Envir-O-Sil

Envir-O-Sil is the low-VOC, high-solids silicone roof restoration system from American WeatherStar for flat roofs. As a commercial roof coating system, it serves commercial roof restoration. The membrane is High-Solids Silicone 412 applied as both the base coat and the top coat, with Terminator 622 and Silicone Brush-Grade 422 on seams and details. The system is aimed at areas with strict environmental regulations.

Suitable substrates are spray polyurethane foam, modified bitumen, built-up roofs, single-ply (TPO, PVC) and EPDM. Envir-O-Sil is used for coating entire roofs, making spot repairs and adding protection at flashing, and it addresses wind, rain, sun and freeze-thaw cycles. Application guidelines exist for single-ply, modified bitumen, built-up roofing and EPDM.

1. Existing roof substrate, pressure washed to remove dirt, dust, debris and contaminants.
2. Terminator 622 and Silicone Brush-Grade 422 on seams and flashing details.
3. High-Solids Silicone 412 base coat.
4. High-Solids Silicone 412 top coat, forming a watertight membrane.

An adhesion test of the base coat on the existing substrate is recommended. Acrylic Bonding Primer 905 and Fabric Bond 930 appear in the component lists for priming and fabric installation.

High-Solids Silicone 412 is a ready-to-use, high-solids, single-component, moisture-cure silicone. It is the standard liquid silicone for spray polyurethane foam roofing and single-ply restoration. Published data:

• Solids by volume: 92 percent plus or minus 2 (ASTM D-2697)
• Elongation: 250 percent plus or minus 25 and tensile strength 330 plus or minus 50 psi on the data sheet; 170 percent plus 25 and 450 psi plus 50 in the guideline
• Flash point: 290 degrees F (COC, ASTM D-92)
• Hardness: 50 plus or minus 5, Shore A
• Water absorption: 2 percent
• Emissivity: initial 0.89 (C-1371)
• Reflectivity: initial 0.87 (C-1549)
• VOC: below 50 g/liter (ASTM D-3960, EPA Method 24)
• Drying time: 1 to 4 hours; shelf life 24 months
• Service range: -40 to 350 degrees F
• Clean up: mineral spirits

Standard colors are white, gray and tan, supplied in 5 gallon and 50 gallon packaging. It is mixed by hand, not with an electric mixer, because it is combustible. Foam is coated within 24 hours, later coats follow within 24 hours of the previous one, and application is not recommended below 40 degrees F or within 1 hour of expected rain. It can be applied at lower temperatures with longer cure time.

• Terminator 622. A 100 percent solids, one-component, moisture-cure siliconized urethane sealant and adhesive in white or gray. Elongation 500 percent, tensile strength 200 psi, hardness 25 after a 5 day ambient cure, low temperature flex -20 degrees F and service range -40 to 200 degrees F. It is applied from 32 degrees F, bonds to damp surfaces, and comes in a 10.3 oz tube or a 2-gallon pail, applied by brush or caulk gun.
• Silicone Brush-Grade 422. A white, high-solids, single-component, moisture-cure silicone mastic for penetrations, curbs, seams and flashings, at 96 percent plus or minus 3 volume solids, elongation above 243 percent at 73 degrees F, tensile strength 289 psi, 4.2 perms, flash point 200 degrees F and a 2 to 8 hour dry time. Ambient temperature of 50 to 90 degrees F is preferred, and it is packed in 5 gallon and 2 gallon sizes.
• Polyester fabric. Spunbound polyester with 35 psi tensile strength, laid into wet coating.

Acrylic Bonding Primer 905 is a black, water-based primer for previously coated metal, smooth and granulated modified bitumen, and built-up roofs. It is 38 percent plus or minus 2 solids by volume, 600 to 800 cps, weighs 8.4 lbs per gallon plus or minus 0.2 and dries in 1 to 2 hours. It is ready to use and sprayed by airless unit (1/2 gpm, #017 tip), brush or short nap roller. It is applied at 50 degrees F or above.

Fabric Bond 930 is a blue, water-based bonding agent that secures polyester fabric to roof surfaces and seals asphaltic surfaces with little or no bleed through. It is 44 percent plus or minus 2 solids by volume, weighs 8.38 lbs per gallon and dries in 2 to 12 hours. It primes asphalt, concrete, wood, tile, metal and clean, dry, non-silicone surfaces, and must be top coated. It is not applied within two hours of sunset, rain, fog or freezing temperatures.

EcoCleaner 925 is a clear, 0 g/liter VOC cleaner diluted 5:1 and applied at 1 gallon per 150 square feet, followed by a wash at a minimum 3,000 psi.

Before the system is applied, the roof is pre-inspected for HVAC flashing, drainage, seams, terminations and reglets, roof penetrations, water leakage, sign or display anchorage, drains and their location, parapet roof detail, wet or damp insulation, and coping and flashing. Washing before application is done at 3000 to 4000 psi.

American WeatherStar warrants that supplied material meets or exceeds published physical properties, and the contractor guarantees workmanship. Each job is approved by American WeatherStar before it begins, a Pre-Project Inspection Report is submitted and approved first, and products are applied by an approved contractor.

Low-VOC silicone coatings of this type fall under silicone roof coatings.