SM-1P-4.5xE — Acrylic-surfaced reinforced roof system

SM-1P-4.5xE is a Western Colloid specification number for a reinforced liquid-applied roofing assembly, revised 01/22 and issued under the heading Western Cool Roof Systems. The classification is upgrade, smooth surface / cap sheet / single ply, with 1 ply polyester reinforcement and an embedded acrylic surface.

The assembly is a cold process method to upgrade existing roofing, including BUR, Mod Bit, EPDM, TPO and Hypalon. It is water based, has very low odor and is reinforced with light weight polyester fabric. The surface is a highly reflective elastomeric coating.

The system has three layers. Amounts and dry weights are approximate and apply per 100 square feet.

• Base coat: #298 Asphalt Emulsion, 6 gallons, 23 pounds dry.
• Reinforcement: polyester fabric, 1 ply, 2.5 pounds.
• Surface and reflective coating: ElastaHyde White Acrylic, 4.5 gallons, 32 pounds dry.

Total system dry weight is 57.5 pounds per 100 square feet. Approximate total dry thickness is 90 mils. The fabric is stitchbonded polyester, 2.75 ounce firm or 3.0 ounce soft, available in various widths.

The assembly meets U.L. Class A and Factory Mutual Standard 4470 Class 1. It is also listed as meeting California Title 24, LEED (USGBC) and Energy Star criteria.

#298 is an asphaltic bentonite clay emulsion made to ASTM D1227 Type III and D1187. Its dry film remains flexible and does not sag, flow or re-emulsify. In the physical data, total solids are 45 to 50 percent, weight is 8.2 to 8.7 pounds per gallon and the wet film is non-combustible.

The emulsion shows no cracking or flaking at 32 degrees F and no sag, blistering or slipping at 212 degrees F. VOC is 0 actual and 0 regulatory.

ElastaHyde #720 ARC is a 100 percent acrylic white reflective coating that meets ASTM D6083 for 100% acrylic roof coating. It is listed by the Cool Roof Rating Council and can be used to comply with 2016 California Title 24 cool roof requirements. The ENERGY STAR guidelines are met for white, Platinum Gray and California Tan only.

• Initial solar reflectivity: 84 percent (ASTM C1549).
• Initial thermal emittance: 89 percent (ASTM C1371).
• SRI: 106 initial and 93 aged (ASTM E1980-01).
• Fire: Class A under U.L. 790 and ASTM E108 when dry.
• Solids: 53 percent by volume and 66 percent by weight.
• Minimum dry thickness 20 mils; recommended 24 mils or more.

CRRC product ID 0682-003 for white lists solar reflectance of 0.84 initial and 0.75 weathered. The coating can be produced in colors. Over smooth asphalt, emulsion or non-granulated modified bitumen, #970 A2A Primer goes on before the base coat.

The existing membrane is repaired and made sound and watertight before the new system goes on. Loose gravel, dirt and debris are removed by vacuum, washing, sweeping or power blower. Valleys and ponding areas receive an extra ply of polyester set in #298 before the membrane.

• Blisters: cut out and repaired by the floating patch method, with modified cap sheet embedded in asphalt flashing compound. Sheet edges extend at least 6 inches past the widest point.
• Large splits: the same embedded cap sheet repair. Peel and stick modified cap or APP torch applied sheet may be used instead.
• Small splits: a three course method with #800 Elastic Cement at 5 gallons per 100 square feet (about 1/8 inch), one ply of polyester embedded in the wet cement, then 4 gallons per 100 square feet over the fabric.

The water based system goes on at a minimum of 55 degrees F and rising. It is not applied when rain, inclement weather or temperatures below 40 degrees F are expected within 48 hours, or with ice or frost on the deck. Repair work that uses no water based material may be done just before inclement weather.

Named companion products are #800 Elastic Cement (white or black), #8000 All Weather Elastic Cement, a solvent-based white sealant, #850 SWS walkway coating and #970 A2A, a clear acrylic primer for smooth BUR, emulsion and non-granulated modified bitumen.

The membrane starts with a coat of #298 Asphalt Emulsion at 6 gallons per 100 square feet. Full-width polyester is embedded immediately, beginning at the low edge of the roof and working up the slope. Each ply overlaps the next by a minimum of 3 inches and end laps overlap a minimum of 4 inches. The fabric is lightly broomed so it is fully embedded while still showing on the surface, with no wrinkles or voids.

The polyester stops at the base of the wall or cant and overlaps the wall flashings by at least 3 inches. The wet fabric is not walked on, because foot traffic displaces the emulsion. No top coat of #298 goes over the polyester, and the membrane cures before the next step.

If excess emulsion or a top coat of emulsion does reach the fabric surface, #970 A2A primer is applied at one half gallon per 100 square feet and allowed to dry thoroughly before the ElastaHyde. The roof is washed first to remove asphaltic residue. This primer step is dropped when the polyester is left properly exposed.

• Base flashing: one ply of 6 inch (or wider) polyester set in #298 at 5 gallons per 100 square feet over the cant strip, ending at least 2 inches above the cant and at least 2 inches onto the deck.
• Wall flashing: one full ply of polyester in #298 at 5 gallons per 100 square feet, running up the wall to end under counter flashing, reglet or wall cap flashing. It reaches at least 3 inches onto the deck beyond the base flashing.
• Edge metal: gravel stops are replaced with low or no rise metal edge, nailed at 4 inches on center and stripped in with polyester and #800 Elastic Cement. Where existing edge flashing stays, the roofing is cut back 2 inches from the rise before stripping in.
• Vent and pipe flanges: set in a bed of #8000 All Weather Elastic Cement and nailed, then stripped in with polyester and #800. #800 is not used to set a new flange.
• Surface treatment: after the membrane and before the reflective coating, a three course method of #800 and polyester goes on pipe flashings, cones, exposed metal joints and flanges.

At clamping-type roof drains the clamping ring is removed, old mastic and repair compound are cleaned from the drain and sump, and the sump is three-coursed with #800 or #8000, running into the drain bowl and at least 18 inches from the drain center onto the deck. The ring is then replaced and the membrane overlaps the reinforced cement by at least 3 inches. An optional detail embeds modified cap sheet in modified asphalt flashing compound instead.

Drains, scuppers, valleys, waterways and any location where water ponds for more than 48 hours receive an extra ply of polyester set in ElastaHyde. It extends 12 inches past the ponding area, or past the drain sump, and is set into #720 ARC at 3 gallons per 100 square feet, lightly broomed for full saturation. It goes on after the membrane and before the final ElastaHyde coats.

The ElastaHyde coating totals 4.5 gallons per 100 square feet for an average dry thickness of 36 mils. It goes on in three coats of 1.5 gallons per 100 square feet each, each at a right angle to the one before, with 24 hours of drying after the first and second coats. The material is mixed well and strained for spray application, and it is not thinned or diluted.

The coating is applied early in the day, before the emulsion surface heats and softens. Application stops if the surface turns soft and sticks to equipment or feet.

#850 SWS walkway coating is the optional protection and non-slip layer. It is applied by short nap or smooth roller in two coats of 2 gallons per 100 square feet, with at least 24 hours between coats. At roof doors, hatches and equipment service doors, a reinforcing ply of polyester is embedded in a 2 gallon coat of #850 SWS first, left to dry for at least 24 hours, and then the two finish coats follow.