1 Scope
NOTE This standard governs the manufacture, performance, and installation of rigid grid raised access flooring systems comprising removable panels supported on adjustable pedestals, with or without bolted stringers, over a structural slab. (1.1)
NOTE A raised access floor creates an accessible plenum between the structural slab and the finished floor that houses power, data, and cooling distribution while presenting a level, finished walking surface above. (1.2)
NOTE The accessible underfloor plenum is the defining feature of the system: panels lift out individually so that cabling, conduit, piping, and air distribution can be installed, reconfigured, and maintained without demolition. (1.3)
1.4The raised access floor system shall include panels, pedestals, stringers where required, perimeter and edge closures, cut-panel support, airflow panels where scheduled, and all bracing, fasteners, and accessories required for a complete installation.
1.5Where the underfloor space is used as a supply air plenum for underfloor air distribution, the airflow performance and air-sealing requirements of this standard apply in addition to the structural requirements.
1.6Where the understructure is used as a signal reference grid or as an equipment grounding path, the grounding and bonding requirements of Grounding And Bonding apply in addition to this standard. NOTE This standard does not cover the following, which are specified elsewhere: (1.7)
- The structural slab and slab leveling beyond the tolerances stated herein.
- The cooling equipment served by the plenum (see Computer Room Air Conditioning).
- The cabling and conduit routed within the plenum.
2 Referenced Standards
NOTE The following documents are referenced in this standard. The edition in force on the project's basis-of-design date governs unless a specific edition is cited by the Authority Having Jurisdiction. (2.1)
| Standard |
Title |
| CISCA Recommended Test Procedures for Access Floors |
Recommended Test Procedures for Access Floors (Ceiling and Interior Systems Construction Association) |
| ASTM E84 |
Standard Test Method for Surface Burning Characteristics of Building Materials |
| ASTM E136 |
Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at 750°C |
| ASTM F970 |
Standard Test Method for Static Load for Pile Yarn Floor Coverings |
| NFPA 75 |
Standard for the Protection of Information Technology Equipment |
| NFPA 70 |
National Electrical Code (Article 645 — Information Technology Equipment Rooms; Article 250 — Grounding and Bonding) |
| ASCE 7 |
Minimum Design Loads and Associated Criteria for Buildings and Other Structures (Chapter 13 — Seismic Design Requirements for Nonstructural Components) |
| IBC |
International Building Code |
| ASHRAE TC 9.9 / Datacom Series |
Thermal Guidelines for Data Processing Environments / ASHRAE Datacom Series |
| UFGS 09 69 13 |
Unified Facilities Guide Specification 09 69 13 — Rigid Grid Access Flooring |
3 Submittals
3.1 Action Submittals
3.1.1The Contractor shall submit the following action submittals for review before fabrication:
- Product data for each panel type, pedestal type, stringer type, and accessory, including construction, materials, and finishes.
- Manufacturer's load rating data demonstrating compliance with the scheduled concentrated load, ultimate load, rolling load, and uniform distributed load per CISCA test procedures.
- Shop drawings showing the floor layout, grid module, finished floor height, pedestal and stringer arrangement, seismic bracing layout, ramps, edge closures, and the location and support of cut panels.
- Panel schedule identifying the type, finish, load rating, and quantity of each panel, including airflow and cut panels.
- Samples of each panel finish and each airflow panel type for verification of color, texture, and open area.
- Seismic certification letter from the manufacturer specific to the project's Seismic Design Category, component importance factor, and the IBC and ASCE 7 editions of the basis of design.
☑ Product data (panels, pedestals, stringers, accessories)
☑ Load rating data per CISCA test procedures
☑ Shop drawings (layout, FFH, bracing, ramps, closures, cut panels)
☑ Panel schedule (type, finish, rating, quantity)
☐ Finish and airflow panel samples
☑ Seismic certification letter (project-specific SDC, Ip, IBC/ASCE 7 edition)
3.1.2The seismic certification letter shall reference the project's IBC and ASCE 7 editions; a generic certificate referencing a superseded code edition does not satisfy this requirement.
NOTE A generic seismic certificate referencing an older code edition is a common cause of last-minute documentation rejection by the Authority Having Jurisdiction, which is why project-specific certification is required. (3.1.3)
3.2.1The Contractor shall submit the following informational submittals:
- Independent test reports for concentrated load, ultimate load, rolling load, uniform distributed load, pedestal axial load, and pedestal overturning moment per CISCA test procedures.
- Surface burning characteristic test reports per ASTM E84 for panels and finishes.
- Combustibility test report per ASTM E136 for the panel core where required by the Authority Having Jurisdiction.
- Electrostatic discharge test data and surface resistance range where a static-dissipative finish is specified.
- Manufacturer's installation instructions, including pedestal adhesive and torque requirements.
☑ CISCA load test reports (concentrated, ultimate, rolling, uniform, pedestal)
☑ ASTM E84 surface burning test reports
☐ ASTM E136 core combustibility report
☐ ESD surface resistance test data
☑ Manufacturer's installation instructions
3.3 Closeout Submittals
3.3.1The Contractor shall submit the following closeout submittals:
- Operation and maintenance data, including panel removal and lifting procedures and cleaning recommendations.
- Record drawings showing the as-built floor layout, cut panel locations, and seismic bracing.
- Written warranty executed in the name of the Owner.
- Attic stock inventory documenting the type, finish, and quantity of spare panels and accessories delivered.
☑ Operation and maintenance data
☑ Record drawings (as-built layout, cut panels, bracing)
☑ Written warranty
☑ Attic stock inventory
4 Quality Assurance
4.1The manufacturer shall be regularly engaged in the production of rigid grid raised access flooring and shall furnish independent test data demonstrating compliance with the scheduled load ratings.
4.2The installer shall be trained or certified by the panel manufacturer and shall have completed installations of comparable scope and finished floor height.
4.3All panels, pedestals, and stringers shall be products of a single manufacturer's system; mixing components from different systems is prohibited because grid module, pedestal head geometry, and load paths are not interchangeable.
NOTE Mixing panels and understructure from different manufacturers is a frequent renovation failure: a 600 mm metric panel will not seat correctly on a 24 in grid understructure even though the dimensions appear nearly equal. (4.4)
4.5A field mock-up of a representative floor area shall be erected when required by the project to verify finished floor height, panel fit, finish, and pedestal stability before full installation proceeds.
4.6 Grid Module
4.6.1The nominal grid module shall be as scheduled below; all panels and understructure shall share one module so panels remain interchangeable across the floor.
24 x 24 in (610 x 610 mm)
600 x 600 mm
4.6.2The 24 in grid is the United States standard and is not dimensionally interchangeable with a 600 mm metric grid; the schedule shall confirm one module for the entire floor.
5 Environmental and Service Conditions
NOTE The raised access floor shall perform under the service conditions of the occupancy it serves; data halls, battery rooms, and offices impose different load, airflow, and finish demands that drive system selection. (5.1)
5.2 Occupancy
5.2.1The raised access floor shall be selected for the occupancy and equipment it serves, as scheduled below, because occupancy drives the concentrated load rating, finished floor height, finish, and airflow requirements.
Open office or workstation area
Command or control center
Computer room or data hall
UPS or battery room
Heavy equipment room
Electronics manufacturing or sensitive equipment room
5.3 Plenum Use
5.3.1The function of the underfloor plenum shall be established as scheduled below because it governs plenum depth, air sealing, fire compartmentation, and grounding requirements.
Cabling and power distribution only
Supply air plenum for underfloor air distribution (UFAD)
Combined air distribution and cabling
5.3.2Where the plenum serves as a supply air plenum, the air-sealing and airflow panel requirements of this standard apply; where it carries cabling only, those requirements do not apply but the structural requirements still govern.
6 System Configuration
NOTE The complete system is defined by four coordinated decisions: finished floor height, understructure type, panel core, and finish. These decisions are interdependent and shall be resolved together. (6.1)
6.2 Finished Floor Height
NOTE Finished floor height is the vertical distance from the top of the structural slab to the top of the finished access floor panel. (6.2.1)
6.2.2The finished floor height shall be as scheduled below and shall be coordinated with the structural slab elevation, adjacent floor finishes, door clearances, and ramp lengths early in design.
NOTE Finished floor height changes made late in design force pedestal re-selection and can cascade into conflicts with underfloor duct routing, which is why the height must be fixed and coordinated early. (6.2.3)
6.2.4Where the finished floor height exceeds approximately 12 in, the system shall be of the bolted stringer type to provide lateral stability, and seismic bracing shall be provided where the Seismic Design Category requires it.
NOTE The plenum depth required for underfloor air distribution shall be coordinated with the mechanical engineer because air volume, panel open area, and plenum depth are solved together in the airflow design. (6.2.5)
6.3 Understructure Type
6.3.1The understructure type shall be as scheduled below; the choice governs lateral stability, achievable height, load capacity, and the ease of single-panel removal.
Stringerless (free-standing or snap-on pedestal)
Bolted stringer
Hybrid (bolted stringer in designated zones)
NOTE The two understructure types trade lateral stability against installation speed: (6.3.2)
- A bolted stringer system connects pedestal heads with horizontal members, providing superior lateral stability and higher load capacity, and is required at tall finished floor heights and in seismic zones.
- A stringerless system speeds installation and allows panels to be lifted in any order without tools, which suits lower finished floor heights and lighter loads but does not always permit removal of a single interior panel without displacing neighbors.
6.3.3A stringerless system shall not be specified where maintainability requires removal of any single interior panel without disturbing adjacent panels; this operational requirement is a common reason to choose a bolted stringer or hybrid system.
6.4 Panel Core
6.4.1The panel core type shall be as scheduled below because the core governs load capacity, weight, combustibility, and electromagnetic shielding.
Steel welded or steel encapsulated
Cementitious (concrete-filled steel shell)
Wood core encapsulated in galvanized steel
Aluminum
NOTE The core types differ in load capacity, weight, combustibility, and environmental suitability: (6.4.2)
- Steel welded or steel encapsulated bonds steel top and bottom sheets to internal ribs or fill, providing the highest load capacity and an electromagnetic shielding benefit.
- Cementitious fills a steel shell with concrete, yielding excellent load distribution and a non-combustible core at a weight that can approach 15 lb/ft², and is favored under heavy equipment and in battery rooms.
- Wood-core encapsulates particle board in galvanized steel; it is the lightest option and suits offices and command centers at lower load ratings.
- Aluminum is lightweight and corrosion resistant and is used in corrosive or high-humidity environments where steel would degrade.
6.4.3Where the Authority Having Jurisdiction requires a non-combustible core, the panel core shall be tested to ASTM E136 and the test report submitted.
NOTE The structural performance of a raised access floor is defined by several distinct load metrics, each measured by a separate CISCA test procedure; these metrics are not interchangeable and each shall be satisfied independently. (7.1)
NOTE The single most common structural request for information arises from confusing concentrated load with uniform distributed load; a panel rated for a given point load may have an entirely different uniform load capacity, so both shall be scheduled and verified. (7.2)
7.3 Concentrated Load
7.3.2Each panel shall sustain the scheduled concentrated load with a deflection under load not exceeding 0.080 in and a permanent set after removal of the load not exceeding 0.032 in.
1000 lbf
1250 lbf
1500 lbf
2000 lbf
2500 lbf
7.3.3The concentrated load rating shall be matched to the equipment footprint and loading of the served occupancy; light office floors commonly use 1000 lbf, standard data halls 1250 lbf, heavy data halls 1500 lbf, and UPS or battery rooms 2000 to 2500 lbf.
NOTE Mismatching the equipment load type and footprint to the panel rating is the most common structural request for information on raised floor projects, which is why the rating is tied explicitly to the occupancy. (7.3.4)
7.4 Ultimate Load
NOTE The ultimate load is the safety margin above the working concentrated load; the panel shall not collapse below it. (7.4.1)
7.4.2Each panel shall sustain an ultimate concentrated load of not less than three times the scheduled concentrated load rating without structural failure per CISCA test procedure.
7.5 Rolling Load
NOTE The rolling load test simulates repeated passes of a loaded wheel, such as an equipment dolly, across the panel surface. (7.5.1)
7.5.2Each panel shall sustain the scheduled rolling load with a combined surface deformation not exceeding 0.040 in after the specified number of passes per CISCA test procedure.
NOTE The uniform distributed load is the load spread evenly across the panel surface, representing closely spaced racks or stored material. (7.6.1)
7.6.2Each panel shall sustain the scheduled uniform distributed load without exceeding the deflection limit established by the CISCA test procedure.
2501000
Default: 350 lbf/ft2
7.7.1Each pedestal assembly shall sustain the scheduled axial load without yielding per CISCA pedestal axial load test procedure.
500015000
Default: 5000 lbf
7.7.2Each pedestal assembly shall resist the overturning moment established by the CISCA pedestal overturning moment test procedure without separation of the base plate from the slab.
8 Pedestals and Stringers
NOTE Pedestals transfer all floor loads to the structural slab and set the finished floor height; their base plate area, adjustment, and locking govern stability and are specified here. (8.1)
8.2 Pedestal Base Plate
8.2.1Each pedestal base plate shall provide a minimum bearing area of 16 in² and a minimum thickness of 3 mm to distribute load into the slab without local crushing of the adhesive bond or slab surface.
8.2.2Each pedestal base shall be bonded to the structural slab with the manufacturer's recommended adhesive and, where the Seismic Design Category requires, mechanically anchored.
8.3 Pedestal Adjustment and Locking
8.3.1Each pedestal shall be height-adjustable over a range sufficient to accommodate slab tolerance and shall include a positive locking device to prevent loss of adjustment under vibration or load.
8.3.2The pedestal shaft and head shall engage with sufficient thread length to develop the full axial capacity and shall not back off under the rolling and vibratory loads of normal service.
8.4 Stringers
8.4.1Where a bolted stringer system is specified, stringers shall mechanically fasten to pedestal heads to form a rigid grid, with gaskets where required to maintain the plenum air seal.
8.4.2Bolted stringers shall be provided in all directions required to brace the grid against the lateral loads of the service condition, including seismic loads where applicable.
9 Panel Finishes
NOTE The panel finish is the visible walking surface and, in electronics environments, an electrostatic control surface; finish selection follows occupancy and is specified here independently of the panel core. (9.1)
9.2 Finish Type
9.2.1The panel finish shall be as scheduled below and shall be factory-applied and bonded to the panel; field-applied finishes are not permitted because they compromise edge alignment and removability.
High-pressure laminate (HPL)
Static-dissipative high-pressure laminate
Vinyl composition tile (VCT)
Luxury vinyl tile (LVT)
Carpet tile
Bare or powder-coated steel
NOTE High-pressure laminate is the most common finish for data centers and offices; static-dissipative grades are used where electronics require electrostatic control. (9.2.2)
9.2.3Where carpet tile finish is specified, the finish shall be evaluated for compressive resistance per ASTM F970 to confirm it does not deform under sustained equipment loading.
NOTE Bare or powder-coated steel finish is used only in plenum or sub-floor areas that are not walked on; it shall not be specified for occupied walking surfaces. (9.2.4)
9.3 Electrostatic Discharge Control
9.3.1Where the occupancy is electronics manufacturing or a sensitive equipment room, a static-dissipative finish shall be provided and its surface resistance shall fall within the scheduled range.
1.0 x 10^6 to 1.0 x 10^9 Ω (static-dissipative)
2.5 x 10^4 to 1.0 x 10^6 Ω (conductive)
9.3.2The static-dissipative finish shall be electrically connected to the pedestal understructure so that accumulated charge drains to ground; the finish grounding path shall be continuous across the floor.
NOTE Electrostatic finish grounding drains charge from the walking surface and is not equivalent to equipment grounding of the understructure; the two are separate systems and shall both be provided where required. (9.3.3)
10 Airflow Panels
NOTE Where the plenum serves underfloor air distribution, a portion of the floor is replaced with airflow panels that deliver conditioned air to the space; their quantity, open area, and damping are coordinated with the mechanical design and specified here. (10.1)
NOTE Airflow panel selection is a mechanical coordination task, not an independent finish choice; the percentage of airflow panels and their open area shall be confirmed against the airflow model before the panel schedule is finalized. (10.2)
10.3 Airflow Panel Open Area
10.3.1Airflow panels shall provide the scheduled open area; over-perforation short-circuits cooling air and under-perforation starves equipment, so the open area shall match the airflow design.
10.3.2The percentage of the floor provided as airflow panels and the location of those panels shall be coordinated with the underfloor air distribution model and shall be located as indicated. airflow panel locations NOTE Specifying airflow panel open area without coordinating with the mechanical engineer's underfloor air distribution model causes hot spots and short-circuit cooling, which is why coordination is required before the schedule is finalized. (10.3.3)
10.4 Damper Panels
10.4.1Where localized airflow control is required, gasketed damper panels with manual or motorized dampers shall be provided at the locations indicated to balance air delivery within the space. damper panel locations NOTE A damper panel allows the air volume at a specific grid location to be adjusted in service, which supports hot-aisle containment and tuning of the air balance after commissioning. (10.4.2)
11 Grounding and Bonding
NOTE A conductive understructure can serve as a signal reference grid and as part of the equipment grounding path; where it does, it shall be bonded in accordance with the National Electrical Code and
Grounding And Bonding.
(11.1) 11.2Where the floor is used as a signal reference grid or equipment grounding path, all non-current-carrying metal parts of the understructure, including pedestals and stringers, shall be bonded to the equipment grounding conductor in accordance with NEC Article 250 and Article 645.
11.3Bonding conductors shall connect the pedestal grid to the building grounding electrode system at the frequency and conductor size indicated. understructure bonding points NOTE The understructure bonding for the signal reference grid is a separate system from the electrostatic finish grounding; specifying one does not satisfy the other, and both shall be provided where each is required. (11.4)
NOTE Use of the underfloor space as a wiring method under NEC Article 645 shall be confirmed with the Authority Having Jurisdiction, because some jurisdictions do not adopt Article 645 and require conduit under the floor regardless of the plenum designation. (11.5)
12 Fire and Plenum Compartmentation
NOTE Raised access floors are not fire-resistance-rated assemblies in the listing sense; fire safety in the plenum is achieved by barriers within the plenum and by controlling combustible loading, not by a rating on the floor assembly itself. (12.1)
12.2Panels and finishes shall meet a Class A surface burning classification with a flame spread index not exceeding 25 and a smoke developed index not exceeding 50 when tested per ASTM E84.
12.3A fire-resistance rating shall not be specified for the access floor assembly itself unless a listed assembly demonstrably exists; compartmentation shall instead be achieved by rated barriers within the plenum.
12.4Where the plenum crosses a fire-rated partition line, a fire-rated barrier shall be provided within the plenum to maintain continuity of the partition's rating, coordinated with the fire protection design. plenum fire barrier locations 12.5Combustible loading and fire detection under the raised floor shall comply with NFPA 75 for information technology equipment rooms.
13 Air Leakage
NOTE In an underfloor air distribution system, air that leaks at panel joints, the perimeter, and penetrations is cooling capacity lost before it reaches the equipment; uncontrolled leakage can waste 20 to 40 percent of the underfloor air. (13.1)
13.2Where the plenum serves underfloor air distribution, the assembled floor, perimeter, and penetrations shall not exceed the scheduled maximum air leakage rate.
0.050.5
Default: 0.1 cfm/ft2
13.3Panel perimeters and the floor perimeter shall be sealed with factory gaskets or site-applied sealant to limit leakage to the scheduled rate.
13.4Every penetration of the floor for cabling, conduit, or piping shall be fitted with a sealed sleeve, grommet, or brush gasket; leaving penetrations unsealed invalidates the airflow design.
14 Cut Panels and Penetrations
NOTE A panel cut for a cable opening, column closure, or equipment cutout loses support at one or more corners and will rock, deflect, or overload its neighbors unless supplemental support is provided; cut-panel support is a frequent site request for information and is specified here. (14.1)
14.2Every panel cut so that it loses corner support shall be provided with supplemental support, such as a support angle, pedestal saddle, or stringer extension, sized to restore the panel's load rating.
14.3Supplemental cut-panel support shall be located as indicated, particularly at cable openings, column closures, and equipment cutouts. cut-panel support locations 14.4Cut edges shall be sealed and, where the plenum serves air distribution, gasketed to maintain the plenum air seal.
15 Edge, Perimeter, and Ramps
NOTE The perimeter closure completes the floor at walls, transitions, and changes in level; it maintains the plenum air seal, the finished appearance, fire barrier continuity, and accessible ramp compliance, and shall not be delegated to the field without design criteria. (15.1)
15.2Fascia panels and closure strips shall be provided at the floor perimeter and at transitions to adjacent floor levels to maintain the plenum air seal and a finished appearance.
15.4Where a ramp serves an accessible route, its running slope shall not exceed 1:12 to comply with accessibility requirements.
1220
Default: 12 ratio (1:n)
15.5The edge closure system shall maintain continuity of any fire-rated barrier and of the plenum air seal across the transition.
16 Seismic Bracing
NOTE In moderate and high seismic design categories the raised floor is a nonstructural component that must be braced against lateral earthquake loads; bracing hardware is not included in base system pricing and shall be specified explicitly to avoid value-engineering deletion and code non-compliance. (16.1)
16.2Seismic bracing shall be provided where the project's Seismic Design Category is C through F, in accordance with ASCE 7 Chapter 13 and the IBC.
16.3Diagonal sway bracing shall be provided at the pedestal base or stringer level, and the maximum unbraced panel run shall not exceed the manufacturer's certified limit for the Seismic Design Category.
16.4The component importance factor shall be as scheduled below; essential facilities such as data centers and emergency operations centers require the higher factor.
1.0 (standard occupancy)
1.5 (essential facility)
16.5The manufacturer shall furnish a seismic certification letter specific to the project's Seismic Design Category, component importance factor, and the IBC and ASCE 7 editions of the basis of design.
17 Installation
NOTE Installation shall not begin until the structural slab has been cleaned, leveled within tolerance, and accepted, because pedestal adhesive bond and finished floor flatness both depend on slab condition. (17.1)
17.2The structural slab shall be clean, dry, and free of laitance, curing compounds, and debris before pedestal adhesive is applied.
17.3Pedestals shall be set on a grid laid out from established control lines so that panel joints align and the grid module is held uniform across the floor.
17.4Pedestal base adhesive shall be cured per the manufacturer's instructions before panels are loaded or traffic is permitted on the floor.
17.5Stringers, where specified, shall be installed and fastened before panels are placed, so that the grid is braced as it is assembled.
17.6 Installation Tolerances
17.6.1The finished floor surface shall be level within the scheduled flatness tolerance measured across the panel field.
0.040.125
Default: 0.06 in per 10 ft
17.6.2Panel-to-panel height differential at joints shall not exceed the manufacturer's tolerance so that the surface presents no trip hazard and panels remain interchangeable.
17.7Panels shall be cut from full panels for openings and penetrations using the manufacturer's methods, and every panel that loses corner support shall receive the supplemental support specified in this standard.
17.8Field-cut openings shall be deburred and sealed, and gasketed where the plenum serves air distribution.
18 Testing
NOTE Field testing verifies that the installed floor meets the structural, flatness, and, where applicable, air leakage requirements of this standard before the floor is accepted. (18.1)
18.2A representative sample of installed panels shall be field-verified for stability and the absence of rocking, particularly at cut panels and at the perimeter.
18.3The installed floor surface shall be verified against the scheduled flatness tolerance after installation is complete.
18.4Where the plenum serves underfloor air distribution, the assembled plenum shall be tested for air leakage and shall not exceed the scheduled maximum leakage rate before the cooling system is balanced.
18.5Where the understructure serves as a signal reference grid or equipment grounding path, the continuity of the bonding network shall be verified by resistance measurement.
19 Delivery, Storage, and Handling
19.1Panels and accessories shall be delivered in the manufacturer's original packaging, labeled with type, finish, and load rating.
19.2Panels shall be stored flat, indoors, protected from moisture and physical damage, and acclimated to the room environment before installation where the finish requires it.
19.3Panels with finished surfaces shall be handled to protect the finish from scratching, soiling, and edge damage during delivery and installation.
20 Warranty
20.1The manufacturer shall warrant the raised access floor system against defects in materials and workmanship for the scheduled period from the date of substantial completion.
1 year
2 years
5 years
10 years
20.2The warranty shall cover panel structural failure, finish delamination, and pedestal failure under the rated service loads.
21 Spare Parts
NOTE Spare panels and accessories shall be furnished so that damaged panels can be replaced in service without waiting for new production, which can interrupt operation of a live data hall. (21.1)
21.2The Contractor shall furnish attic stock of full panels, airflow panels, and pedestals of each type and finish installed, in the scheduled quantity as a percentage of the installed count.
15
Default: 2 percent of installed
21.3Spare panels shall match the installed panels in type, finish, and load rating, and shall be delivered in protective packaging labeled for storage.