Foam-Gard

Foam-Gard is a coated spray polyurethane foam (SPF) roof restoration system from American WeatherStar. Its family is commercial roof coating systems, and its application is commercial roof restoration. Instead of a coating applied directly to the old surface, the system builds a foam layer over the existing roof and protects that foam with elastomeric coatings. The base coat can be acrylic, silicone or urethane.

Foam-Gard is one of several American WeatherStar systems, and it is the one in the range built around an insulating foam layer. The foam acts as a heat, moisture and air barrier for commercial and industrial roof substrates. Because the foam can be sprayed at varying thickness, it is also used to add slope and to fill low areas on the existing roof.

The assembly is shown in four numbered steps in the brochure:

1. Existing roof substrate, pressure washed to remove dirt, dust, debris and other contaminants.
2. Spray polyurethane foam.
3. Roofing granules, broadcast directly into the elastomeric top coat.
4. Elastomeric roof coating, applied in multiple coats, in acrylic, silicone or urethane.

The foam is the insulating and leveling layer. The coating over it provides UV protection, reflectivity and supplemental waterproofing. The granules are added to the wet top coat to raise weather resistance.

Foam-Gard is installed over six existing roof types:

• Built-up roofs, including smooth and gravel surfaced BUR
• Concrete
• EPDM
• Metal
• Modified bitumen, including granulated modified bitumen
• Single-ply membranes, listed as TPO and PVC

Separate application guidelines exist for the built-up, metal, modified bitumen and single-ply versions, each running 11 pages. A further guideline covers recoating an existing SPF roof for all American WeatherStar systems.

The polyurethane foam is a closed cell, two-component product made by combining an isocyanate (A) component with a polyol (B) component. The published physical characteristics are:

• Density: 2.8 to 3.0 lbs./ft3 (ASTM D1622)
• Compressive strength: 40 psi minimum (ASTM D1621)
• K-value: 0.16 to 0.18 BTU per ft2/hr. degree F per inch (ASTM C177, C518, C1363)
• Flammability: below 75 (ASTM E84)

The flame spread rating is a laboratory measurement of response to heat and flame under controlled conditions. It is not a statement about hazard under actual fire conditions.

The foam, together with the elastomeric coating and other components as an assembly, is required to meet UL 790 for a Class A application and, or, a Factory Mutual RoofNAV Class 1 application, and, or, local building code requirements. Foam primers are those recommended by the maker of the spray foam. The fire safety reference named for the foam is CPI Bulletin AX-230, Fire Safety Guidelines for Use of Rigid Polyurethane and Polyisocyanate Foam Insulation in Building Construction.

Several coatings can serve as the elastomeric system, and their published properties differ.

• Acrylic 211. A solar reflective coating at 55 percent plus or minus 2 volume solids, viscosity 4,500 plus or minus 500 cps, elongation 233 plus or minus 20 percent and tensile strength 273 plus or minus 20 psi. Standard colors are white, gray and tan.
• High-Tensile Acrylic 211. A high-solids elastomeric with elongation of 600 plus or minus 50 percent and tensile strength of 500 plus or minus 50 psi. Colors are white, gray, tan and custom.
• Silicone 410. A solvent-borne, moisture-cure silicone at 69 percent volume solids, 318 percent initial elongation, 500 psi tensile strength, 84 percent reflectivity, 0.85 emissivity and an SRI of 105.
• High-Solids Silicone 412. A single-component, moisture-cure silicone at 92 percent plus or minus 2 volume solids, 250 percent elongation, 330 psi tensile strength and a service range of -40 to 350 degrees F. It is the standard specification for liquid silicone used on spray polyurethane foam roofing.
• Aromatic Urethane 520. A single-component, moisture-cure polyurethane at 70 percent volume solids, 475 percent elongation and 715 psi tensile strength, supplied in silver. It was developed as a protective coating for sprayed-in-place foam. An adhesion test is recommended of the Aromatic Urethane 520 base coat on the existing substrate.
• Aromatic Urethane 508. A single-component, moisture-cure urethane base coat, dark gray, with 725 psi plus or minus 50 tensile strength. It has to be top coated with Silicone 410, High Solids Silicone 412 or Aliphatic Urethane 510, and top coats go on within 48 hours.

• Pressure washing at 3000 to 4000 psi is recommended for cleaning.
• Existing coatings are checked for adhesion, and loosely adhered coating is removed.
• Spray polyurethane foam is applied uniformly at a thickness of 1 inch to 1.5 inches minimum, or more where specified, over the entire roof surface.
• Coatings go onto clean, dry, sound surfaces free of contaminants.
• The interval between coating applications is 24 hours.
• If the foam layer is left exposed for more than 24 hours, Acrylic Bonding Primer 905 may be required to promote adhesion.

Silicone coatings are placed on fresh foam within 24 hours, and later silicone coats within 24 hours of the previous one. Silicone is not recommended below 40 degrees F or when rain is expected within 1 hour. Both acrylic coatings are designed for positive drainage and are applied between 50 and 110 degrees F ambient.

For warranty eligibility, each job must be approved by American WeatherStar before it begins, and products are applied by a single contractor approved by American WeatherStar. Its StarGard Warranty Program offers long-term NDL (no dollar limit) labor and material warranty plans for qualified systems installed by an American WeatherStar Approved Contractor. For an SPF recoat to qualify for a labor and material warranty, an infrared scan must be performed on the roof and all wet SPF must be removed and replaced.

Roofing systems of this kind, with a foam base and liquid coating over existing low-slope roofs, fall under flat roofing systems.