SMEA-2P-6xE — Acrylic-surfaced reinforced roof system

SMEA-2P-6xE is a Western Colloid roof system with an emulsion membrane and an acrylic surface. It is titled Upgrade Smooth Surface / Cap Sheet / Single Ply, with one ply of polyester set in emulsion for the membrane and one ply of polyester set in acrylic for the surface. The cold process, water based system upgrades existing BUR, Mod Bit, EPDM, TPO and Hypalon roofs. It has very low odor, uses light weight polyester reinforcement and finishes with a reflective elastomeric coating. California Title 24, LEED (USGBC) and Energy Star are named for this assembly, together with Factory Mutual Standard 4470 Class 1 and U.L. Class A.

The system is classified as a cap, single-ply, smooth surface assembly, with a title of 2-Ply Polyester Reinforced and Reinforced Acrylic Surface. It is U.L. Classified and FM 4470 Class 1 Approved. The specification is numbered 18 and was revised 10/20.

Five layers form the system, with approximate dry weights per 100 sq. ft.

• Base coat of #298 Emulsion: 6 gallons, 23 lb
• Polyester fabric set in emulsion: 1 ply, 2.5 lb
• Base coat of ElastaHyde: 3 gallons, 21 lb
• Polyester fabric set in ElastaHyde: 1 ply, 2.5 lb
• Surface and reflective coating of ElastaHyde White Acrylic: 3 gallons, 21 lb

Total system dry weight is 70.0 lb and approximate total dry thickness is 115 mils. The three-ply SMEA-3P-6xE adds a second emulsion ply and totals 95.5 lb.

The membrane is repaired until it is sound and watertight before any coating is applied. Debris is removed by vacuum, washing, sweeping or power blower. Valleys and ponding areas are washed, and priming with diluted #298 emulsion is used where needed. The same areas also get an extra ply of polyester in #298. Blisters are repaired with a floating patch and splits with modified cap sheet in asphalt flashing compound, with patch edges reaching at least 6 inches past the damage. Small splits get a three course repair of #800 Elastic Cement with polyester fabric.

The emulsion layer is one coat of #298 at 6 gallons per 100 sq. ft. and one full-width polyester ply, started at the low edge of the roof. Plies overlap a minimum of 3 inches and end laps a minimum of 4 inches. The ply is lightly broomed until it is saturated with no wrinkles or voids and it stops 2 inches above the cant. Walking on the fabric while the emulsion is wet displaces it, and no top coat of #298 is applied. Once the emulsion has dried, the acrylic layer follows early in the day. ElastaHyde is applied at 3 gallons per 100 sq. ft. with a full-width polyester ply embedded in the wet coat, ending 2 inches above the cant. The reflective surface is two coats of ElastaHyde at 1 1/2 gallons per 100 sq. ft. each, applied cross-hatch, with 24 hours of drying after the first.

The system is water based. Application takes place at a minimum of 55 degrees F and rising. Application is not attempted when rain, inclement weather or temperatures below 40 degrees F are expected within 48 hours. Ice or frost on the roof surface or deck rules out application. #298 Asphalt Emulsion and the other water based layers cure through dehydration.

T272 is the 3.0 ounce soft stitchbonded fabric, sold as WCP-HS. It is a medium-soft product that conforms well on smooth or semi-smooth surfaces such as cap sheet. Its close knit may call for light brooming to embed it and release air pockets. Properties are 0.025 inch thickness, 57 lb tensile, 61 percent elongation, 176 lb burst strength and 16 lb trapezoid tear. It is used as flashing reinforcement with mastics and elastomerics, and in narrow widths in elastomeric metal roof systems. Rolls come in 10 square (40 inches by 324 feet) and in 4, 6, 12 and 18 inch widths. The alternative W26/T326 fabric is 2.75 ounces with a firm finish, 41 lb tensile and 25 percent elongation.

#298 Asphalt Emulsion is applied as a surface protectant or waterproofing compound with polyester or fiberglass reinforcement. Its listed uses include a uniform weathering surface on smooth or mineral surfaced built-up roofing, a protective surface for metal roofing, masonry, stucco, parapet walls and curbs, a damp proofing compound for below grade walls, and a base coat for SilverWhite #525 or ElastaHyde. #800 Elastic Cement adheres to asphalt emulsion, wood, metal and masonry without special primers, while new glazed asphalt roofs are primed with #970 Primer first. ElastaHyde is rated for 1000 hours of xenon arc UV exposure with a Pass (ASTM D4798), has elongation above 250 percent initially and above 175 percent after weathering, and has tensile strength above 250 psi (ASTM D2370). It is the surface layer of this reinforced liquid-applied roof system.

Published properties of the layers that make up the membrane and surface follow.

• #298 Asphalt Emulsion total solids: 45-50 percent
• #298 weight per gallon: 8.2-8.7 lb
• #298 consistency: brush or spray
• #298 drying time: 12 hours firm set at 70 degrees F and 50 percent relative humidity
• #298 minimum application temperature: 50 degrees F
• #298 VOC: actual 0, regulatory 0
• #298 flexibility at 32 degrees F: no cracking or flaking
• #298 heat resistance at 212 degrees F: no sag, blistering or slipping
• #298 containers: 5-gallon pails, 55-gallon drums, totes and bulk
• #800 Elastic Cement total solids: 65-70 percent by weight
• #800 elongation: greater than 500 percent
• #800 tack free time: 1 hour
• #800 cure time: 1 to 2 days
• ElastaHyde 720 ARC solids: 53 percent by volume and 66 percent by weight
• ElastaHyde 720 ARC coverage: 75 to 100 sq. ft. per gallon per coat
• ElastaHyde 720 ARC application temperature: 50 to 100 degrees F ambient
• ElastaHyde 720 ARC VOC: actual 10, regulatory 20

ElastaHyde 720 ARC white has an initial solar reflectance of 84 percent, thermal emittance of 89 percent and an SRI of 106, falling to 93 aged. It is listed by the Cool Roof Rating Council in white, California Tan and Platinum Gray. A quick set version, #720 QS, is made for application when damp, wet or rainy weather is expected.

• #8000 All Weather Elastic Cement: solvent-based white sealant for asphalt BUR, modified bitumen, metal and single ply roofs including EPDM, PVC, TPO and Hypalon, used where wet conditions are present
• #850 SWS Walkway Coating: water based acrylic coating with an aggregate that forms a textured non-slip surface on smooth and coated roofs
• #970 Primer: used on new glazed asphalt roofs before #800 Elastic Cement
• WCP-SF fabric (W-26, Tietex T326): 2.75 ounce, 0.025 inch thick, 127 lb burst strength, 14 lb trapezoid tear, sold in 10 square rolls of 40 inches by 324 feet