Home Improvements Can Protect Houses, Lives in Tornados

Jul 09 2011

By Stacy Downs

It can take seconds for a monster tornado to tear a stick-built Midwest house to shreds. But even much weaker winds have damaged regional residences this storm season. We've seen the destroyed roofs and broken windows that prove it.

Fred Haan, a mechanical engineering professor at Rose-Hulman Institute of Technology in Terre Haute, Ind., builds 5-inch-tall houses with little holes drilled inside them — small-scale versions of our life-size abodes — to see how they fare versus tornadoes big and small. A giant simulating machine at Iowa State University creates twisters that are 3 feet in diameter. The models are typically demolished in seconds.

"The main issue with houses in the Midwest is the lack of strong connections," says Haan, whose academic research helps lead to better storm-shielding products.

Relying on gravity, roofs rest on walls sitting atop foundations, and there is nothing fastening those components together. Unfortunately, saving frame-construction houses from 200-mph winds that occur in EF-4 or EF-5 tornadoes, such as the May 22 Joplin tornado, is almost impossible. But there are steps to help strengthen houses so they can survive more than a 3-second gust of 90-mph wind, the standard to which most houses in the Midwest are built.

For example, better-quality hardware can make a big difference.

"An extra $500 or $600 spent on replacing a roof could improve things a lot," says Tim Reinhold, chief engineer at the Insurance Institute for Business & Home Safety, which does research for the insurance industry.

Ring-shank nails are the most effective roof fasteners, Reinhold says. The flat-top nails look similar to screws, with ridges along the length of the nail that penetrate the wood. The nails have much better holding power than typical nails with smooth shanks, because the rings act as wedges to keep nails firmly in place. Ring-shank nails typically add about $250 to an average roof cost.

Also, metal brackets commonly known as hurricane clips are effective at connecting roofs to walls. Hurricane clips attach the top plate to trusses or rafters, greatly increasing the strength between the two. These could help a home withstand wind speeds up to 135 mph, or a tornado up to an EF-2. Roughly 90 percent of tornadoes are at this level or below.

"Metal strapping isn't like some exotic thing," Haan says. "I lived in Iowa, and my house was built with it, without me requesting it. Some builders use it on their own, without building codes mandating it."

Large openings in a house are also its weak points. That means doors, especially garage doors, and big banks of windows. So simple upgrades like steel-reinforced doors and high-quality jambs and latches also can help fight wind damage.

"Tornadoes are about generating a suction," Haan says. "Those openings increase pressure inside a house and get underneath your roof."

This year's storms have prompted Kerry Mooneyham, a paralegal who lives in Platte County outside Parkville, to research roof shingles.

"I've been reading about impact-resistant shingles," says Mooneyham, whose hail-damaged roof needs replacing. "I'm willing to pay extra for them, up to a point."

Making houses more durable costs money that people might not be willing to pay, says Mark Heinze, co-owner of Phoenix Renovation and Restoration, an Overland Park company that repairs houses after storm damage.

"Unless codes mandate things, insurance companies won't pay, and most people won't want to pay the difference because they're not sexy improvements," says Heinze, president of the Kansas City chapter of the National Association of the Remodeling Industry.

Still, Heinze says, more cities are beginning to require additional protective measures against storm damage. For example, Olathe code enforcers now mandate ice and water shields for roofs, which can add 15 percent to roof costs.

City officials in Joplin are reviewing building codes and are considering hurricane clips for home construction.

"I hope Joplin does it right, like Greensburg," says Tim Marshall, an engineer and meteorologist of Haag Engineering, a consulting firm in Dallas. "I hope houses and other buildings get built stronger and better, even if it takes a little longer."

Stronger in storms From top to bottom, you can fortify your exterior.
Roof If you need to have your roof replaced, specify:

• Ring-shank nails. The design of a ring-shank nail resembles a screw, except that the head is flat.

• Hurricane clips. The metal bracing connects roofs to walls.

• Shingles. Look for materials rated by UL 2218 or FM 4473 as Class 3 or 4, which indicates they have been tested and found to stand up to increasing levels of hail damage. Also make sure the roof cover you choose is rated for the wind speed in your area. For example, shingles meeting the ASTM D 3161 Class F standard are rated for wind speeds up to 110 mph, while shingles meeting the ASTM D 7158 Class H standard are rated for wind speeds up to 150 mph.

Asphalt shingles are the best value with their hail resistance and wind warranties up to 130 mph. Metal is susceptible to hail damage. Slate is durable but more expensive.

Siding • Cement board is more resistant than vinyl. Cement is not rated by impact and wind like shingles.

Doors • High-pressure rated. This is important for attached garages, the largest hole in your house. High-pressure rated garage doors are $300-$400 more than the average garage door. "It may be a special order, but it's worth it," says Tim Reinhold, chief engineer at the Insurance Institute for Business & Home Safety. Avoid garage doors that have a removable brace, Reinhold says. "In a strong storm, you're not going to go to the garage door to put on a brace."

Windows • Impact-resistant windows, such as Andersen Windows with Stormwatch protection — designed for hurricane-prone coastal cities — have stronger frames and hardware to withstand wind and debris. A clear film is sandwiched between two sheets of glass so the glass doesn't shatter into the house if the glass breaks. The windows are up to 30 percent more in price, compared with regular windows.

Foundation •Walls bolted to foundation. This is invasive and is best done when the house is constructed but can be retrofitted if you're replacing drywall or adding siding.

A safe room in a house is the best way to protect people in a tornado. To build one using Federal Emergency Management Agency specifications, go to www.fema.gov and search "safe room." Pre-fabricated rooms are available for less than $5,000. The National Storm Shelter Association (www.nssa.cc) lists verified safe room vendors, according to FEMA.

Tim Marshall of Haag Engineering in Dallas surveys storm damage. In Oklahoma, he met someone who invested in an in-ground shelter, crediting it with saving his family. "He said it was the best $1,800 he'd ever spent."

Marshall says lots of families have a fire plan but not a tornado plan. "Some people have as little as 10 seconds to take action, so it's crucial to know what to do."

• Close exterior doors and windows to minimize rain and flying debris; also interior doors if you have time. This provides more barriers between you and the storm.

• If you don't have a safe room/shelter, go to a basement or small interior room without windows, such as a bathroom, during the storm. The more walls between you and the outside, the better. Sit underneath something sturdy like a workbench or staircase, or go to a bathtub and cover yourself with a mattress.

Edith Lawellin of Joplin credits a weather-alert feature on her home security system for saving her life. A National Weather Service alert from Alarm.com beeped on her Vivint home-security panel before city sirens sounded, giving her time to take shelter in a reinforced closet. Her house was destroyed, but she survived. The service costs up to $1 extra per month on top of normal security service charges.

Ask storm experts what type of house they would build for themselves and the answer is unanimous: a concrete one.

"Eight-inch concrete walls are like having a storm shelter throughout your whole home," says Tim Reinhold, chief engineer at the Insurance Institute for Business & Home Safety.

Insulated concrete forms cost 4 percent to 8 percent more than traditional frame houses.

Engineer Tim Marshall, who has surveyed the aftermath of severe weather across the U.S., including Joplin, says of all possessions, survivors are most excited when they find pictures among the house debris.

"They're interested in saving wedding photos, not the Sheetrock," he says.

It's a good idea to put scanned photos and back-up computer files on a portable hard drive along with important documents (birth certificates, wills, insurance papers and passports) — stored in airtight plastic food bags — in a safe.

• The Inprint by 9G Products is designed and distributed in Bonner Springs. It uses fingerprints, not codes or keys, and is available through dealers across the U.S. and at www.9gproducts.com for $349.