DDAA-2P-10xE — New-construction reinforced roof system

DDAA-2P-10xE is a two-ply all-acrylic Western Colloid roof system. Its title is New Construction or Re-Roof, Insulation/DensDeck Prime, with a 2 ply polyester reinforced acrylic surface. The system installs a new cold process, water based membrane on approved combustible or non-combustible decks. It is used over concrete or wood decks with insulation and DensDeck Prime, directly on concrete, or over existing membranes. The system is renewable, has very low odor and finishes with a reflective elastomeric coating. Named criteria are U.L. Class A, Factory Mutual Standard 4470 Class 1, California Title 24, LEED (USGBC) and Energy Star, with wind uplift of 1-510 (FM) over DensDeck and 1-990 (FM) over concrete.

Seven layers form the membrane. Approximate dry weights are per 100 sq. ft.

• Base coat of ElastaHyde: 3 gallons, 21 lb
• Polyester fabric, first ply: 2.5 lb
• Interply coat of ElastaHyde: 2.5 gallons, 17.5 lb
• Polyester fabric, second ply: 2.5 lb
• First top coat of ElastaHyde: 1.5 gallons, 10.5 lb
• Second top coat of ElastaHyde: 1.5 gallons, 10.5 lb
• Reflective surface coating of ElastaHyde: 1.5 gallons, 10.5 lb

Total system dry weight is 75.0 lb and approximate total dry thickness is 108 mils.

A wood deck has all nails secured and gaps between deck joints of no more than 1/4 inch, and any deteriorated areas are repaired or replaced. A concrete deck is cured, smooth and uniform, without ridges or voids, and clean of dust and debris. When an existing roof stays in place, loose gravel, dirt, dust and debris are removed by vacuum, sweeping or power blower, and the surface is made uniform without ridges or raised areas. Where insulation goes in, curbs, flashings and vents are raised to meet local or state code requirements.

Boards are adhered to the deck with approved adhesive in line with the wind uplift rating and the associated ribbon spacing patterns. The maximum board size with board adhesives is 4 ft by 4 ft for insulation and 4 ft by 8 ft for roof boards. Insulation boards may also be attached with mechanical screws and plates at 18 fasteners per 4 by 8 board. DensDeck Prime is attached to the insulation with INSTA STIK adhesive in 12 inch ribbons. The adhesive is a single-component polyurethane board adhesive with a minimum ambient and surface temperature of 33 degrees F and rising.

The first ply goes on with ElastaHyde at 3 gallons per 100 sq. ft. and half-width then full-width polyester. After it cures, ElastaHyde at 2 gallons per 100 sq. ft. receives the second full-width ply. Both plies stop 2 inches above the cant. After the membrane dries, two top coats of ElastaHyde at 1 1/2 gallons per 100 sq. ft. are applied at right angles, with 24 hours between them. A reflective coat of 1 1/2 gallons per 100 sq. ft. finishes the roof.

ElastaHyde 720 ARC meets ASTM D6083 for 100 percent acrylic roof coating. White has a solar reflectivity of 84 percent initially (ASTM C1549), a thermal emittance of 89 percent (ASTM C1371), and an aged SRI of 93. Permeance is below 15 and low temperature flexibility is Pass at 15 degrees F (ASTM D522). #800 Elastic Cement cures through dehydration over 1 to 2 days, and its tack-free time is 1 hour. Applied by the three course method, it gives a finished membrane about 1/8 inch thick. Penetration repairs use the same #800 and polyester detail that is part of the liquid-applied reinforced roofing system.

The preparation and repair steps that use no water based materials can be done just before inclement weather. Stored materials are kept out of the weather with lids closed, and loads left on the roof stay within its live load limit.

• Polyester fabric: Western Colloid 2.75 ounce firm or 3.0 ounce soft stitchbonded polyester, supplied in various widths, used to reinforce asphalt emulsion, acrylic coating and flashing materials
• #8000 All Weather Elastic Cement: a solvent-based white sealant that sets the flange of a new or replaced pipe jack, and a stated alternative to #800 where more immediate water resistance is needed
• #850 SWS walkway coating: a water based coating of acrylic resins and binders with an aggregate that forms a textured, non-slip surface with high abrasion resistance

• Flammability: non-flammable wet, Class A dry (U.L. 790 and ASTM E108)
• 1000 hour xenon arc UV exposure: Pass (ASTM D4798)

• Solids: 53 percent by volume (ASTM D2697) and 66 percent by weight (ASTM D1644)
• Weight per gallon: approximately 11.5 to 12 lb
• Viscosity: 100 to 110 KU (ASTM D562)
• Application temperature: minimum 50 degrees F, maximum 100 degrees F ambient
• Drying time: 1 hour at 100 sq. ft. per gallon, 70 degrees F and 50 percent relative humidity
• Dry film thickness: minimum 20 mils, 24 or more recommended
• VOC: actual 10, regulatory 20
• Coverage: 75 to 100 sq. ft. per gallon per coat, 2 1/2 to 6 gallons per 100 sq. ft. in total depending on specification and surface

• White (#800W) or black (#800B); the black dries faster in cold weather
• Packaging: 5-gallon pails
• Total solids: 65 to 70 percent by weight
• Elongation: greater than 500 percent; remains flexible below freezing
• Application temperature: minimum 50 degrees F
• Cure through dehydration: 1 to 2 days; tack free in 1 hour; can be coated in 1 to 2 hours
• Maximum single application: less than 3/16 inch thick, with multiple coats where more is required

#800 Elastic Cement is a heavy-bodied compound of acrylic rubber resins, inert mineral pigments and non-asbestos fibers. It is applied by brush or trowel, and brushing is preferred. The surface can be dry or damp but not wet, and clean of dirt, dust and oil. The cement bonds to asphalt emulsion, wood, metal and masonry without special primers, and new glazed asphalt roofs take #970 primer first. Rusted metal is cleaned and primed with #900R Rust Primer. The cement is non-flammable, low odor and not DOT regulated, and equipment is cleaned with water.