Dens-Deck® Prime Roof Board
G-P Gypsum Corporation
133 Peachtree Street, N.E.
Atlanta, GA 30303
Technical 1-800-225-6119 (8-7 EST)
Dens-Deck® Prime roof board combines an exceptional fire barrier, thermal barrier and recovery board used in various commercial roofing systems with a pre-primed surface to make the bond even stronger. The patented Dens-Deck® design employs glass mat facings front and back that are embedded into a water resistant and moisture resistant treated gypsum core, providing excellent fire resistance, moisture resistance and wind uplift properties. The unique construction of Dens-Deck® Prime provides superior flute spanning and will help stiffen and stabilize the roof deck. Additionally, Dens-Deck® Prime has been shown to withstand delamination, deterioration, warping and job-site damage more effectively than roofing membrane substrates such as paper-faced gypsum board, fiberboard, and perlite insulation.
Roof system manufacturers and designers have found Dens-Deck® Prime roof board to be compatible with many types of roofing systems, including: modified asphalt, single ply, metal systems, recover board, as well as an overlayment for polyisocyanurate and polystyrene insulation. Dens-Deck® Prime 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® Prime may also be used in vertical applications as a backer board or liner for the roof side of parapet walls.
Dens-Deck® Prime allows the bonding of cold mastic modified bitumen and torching directly to the surface. Refer to specific membrane system application instructions. System manufacturers and designers have found Dens-Deck® Prime to be compatible with bonding adhesives for fully-adhered single-ply membrane applications and has been shown to extend the adhesive usage.
Dens-Deck® Primes exceptional moisture resistance and low R-value make it the preferred substrate for vapor retarders. An excellent fire barrier, Dens-Deck® Prime 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® Prime 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® Prime can replace any generic type X gypsum board in any roof assembly in the UL Fire Resistance Directory under the prefix P.
Dens-Deck® Prime is designed to act with a properly designed roof system. The actual use of Dens-Deck® Prime roof board as a roofing component is the responsibility of the roofing systems 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 specific manufacturers instructions for applying the various roofing types to Dens-Deck® Prime roof board.
Panels must be kept dry before, during and after installation. Apply only as much Dens-Deck® Prime 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® Prime 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® Prime 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® Prime; 5" for 1/2" Dens-Deck® Prime; and 8" for 5/8" Dens-Deck® Prime Fireguard® Type X.
Refer to the installation instructions for the specific roof system to be installed for additional requirements.
Flame spread 0, smoke developed 0, when tested in accordance with ASTM E 84 or CAN/ULC-S102. Noncombustible when tested in accordance with ASTM E 136.
Dens-Deck® Prime Fireguard®: UL Classified when tested in accordance with ASTM E 119.
1/4 Dens-Deck® Prime has been G-P sponsored tested with 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® Prime in their FMRC-approved construction designs.
- Dens-Deck® Prime should be used with fasteners specified in accordance with FM requirements and roof membrane manufacturers written recommendations.
- For wind uplift/FMRC compliance where Dens-Deck® Prime is mechanically attached to metal decks, Dens-Deck® Prime shall be installed to the specifics of the FMRC design assembly.
- For installations involving BUR, EPDM, thermoplastics and modified bitumen roof systems, call Technical Hotline at 1-800-ROOF-411 for fastener patterns of G-Ps FMRC uplift assemblies.
- In accordance with approved shop drawings, FM-approved fasteners shall be installed with plates through the Dens-Deck® Prime, flush with the surface.
- Where Dens-Deck® Prime is installed over combustible wood decks or insulation, all joints should be staggered. The optional separator sheet should be installed prior to Dens-Deck® Prime installation.
- Edge joints should be located on, and parallel to, deck ribs. End joints of adjacent lengths of Dens-Deck® Prime should be staggered.
- For FM Class I-60, fastener density typically is increased by 50% at the roof corners, in conjunction with FM-approved covering.
- For FM Class I-90, fastener density typically is increased by 50% at the roof corners and roof perimeter, in conjunction with FM-approved covering.
- Adhered Systems: Insta-Foam Products, Inc.s Insta-Stik Adhesive used with 1/4" Dens-Deck® Prime achieved a FMRC Class I-180 according to test report 1Y7A5.AM in selected Class 1 insulated steel and concrete deck roof construction. Contact Insta-Foam Products, Inc. for details at 1-800-800-FOAM.
- Dens-Deck® Prime shall be installed with ends and edges butted tightly.
- Dens-Deck® Prime is manufactured to conform to ASTM C1177.
| Product Specifications (Nominal) |
5/8"15.9mm Fireguard® type X
|Lengths||8' 2440mm standard, tolerance 1/4" 6.4mm;|
Optional: 4' 1220mm available
|Spanning||1/4" Dens-Deck® Prime spans flute widths up to 2 5/8";|
1/2" Dens-Deck® Prime spans flute widths up to 5";
5/8" Dens-Deck® Prime spans flutes up to 8" wide
| Properties || 1/4"|
|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/primed||Glass mat/primed||Glass mat/primed|
|Flexural Strength, Parallel, lbs. min.4 ||405 ||805 ||1005 |
|Flexural Strength, Perpendicular, lbs. min.4 ||505 ||1005 ||1405 |
|Flute Spanability1 ||2-5/8"||5"||8"|
|Permeance Perms2 ||50||35||32|
|R Value3 ||.28||.56||.67|
|Coefficient of Thermal Expansion, Inches/inch/°F||8.5 x 10-6 ||8.5 x 10-6 ||8.5 x 10-6 |
|Linear Variation with Change in Moisture in/in/%RH||6.25 x 10-6 ||6.25 x 10-6 ||6.25 x 10-6 |
|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||FMRC Class 1, UL 1256, ULC S-126, UL Class A, ULC 102||FMRC Class 1, UL Classified P assemblies, ULC S-101|
|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.
1 Campus Drive
Parsippany, NJ 07054
Tollfree: (800) 766-3411
Web site: http://www.gaf.com