Huffs and Puffs Won’t Blow These Roofs Down

Linda F. Benedict, Bogren, Richard C.

Losing the roof on your home to high winds can be an expensive proposition.

High winds can literally lift the roof off a house. Then you not only have to take care of the damage to the roof itself but also the damage to the inside of the house.

Most experts agree that the cost of water damage can be greater than the cost of replacing the roof. And experts also agree that homeowners can reduce the potential for water damage by making roofs more wind-resistant.

One significant way of making roofs more secure is to be sure enough fasteners are used to attach the roof decking to the rafters, said Jeff Burton, building codes manager for the Institute for Business and Home Safety (IBHS). Burton visited the LSU AgCenter’s LaHouse project in August as a consultant. LaHouse is the shortened name for the Louisiana House and Landscape Resource Center, which is being built near the LSU campus as a demonstration, exhibit facility.

IBHS, located in Tampa, Fla., is a national nonprofit initiative of the insurance industry to reduce deaths, injuries, property damage, economic losses and human suffering caused by natural disasters.

Codes set the number of nails per foot, Burton said. And nails, rather than staples, are the preferred fastener. While much of Louisiana doesn’t have residential building codes, builders can still use the codes as a guide to building stronger, safer buildings.

LaHouse goes beyond nails in creating a wind-resistant roof by incorporating a “continuous load path for uplift.” The rafters are strapped to the walls, and the walls are strapped to the foundation. Since they all are tied together, energy from the wind blowing on the roof is transferred to the ground.

Pat Skinner, LSU AgCenter disaster programs coordinator, said that when the rafters are strapped to the wall, the wind must also lift the wall as well as the roof. And when the wall and sill plate are strapped to the foundation, the wind also has to lift the foundation. “Strapping transfers the uplift force on the roof all the way to the ground,” she said.

If you manage to keep the roof structure and most of the covering, a little roof damage can create quite a problem – if it’s raining.

“You can get a tremendous amount of water damage from small roof failures,” Skinner said. “So it’s important to tape the seams of the sheathing, then use roof underlayment and coverings that are resistant to both wind and water.”

Traditional roofing felt is fairly vulnerable to high winds, Skinner said. If your shingles, tiles or other covering blow off, the felt will soon follow. LaHouse is demonstrating three newer underlayment products, including one waterproof peel-and-stick product.

“With this type of product, a loss of shingles or tiles should result in little water intrusion,” Skinner said. “The tile and metal roofs selected for LaHouse are hurricane rated.

"LaHouse construction exceeds the requirements of the International Residential Code as it would apply to Baton Rouge, Skinner said. The building code for roofs includes consideration for windborne debris and resisting uplift.

LaHouse is “code plus to be a Louisiana model for IBHS’s Fortified for Safer Living program,” Skinner said. The experts emphasize codes are considered minimum requirements.

“You can affordably build a house to a higher level than the minimum code,” Burton said. “You want to make sure people are safe.”

Although codes are designed for new construction, homeowners can retrofit existing homes to protect roofs from wind, Burton said. For example, nails can be spaced more closely when a new deck is installed, or an existing deck can be renailed when new roofing is installed. This is particularly important if the original deck was attached with staples rather than nails.

Other considerations include assuring the roofing material is rated for the area’s wind expectations and that the material is installed according to the manufacturer’s specifications, Burton said.

Rick Bogren

(This article appeared in the fall 2005 issue of Louisiana Agriculture.)
1/6/2006 2:33:43 AM
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