Asphalt Shingle Roofing for High-Wind Regions www.fema.gov HURRICANE RECOVERY ADVISORY Recovery Advisory No. 2 – Asphalt Shingle Roofing for High-Wind Regions September 2004 Purpose: To recommend practices for installing asphalt roof shingles that will enhance wind resistance in high-wind, hurricane-prone areas (both coastal and inland). Key Issues • Special installation methods are recommended for asphalt roof shingles used in high-wind, hurricane-prone areas (i.e., greater than 90-mph, 3-second peak gust design wind speed). • Use wind-resistance ratings to choose among shingles, but do not rely on ratings for performance. • Consult local building code for specific installation requirements. Requirements may vary locally. • Always use underlayment. See Fact Sheet No. 1 for installation techniques in hurricane-prone areas. Construction Guidance 1. Follow shingle installation procedures for enhanced wind resistance. --Shingle installation at eaves --Shingle installation at hips and ridges --Shingle installation at rakes 2. Consider shingle physical properties. --Fastener Pull-Through Resistance [note 3] For Design Wind Speed [note 1] of >90 to 120 mph, minimum recommended 25 lb at 70 degrees Fahrenheit. For Design Wind Speed [note 1] of >120 mph, minimum recommended 30 lb. --Bond Strength [note 3] For Design Wind Speed [note 1] of >90 to 120 mph, minimum recommended 12 lb. For Design Wind Speed [note 1] of >120 mph, minimum recommended 17 lb. Notes 1. Design wind speed based on 3-second peak gust. 2. ASTM D 3462 specifies a minimum fastener pull-through resistance of 20 lb at 70º F. If a higher resistance is desired, it must be specified. 3. Neither ASTM D 225 or D 3462 specify minimum bond strength. If minimum bond strength is desired, it must be specified. --For organic-reinforced shingles, the standard is ASTM B 225, and the characteristics are relatively high fastener pull-through resistance. --For fiberglass-reinforced shingles, the standard is ASTM D 3462, and the characteristics are considerable variation in fastener pull-through resistance offered by different products. --For SBS modified bitumen shingles, a standard does not exist for this product. It is recommended that SBS modified bitumen shingles meet the physical properties specified in ASTM 3462. Because of the flexibility imparted by the SBS polymers, this type of shingle is less likely to tear if the tabs are lifted in a windstorm. 3. Ensure that the fastening equipment and method results in properly driven roofing nails for maximum blow-off resistance. The minimum required bond strength must be specified (see Wind-Resistance Ratings, below). Fastener Guidelines • Use roofing nails that extend through the underside of the roof sheathing, or a minimum of 3/4 inch into planking. • Use roofing nails instead of staples. • Use stainless steel nails when building within 3,000 feet of saltwater. Weathering and Durability Durability ratings are relative and are not standardized among manufacturers. However, selecting a shingle with a longer warranty (e.g., 30-year instead of 20-year) should provide greater durability in hurricane-prone climates and elsewhere. Organic-reinforced shingles are generally more resistant to tab tear-off, but tend to degrade faster in warm climates. Use fiberglass-reinforced shingles in warm, hurricane-prone climates and consider organic shingles only in cool, hurricane-prone climates. Modified bitumen shingles may also be considered for improved tear-off resistance of tabs. Organic-reinforced shingles have limited fire resistance – verify compliance with code and avoid using in areas prone to wildfires. After the shingles have been exposed to sufficient sunshine to activate the sealant, inspect roofing to ensure that the tabs have sealed. Also, shingles should be of “interlocking” type if seal strips are not present. Wind-Resistance Ratings Wind resistance determined by test methods ASTM D 3161 and UL 997 does not provide adequate information regarding the wind performance of shingles, even when shingles are tested at the highest fan speed prescribed in the standard. Rather than rely on D 3161 or UL 997 test data, shingle uplift loads should be calculated in accordance with UL 2390. Shingles having a bond strength (as determined from test method ASTM D 6381) that is at least twice as high (i.e., a minimum safety factor of 2) as the load calculated from UL 2390 should be specified/purchased. [End of Recovery Advisory No. 2]