Shingle Wind Resistance Ratings

Shingle wind resistance ratings are laboratory classifications that indicate how well asphalt and other steep-slope roofing products resist being blown off. In North America, two ASTM International test methods dominate product literature and building codes.

ASTM D3161 (fan-induced method)

ASTM D3161 blows a stream of air from a fan across installed test specimens on a deck set at a 2:12 (17 percent) slope, or the lowest slope the manufacturer allows. It applies to discontinuous, air-permeable steep-slope products, including asphalt, polymer, fiber-cement, concrete, clay, metal and photovoltaic shingles. It does not apply to continuous membranes or mechanically seamed metal panels. Products are classified by the fan speed they withstand, with Class F the highest classification. The standard itself notes that results do not directly correlate to wind speeds experienced in service.

ASTM D7158 (uplift resistance)

ASTM D7158, first published in 2005 and adopted into the 2009 International Residential and Building Codes, measures the uplift resistance of the shingle's sealant bond and calculates performance at different design wind speeds. Its classes are:

• Class D: up to about 145 km/h (90 mph)
• Class G: up to about 193 km/h (120 mph)
• Class H: up to about 241 km/h (150 mph)

Use in codes and programs

US building codes reference these classes for asphalt shingles based on the site's design wind speed. The FORTIFIED Roof standard requires shingles rated ASTM D3161 Class F or ASTM D7158 Class H. Other regions use their own national test methods and design-pressure approaches, so North American shingle classes do not translate directly to products sold elsewhere.

Limits of ratings

A rating describes a new product installed correctly in a laboratory. Real performance depends on:

• fastener placement in the nailing zone and correct number of nails;
• whether the sealant strips have bonded (which needs warm weather after installation);
• edge and starter details;
• product aging, which can weaken sealant bonds.

Post-storm investigations repeatedly identify misplaced nails and poor starter courses as causes of shingle loss on roofs with rated products.