1 Scope
NOTE This standard covers the materials, design basis, fabrication, attachment, sealing, and testing of exterior metal wall panel systems that form the visible cladding of the above-grade wall enclosure. (1.1)
NOTE The work includes the metal panels themselves; the panel cores and factory insulation where present; the coil and panel finishes; the sub-girts, hat channels, clips, and other attachment and support components that carry the panel back to the structure or sheathing; the panel joints, gaskets, and sealants; the perimeter and penetration closures and the interface trim that ties the panel system to flashings, openings, and the air and water control layers behind it; and the laboratory and field verification that the installed wall meets its air, water, structural, thermal, and fire performance requirements. (1.2)
NOTE A metal wall panel is not, by itself, a complete wall. (1.3)
NOTE It is one layer of a multi-layer assembly whose other layers — the air barrier, the water-resistive barrier, the continuous insulation, and the structural backup — perform functions the panel does not, and the panel's job is to shed the bulk of the weather, resist wind load, and present the architectural face. (1.4)
NOTE The single most consequential idea in this standard is therefore that the panel and the layers behind it are designed and sequenced together: a perfectly fabricated panel installed over a discontinuous air barrier, or without a drainage path behind it, produces a wall that leaks air, traps water, and rots regardless of the panel's own quality. (1.5)
NOTE The way a metal panel wall manages water is the defining distinction among system types. (1.6)
NOTE A face-sealed (barrier) wall relies on the panel face and its sealed joints as the sole line of water defense, and it fails the moment any joint sealant fails. (1.7)
NOTE A drained-and-back-ventilated or pressure-equalized rainscreen, by contrast, accepts that some water will get past the outer face and provides a drained, ventilated cavity behind the panel and a continuous water-resistive barrier on the back-up wall that is the true water line of defense. (1.8)
NOTE Modern commercial practice favors the rainscreen approach because it is forgiving of the inevitable imperfection in field-applied joints, and because the pressure-equalized variety reduces the pressure difference that drives water through openings in the first place. (1.9)
NOTE The chosen water-management strategy governs nearly every other decision in this standard and is fixed first. (1.10)
NOTE The boundary of work under this standard is the metal panel cladding system and its attachment, from the face of the panel back to and including the clips, sub-girts, and fasteners that engage the structure or the sheathing. (1.11)
NOTE This standard covers the connection of the panel system to those adjacent systems. (1.13)
1.14All work shall comply with the adopted edition of the International Building Code (IBC), the structural load provisions of ASCE 7, and the panel manufacturer's published engineering and installation requirements.
1.15The wall shall be designed as a system, and the panel system's interfaces to the air barrier, to the flashings, and to the openings shall be detailed and coordinated before any panel is selected.
2 Referenced Standards
2.1Where the contract documents, the adopted building or energy code, the panel manufacturer's published instructions, or a referenced standard conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
| Standard |
Title |
| IBC |
International Building Code — Chapter 14 (Exterior Walls), Section 1402 (weather protection), Section 1407 (metal composite materials), and Chapter 26 / Section 2603 (foam plastic insulation) |
| ASCE 7 |
Minimum Design Loads and Associated Criteria for Buildings and Other Structures (components-and-cladding wind pressures) |
| NFPA 285 |
Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Non-Load-Bearing Wall Assemblies Containing Combustible Components |
| ASTM E84 |
Standard Test Method for Surface Burning Characteristics of Building Materials (flame-spread / smoke-developed index) |
| ASTM E283 |
Standard Test Method for Determining Rate of Air Leakage Through Exterior Windows, Curtain Walls, and Doors Under a Specified Pressure Difference Across the Specimen |
| ASTM E331 |
Standard Test Method for Water Penetration of Exterior Windows, Skylights, Doors, and Curtain Walls by Uniform Static Air Pressure Difference |
| ASTM E330 |
Standard Test Method for Structural Performance of Exterior Windows, Doors, Skylights, and Curtain Walls by Uniform Static Air Pressure Difference |
| ASTM E1592 |
Standard Test Method for Structural Performance of Sheet Metal Roof and Siding Systems by Uniform Static Air Pressure Difference |
| ASTM E1233 |
Standard Test Method for Structural Performance of Exterior Windows, Doors, Skylights, and Curtain Walls by Cyclic Static Air Pressure Differential (pressure-cycling for pressure-equalized rainscreen verification) |
| AAMA 508 |
Voluntary Test Method and Specification for Pressure Equalized Rain Screen Wall Cladding Systems |
| AAMA 509 |
Voluntary Test and Classification Method for Drained and Back-Ventilated Rain Screen Wall Cladding Systems |
| AAMA 501.1 |
Standard Test Method for Water Penetration of Windows, Curtain Walls, and Doors Using Dynamic Pressure |
| AAMA 501.2 |
Quality Assurance and Diagnostic Water Leakage Field Check of Installed Storefronts, Curtain Walls, and Sloped Glazing Systems (field nozzle test of fixed, sealed joints) |
| ASTM E2140 |
Standard Test Method for Water Penetration of Metal Roof Panel Systems by Static Water Pressure Head |
| ASTM C1363 |
Standard Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus |
| NFRC 100 / 101 |
Procedures for Determining Fenestration / Component U-factors (referenced for thermal-transmittance and thermal-bridging evaluation of metal assemblies) |
| ASTM C518 |
Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus (core insulation R-value) |
| AAMA 2605 |
Voluntary Specification, Performance Requirements and Test Procedures for Superior Performing Organic Coatings on Aluminum Extrusions and Panels (70% PVDF) |
| AAMA 2604 |
Voluntary Specification, Performance Requirements and Test Procedures for High Performance Organic Coatings on Aluminum Extrusions and Panels (50% PVDF / SMP) |
| AAMA 621 |
Voluntary Specification for High Performance Organic Coatings on Coil Coated Architectural Hot Dipped Galvanized (HDG) and Zinc-Aluminum Coated Steel Substrates |
| ASTM D2244 |
Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates (ΔE color change) |
| ASTM D4214 |
Standard Test Methods for Evaluating the Degree of Chalking of Exterior Paint Films |
| ASTM D523 |
Standard Test Method for Specular Gloss (gloss retention) |
| ASTM A653/A653M |
Standard Specification for Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-Dip Process |
| ASTM A792/A792M |
Standard Specification for Steel Sheet, 55% Aluminum-Zinc Alloy-Coated (Galvalume) by the Hot-Dip Process |
| ASTM B209/B209M |
Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate |
| UL 263 (ASTM E119) |
Standard for Fire Tests of Building Construction and Materials (fire-resistance rating of rated assemblies) |
| UL 723 |
Test for Surface Burning Characteristics of Building Materials (equivalent to ASTM E84) |
2.2Materials, fabrication, and installation shall comply with the latest adopted editions of the referenced standards and codes.
2.3The panel manufacturer's tested-assembly limits — span, load, and the specific NFPA 285-compliant assembly configuration — shall not be exceeded or altered even where this standard or the drawings would otherwise permit it.
3 Submittals
3.1 Action Submittals
3.1.1The Contractor shall submit the following for the Engineer's review and return before procurement and fabrication.
NOTE The panel's fire compliance, structural capacity, and weathertightness all depend on the specific tested assembly configuration and cannot be evaluated product by product, so the package is reviewed as a coordinated whole. (3.1.2)
- Product data for the panel system, identifying the panel family (IMP, single-skin, MCM/ACM, plate/cassette), the metal substrate and its specification and gauge or thickness, the core or insulation type and thickness, the finish system, the system water-management type (face-sealed, drained-and-back-ventilated, or pressure-equalized rainscreen), and the attachment method (concealed-fastener or exposed-fastener)
- Shop drawings showing panel layout and module, joint locations and joint type, the complete attachment and support system (clips, sub-girts, hat channels, fasteners) with the load path to the structure, every perimeter and penetration closure, end dams and flashings at openings, expansion and movement joint locations, inside and outside corners, base and parapet terminations, and the relationship of the panel to the air barrier and water-resistive barrier plane behind it
- Structural calculations, sealed by a professional engineer where required by the jurisdiction, demonstrating that the panel, its attachments, and the supporting sub-framing resist the positive and negative components-and-cladding wind pressures from ASCE 7 with the required safety factor, within the panel manufacturer's tested span and load limits, with maximum deflection within the specified limit
- NFPA 285 compliance evidence for combustible-component assemblies — a passing NFPA 285 test report for the specific assembly, or an engineering analysis (engineering judgment) prepared by a qualified fire-protection engineer extending a tested assembly to the proposed configuration — documenting that the as-designed wall (panel, core, insulation, air/water barrier, framing, and the back-up wall) is within the bounds of the tested or evaluated assembly
- Surface-burning (ASTM E84) test data for the panel and core, and for MCM the assembly flame-spread and smoke-developed indices per IBC Section 1407
- Finish product data and the finish warranty, showing the AAMA grade (2605, 2604, or 621 for coil-coated steel) and the color change (ΔE per ASTM D2244), chalk (ASTM D4214), and gloss-retention (ASTM D523) limits and warranty period
- Color and finish samples on the actual specified metal substrate, of sufficient size to evaluate color, gloss, and metallic or mica orientation in natural daylight
- Air, water, and structural performance test reports for the panel system (ASTM E283, E331, E330 or E1592, and, for rainscreen systems, AAMA 508 / AAMA 509 and the ASTM E1233 pressure-cycling data)
- Manufacturer's installation instructions and the installer's qualifications
- A written field water-test (AAMA 501.2) plan where field water testing is specified, identifying the joints to be tested, the test method, and the acceptance criteria
☐ Panel system product data (family, substrate/gauge, core, finish, water-management type, attachment)
☐ Shop drawings (layout, joints, attachment/support, closures, openings, corners, terminations, air/water barrier interface)
☐ Structural calculations to ASCE 7 components-and-cladding (PE-sealed where required)
☐ NFPA 285 test report or engineering judgment for combustible-component assemblies
☐ ASTM E84 surface-burning data (panel/core; MCM assembly per IBC 1407)
☐ Finish product data and finish warranty (AAMA 2605/2604/621; ΔE, chalk, gloss)
☐ Color and finish samples on actual substrate
☐ Air/water/structural test reports (E283, E331, E330/E1592; AAMA 508/509, E1233 for rainscreen)
☐ Manufacturer installation instructions and installer qualifications
☐ AAMA 501.2 field water-test plan (where field testing is specified)
3.1.3The panel system, its attachment, the finish, and the documentation of fire performance shall be submitted together as a coordinated package.
3.1.4Piecemeal product-by-product submittal shall not be accepted.
3.2 Closeout Submittals
3.2.1At substantial completion, the Contractor shall provide the following before the panel work is accepted.
- Executed finish warranty (film integrity, color change, chalk) and the manufacturer's weathertightness or system warranty
- Executed Contractor installation warranty
- Field water-test (AAMA 501.2) reports where field testing was performed, recording each joint tested, the result, and the remediation and re-test of any leak
- Marked-up as-built shop drawings showing actual joint, expansion-joint, and field-cut conditions
- Touch-up finish in the specified color in sealed factory containers, and owner attic stock (spare panels and trim) where required by the contract documents
- Maintenance instructions for cleaning, periodic joint-sealant inspection, and finish care
☐ Executed finish warranty and manufacturer weathertightness/system warranty
☐ Executed Contractor installation warranty
☐ AAMA 501.2 field water-test reports (where field testing was performed)
☐ Marked-up as-built shop drawings (joints, expansion joints, field-cut conditions)
☐ Touch-up finish in sealed factory containers, and Owner attic stock (spare panels and trim) where required
☐ Maintenance instructions (cleaning, joint-sealant inspection, finish care)
4 Quality Assurance
4.1 Installer Qualifications
NOTE Metal panel work is unforgiving of inexperience precisely where it matters most — at the corners, terminations, and penetration closures, where the watertightness and the fire-compliant continuity of the assembly are won or lost, and which are difficult to inspect after the work is enclosed. (4.1.1)
○ Manufacturer-trained and approved installer for the specific panel system (standard)
○ Manufacturer-approved installer with documented comparable project experience
4.1.2The panel installer shall be trained and approved by the panel manufacturer for the specific system.
4.1.3The panel installer shall have documented experience installing metal panel systems of comparable type, scale, and complexity.
4.2 Pre-Installation Conference
NOTE The purpose of the conference is to resolve, in advance and on paper, which trade installs each part of every transition and closure, in what sequence, and how responsibility for air and water continuity and for the NFPA 285-compliant configuration is handed off. (4.2.1)
NOTE The overwhelming majority of metal panel wall failures originate at these trade boundaries, not in the panels themselves. (4.2.2)
4.2.3Before panel work begins, the Contractor shall convene a pre-installation conference with the Engineer, the panel manufacturer's representative, the panel installer, and the installers of every adjacent trade whose work meets the panel system — air barrier, sheet metal flashing, fenestration, and joint sealants.
4.2.4The conference shall resolve which trade installs each transition and closure, in what sequence, and how responsibility for air and water continuity and for the NFPA 285-compliant configuration is handed off.
4.3 Mockup
○ Field mockup with field joint, corners, base and head terminations, and a penetration closure (standard)
○ Field mockup of panel field and one corner and one termination only (small projects)
○ Mockup not required (minor scope)
4.3.1The Contractor shall construct a field mockup of a representative panel area incorporating at least one of each critical condition — a typical field joint, an inside and an outside corner, a base or sill termination, a parapet or head termination, and a penetration closure — together with the air barrier and water-resistive barrier behind it and the interface flashings.
4.3.2The mockup shall be reviewed and accepted by the Engineer and the manufacturer's representative and shall establish the standard of workmanship for the project.
4.3.3Where required, the mockup shall be subjected to a field water test (AAMA 501.2) before approval.
5 Environmental and Service Conditions
5.1 Wind Load
5.1.1Negative (suction) pressure usually governs metal panel attachment, because the panel and its clips must hold the panel onto the wall against wind trying to pull it off, and a panel pulled off in a storm becomes a projectile.
NOTE Corner and edge zones see substantially higher suction than the wall field and govern attachment spacing there. (5.1.2)
20120
20304050607590120
Default: 40 psf
30200
3045607590120150200
Default: 75 psf
5.1.3The panel system, its attachments, and its sub-framing shall resist the positive and negative (inward and, more critically, outward suction) components-and-cladding wind pressures determined per ASCE 7 for the building's height, exposure, risk category, and the wall zone in question.
5.1.4The panel layout and clip or fastener pattern shall reflect the increased pressure in the corner and edge zones.
5.2 Thermal Movement
NOTE Metal panels expand and contract significantly with temperature. (5.2.1)
NOTE Dark-colored panels in direct sun reach high surface temperatures and move more than light panels. (5.2.2)
NOTE Concealed-fastener systems accommodate movement at clips and floating connections; exposed-fastener systems accommodate it at slotted holes and oversized fastener holes that let the panel slide relative to the fastener. (5.2.3)
120220
120150180200220
Default: 180 °F
5.2.4The panel system shall be designed and detailed to accommodate thermal movement without buckling, oil-canning, fastener pull-through, or joint failure.
5.2.5The design temperature range shall reflect the panel color and orientation.
5.2.6The attachment shall fix the panel at one point and allow movement elsewhere, and shall never restrain the panel at two points so that thermal stress has nowhere to go.
5.3 Corrosion Exposure
NOTE Coastal sites (within a few miles of salt water), de-icing-salt exposure, and industrial atmospheres are aggressive to metal cladding and call for a more corrosion-resistant substrate (aluminum, or Galvalume rather than galvanized steel) and a higher-grade finish, and call for stainless steel fasteners and careful dissimilar-metal isolation. (5.3.1)
NOTE Galvanic compatibility is a hard constraint: dissimilar metals in contact, or noble-metal runoff onto a less noble metal below, corrode for the life of the building. (5.3.2)
○ Normal atmospheric / inland (standard)
○ Coastal / marine (within ~5 miles of salt water) — corrosion-resistant substrate and Type 316 fasteners
○ Industrial / chemical / de-icing-salt exposure — corrosion-resistant substrate and finish
5.3.3The metal substrate and finish shall be selected for the corrosivity of the environment.
5.3.4Dissimilar metals in contact, and noble-metal runoff onto a less noble metal below, shall be isolated to prevent galvanic corrosion.
5.3.5Aluminum and zinc-coated steel shall not be left in continuous contact with wet alkaline materials (fresh concrete, mortar runoff), and that contact shall be avoided or isolated.
NOTE The panel system is selected and verified against air leakage, water penetration, structural (wind) load, thermal transmittance, and fire performance. (6.1)
6.2These are properties of the tested assembly — the panel together with its joints, attachment, and closures — not of the bare panel, and the Contractor shall submit test reports on the assembly configuration that matches the project, because a system that passes in one joint and attachment configuration can fail in another.
6.3 Air Leakage
NOTE Air leakage through the cladding wastes energy and, far more damaging, carries interior humidity into the wall where it condenses. (6.3.1)
NOTE The panel system contributes to the wall's air control, but the continuous air barrier on the back-up wall — specified in
Air Barriers — is the primary air control layer, and the panel air-leakage requirement is in addition to, not a substitute for, that air barrier.
(6.3.2) 0.020.12
0.020.040.060.12
Default: 0.06 cfm/ft² @ 6.24 psf (300 Pa)
6.3.3The panel system shall limit air leakage through the assembly to not more than the specified rate when tested per ASTM E283 at the specified static pressure difference.
6.3.4The panel air-leakage requirement and the continuous air barrier on the back-up wall shall be coordinated so the assembly is continuous.
6.4 Water Penetration
NOTE What "no water penetration" means depends on the water-management strategy. (6.4.1)
6.4.2In a face-sealed (barrier) wall the panel face and its sealed joints must stop all water, and the test pressure is held against that single line of defense.
NOTE In a drained-and-back-ventilated or pressure-equalized rainscreen, water that passes the outer joints is permitted into the drained cavity provided it is drained back out and does not reach the interior past the water-resistive barrier; the test confirms that the back-up water line and the drainage path perform. (6.4.3)
2.8615
2.866.248101215
Default: 6.24 psf
6.4.4There shall be no uncontrolled water penetration to the interior of the assembly when tested per ASTM E331 (static) and, where dynamic testing is specified, AAMA 501.1 (dynamic), at the specified test pressure.
6.4.5The test pressure shall be a defined fraction of the design wind pressure and shall be stated in the contract documents.
NOTE ASTM E1592 is the test method specific to formed sheet metal roof and siding panels and is the appropriate structural test for single-skin profiled and many IMP wall systems; ASTM E330 is the uniform-static-pressure test used broadly for cladding and is appropriate for plate, cassette, and curtain-wall-like panel systems. (6.5.1)
NOTE Deflection is limited not only to prevent damage but to prevent the visible waviness (oil-canning) and the joint-opening that excessive deflection causes; the deflection limit governs panel gauge, profile stiffness, and span between supports. (6.5.2)
○ L/120 (typical for metal wall panels)
○ L/180 (stiffer; flat plate and prominent flush surfaces)
○ L/240 (where minimal visible deflection is required)
○ ASTM E1592 — formed sheet metal roof and siding systems (single-skin profiled, many IMP)
○ ASTM E330 — uniform static air pressure (plate, cassette, curtain-wall-type panels)
6.5.3The panel and its attachment shall sustain the design positive and negative wind pressures without permanent deformation, disengagement, or failure when tested per ASTM E330 (or ASTM E1592 for formed sheet metal panels and siding systems).
6.5.4Panel deflection under design load shall not exceed the specified limit.
NOTE Metal is a powerful thermal bridge: a metal fastener, clip, or sub-girt that crosses the insulation short-circuits it, and the effective R-value of a metal-clad wall with through-metal attachments can be far below the nominal R-value of the insulation. (6.6.1)
6.6.2Factory-foamed IMPs carry their insulation in the panel core (R-value per ASTM C518) and reduce thermal bridging because the metal skins are separated by the foam, but the panel joints and the perimeter attachments still bridge and shall be accounted for.
NOTE Single-skin and open-jointed panel systems rely on continuous insulation behind the panel, specified in
Building Thermal Insulation, and on thermally-broken clip systems to limit bridging.
(6.6.3) ○ IMP factory core R-value (ASTM C518) plus assembly thermal-bridging evaluation of joints and attachments
○ Continuous insulation behind panel (per [[sync/building-thermal-insulation]]) with thermally-broken clips; assembly U-factor by ASTM C1363 / thermal-bridging calc
0.030.12
0.030.0450.0550.0640.0840.12
Default: 0.064 Btu/h·ft²·°F
6.6.4The opaque metal wall assembly shall meet the assembly U-factor (or continuous-insulation R-value) required by the adopted energy code for the climate zone, accounting for the thermal bridging of metal attachments.
6.6.5The assembly U-factor shall be evaluated by hot-box test per ASTM C1363 or by a thermal-bridging calculation method (consistent with the NFRC component procedures) that captures the metal bridging, and shall not be determined by simply adding up the nominal R-values of the layers.
NOTE Fire performance is the most code-critical requirement in this standard, and it turns entirely on whether the assembly contains combustible components — which most modern metal panel walls do, because foam-plastic-core IMPs and polymer-core MCM panels are both combustible, as are most foam-plastic continuous insulations behind single-skin panels. (6.7.1)
6.7.2The IBC governs these assemblies through two related but distinct triggers, and the design shall identify which apply before the panel is selected.
6.7.3 NFPA 285 Trigger and Compliance
NOTE NFPA 285 is a full-scale fire-propagation test of a complete wall assembly: it evaluates whether fire, once started, spreads vertically up the exterior face and through the wall cavity beyond acceptable limits. (6.7.3.1)
NOTE It is mandated precisely because combustible cores and foam-plastic insulations, while excellent thermal performers, can carry flame up a multi-story facade if the assembly is not detailed to interrupt that spread. (6.7.3.2)
NOTE The compliance is a property of the *entire assembly as tested* — the specific panel, core, insulation, air and water barrier, framing, and back-up wall, in the tested thicknesses and configuration — and substituting any combustible component or changing the assembly invalidates the compliance. (6.7.3.3)
6.7.3.4Where the project assembly does not exactly match a tested assembly, compliance may be demonstrated by an engineering analysis (engineering judgment) prepared by a qualified fire-protection engineer that extends a passing test to the proposed configuration within defensible limits.
○ Required — assembly contains combustible components (foam-core IMP, polymer-core MCM, or foam-plastic CI) on Type I-IV construction; passing NFPA 285 test of the assembly
○ Required — combustible components present; compliance by fire-protection engineer's engineering judgment extending a tested assembly
○ Not triggered — assembly contains no combustible components (e.g., mineral-wool-core IMP with non-combustible insulation and skins)
6.7.3.5Where the exterior wall assembly of a building of Type I, II, III, or IV construction contains a combustible component — foam plastic insulation (IBC Section 2603), metal composite material (IBC Section 1407), or other combustible cladding component — the assembly shall be tested in accordance with, and comply with the acceptance criteria of, NFPA 285.
6.7.3.6The Contractor shall not assemble a combustible-component wall on Type I-IV construction without documented NFPA 285 compliance for the as-built assembly.
6.7.4 Surface Burning and MCM-Specific Requirements
NOTE The distinction between a fire-retardant (FR) core and a standard core MCM is consequential: a standard-core MCM relies entirely on the assembly detailing and the NFPA 285-tested configuration to limit fire spread, whereas an FR-core MCM has a mineral-filled core that resists ignition and contributes far less fuel. (6.7.4.1)
6.7.4.2Many jurisdictions and many tested assemblies require the FR core, and the core type shall be confirmed against the NFPA 285 assembly and the AHJ's requirements before selection.
NOTE The thermal barrier between the MCM and the interior (typically gypsum board) is a required code element, not an option. (6.7.4.3)
○ Fire-retardant (FR) mineral-filled core — required for most code-compliant assemblies (recommended)
○ Standard polymer core — only where the specific NFPA 285 assembly and the AHJ permit
○ Not applicable — system is not MCM/ACM
○ Flame-spread ≤ 25 and smoke-developed ≤ 450 (Class A; required for MCM per IBC 1407)
○ Non-combustible skins and core (mineral-wool-core IMP); E84 not the governing path
6.7.4.4Metal composite material (MCM) shall have a flame-spread index of not more than 25 and a smoke-developed index of not more than 450 when tested per ASTM E84 as an assembly in the maximum thickness intended.
6.7.4.5The MCM core shall not contain foam plastic insulation.
6.7.4.6The MCM assembly shall comply with NFPA 285.
6.7.4.7The MCM shall be separated from the interior by an approved thermal barrier.
7 Panel Materials and Construction
7.1 Panel System Type
NOTE Insulated metal panels deliver the metal skins, the insulation, the air barrier, the water-resistive barrier, and the vapor barrier in one factory-foamed component with an engineered interlocking side joint, which makes for a fast, single-trade installation and an excellent continuous-insulation value, at the cost of a combustible foam core (unless mineral-wool-cored) that triggers NFPA 285. (7.1.1)
NOTE Single-skin formed panels are the most economical and the most flexible architecturally, but they are only the rain-shedding outer layer and rely entirely on a separate air barrier, water-resistive barrier, and insulation behind them. (7.1.2)
NOTE Metal composite material panels give a dead-flat, large-format, premium appearance with a thin, light skin, but they are combustible (polymer core) and are tightly governed by IBC Section 1407 and NFPA 285. (7.1.3)
NOTE Flat plate and cassette panels give the flush, monolithic plate appearance with a solid (non-laminated) metal and concealed attachment, at higher weight and cost than MCM. (7.1.4)
○ Insulated metal panel (IMP) — factory-foamed core bonded between two metal skins; single-component thermal and weather barrier
○ Single-skin formed / profiled panel — one metal skin, profiled for stiffness, over separate insulation and air/water barrier
○ Metal composite material (MCM/ACM) — two thin metal skins bonded to a polymer core, routed and returned into cassettes
○ Flat plate / cassette panel — single solid metal plate formed into a stiffened cassette (concealed attachment)
7.1.5The panel system type shall be as selected and shall be installed as a complete tested system with the manufacturer's matched attachment, closures, and trim.
7.2 Water-Management Strategy
NOTE A pressure-equalized rainscreen provides a vented, compartmentalized cavity behind the panel so the air pressure in the cavity equalizes with the exterior; with little pressure difference across the outer joints, far less water is driven through them, and the back-up water-resistive barrier handles the small remainder. (7.2.1)
NOTE It is the highest-performing and the most appropriate strategy for tall and high-exposure buildings, and is verified to AAMA 508. (7.2.2)
NOTE A drained-and-back-ventilated rainscreen provides the vented, drained cavity but does not compartmentalize for pressure equalization; it is simpler, very effective for most buildings, and verified to AAMA 509. (7.2.3)
NOTE A face-sealed wall has no cavity and relies on the perfection of its sealed joints; it is acceptable only on low, simple, low-exposure walls where the joint maintenance burden is accepted. (7.2.4)
○ Pressure-equalized rainscreen (PER) — vented, compartmentalized cavity; AAMA 508 (recommended for high-exposure and tall buildings)
○ Drained and back-ventilated (DBV) rainscreen — vented, drained cavity; AAMA 509
○ Face-sealed (barrier) — panel face and sealed joints are the sole water line (low-exposure, simple geometry)
7.2.5The water-management strategy shall be as selected, and the panel system, its joints, and the back-up wall shall be detailed consistently with it.
NOTE The substrate is selected for corrosion environment, formability, weight, and cost. (7.3.1)
NOTE Aluminum (ASTM B209) is light, corrosion-resistant in most atmospheres, the standard skin for MCM and plate panels, and forms cleanly; it is more expensive per pound and softer (more prone to denting and oil-canning) than steel. (7.3.2)
NOTE Galvanized steel (ASTM A653, minimum G90 for exterior architectural use) is the most economical and the stiffest, and is the standard for IMP and single-skin steel panels; G60 coating is not acceptable for exterior use. (7.3.3)
NOTE Galvalume steel (ASTM A792, AZ50 or AZ55) gives substantially longer atmospheric service life than galvanized but is attacked by alkaline runoff (mortar, fresh concrete). (7.3.4)
NOTE Heavier gauge increases stiffness and dent resistance and reduces oil-canning but increases weight, forming difficulty, and cost. (7.3.5)
○ Aluminum sheet — ASTM B209 (standard for MCM, plate, and coastal/light applications)
○ Galvanized steel — ASTM A653, minimum G90 (standard for IMP and single-skin steel)
○ Galvalume steel — ASTM A792, AZ50 or AZ55 (extended atmospheric service life)
26 ga (0.0179 in nominal — light single-skin and IMP liner skins)
24 ga (0.0239 in — typical single-skin and IMP exterior face)
22 ga (0.0299 in — long span, high-exposure, or heavier profile)
Per manufacturer's tested gauge for the span and wind pressure
0.032 in (single-skin and light formed panel)
0.040 in (typical single-skin and MCM skin)
0.125 in (flat plate / cassette panel)
0.188 in (heavy plate / long-span cassette)
Per manufacturer's tested thickness for the span and wind pressure
3 mm (light interior or low-exposure use)
4 mm (standard architectural MCM)
6 mm (heavy / long-span architectural MCM)
7.3.6The metal substrate, its specification, and its thickness or gauge shall be as selected and shall meet the structural performance requirement for the panel span and the design wind pressure.
7.3.7G60-coated steel shall not be used for exterior architectural panels; galvanized steel for exterior use shall be a minimum of G90.
7.3.8Galvalume steel shall not be used where it is continuously wetted by alkaline runoff such as mortar or fresh concrete.
7.3.9The selected gauge or thickness shall meet the structural and deflection requirements and the manufacturer's tested limits for the span.
NOTE The IMP core is both the insulation and the structural shear connection between the two skins, and the core choice is a direct fire-versus-thermal trade-off. (7.4.1)
NOTE Polyisocyanurate (polyiso) and polyurethane foam cores give a high thermal resistance (nominally on the order of R-7 to R-8 per inch) at low weight, but they are foam plastics, are combustible, and trigger NFPA 285 (and the foam-plastic provisions of IBC Section 2603). (7.4.2)
7.4.3Mineral-wool cores are non-combustible, achieve fire-resistance ratings (1-, 2-, and 3-hour assemblies are available), and may avoid the NFPA 285 trigger entirely where the rest of the assembly is non-combustible, but they have a lower R-value per inch (on the order of R-4 per inch) and are heavier, so a mineral-wool panel is thicker and heavier for the same thermal performance.
○ Polyisocyanurate (polyiso) or polyurethane (PU) foam — high R-value/in, combustible, triggers NFPA 285 / IBC 2603 (standard where fire rating allows)
○ Mineral wool — non-combustible, fire-resistance-rated, lower R-value/in, heavier (required where fire rating or non-combustible assembly governs)
2 in
2.5 in
3 in
4 in
5 in
6 in
○ Not fire-resistance-rated (non-rated wall)
○ 1-hour rated assembly (UL 263 / ASTM E119) — mineral-wool core
○ 2-hour rated assembly (UL 263 / ASTM E119) — mineral-wool core
7.4.4Where an insulated metal panel is used, the core type and thickness shall be as selected.
7.4.5The IMP core type shall be consistent with the fire performance requirement and the NFPA 285-tested assembly, confirmed against the project's fire-rating and NFPA 285 requirements before the panel is selected.
7.5 Finish
NOTE PVDF (polyvinylidene fluoride) fluoropolymer coatings are the architectural standard for exterior metal panels because of their outstanding ultraviolet, color, and chalk resistance. (7.5.1)
NOTE A full-strength 70% PVDF coating conforms to AAMA 2605 on aluminum (or AAMA 621 on coil-coated galvanized and zinc-aluminum-coated steel) and provides the premium ten-year color-retention and chalk performance — typically not more than 5 ΔE color change per ASTM D2244, a chalk rating of 8 or better per ASTM D4214, and at least 50% gloss retention per ASTM D523. (7.5.2)
NOTE A 50% PVDF or silicone-modified polyester (SMP) blend conforms to AAMA 2604 and is appropriate for moderate exposure at lower cost. (7.5.3)
NOTE Commercial coatings (AAMA 2603) are for low-exposure or concealed use only. (7.5.4)
○ 70% PVDF fluoropolymer — AAMA 2605 (aluminum) or AAMA 621 (coil-coated steel) — premium architectural (recommended)
○ 50% PVDF / SMP blend — AAMA 2604 — high-performance general
○ Commercial coating — AAMA 2603 — low-exposure or concealed only
Per Engineer of Record — see finish schedule on drawings
7.5.5The exposed metal finish shall be as selected and shall carry the manufacturer's finish warranty for color change, chalk, and film integrity for the specified period.
7.5.6Commercial coatings (AAMA 2603) shall not be specified for prominent exterior surfaces.
8 Attachment and Support
8.1 Attachment Method
NOTE Concealed-fastener systems engage the panel at hidden clips, interlocks, or rout-and-return returns, leaving an unbroken, fastener-free visible face; they are the standard for prominent architectural work because they eliminate the leak paths, the maintenance, and the appearance of an exposed-fastener field, and they let the panel float for thermal movement. (8.1.1)
NOTE Exposed-fastener systems drive fasteners with sealing washers through the panel face into the support; they are economical and fast for utilitarian and industrial single-skin walls, but every fastener is a penetration of the weather face that depends on its washer and on correct (not over- or under-driven) installation, and the fasteners are visible. (8.1.2)
○ Concealed-fastener (clips / interlock / rout-and-return) — no face penetrations (standard for architectural work)
○ Exposed-fastener (fasteners with sealing washers through panel face) — utilitarian / industrial single-skin
8.1.3The panel attachment shall be concealed-fastener or exposed-fastener as selected, and the attachment shall resist the design wind pressures within the manufacturer's tested limits.
8.1.4The fastener pattern and clip spacing shall be tightened in the corner and edge wind zones.
8.2 Sub-Framing and Clips
NOTE The sub-framing is the load path from the panel to the building structure and is also, where it crosses the insulation, the principal thermal bridge in the wall. (8.2.1)
NOTE Continuous metal sub-girts that bear directly on continuous insulation crush and short-circuit it; the current practice for high-performance walls is a thermally-broken clip-and-rail or a spaced clip system that minimizes the through-metal area. (8.2.2)
○ Thermally-broken clip-and-rail over continuous insulation (high-performance; minimizes thermal bridging)
○ Metal sub-girts / hat channels (where thermal bridging is acceptable or insulation is in the panel)
○ Direct attachment to sheathing/framing (IMP and single-skin without exterior CI)
○ Stainless steel Type 304, with sealing washer where exposed (standard)
○ Stainless steel Type 316, with sealing washer (coastal / corrosive)
○ Per manufacturer for the substrate and exposure
8.2.3Panels shall be attached to sub-girts, hat channels, or clips engineered to carry the panel loads to the structure.
8.2.4Thermally-broken clips shall be used where the energy code requires the thermal bridging of the attachment to be controlled.
8.2.5The sub-framing material shall be compatible with the panel and fastener metals to avoid galvanic corrosion, and shall be corrosion-protected for the exposure.
9 Joints and Sealants
9.1 Panel-to-Panel Joints
NOTE The joint is where panels meet and where most water and air management happens, and the joint detail is integral to the tested performance. (9.1.1)
NOTE Interlocking and gasketed joints in IMP and concealed-fastener systems are engineered to drain and to resist air leakage without a face-applied sealant bead; open-reveal joints in rainscreen systems are intentionally open and rely on the cavity and the back-up water-resistive barrier, not on a sealed face. (9.1.2)
○ Interlocking / shiplap (IMP, concealed-fastener single-skin) — drained, gasketed
○ Open reveal (rainscreen) — intentionally open; cavity and back-up WRB manage water
○ Sealed butt joint with backer and sealant (face-sealed walls only)
9.1.3Panel side and end joints shall be the manufacturer's engineered joint for the system — interlocking, shiplap, reveal, or gasketed — installed to maintain the joint's air, water, and (for rainscreen systems) pressure-equalization function.
9.1.4The joint type shall match the water-management strategy.
9.1.5An open reveal joint shall never be used on a face-sealed wall.
9.1.6A face-sealed butt joint shall never be relied on as the water line of a rainscreen.
9.2 Sealants
NOTE Where sealant is the water line — at face-sealed joints, at perimeter and opening conditions, and at penetration closures — its movement capability, finish compatibility, and joint design govern its life. (9.2.1)
NOTE A rigid sealant bead across a moving joint will tear. (9.2.2)
NOTE Perimeter and movement-joint sealants are specified in
Joint Sealants and coordinated here; the panel manufacturer's approval of the specific sealant for its system is required.
(9.2.3) ○ Required — sealant manufacturer to confirm adhesion to specified PVDF finish, with primer if required (submit adhesion data)
○ Not applicable — no sealed joints in contact with the finished face (open-joint rainscreen)
9.2.4Field sealants at panel joints, perimeters, and terminations shall be the manufacturer-approved sealant for the joint, compatible with the panel finish, and installed over a backer rod to the correct joint geometry where a sealed joint is used.
9.2.5Sealant on a PVDF finish shall be confirmed by the sealant manufacturer's adhesion data on the actual finish, with a primer where required.
9.2.6Movement joints shall be sized for the movement with a backer rod and a properly proportioned hourglass bead, and shall not be overfilled.
10 Flashing and Trim Interface
NOTE The flashings and trim that frame the panel are where the panel system hands off to the rest of the envelope, and they are the most failure-prone part of the installation. (10.1)
○ Pan-formed base and sill flashing with end dams, draining cavity water to exterior (standard for rainscreen)
○ Through-wall base flashing with weeps draining to exterior
○ Sealed base closure (face-sealed walls only)
10.3The panel system shall interface with the perimeter flashings, copings, base and head closures, sill flashings with end dams, and corner and reveal trim so that water reaching the panel system or its cavity is collected and drained to the exterior, and so that the air and water control layers remain continuous across the transition.
10.4Head flashings over openings and at horizontal interruptions shall turn up behind the water-resistive barrier and drain over and out beyond the panel face.
10.5Sill and base flashings shall be pan-formed with end dams to collect and expel cavity water.
10.6Copings shall shed water away from the panel head.
10.7Inside and outside corners shall maintain the joint and drainage continuity.
11 Testing
11.1 Laboratory Testing
NOTE Laboratory qualification proves the system performs in a controlled configuration before it is committed to the building. (11.1.1)
NOTE For pressure-equalized rainscreens, the AAMA 508 procedure deliberately perforates the back-up (air-barrier) plane to simulate an imperfect field installation and then confirms that the cavity still equalizes pressure and that water does not penetrate — a far more realistic test than one that assumes a perfect air barrier. (11.1.2)
☐ Air leakage — ASTM E283
☐ Water penetration, static — ASTM E331
☐ Water penetration, dynamic — AAMA 501.1 (where specified)
☐ Structural — ASTM E330 or ASTM E1592
☐ Pressure-equalized rainscreen classification — AAMA 508 (PER systems)
☐ Drained-and-back-ventilated classification — AAMA 509 (DBV systems)
☐ Pressure cycling — ASTM E1233 (rainscreen verification)
11.1.3The panel system shall be qualified by laboratory testing of the assembly for air leakage (ASTM E283), water penetration (ASTM E331, and AAMA 501.1 where dynamic testing is specified), and structural performance (ASTM E330 or ASTM E1592).
11.1.4Rainscreen systems shall additionally be classified per AAMA 508 (pressure-equalized) or AAMA 509 (drained-and-back-ventilated) with pressure-cycling per ASTM E1233.
11.1.5The Contractor shall submit the test reports for the configuration matching the project.
11.2 Field Water Testing
NOTE Field water testing catches the installation defects — missed seals, omitted end dams, reversed laps — that laboratory testing of a perfect specimen cannot. (11.2.1)
NOTE AAMA 501.2 directs a calibrated water spray from a standard nozzle along fixed, permanently sealed joints (it is not used on drained, open, or weep-equipped joints, which are designed to admit and drain water) to confirm the sealed joints hold. (11.2.2)
○ Required at representative joints and terminations; repair and re-test until passing (recommended)
○ Required at a defined sample of conditions; report results
○ Not required (laboratory qualification only)
11.2.3Where specified, the installed panel system shall be field-tested for water penetration at representative joints, terminations, and penetration closures using the AAMA 501.2 nozzle method on fixed, sealed joints.
11.2.4Any leakage shall be located, repaired, and re-tested.
11.2.5The test shall be performed early enough that defects can be corrected before the wall is enclosed, and on a representative sample of the most failure-prone conditions.
12 Installation
12.1 General
12.1.1The Contractor shall install the panel system in accordance with this standard, the approved shop drawings, the manufacturer's instructions, and the NFPA 285-compliant assembly configuration where combustible components are present.
12.1.2Where these conflict, the more stringent governs.
12.1.3No combustible-component assembly shall be deviated from its tested or evaluated configuration without renewed NFPA 285 documentation.
12.2 Substrate and Air/Water Barrier Verification
NOTE Once the panel is up, the air and water barrier behind it cannot be reached without removing the panel; the inspection regime is therefore front-loaded. (12.2.1)
NOTE The air barrier is specified in
Air Barriers and the inspection and acceptance of it before cover-up is a hold point.
(12.2.2) 12.2.3Before panel installation begins, the Contractor shall verify that the back-up wall, the continuous air barrier, and the water-resistive barrier are complete, continuous, inspected, and accepted, and that all transition flashings and penetration seals behind the panel are installed.
12.2.4The panel installer shall not cover an incomplete or unaccepted air or water barrier.
12.3 Sequence and Coordination
12.3.1The Contractor shall install the panels and their attachment in the planned sequence established at the pre-installation conference, coordinated with the flashing, fenestration, and sealant trades, so that flashings that must precede the panel are in place, drainage paths are continuous, and the panel face is not relied upon to seal a condition that should have been flashed behind it.
12.4 Handling of Field Cuts and Touch-Up
12.4.1Field cuts shall be deburred and the cut edges treated per the manufacturer.
12.4.2Field-painted touch-up shall match the factory finish and shall be limited to small concealed or non-prominent areas, because field paint weathers differently than the factory finish.
12.4.3Panels with visible damage or cracked finish on prominent surfaces shall be replaced, not touched up.
13 Delivery, Storage, and Handling
13.1Panels shall be delivered in the manufacturer's protective packaging with the protective film (where supplied) intact, and shall be stored off the ground, sloped to drain, under cover, and protected from standing water between stacked panels.
13.2The protective film shall be removed within the manufacturer's stated maximum exposure period, because films left in sunlight too long bond to the finish and become difficult to remove and can mar the coating.
13.3Panels shall be lifted and carried on edge, not dragged, to avoid scratching the finish and denting the face.
13.4Insulated metal panels shall be protected from point loads that crush the foam core and break the skin-to-core bond.
14 Warranty
NOTE The finish warranty is the long-life warranty that protects the building's appearance, and its term tracks the finish grade: a full-strength PVDF (AAMA 2605 / AAMA 621) finish carries the premium long-term color and chalk warranty, while lower finish grades carry shorter terms. (14.1)
20 years (PVDF / AAMA 2605 / AAMA 621 — premium)
10 years (AAMA 2604)
Per manufacturer's standard finish warranty for the specified grade
Not provided (Contractor installation warranty only)
5 years
10 years
Per manufacturer's standard system warranty
14.2The Contractor shall warrant the panel installation against leaks, panel disengagement, and defects in workmanship for a period of not less than two years from substantial completion, or for the period stated in the contract documents if longer.
14.3The Contractor shall provide the manufacturer's finish warranty covering film integrity, color change (ΔE per ASTM D2244), and chalk (ASTM D4214).
14.4Where a system or weathertightness warranty is offered, the Contractor shall provide the manufacturer's system warranty for the period the manufacturer provides.
14.5The Contractor shall satisfy the manufacturer's conditions — approved installer, matched components, and any required field documentation — on which the warranty depends.
14.6Any leak attributable to a defective panel joint, closure, or termination, and any finish failure within the warranted limits, shall be corrected at the Contractor's expense.
15 Spare Parts (Attic Stock)
1% of installed panel area of each panel type and color, plus matching trim and closures
2% of installed panel area of each panel type and color, plus matching trim and closures
Per contract documents
Not required
15.1The Contractor shall deliver to the Owner, where required by the contract documents, attic stock of panels, closures, and trim in the specified finishes and colors so that future damaged panels can be replaced with matching material, since a custom finish color may be unavailable or may not match a later production run.
15.2Touch-up finish in each specified color shall be provided in sealed factory containers.