Max-Ply

Max-Ply is the fabric-reinforced roof restoration system from American WeatherStar. Max-Ply belongs to the commercial roof coating systems group and is used in commercial roof restoration. Its core is a polyester fabric embedded in a wet base coat across the whole roof, and the membrane is finished with a silicone, urethane or acrylic coating. It is a full-fabric membrane system.

The system is suitable for single-ply roofs (EPDM, TPO, PVC), modified bitumen (smooth or granulated), built-up roofing (BUR) and structural concrete. It can restore entire roof surfaces, reinforce high-stress areas, and cover seams, penetrations and flashing. Separate application guidelines exist for single-ply, EPDM, modified bitumen, built-up roofing and concrete, each 10 pages, with revision dates of 10/06/25 and 11/04/25.

1. Existing roof substrate, pressure washed to remove dirt, dust, debris and other contaminants, with a primer applied if needed.
2. Fabric reinforced base coat. Polyester fabric is embedded in a wet base coat and laid flat, fully adhered to the substrate.
3. Saturation coat. A second coat encapsulates the fabric.
4. Top coat. A protective finish seals the system.

The finish chemistry is selectable. Silicone, urethane and acrylic finishes are all used with the fabric, and the system is tailored by choice of coating. Formulations are low in VOC.

The fabric is a spun-bound polyester roofing fabric. It is a 100 percent polyester, hydraulically entangled textile with these values:

• Elongation: 100 percent
• Tensile strength: 35 psi
• Weight: 11 lbs per square
• Bulk: 22 mils
• Widths available: 36, 20, 12, 6, 4 and 2 inches

The open aperture design lets coating flow through, so the roofing layer is saturated rather than laminated. The fabric is installed with Fabric Bond 930 or another American WeatherStar base coat: a layer of coating is applied, the fabric is laid into the wet coating, and once the coating sets another layer goes over the top side.

The guideline lists seven coatings for the base, saturation and top coats:

• Silicone 410. UV-resistant silicone; elongation 318 percent; 69 percent plus or minus 2 volume solids.
• High-Solids Silicone 412. UV-resistant high-solids silicone; 92 percent plus or minus 2 volume solids.
• Aliphatic Urethane 510-CA. Single-component, moisture-cure aliphatic polyurethane; elongation 230 percent; tensile strength 2,300 psi; 76.7 percent volume solids.
• Aromatic Urethane 508. Single-component, moisture-cure aromatic polyurethane; elongation 475 percent plus or minus 50; tensile strength 725 plus or minus 50 psi; 70 percent plus or minus 2 volume solids.
• Aromatic Urethane 520. Single-component, moisture-cure aromatic polyurethane; 70 percent plus or minus 2 volume solids.
• Acrylic 211. Elastomeric acrylic; elongation 233 plus or minus 20 percent; tensile strength 273 plus or minus 20 psi; 55 percent plus or minus 2 volume solids.
• High-Tensile Acrylic 211. Elongation 600 plus or minus 50 percent; tensile strength 500 plus or minus 50 psi; 55 percent plus or minus 2 volume solids.

This coating was developed as the top coat for American WeatherStar's Ure-A-Max system and is also used as a top coat for polyurethane foam. It is white and supplied in 5 gallon packaging. Its lower moisture vapor permeability (0.9 perms) gives more resistance to moisture penetration, and moisture cure gives a longer production window. Other data:

• Viscosity: 100 KU
• Weight: 10.77 lbs per gallon
• Flash point: 93 degrees F
• Hardness: 85, Shore A
• Water absorption: below 2 percent
• Dry times: dry to touch 6 hours, tack-free 12 to 16 hours, recoat 18 hours
• Service range: -50 to 200 degrees F; shelf life 1 year
• Clean up: acetone

Top coats go on within 48 hours of the base or intermediate coat, and the coating is not applied when ambient temperature falls below 40 degrees F. It meets SCAQMD VOC requirements.

• Aromatic Urethane 520 is silver, with 475 percent plus or minus 50 elongation and 715 plus or minus 25 psi tensile strength on its data sheet, and dry times of 6 hours to touch, 8 to 12 hours tack-free and 12 to 16 hours to recoat.
• Aromatic Urethane 508 is dark gray with a 6 hour dry-to-touch time and a 48 hour window for top coats. It is topped with Silicone 410, High Solids Silicone 412 or Aliphatic Urethane 510.
• Silicone 410 has 0.85 emissivity, 84 percent reflectivity and an SRI of 105. High-Solids Silicone 412 has initial 0.87 reflectivity and 0.89 emissivity, and dries in 1 to 4 hours.

• Cleaning by pressure washing at 3000 to 4000 psi is recommended.
• Existing coatings are checked for adhesion, and loose coating is removed.
• Coatings go onto clean, dry, sound surfaces.
• The interval between coating applications is 24 hours.
• Components are stored in original unopened containers between 50 and 75 degrees F.
• Acrylic Bonding Primer 905 is the water-based bonding primer in the component list, and EcoCleaner 925, a biodegradable cleaner, is diluted 5:1 and applied at 1 gallon per 150 square feet before a wash at a minimum of 3,000 psi.

Each project is reviewed and approved by American WeatherStar before work begins for warranty eligibility, and the system is applied by a contractor it has approved.

As a reinforced membrane over existing roofs, Max-Ply is part of liquid-applied roofing.