SM-2P-16-A — Aluminum-surfaced roof restoration system

SM-2P-16-A is a Western Colloid fluid-applied reinforced roof system specification, revised 10/20, for recovering a smooth surface or cap sheet. It has two plies of polyester reinforcement and an aluminum reflective surface, and it sits in the Western Cool Roof Systems group. The manufacturer's specification index lists it as a smooth cap, 2-ply polyester reinforced system using #298 Emulsion and #525 SilverWhite Aluminum.

The method is a cold process to upgrade existing roofing, including built-up and modified bitumen. It is water based with very low odor, reinforced with lightweight polyester fabrics and surfaced with a reflective elastomeric aluminum coating. It is intended to extend the life of the existing membrane. All layers beneath the aluminum are #298 asphalt emulsion and polyester. The existing roofs it upgrades include built-up and modified bitumen roofing.

The assembly has five numbered layers, with approximate dry weights per 100 square feet.

• 1. Base coat: #298 emulsion, 6 gallons, 23 lb.
• 2. Polyester fabric, two plies, 5 lb.
• 3. Interply coat: #298 emulsion, 5 gallons, 19 lb.
• 4. Top coat of #298 emulsion, 5 gallons, 19 lb.
• 5. Reflective surface coating of SilverWhite aluminum, 1.5 gallons, 4.5 lb.

Total system dry weight is approximately 70.5 lb, and total dry thickness is approximately 140 mils.

The fabric is Western Colloid W26/T326 at 2.75 ounce firm, or T272 at 3.0 ounce soft, both stitchbonded and used as reinforcement in asphalt emulsion or acrylic coatings.

• WCP-SF (W-26 firm, equal to Tietex T326) is a 2.75 ounce stitchbonded fabric with a firm but pliable, starched finish. It conforms to smooth or semi-smooth surfaces and works over smooth and cap sheet surfaces. Fewer stitches per inch improve wetting and reduce brooming, and the firm finish gives fewer wrinkles and a straighter lay. Properties: thickness .025 inch, average tensile 41 lb, elongation 25%, burst strength 127 lb, trapezoid tear 14 lb. It comes in 10 square rolls, 40 inches by 324 feet.
• WCP-HS (T272) is the 3 ounce soft alternative, also used to reinforce flashings with mastics and elastomerics.

• #298 Asphalt Emulsion is ASTM D 1227 Type III, made in a continuous colloid mill process without added surfactants or additives. It is also known as Glas-Shield Waterproofing Compound for cold process roofing.
• SilverWhite #525 is an aluminum asphaltic emulsion for a protective coating with a high degree of reflectivity, made from #298 emulsion, special resins and polished aluminum flake.
• #800 Elastic Cement is a water-based acrylic resinous plastic emulsion in white or black for terminations, metal joints and drain sumps.
• #8000 All Weather Elastic Cement is a solvent-based white sealant that can replace #800 when more immediate water resistance is needed.

#525 SilverWhite reflects up to 76% of sun rays, with initial reflectivity of 76% by ASTM E97. Its base is Type III asphalt emulsion and its pigment is polished aluminum flake. Elongation is 166% and tensile strength is 31 psi by ASTM D412. It weighs approximately 8.5 lb per gallon, is non-flammable wet, and is Class A dry. It covers about 100 square feet per gallon and is available in 5 gallon pails, 55 gallon drums and bulk.

Brushing uses a 24 inch soft-bristle broom, and the coating is wind-rowed and broomed at an angle. Spray is preferred, and a roller is less effective. A damp but not wet surface is acceptable. It is applied between 55 and 100 degrees F and not within 72 hours of expected rain, heavy dew or moisture.

#298 emulsion has 45 to 50% solids and a weight of 8.2 to 8.7 lb per gallon, and VOC is zero. It sprays at 3 to 6 gallons per 100 square feet, or goes on at 3 gallons per coat by brush, roller, broom or squeegee, with a second coat at a right angle. Fabric is brushed into the wet emulsion before the next coat. It firms in 12 hours at 70 degrees F and 50% relative humidity, and is applied at 50 degrees F or above.

SilverWhite is intended for emulsion that is dry and fully cured, which takes 3 to 10 days in warm, dry weather. Over uncured emulsion the film may turn gray, dark gray or brown. Recoating an existing SilverWhite surface follows cleaning, preferably with 2 to 3 gallons per 100 square feet of #298 or #298E first.

The existing membrane is repaired and made sound and watertight before the reinforced membrane goes on, and its fastening or adhesion is checked. Loose gravel, dirt and debris come off by vacuum, washing, sweeping or power blower. Valleys and ponding areas are washed, may take a primer of #298 diluted 20 to 30 percent with water, and get one extra polyester ply in #298.

• Blisters: removed with a flat shovel, scraper or knife and repaired by the floating patch method, with modified cap sheet embedded in asphalt flashing compound and edges reaching 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 also be used.
• Small splits: a three course method with #800 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 is applied at a minimum of 55 degrees F and rising. It is not applied during wet weather, rain, snow or freeze, or when ice or frost is on the deck. The 48 hours after application must stay clear of expected rain, inclement weather and temperatures below 40 degrees F. Preparation and repair work that uses no water based material may be done just before inclement weather.

The membrane begins with a coat of #298 Asphalt Emulsion at 6 gallons per 100 square feet. A half-width starter strip of polyester is embedded at the low edge, followed by full-width sheets continuing up the roof. A second coat of #298 at 5 gallons per 100 square feet goes over the first ply, and a full-width second ply is embedded starting again at the low edge. Each ply is lightly broomed for full saturation with no wrinkles or voids. Polyester ends 2 inches above the cant, and the wet fabric is not walked on.

A top coat of #298 at 5 gallons per 100 square feet goes over the plies and dries for a minimum of 24 hours. Pipe flashings, cones, exposed metal joints and flanges then receive #800 and polyester in a three course method, and #800 goes on corners at curbs and skylight flashings.

• 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 2 inches onto the deck.
• Wall flashing: one full ply in #298 at 5 gallons per 100 square feet, ending under counter flashing, reglet or wall cap flashing and reaching at least 3 inches onto the deck beyond the base flashing.
• Edge metal: replacement edge sits low or with no rise and is nailed at 4 inches on center, with polyester and #800 stripped over it.
• Vent and pipe flanges: seated in #8000 and nailed; #800 does not set a new flange.
• Clamping-type drains: the sump gets #800 or #8000 in three courses out to at least 18 inches from the drain center, and the membrane laps onto it by at least 3 inches.

Drains, scuppers, valleys, waterways and locations where water ponds for more than 48 hours receive an extra application of SilverWhite #525 at 1.5 gallons per 100 square feet, extending 12 inches past the ponding area. It goes on after the membrane and before the final coat.

The final SilverWhite #525 coat goes over the entire cured roof at 1.5 gallons per 100 square feet. Spray application is preferred. It is applied early in the day, before the emulsion surface heats and softens, after washing off asphaltic residue. SilverWhite #530 is the product named for roller or brush touch-up.