G-P Gypsum Corporation
133 Peachtree Street, N.E.
Atlanta, GA 30303
Technical Hotline: 1 -800-225-6119 (8-7 ET)
Dens-Deck® roof board is an exceptional fire barrier, thermal barrier and recovery board used in various commercial roofing systems. The patented Dens-Deck® design employs glass mat facings front and back that are embedded into a water-resistant gypsum core, providing excellent fire resistance, moisture resistance and wind uplift properties. The unique construction of Dens-Deck® provides superior flute spanning that stiffens and provides increased foot traffic resistance to the roof deck. Additionally, Dens-Deck® has been shown to withstand delamination, deterioration, warping and job-site damage more effectively than other roofing membrane substrates such as paper-faced gypsum board, fiberboard and perlite insulation.
Roof system manufacturers and designers have found Dens-Deck® roof
board to be compatible with many types of roofing systems, including: built-up,
modified bitumen, single ply, metal systems, wood shingle and shake, tile, slate,
recover board, as well as an overlayment protection board for polyisocyanurate and
polystyrene insulation. Dens-Deck® can also be used as a form board
for poured gypsum concrete deck in roof applications as well as a substrate for
spray foam roofing systems. 1/2" and 5/8" Dens-Deck® may also be
used in vertical applications as a backer board or liner for the roof side of parapet
Some membrane manufacturers have hot mop asphalt or torch applications directly to Dens-Deck® without using a primer or base sheet. Refer to specific membrane system application instructions. System manufacturers and designers have found Dens-Deck® to be compatible with bonding adhesives for fully-adhered single-ply membrane applications.
Dens-Deck’s exceptional moisture resistance and low R-value make it the preferred substrate for vapor retarders.
An excellent fire barrier, Dens-Deck® features a noncombustible core and inorganic surface that offers greater fire protection than other conventional commercial roofing products when applied over combustible roof decks and steel decks. Dens-Deck® is FM tested and approved as the only 1/2" gypsum product to meet the calorimeter requirements for conventionally insulated decks. Tested in accordance with ASTM E 84, its surface burning characteristics are Flame Spread-0 and Smoke Developed-0. 5/8" Dens-Deck® can replace any generic type X gypsum board in any roof assembly in the UL Fire Resistance Directory under the prefix “P”.
Dens-Deck® is designed to act with a properly designed roof system.
The actual use of Dens-Deck® roof board as a roofing component is
the responsibility of the roofing system’s designing authority.
Conditions beyond the control of G-P Gypsum such as weather conditions, dew, application temperatures and techniques may cause adverse effects with adhered roofing systems. Always consult the roofing system manufacturer’s specific instructions for applying the various roofing types to Dens-Deck® roof board.
Panels must be kept dry before, during and after installation. Apply only as much Dens-Deck® as can be covered by a roof membrane system in the same day.
Accumulation of water due to leaks or condensation in or on Dens-Deck® roof board must be avoided during construction and after construction. Avoid over-use of non-vented direct-fired heaters during winter months. Avoid application of Dens-Deck® during rains, heavy fogs and other conditions that may deposit moisture on the surface.
When applying solvent-based adhesives or primers, allow sufficient time for the solvent to flash off to avoid damage to roofing components.
Maximum flute span is 2-5/8" for 1⁄4" Dens-Deck®; 5" for 1/2" Dens-Deck®; and 8" for 5/8" Dens-Deck® Fireguard® Type X. 1/4" Dens-Deck® is not recommended for vertical parapet applications.
Refer to the installation instruction for the specific roof system to be installed for additional requirements.
Flame spread 0, smoke developed 0, when tested in accordance with ASTM E84 or CAN/ULC-S102.
Noncombustible when tested in accordance with ASTM E136.
Dens-Deck® Fireguard®: UL Classified when tested in accordance with ASTM E119.
1/4" Dens-Deck® has been tested by Factory Mutual for 60 psf and 90 psf wind uplift for BUR, EPDM, thermoplastics and modified bitumen roof systems. Higher wind uplift ratings have been achieved by numerous membrane manufacturers using Dens-Deck® in their FMRC-approved construction designs.
|Product Specifications (Nominal)|
5/8"—15.9mm Fireguard® type X
8' — 2440mm standard, tolerance 1/4" — 6.4mm;
Optional: 4' — 1220mm available;
Other lengths special order
1/4" Dens-Deck® spans flute widths up to 2 5/8";
1/2" Dens-Deck® spans flute widths up to 5";
5/8" Dens-Deck® spans flutes up to 8" wide
|Thickness, nominal inches||5/16"||1/2”||5/8"|
|Length, standard||8' ± 1/4"||8' ± 1/4"||8' ±1/4"|
|Weight, lbs./M sq. ft., nominal||1100||1950||2500|
|Surfacing||Glass mat||Glass mat||Glass mat|
|Flexural Strength, Parallel, lbs. min.4||405||805||1005|
|Flexural Strength, Perpendicular, lbs. min.4||505||1005||1405|
|Coefficient of Thermal Expansion, Inches/inch/°F||8.5 x 106||8.5 x 106||8.5 x 106|
|Linear Variation with Change in Moisture in/in/%RH||6.25 x 106||6.25 x 106||6.25 x 106|
|Absorption, % max4||10.0||10.0||10.0|
|Surface Water Absorption, grams4||2.5||2.5||2.5 Flame Spread|
|Smoke Developed (ASTM E 84)||0||0||0|
|Fire Classification||UL Class A, ULC S-102, UL 1256, ULC S-126, UL 790, ULC S-107||FMRC Class 1, UL 1256, ULC S-126, UL Class A, ULC 102, UL 790, ULC S-107||FMRC Class 1, UL Classified ‘‘P’’ assemblies, UL 790, ULC S-107|
|FM Uplift Approvals||60 and 90 psf uplift||FMRC 1-60, 1-90||FMRC 1-60, 1-90|
1 Tested in accordance with ASTM E661 (400 lb. conc. load)
2 Tested in accordance with ASTM C355 (dry cup method)
3 Tested in accordance with ASTM C518 (heat flow meter)
4 Tested in accordance with ASTM C473
5 ASTM C 1177 minimums
All documents are U.S. English unless otherwise noted