makes most gypsum ceilings simpler to build than an acoustical grid in the same room. (10.3.2)
10.3.3 Where the ceiling has a free edge, a change in level, or an opening larger than the furring spacing, the framing at that edge shall be braced to the structure.
10.3.4 The perimeter of a suspended ceiling shall be supported at the wall by a wall angle or a runner where the ceiling is fixed at the perimeter, or shall be held clear of the wall where perimeter relief is selected in this standard.

10.4 Soffits and Bulkheads

10.4.1 Soffits, bulkheads, and the vertical faces that bound an acoustical ceiling field shall be framed with nonstructural studs and runners braced to the structure at not more than 48 in. on center, or with a proprietary soffit framing system installed under its evaluation report.
10.4.2 The dimensions, profiles, and locations of soffits and bulkheads shall be as indicated on the reflected ceiling plans and the ceiling details.
10.4.3 The bottom of a bulkhead that receives the edge of an acoustical ceiling shall be framed to carry the wall angle of that ceiling at the height its suspension requires, coordinated under Suspended Acoustical CeilingsSuspended Acoustical CeilingsResolves to the current adopted revision.sync/suspended-acoustical-ceilings.
10.4.4 A bulkhead at a rated corridor or a rated horizontal membrane shall be built to the design number cited for the membrane, and the joint between the bulkhead and the membrane shall be closed as that design number requires.

10.5 Rated Horizontal Membranes

10.5.1 Requirements in this article apply where fire-resistance-rated horizontal membranes are selected in the datasheet field for the assemblies in scope.
NOTE A rated gypsum board ceiling is the membrane of a floor-ceiling or roof-ceiling assembly, or the horizontal enclosure of a corridor or a shaft, and it earns its rating only as part of the assembly the design number describes, including the structure above it, the cavity fill, and the openings through it. (10.5.2)
10.5.3 The board type, thickness, layers, furring spacing, fastener pattern, and joint treatment of a rated horizontal membrane shall be as the cited design number states.
10.5.4 Openings in a rated membrane for luminaires, air devices, and access panels shall be limited to the size and aggregate area the design number permits and shall be protected as it requires.
10.5.5 Where the design number requires a specific clip, channel, or grid for the membrane, that product shall be furnished and shall not be substituted.
10.5.6 A rated horizontal membrane shall not be penetrated by hangers, wires, or supports for work below it except as the design number permits.

11 Fire-Resistance-Rated Construction

11.1 Execution to the Design Number

11.1.1 Requirements in this article apply where fire-resistance-rated partitions and horizontal membranes are selected in the datasheet field for the assemblies in scope.
11.1.2 The base layer in a multi-layer rated assembly shall be fully fastened at the pattern the design number states before the face layer is applied, and the face layer shall be fastened or laminated as the design number states.
11.1.3 Joints in the face layer shall be offset from joints in the base layer by not less than one framing space, and joints on opposite faces of a rated partition shall be staggered so that no joint on one face is opposite a joint on the other.
11.1.4 Joints and fastener heads in a rated assembly shall be treated with tape and compound as the design number and Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code require, and a joint that will be concealed shall receive not less than the Level 1 treatment of this standard.
11.1.5 Board in a rated assembly shall be installed with the edges and ends in moderate contact, and gaps at joints shall not exceed 1/8 in.
11.1.6 Where a rated partition is also sound-rated, the requirements of both tested assemblies shall be met, and where they conflict, the Contractor shall report the conflict to the Architect of Record before proceeding.
11.1.7 Rated partitions shall be labeled above the ceiling at not more than 30 ft along their length with the design number and the hourly rating, in lettering not less than 3 in. high, where Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code requires it.

11.2 Head-of-Wall and Base-of-Wall Joints

11.2.1 The joint between the top of a rated partition and the structure above, and the joint at its base where the floor is not level, shall be closed with the listed joint system that FirestoppingFirestoppingResolves to the current adopted revision.sync/firestopping furnishes for the rating and the movement of the partition.
11.2.2 Board shall be held clear of the deck flutes and the structure at the head of a rated partition by the distance the listed joint system requires, and the flutes above the runner shall not be filled with board or unlisted material by this trade.
NOTE The head-of-wall joint system is listed with the wall assembly, the deck profile, and a movement class, so a joint system that matches the wall but not the deck is not a listed condition; the board installer's job is to leave the gap the listing expects and nothing more. (11.2.3)

11.3 Control Joints in Rated Assemblies

11.3.1 Control joints in a fire-resistance-rated partition or membrane shall be installed under GA-234 with the backing the design number or GA-234 requires behind the joint.
11.3.2 The backing behind a rated control joint shall be continuous for the full height of the assembly and shall be attached to the framing on both sides of the joint.
NOTE A control joint cuts the face layer of a rated wall from top to bottom, and without backing behind the cut the wall has a slot through which fire passes; GA-234 is the tested detail that closes the slot without rigidly connecting the two sides. (11.3.3)

11.4 Area Separation Walls

11.4.1 Requirements in this article apply where area separation walls are selected in the datasheet field for the assemblies in scope.
NOTE An area separation wall is a fire wall between attached dwelling units or fire areas in light-frame construction, built as a freestanding two-hour assembly of two layers of 1 in. Type X shaftliner in steel H-studs, held to the framing on each side by aluminum breakaway clips; when one side burns, the clips soften and release, the burning structure falls away, and the wall stands on its own with the other side intact. (11.4.2)
11.4.3 Area separation walls shall be built to the design number cited for them on the partition schedule and under GA-620.
11.4.4 Shaftliner panels shall be 1 in. Type X shaftliner conforming to ASTM C1396, installed vertically in H-studs with the panel edges fully engaged in the stud webs and with horizontal joints staggered between the two layers as the design number states.
11.4.5 H-studs, top and bottom runners, and breakaway clips shall be the products the design number names, and the clips shall be installed at the spacing the design number states and shall be aluminum unless the design number names another material.
11.4.6 A clearance of not less than 3/4 in. shall be maintained between the shaftliner assembly and the framing on each side, and the clearance shall be kept free of blocking, board, and other material that would tie the framing to the wall.
11.4.7 The wall shall extend continuously from the foundation to the underside of the roof sheathing, with the parapet or the roof intersection built as the design number and the adopted building code require for a fire wall.
11.4.8 The mineral wool or other fill the design number requires in the clearance space at the roof and at floor lines shall be installed before the adjacent framing is closed.

11.5 Thermal Barrier Over Foam Plastic

11.5.1 Where gypsum board is the thermal barrier separating foam plastic insulation from the interior of the building, it shall be not less than 1/2 in. thick, shall be applied to the framing or furring over the foam plastic without gaps, and shall be fastened at the spacing Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code and the foam plastic manufacturer's evaluation report require.
NOTE The adopted building code requires foam plastic to be separated from the interior by a thermal barrier that delays its ignition, and 1/2 in. gypsum board is the prescriptive barrier the code names; the board over an insulated furred wall is doing that job whether or not anyone specified it, which is why the fastening and the continuity of that board are held to the code rather than to the finish. (11.5.2)

12 Sound-Rated Construction

12.1 Perimeter Acoustic Sealant

12.1.1 Requirements in this article apply where sound-rated partitions are selected in the datasheet field for the assemblies in scope.
12.1.2 The perimeter of each face of a sound-rated partition shall be sealed with acoustical sealant applied under ASTM C919 at the floor runner, at the head, at abutting walls and columns, and around every penetration and outlet.
12.1.3 Sealant shall be applied as a continuous bead under the floor and head runners before they are fastened, and as a continuous bead at the perimeter of each board layer before the next layer or the finish is applied.
12.1.4 Sealant shall be the non-hardening acoustical sealant furnished under Joint SealantsJoint SealantsResolves to the current adopted revision.sync/joint-sealants, and a sealant that hardens or shrinks shall not be used at a sound-rated perimeter.
NOTE A gap of 1/8 in. along the base of a 10 ft partition is an opening of about 15 sq in., and an opening that size in a partition rated in the mid-50s passes more sound than the whole wall does; the sealant bead is the single lowest-cost component of the assembly and the one most often skipped. (12.1.5)
12.1.6 The cavity fill shall be in place and inspected under Acoustic InsulationAcoustic InsulationResolves to the current adopted revision.sync/acoustic-insulation before the closing face of a sound-rated partition is sealed.

12.2 Electrical Boxes in Sound-Rated Partitions

12.2.1 Requirements in this article apply where sound-rated partitions are selected in the datasheet field for the assemblies in scope.
12.2.2 Electrical boxes on opposite faces of a sound-rated partition shall be offset horizontally by not less than the distance indicated in the datasheet and shall not be installed in the same stud cavity.
Minimum Horizontal Offset Between Boxes on Opposite Facesrange
in.
1216243248
NOTE An offset of 24 in. places the boxes in separate cavities at both 16 in. and 24 in. stud spacing and is the norm most sound-rated details show; a zero offset is the fixed head condition at a partition whose tested assembly carries putty-padded back-to-back boxes, and offsets larger than 24 in. buy a margin at partitions rated in the high 50s and above. (12.2.3)
12.2.4 The sealing of electrical boxes in sound-rated partitions shall be as indicated in the datasheet.
Sealing of Electrical Boxes in Sound-Rated Partitionsradio
○ Putty pads on every box in a sound-rated partition
○ Putty pads on boxes only where the tested assembly or the adopted code requires them
○ Boxes sealed to the board with acoustical sealant without putty pads
NOTE Putty pads on every box add a few dollars per box and close the box as a sound path regardless of who cut the opening, which is the norm at partitions rated 50 and above; pads only where the listing requires them is the economy at a partition whose rating leaves margin for a few open boxes; and sealant alone closes the joint between the box and the board but not the box itself, and is the least effective of the three. (12.2.5)
12.2.6 Putty pads shall be the listed pads that, in a rated partition, are also required under FirestoppingFirestoppingResolves to the current adopted revision.sync/firestopping for the membrane penetration, and one pad shall serve both functions.
12.2.7 Openings cut in the board for boxes shall fit the box with not more than 1/8 in. clearance on any side, and the clearance shall be filled with acoustical sealant.

12.3 Flanking Paths

NOTE A sound-rated partition that stops at a suspended ceiling delivers the rating of the plenum path over it or of the partition, whichever is lower, and the plenum treatment for those partitions is furnished under Acoustic InsulationAcoustic InsulationResolves to the current adopted revision.sync/acoustic-insulation. (12.3.1)
12.3.2 Ducts, pipes, and conduit that pass through a sound-rated partition shall be sleeved or wrapped and sealed at both faces with acoustical sealant so that the annular space is closed.
12.3.3 A sound-rated partition shall extend to the underside of the structure above, or shall be paired with a plenum barrier or a rated ceiling, as the partition schedule shows, and shall not be terminated at a ceiling that the schedule shows it extending past.
NOTE Door and frame perimeter seals at openings in sound-rated partitions are furnished under Doors Frames And HardwareDoors, Frames, and HardwareResolves to the current adopted revision.sync/doors-frames-and-hardware. (12.3.4)

13 Board Application and Fastening

13.1 Application

13.1.1 Gypsum board shall be applied under ASTM C840 and GA-216 and, at rated and sound-rated assemblies, as the cited design number states.
13.1.2 Framing shall be plumb, level, and at the specified spacing before board is applied, and a stud that is bowed, twisted, or out of plane by more than 1/8 in. in 10 ft shall be corrected before boarding.
13.1.3 Board on walls shall be applied with the long edges perpendicular to the framing where the height permits, and where the board is applied parallel, the edges shall land on framing.
13.1.4 Board on ceilings shall be applied before board on walls, with the long edges perpendicular to the furring or joists.
13.1.5 Board shall be cut by scoring and snapping, or by sawing where the cut will be exposed, and cut edges shall be smoothed so that they seat against the adjacent board.
13.1.6 Ends and edges of the board shall be in moderate contact without forcing, and a gap wider than 1/4 in. at a joint in a non-rated assembly shall be prefilled with setting-type compound before taping.
13.1.7 Butt joints between board ends shall be staggered from those in adjacent courses and, on ceilings, shall be back-blocked or placed at a furring member.
NOTE Perpendicular application puts the tapered edges at the horizontal joints, where they are finished flat with the least compound, and reduces the number of butt joints, which are the joints that show; the exception is a wall taller than the board is long, where a parallel application puts every edge on a stud and the butt joints at the head, out of sight. (13.1.8)

13.2 Fasteners to Steel Framing

13.2.1 Screws for attaching board to steel framing shall be self-drilling, self-tapping bugle-head screws conforming to ASTM C1002 where the framing is not thicker than 33 mil and to ASTM C954 where it is thicker.
13.2.2 Screw length shall provide not less than 3/8 in. of penetration through the framing member for the total board thickness applied, and in multi-layer applications shall be selected for the layer being fastened.
13.2.3 Screws shall be spaced as ASTM C840 requires for the board thickness, the framing spacing, and the location on a wall or a ceiling, or as the cited design number states, whichever is closer.
13.2.4 Screws shall be placed not closer than 3/8 in. to the edge or end of the board and shall be driven so that the head is seated slightly below the board face without breaking the face paper.
13.2.5 Screws shall be driven starting at the center of each board and working toward the edges so that the board is drawn against the framing without buckling.
NOTE A screw driven through the paper has lost most of its holding power and every one of them pops a few months after the paint goes on; a screw left proud telegraphs through the compound, and the depth-setting nosepiece on a screw gun is the only thing between the two. (13.2.6)

13.3 Fastening to Wood Framing

13.3.1 Requirements in this article apply where partitions on wood framing are selected in the datasheet field for the assemblies in scope.
13.3.2 The fastening of board to wood framing shall be as indicated in the datasheet.
Fastening of Board to Wood Framingradio
○ Type W screws conforming to ASTM C1002
○ Nails conforming to ASTM C514
○ Adhesive conforming to ASTM C557 with screws or nails at reduced spacing
NOTE Screws hold in wood that shrinks and are the norm in commercial work, and a listed assembly on wood framing commonly states screws; nails are faster, are the norm in residential framing, and pop where the framing dries in service unless they are ring-shank; adhesive with reduced fastening cuts the fastener count on a plain wall and bridges a slightly irregular stud, and it is not admissible in a rated assembly unless the design number includes it and not usable over a vapor retarder or a faced insulation. (13.3.3)
13.3.4 Fasteners into wood shall penetrate the framing by not less than 5/8 in. for screws and 3/4 in. for nails, at the spacing ASTM C840 requires for the fastener and the location.
13.3.5 Board shall not be applied to wood framing whose moisture content exceeds 19 percent, and where the framing is wetter, application shall wait until it dries.

13.4 Multi-Layer Application

13.4.1 In multi-layer applications for fire resistance, sound rating, or abuse resistance, the base layer shall be fully fastened before the face layer is applied.
13.4.2 Face-layer joints shall be offset from base-layer joints by not less than one framing space in both directions, and the face layer at a corner shall lap the base layer of the adjoining wall.
13.4.3 Where the face layer is laminated to the base layer with adhesive, the adhesive shall be the product the design number or the board manufacturer names, applied in the pattern published for it, with the supplemental fasteners the design number states.
13.4.4 Adhesive alone shall not attach the face layer in a fire-resistance-rated assembly unless the design number includes and describes the adhesive application.
13.4.5 Laminating screws conforming to ASTM C1002 Type G shall be used only where the face layer is fastened to the base layer rather than to the framing, and only where the design number permits it.

14 Accessories and Trim

14.1 Accessory Standards

14.1.1 Corner bead, casing bead, edge trim, reveal trim, and control joints shall conform to ASTM C1047.
14.1.2 Accessories shall be fastened, crimped, clinched, stapled, or embedded as ASTM C840 and the accessory manufacturer publish for the accessory and the substrate.
14.1.3 Accessories shall be installed straight, plumb, level, and in one piece for the length of the run where the run does not exceed the stock length, with joints at splices tight and aligned.
14.1.4 Accessories of dissimilar metals shall not be joined where moisture could create a galvanic couple.
14.1.5 Accessories in a room with elevated humidity or intermittent wetting shall be rigid PVC, zinc alloy, or hot-dip galvanized steel, and paper-faced or electrogalvanized steel accessories shall not be installed there.

14.2 Corner Bead

14.2.1 Corner bead shall be installed at every exposed exterior corner of gypsum board and at every exposed board edge that meets another plane at an angle.
14.2.2 The material of the corner bead shall be as indicated in the datasheet.
Corner Bead Materialselect
Galvanized steel bead
Paper-faced galvanized steel bead
Rigid PVC bead
Paper-faced rigid PVC bead
Zinc alloy bead
NOTE Galvanized steel bead resists impact best and is fastened through its flanges, and its nose cracks the compound where a wall is struck repeatedly; paper-faced steel is embedded in compound and bonds to the board, so a struck corner dents without cracking the finish, which is why it is the norm on painted commercial walls; PVC does not rust and does not dent, and it bends at a heat gun for a curved corner; paper-faced PVC combines those properties at the highest cost per foot; and zinc alloy is the material for a wet room or an exterior soffit where a steel bead would rust through the paint. (14.2.3)
14.2.4 The profile of exposed corners shall be as indicated in the datasheet.
Exposed Corner Profileradio
● Square corner
○ Bullnose corner
○ Chamfered corner
NOTE A square corner is the norm and takes any base, casing, and door frame without a transition piece; a bullnose is a rounded corner of 3/4 in. or larger radius that resists chipping and softens a corridor, and it requires a matching bullnose base, casing, and frame return at every trim it meets; a chamfered corner is a flat 45° face that shares the transition problem with bullnose and is furnished for a specific detail. (14.2.5)
14.2.6 The corners that receive a profile other than square shall be as indicated on the interior elevations.

14.3 Casing Bead and Edge Trim

14.3.1 Casing bead or edge trim shall be installed wherever board terminates against a dissimilar material, at door and window frames that do not wrap the board, at columns, at masonry, and at any exposed edge that is not finished with corner bead or a tapered joint.
14.3.2 The material of casing bead and edge trim shall be as indicated in the datasheet.
Casing Bead and Edge Trim Materialselect
Galvanized steel
Rigid PVC
Zinc alloy
NOTE Galvanized steel is the norm for a dry, painted interior and is the least expensive; rigid PVC is furnished where the trim meets a wet room, a shower surround, or an exterior soffit and where a steel trim would rust; and zinc alloy is the metal trim for those same locations where a paintable metal edge is wanted. (14.3.3)
14.3.4 A sealant joint shall be provided between the casing bead and the dissimilar material where the joint will be exposed, and the sealant is furnished under Joint SealantsJoint SealantsResolves to the current adopted revision.sync/joint-sealants.

14.4 Reveal and Shadow-Line Trim

14.4.1 Reveal trim and shadow-line trim shall be installed where a recessed joint or a shadow line is shown, plumb and level, in continuous runs, and finished to the same level as the adjacent board.
14.4.2 The locations, profiles, and reveal dimensions of reveal trim shall be as indicated on the interior elevations and the ceiling details.
NOTE A reveal at a ceiling perimeter also serves as the perimeter relief of this standard where the ceiling board is held clear of the wall behind the trim. (14.4.3)

15 Control Joints

15.1 Control Joint Locations

15.1.1 Control joints shall be installed in partitions and ceilings at the locations ASTM C840 requires and at the locations shown on the interior elevations and the reflected ceiling plans.
15.1.2 The maximum length of a partition between control joints shall be as indicated in the datasheet.
Maximum Partition Length Between Control Jointsrange
ft
1015202530
NOTE ASTM C840 sets 30 ft as the maximum run of partition or ceiling without a control joint, and 30 ft is the norm; a tighter spacing is selected at a long unbroken corridor wall in a building with large seasonal humidity swing, at a wall on a long-span floor, or where the finish is a gloss paint that shows every hairline, and it costs a visible joint every time it is invoked. (15.1.3)
15.1.4 A control joint shall be installed where a partition or ceiling crosses a construction joint, an expansion joint, or a change in the supporting structure, and at each side of a change in framing direction.
15.1.5 A control joint shall be installed in a ceiling without perimeter relief where the run exceeds 30 ft in either direction or the area bounded by control joints exceeds 900 sq ft, and in a ceiling with perimeter relief where the run exceeds 50 ft or the area exceeds 2,500 sq ft.
15.1.6 A control joint shall be installed at the head of a door opening in a partition longer than the datasheet spacing, extending from the top corner of the frame to the ceiling or the structure, unless the opening is framed to the head with a continuous header stud.
NOTE A partition cracks where the movement concentrates, and the corner of a door opening is the stress riser in any long wall; a control joint run up from the frame head puts the crack where it is meant to be and hides it in a groove. (15.1.7)
15.1.8 Control joints shall not be installed in a rated assembly except as GA-234 and the Control Joints in Rated Assemblies article of this standard permit.

15.2 Control Joint Product and Installation

15.2.1 The material of control joints shall be as indicated in the datasheet.
Control Joint Materialselect
Zinc alloy control joint
Rigid PVC control joint
Galvanized steel control joint
NOTE Zinc alloy is the norm for control joints because it does not rust under the compound and its tape strip peels cleanly after finishing; rigid PVC is the joint for a wet room or an exterior soffit and can be bent for a curved run; and galvanized steel is the least expensive and is admissible where the joint stays dry and the finish is not a gloss that would show a rust stain. (15.2.2)
15.2.3 A control joint shall be a preformed section that leaves a continuous open groove of not less than 1/4 in. between the two faces of board, and a taped joint, a V-groove, or a scored line shall not be substituted for it.
15.2.4 Control joints shall be set plumb on walls and straight on ceilings, in continuous runs from the floor to the head of the partition or from edge to edge of the ceiling.
15.2.5 The board shall be cut through, and the framing behind the joint shall be interrupted or doubled, so that the two sides of the joint are free to move.
15.2.6 The flanges of the control joint shall be fastened to the board on each side, and compound shall be feathered over the flanges and shall not be applied into the groove.
15.2.7 The protective tape over the groove shall remain in place through finishing and painting and shall be removed after the final coat.
NOTE A control joint filled with compound or paint is a taped joint with a metal strip in it, and it cracks beside the strip within the first season. (15.2.8)

15.3 Perimeter Relief at Ceilings

15.3.1 Whether gypsum board ceilings are provided with perimeter relief shall be as indicated in the datasheet.
Perimeter Relief at Gypsum Board Ceilingsradio
○ Perimeter relief, with the ceiling board held clear of the walls
○ Ceiling board fastened to the perimeter walls
NOTE Perimeter relief holds the ceiling board about 1/4 in. clear of the walls behind a casing bead or a reveal trim, so that the ceiling moves with the structure above without cracking at the corner, and it raises the ceiling area permitted between control joints from 900 to 2,500 sq ft; a ceiling fastened at the perimeter finishes with a taped inside corner, which is cheaper per foot and is the norm in residential work and in small rooms where the area limit is never reached. (15.3.2)
15.3.3 Where perimeter relief is provided, the ceiling board shall not be fastened to the perimeter wall framing or to the wall angle, and the first ceiling fastener shall be not closer than 8 in. to the wall.
15.3.4 Where perimeter relief is provided in a rated horizontal membrane, the relief detail shall be one the design number permits.

16 Joint Treatment

16.1 Joint Compound and Tape

16.1.1 Joint compound shall conform to ASTM C475 and shall be a product the board manufacturer accepts for the board and the facing furnished.
16.1.2 The compound used to embed tape shall be as indicated in the datasheet.
Tape Embedment Compoundradio
○ Setting-type compound
○ Drying-type compound
NOTE Setting-type compound hardens by hydration, reaches its strength in a stated set time whether or not the air is dry, shrinks less, and bonds tape more strongly, which suits it to the embedment coat, to prefill, to back-blocking, and to work in a cold or humid space; it cannot be reworked once it sets and is harder to sand. Drying-type compound is a single product for every coat, sands easily, and is the choice of most crews for speed, and it is the one that fails to dry in a humid, unventilated space. (16.1.3)
16.1.4 Where glass fiber mesh tape is used, the embedment compound shall be setting-type compound regardless of the datasheet selection.
16.1.5 Joint tape shall conform to ASTM C475.
16.1.6 The joint tape shall be as indicated in the datasheet.
Joint Taperadio
● Paper tape
○ Glass fiber mesh tape
NOTE Paper tape is the norm because it is strongest across the joint, folds cleanly at an inside corner, and is what the finish levels assume; glass fiber mesh tape is self-adhering and faster to place, is the tape for patching and for glass-mat and backer boards whose facing the paper tape does not bond to, and it depends on setting-type compound for its strength. (16.1.7)
16.1.8 Inside corners shall be taped with paper tape or a paper-faced corner tape, and mesh tape shall not be used at an inside corner.

16.2 Levels of Finish

NOTE The levels of finish are the six stages GA-214 and ASTM C840 define, from bare board through a skim-coated surface, and each level is a description of what has been done to the joints, the fasteners, and the accessories rather than a measure of quality; the level a surface needs is set by the decoration it will receive and the light that will fall on it, and the argument over whether a wall is acceptable is settled by naming the level before the work starts. (16.2.1)
NOTE In this standard the levels are understood as follows: (16.2.2)
  • Level 0: no taping, finishing, or accessories; the board is left as applied
  • Level 1: tape embedded in compound at every joint and inside corner, with the surface free of excess compound and with tool marks and ridges acceptable
  • Level 2: tape embedded and covered by a thin coat of compound, and fastener heads and accessories covered by one coat, with tool marks and ridges acceptable
  • Level 3: Level 2 plus one additional coat over the joints and inside corners and a second coat over fasteners and accessories, with the surface smooth and free of tool marks and ridges
  • Level 4: Level 3 plus a further coat over the flat joints and over fasteners and accessories, feathered and sanded, with inside corners at two coats
  • Level 5: Level 4 plus a skim coat over the entire surface so that the board face and the compound take paint alike
16.2.3 The finish level of exposed surfaces, where the room finish schedule does not state a different level for a surface, shall be as indicated in the datasheet.
Finish Level at Exposed Surfacesrange
level
12345
NOTE Level 4 is the norm for a painted commercial interior because a flat or eggshell paint over it hides the difference between board and compound under ordinary lighting; Level 5 is required by gloss and semi-gloss paints, by thin wall coverings, by dark colors, and by any wall or ceiling that is lit by grazing light from a window or a wall washer, and it adds a full skim coat to every square foot; Level 3 is the surface under a heavy texture, Level 2 the surface behind tile or in a mechanical room, and Level 1 the concealed side of a rated wall. (16.2.4)
16.2.5 The finish level of concealed surfaces, including plenums, chases, and the concealed face of rated partitions, shall be as indicated in the datasheet.
Finish Level at Concealed Surfacesrange
level
123
16.2.6 The surfaces that receive a finish level other than the datasheet values shall be as indicated on the room finish schedule.
16.2.7 Surfaces scheduled to receive a gloss or semi-gloss paint, a wall covering thinner than a Type II vinyl, or a critical lighting condition identified on the room finish schedule shall be finished to Level 5 regardless of the datasheet value.
16.2.8 Surfaces scheduled to receive a wall covering shall be finished to not less than Level 4.
16.2.9 Surfaces that will be tiled shall be finished to Level 2 with the joint treatment the backer manufacturer publishes for tile.
16.2.10 Where the parties disagree whether a surface meets its finish level, the Architect of Record shall make the initial determination by inspection under the lighting conditions in which the surface will be viewed in service.
16.2.11 The finished surface shall be inspected under the permanent lighting, or under temporary lighting placed where the permanent lighting will be, and not under construction lighting alone.
NOTE Construction lighting hung from the ceiling shines down a wall at an angle that hides joint telegraphing, and the same wall lit from a window or a wall washer at a grazing angle shows every ridge; a Level 5 finish approved under work lights is still the finish level the surface got, and the inspection lighting is what makes the approval mean anything. (16.2.12)

16.3 Level 5 Skim Material

16.3.1 The material of the Level 5 skim coat shall be as indicated in the datasheet.
Level 5 Skim Coat Materialradio
○ Trowel- or roller-applied joint compound skim coat
○ Spray-applied high-build primer-surfacer formulated for Level 5 finishing
NOTE A compound skim coat is applied by the taping crew, sanded, and primed like the rest of the wall, and it is the surface that a plaster-like flatness is built on; a spray-applied primer-surfacer is applied by the painting crew in one pass, is faster on a large area, and fills texture rather than leveling it, so it is the choice where the board and compound are already flat and the aim is uniform porosity under a gloss paint. (16.3.2)
16.3.3 Where a spray-applied primer-surfacer is selected, the product shall be one the board manufacturer and the paint manufacturer accept as a Level 5 surface, and its application shall be coordinated with Interior PaintingInterior PaintingResolves to the current adopted revision.sync/interior-painting.

16.4 Finish at Rated Assemblies

16.4.1 The joint treatment a design number requires shall be applied to both faces of a rated assembly regardless of the finish level scheduled for either face.
16.4.2 A rated partition whose concealed face is above a ceiling shall receive on that face not less than the Level 1 treatment of this standard, or the treatment the design number states, whichever is greater.

16.5 Textured Finishes

16.5.1 The textured finish applied to gypsum board surfaces, where the room finish schedule calls for texture, shall be as indicated in the datasheet.
Textured Finishselect
Smooth, with no applied texture
Spray-applied orange peel texture
Spray-applied knockdown texture
Spray-applied sand or aggregate texture
Hand-applied skip trowel texture
Hand-applied smooth trowel finish
NOTE Smooth is the norm in commercial work and the only surface a gloss paint or a wall covering accepts; orange peel is a fine spray that hides a Level 3 surface at the least cost and is the residential norm in much of the country; knockdown is a heavier spray flattened with a trowel that hides more and shows more dirt; a sand or aggregate texture hides the most and is the surface for a garage or a back-of-house ceiling; skip trowel and smooth trowel are hand-applied plaster-like finishes that cost as much as veneer plaster and are chosen for their appearance rather than for concealment. (16.5.2)
16.5.3 The surfaces that receive texture, and the pattern and density of the texture, shall be as indicated on the room finish schedule.
16.5.4 A textured finish shall be applied over not less than a Level 3 surface for a heavy texture and not less than a Level 4 surface for a light texture, and the surface shall be primed before a spray texture is applied unless the texture manufacturer publishes application over unprimed board.
16.5.5 Texture shall be uniform in pattern, density, and thickness across each surface and from one surface to the next in a room, and the accepted sample or mock-up shall be the standard for uniformity.
16.5.6 A textured ceiling shall be applied only to board that the Ceiling Board article of this standard permits under a water-based texture at the framing spacing installed.

17 Patching and Tie-In to Existing Construction

17.1 Where new board meets retained construction under Selective DemolitionSelective DemolitionResolves to the current adopted revision.sync/selective-demolition, the retained board shall be cut back to sound material at a framing member, and the new board shall be fastened to framing on both sides of the joint.
17.2 The joint between new and retained board shall be taped and finished to the level scheduled for the surface, and the finish shall be feathered onto the retained surface so that the joint does not read under the finish coat.
17.3 Where a retained assembly is fire-resistance-rated, the patch shall restore the board type, thickness, layers, and fastening the design number states, and the rating shall not be restored by compound or by unlisted material.
17.4 Where a retained assembly is sound-rated, the cavity fill and the perimeter sealant at the patch shall be reinstated before the patch is closed.
17.5 Holes and damaged areas in board that will be finished shall be patched with board of the same type and thickness, supported on framing or backing on all sides, and shall not be filled with compound alone where the opening exceeds 2 in. in any direction.

18 Delivery, Storage, and Handling

18.1 Gypsum panel products shall be delivered, stored, and handled under ASTM C1264 and the manufacturer's published instructions.
18.2 Board shall be delivered in the manufacturer's packaging and stored flat, on a level surface, off the floor, indoors, and protected from weather, moisture, and direct sunlight.
18.3 Board shall not be stored on edge except for the brief period of moving it to its point of installation.
NOTE Board stacked flat on an uneven surface takes the shape of the surface, and board stored on edge sags at the center, and neither returns to flat when it is hung; board stacked in the middle of a floor span in one pile also loads the floor beyond what most floors were designed for, which is why bundles are spread along bearing walls. (18.4)
18.5 Board shall be stacked in piles that do not exceed the floor's design capacity and shall be distributed along bearing lines rather than at the center of a span.
18.6 Board that is wet, that has a delaminated facing, a crushed edge, or a soft core, or that shows mold growth shall be removed from the site.
18.7 Framing members shall be stored off the ground and protected from water, and members with red rust that has pitted the steel shall be rejected.
18.8 Joint compound, adhesive, and sealant shall be stored above freezing and shall not be used after the manufacturer's stated shelf life.

19 Warranty

19.1 The Contractor shall warrant the gypsum board work, including the framing, fastening, blocking, joint treatment, finish, and texture, against defects in materials and workmanship for the period indicated in the datasheet, measured from the date of substantial completion.
Installation Warranty Periodrange
years
1235
19.2 Defects covered by the warranty include fastener pops, joint ridging, joint cracking, bead delamination, nail or screw telegraphing, sagging ceiling board, texture inconsistency, and cracking caused by the omission or incorrect installation of control joints, perimeter relief, or deflection heads.
NOTE Hairline cracking at joints that results from seasonal movement of the structure is not a defect where control joints, perimeter relief, and deflection heads were installed as this standard requires. (19.3)
19.4 The warranty shall not cover damage from water entering the building after acceptance, from structural movement beyond the movement capacity the contract documents state, from loads applied by others, or from work by others that opened or altered the assembly.
19.5 Where the contract documents state a longer warranty period than the datasheet, the longer period shall govern.
19.6 The Contractor's cost of a warranty correction shall include the removal and replacement of finishes over the defect, the restoration of any rated or sound-rated assembly disturbed, and the refinishing of the surface to its scheduled level and texture.
19.7 Work performed under this warranty shall itself be warranted for a full new term equal to the original period measured from the date the correction is completed, or for the remainder of the original period, whichever ends later.
19.8 Where the Contractor observes a condition during the work that will shorten the life of the gypsum board assemblies, including water entry, an unconditioned interior, structural deflection greater than the deflection head was built for, or another trade defeating a deflection head or a control joint, the Contractor shall report it to the Architect of Record in writing before the affected assembly is closed.