Thunderstorms: Roof - Choosing the Right Covering
Material provided by Federal Alliance for Safe Homes http://www.flash.org/
- Attractive and relatively lightweight
- Last up to 40 years
- May have a Class A or B fire rating
- Can dimple permanently when hit by hail
- Recommended Installation:
- Use clips or cleats instead of exposed fasteners because they aren’t exposed to weather and allows the metal to expand and contract reducing the opportunity for buckling
- Fasteners should be corrosion resistant and penetrate the sheathing
- Can last three times longer than shingles
- Expensive and very heavy
- Some roof structures are unable to support slate
- Recommend Installation:
- Should be attached with flat head copper-wire slating nails
- In high wind areas, apply a dab of roof cement or polyurethane sealant under the exposed part and the slate
- Install using four nails per slate
- Popular in some areas
- Available in concrete or clay
- Concrete tiles are more durable and can last more than 30 years
- Performance in hail storms varies by type.
- Clay tiles are brittle and can be easily chipped or broken
- Tiles are heavy and some structures are unable to support the weight
- Can take longer to install making labor costs more expensive
- Recommend Installation:
- Use wind clips or storm anchors in high wind or seismic areas
- Two screws per tile give the highest wind uplift resistance and will help the tile resist shifting
Wood Shingles and Shakes
- Made from cedar, southern pine or other woods
- Attractive appearance
- Perform moderately well against hail
- Some local codes limit their use
- May not be rated for fire unless they’re treated with a fire retardant
Keep these points in mind when you have your roof covering repaired or replaced:
- If you are having an old roof replaced, your contractor should remove the existing shingles and underlayment rather than install new shingles over them. This approach allows the contractor to inspect the sheathing and make any repairs that may be necessary.
- The first course of shingles should be sealed to the starter strip with dabs or bands of roof cement. Details are provided in FEMA 499, Technical Fact Sheet No. 20.
- If your building is within 3,000 feet of saltwater, the nails or screws should be hot-dip galvanized or stainless steel.
- Check local code requirements for roof repair or replacement criteria. Your local building official should be able to provide additional recommendations.
Benefits of Using This Mitigation Strategy
- Helps to prevent damage to a structure and its contents
- Helps to prevent injuries to occupants
A roofing contractor will charge approximately $10 to $15 per square foot of roof area to remove and replace shingles and underlayment.
Technical Information Provided by FEMA