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Build a storm-resistant house
Dear Ms. Builder: My husband and I are planning to build a new house. With all of the recent tornadoes, hurricanes, etc., I want to be as safe as possible. Please give me some tips on building a safe house? - Amanda F.
Dear Amanda: There are methods to make a house "safer", but not totally "safe". No matter how strong you build your house, it most likely will not withstand a direct hit by a Fujita Scale 4 or 5 tornado.
By building your house stronger and safer, your family will have additional time to seek shelter before the walls and roof are gone. Having your house hold together for just an extra 30 seconds may make the difference between life and death.
Before giving you tips on building a safer, high wind resistant house, it would be wise for you to consider building a storm shelter within your new home. This is basically a superstrong closet with masonry walls and ceiling and a metal-reinforced door.
A typical family of four can get by with a 4 ft. by 8 ft. shelter. This might sound small, but tornadoes usually moves through quickly, so you will not be inside of it for a long time. When you open the door, it may be the only thing still standing.
Make the walls with 8-in. concrete blocks with metal reinforcing rods in the cores. Fill the cores with pea gravel/concrete mixture to create a very strong, simple-to-build enclosure.
Steel rods from the floor should extend several feet up into the blocks and rods from the walls should extend up into the concrete roof when it is poured. Install some small vents in the enclosure. This is for air circulation and to equalize the pressure as the storm passes over.
The door can be easily made with double- or triple sheets of plywood. Cover the outside with 14-gauge sheet steel to stop any high-speed objects. A sliding-type of door, with strong channels top and bottom, often stays in place better than a standard hinged door.
Now the general house construction tips. The basic architecture of the house should include as many corner offsets as possible. Not only will these make the house look more interesting, but they increase the strength of the house. The weakest house is a simple rectangular design.
A hip roof, with more corners and angles, is stronger than a gable roof. Also, no matter which direction the winds come from, they will tend to flow smoothly over a hip roof. If high winds catch a gable roof from the wrong angle, it will be gone in an instant.
The key to building a high-wind-resistant house is having the roof and walls continuously connected to the foundation or slab. Obviously, a single-story ranch house design makes this easier. If you do not have a large enough lot, you will have to build a two-story house.
Have your builder use 12-in. long anchor bolts spaced on 4-ft. centers to attach the walls to the slab. Simpson Strong-Tie Company (800-999-5099) makes special straps to use in addition to anchor bolts. Actually, you really cannot have too many more mechanical wall attachment methods.
Make sure that your builder uses a pneumatic nail gun when assembling the walls. These guns use special nails that have an adhesive compound on them, so they hold in much better than hand-driven nails. This adhesive liquefies from friction when the nail is shot in and quickly sets up in the wood.
If your walls are a standard 8-ft. height, use 9-ft. plywood or OSB sheathing. This will allow it to be attached from the foundation to the subfloor above. Simpson and USP Lumber Connector (800-526-8724) make framing connectors to stabilize the entire structure.
Send your questions to Ms. Builder, 6906 Royalgreen Dr., Cincinnati, OH 45244 or visit www.dulley.com/msbuilder.