As tornado season approaches across much of the United States, homeowners begin to worry about the worst-case scenario: a tornado hitting and demolishing their home. It’s scary, dangerous and real. Always check with a local roofer for more tips specific to your area and type of home. While it’s probably impossible to secure a roof completely from a tornado, you can take certain steps to ensure that your roof has been installed and maintained properly.
Just this year, parts of Texas and much of the midwest experienced multiple devastating tornadoes. Even here at home in the toledo area,we saw our schools damaged and local disaster. After the tornado, the NAHB(National Association of Home Builders) conducted some testing and research on the destruction of homes and made some specific conclusions regarding roof construction. They found that adding a few extra nails to roof coverings made significant difference for homes on the periphery of the vortex. They also concluded that tie-down straps did help hold down roof assemblies. Further, the type of wall bracing did not seem to have significant effect on preventing damage. In many cases, the tornado simply lifted the entire roof off the braced wall or lifted the braced wall off the foundation.
By applying the following code enhancements, you can dramatically improve the odds that your homes will survive wind disasters. (Source: Builderonline.com)
1. Roof sheathing attachment: Use minimum 8d nails. Avoid over-driving with nail guns. Space all nails at 6 inches on center, especially at gable end.
2. Roof tie: Connect the trusses/rafters to wall studs using steel straps. The strap must be nailed to both top plates, not just the top one.
3. Foundation anchorage: Properly lay out and install foundation anchors.
4. Wall top plates: Overlap wall top plates and nail them securely at all corners to prevent wall blowouts.
5. Cathedral gable end walls: Use balloon framing and attach the top plate to roof sheathing at a spacing of 4 inches on center.
6. House shape and size: One-story homes with shallow roof pitch fare best. Hip roofs fare better than gable roofs.
7. Wall sheathing: Specify OSB or plywood. Double the nailing of the sheathing of floor deck.
8. Siding: Consider brick, wood, or fiber cement. If you use vinyl, switch to a thicker product line.
Lets just hope that here in southeast Michigan and the Toledo region do not experience tornadoes. After the devastating blow to Texas and Kansas recently, it is imperative we do all that we can here in tornado alley to prepare.
Source: NAHB Research Center