9 Upgrades to Windproof Your Roof
Master these roof-installation details to keep asphalt shingles on and rain out of your house.
Synopsis: You have one chance to protect a roof against the elements: during installation. This article details nine methods for making an asphalt-shingle roof more weather-resistant—improving the drip edge, using adhesive at the edges, maximizing nail placement, eliminating the overhang, selecting the right shingles, using better nails, securing the hip and ridge, getting the right ridge vent, and using roof cement as a cold-weather backup. You can watch the related webinar for additional information.
Asphalt shingles are getting better all the time, but the elements can still get the best of them. Nor’easters, hurricanes, and even heavy winds can blow shingles off a roof, leaving a house vulnerable to leaks. Roofs in high-wind regions—areas that experience wind gusts greater than 90 mph according to FEMA— are the most susceptible to this type of damage. We can’t control the weather, but we can take measures to make a new asphalt-shingle roof more wind resistant.
Today’s asphalt shingles are likely to last twice as long as the ones I installed when I started building in the late 1970s, but that longevity raises the chances that the roof will experience severe weather in its lifetime. You only get one shot at taking the extra steps needed to ensure that it can weather the storm—and that’s during installation.
To improve my roof jobs, I’ve adopted and adapted some of the methods promoted by the Institute for Business and Home Safety’s (IBHS) Fortified Home program, whose goal is to improve the disaster resistance of homes from top to bottom. I also take additional measures—although nothing that will break the bank—that I think make a more wind-resistant roof.
Windproofing starts with the sheathing. Roof-shingle manufacturers generally accept a minimum of 3/8in. thick plywood, 7/16in. OSB, or nominal 1in. thick wood planks. The Fortified Home program’s “Gold” standard calls for 7/16in. sheathing at a minimum. When it comes to resisting nail withdrawal, thicker is better.
1. Improved Drip Edge
Metal drip edges can be critical to helping roof shingles resist wind uplift along the perimeter of the roof. To do this, they have to be fastened securely to the roof sheathing and framing. The IRC, which since 2012 has required metal drip edges along rake and eave edges, calls for fastening them with roofing nails spaced no more than 12 in. o.c., with an overlap of 2 in. between sections. I go a step above code and follow the Fortified Home recommendations for hurricane-force winds, fastening drip edges with roofing nails spaced 4 in. o.c. in a staggered W-pattern and overlapping drip-edge joints by 3 in. I nail into framing rather than just the roof sheathing whenever possible. If there isn’t solid blocking or subfascia, some of the nails can be driven into the rafters or trusses.
Code requires that the roof leg of drip edges extend at least 2 in. onto the roof deck, but drip edges with narrow roof legs won’t reach far enough onto the deck when the fascia leg bottoms out against the fascia. To ensure that this isn’t a problem, I generally use drip edge with a 5-in. to 6-in. roof leg. The cost difference between narrow and wide drip edge is minimal, and I think the performance boost is worth it.
From Fine Homebuilding #281
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More about building in high wind zones:
- Keeping Walls Steady in the Wind
- Uplift and Hold-downs
- Wind-Resistant Framing Techniques
- How it Works: High Winds vs. Houses