Met-A-Gard

Met-A-Gard is the Acrylic 211 metal roof restoration system from American WeatherStar. It is a commercial roof coating system for commercial roof restoration on metal, which is its only listed substrate. The system is ENERGY STAR rated. It applies two coats of Acrylic 211, an ivory-tinted base coat followed by a white top coat, and uses brush-grade acrylic sealants at seams and details.

It is designed for metal roofs with moderate levels of rust and corrosion and with positive drainage. Roofs with ponding water must be corrected before installation. The coating can be used on whole roofs, for spot repairs, or as extra protection at flashing, and it addresses wind, rain, sun and freeze-thaw cycle damage.

1. The metal roof is the substrate and is pressure washed to remove dirt, dust and debris.
2. Red Oxide Rust Prime 912, applied if necessary (step 1A).
3. Acrylic 211 in ivory, as the base coat.
4. Acrylic 211 in white, as the top coat.
5. Acrylic Brush-Grade 220 and Butter-Grade 221 on seams and flashing details.

The ivory base coat gives uniform mil thickness and bonds to the metal. The white top coat completes the membrane. System warranty terms of 5 years and 10 years are marked for Met-A-Gard. A surface temperature comparison marks 152 degrees F before coating and 96 degrees F after.

Acrylic 211 is a 100 percent acrylic elastomeric coating with high-solids emulsion polymers and biocides. Its tensile strength rises at lower temperatures. The metal guideline lists it as a solar reflective coating at 4,500 cps with 233 percent plus or minus 20 elongation, 273 plus or minus 20 psi tensile strength and 55 percent plus or minus 2 volume solids. The data sheet adds:

• Weight: 12.1 lbs per gallon plus or minus 0.2
• Hardness: 50 to 55, Shore A (ASTM D-2240)
• Impact resistance: exceeds 160 lb in/lb (ASTM D-2294)
• Salt spray: no effect after 3,800 hours (ASTM G-117)
• Reflectivity: 0.87; emissivity 0.89
• Permeability: 14 plus or minus 3; water absorption rate 6 to 20 percent
• VOC: below 50 g/liter
• Dry time: 2 to 12 hours
• Service temperature: -40 to 200 degrees F; shelf life 12 months

Standard colors are white, gray and tan, in 5 gallon and 55 gallon packaging. It is water-based and cleans up with water.

• Acrylic Brush-Grade 220. A high-solids elastomeric sealant in white, with viscosity of 70,000 plus or minus 10,000 cps, 55 percent plus or minus 3 volume solids, elongation of 315 percent and tensile strength of 500 psi.
• Acrylic Butter-Grade 221. A water-based, high-solids, 100 percent acrylic elastomeric caulk in white, applied with a synthetic bristle brush. It has 66 percent plus or minus 2 solids by volume, 200 percent elongation, 325 psi tensile strength, a viscosity of 90,000 plus or minus 10,000 cps, Shore A hardness of 45 and permeability of 5 perms per inch at 20 mils. It weighs 11.3 lbs per gallon plus or minus 0.2, dries in 2 to 24 hours, and comes in a 5 gallon pail. It seals mechanical fasteners and vertical seams on metal roofs, and areas around flashings, drains and penetrations, and adheres to asphaltic roofing, metal, concrete, wood and polyurethane. It is a plasticizer-free caulk.
• Polyester fabric. A spun-bound polyester with a tensile strength of 35 psi, 100 percent elongation, 22 mils bulk and widths of 36, 20, 12, 6, 4 and 2 inches.

Red Oxide Rust Prime 912 is a red, 40 percent solids water-based acrylic primer that inhibits rust on metal and acts as an adhesion bonding primer ahead of roof coatings. It is ready to use, weighs 10 lbs per gallon plus or minus 0.2 and dries in 2 to 3 hours.

EcoCleaner 925 is the cleaner named in the guideline. It is a clear, biodegradable, low-foaming cleaner with 0 g/liter VOC, diluted 5:1 and applied at 1 gallon per 150 square feet before power washing at a minimum of 3,000 psi with rinsing until the water runs clear. Acrylic Skylight Sealer 230 reconditions skylights at 1/2 to 1 gallon per 100 square feet and is not enough for cracked skylights.

• Pre-inspection covers HVAC flashing, drainage, water leakage, fasteners, skylights, horizontal and vertical seams, roof penetrations, sign or display anchorage, and coping and flashing.
• An adhesion test of the Acrylic 211 base coat on the metal substrate is recommended.
• New galvanized metal cures at least 90 days or is treated with an approved surface conditioner.
• Rust is inspected for, including on panel undersides where possible.

The acrylic is applied with ambient and surface temperature of at least 50 degrees F and rising, to a maximum of 110 degrees F ambient and 130 degrees F surface, and not within 5 degrees F of the dew point.

An NDL (no dollar limit) warranty requires metal panels to be attached with gasketed threaded fasteners installed directly into metal purlins. Attachment into wood substrates, or with nails or non-approved fastening methods, is not eligible. American WeatherStar warrants that supplied material meets or exceeds published physical properties. Each job is approved by American WeatherStar before it begins, and a Pre-Project Inspection Report is submitted and approved first.

Acrylic systems for existing roofs of this kind are covered under metal roof restoration.