Building A Storm Shelter: Safe Rooms
Safe Rooms
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Q I live in “Tornado Alley” in the panhandle of Texas. So far we haven’t been hit by any twisters, but we’ve had our share of close calls. On several occasions, we’ve waited it out in the bathroom because it’s windowless and in the center of the house. Lately I’ve been hearing about storm shelters that can be built right into the house. Can I build one myself? How are they built?
A Yes, you can construct your own storm shelter (now called a “safe room”). Most people go to an interior room as you did or head for the cellar and hope for the best. Unfortunately, even those areas aren’t designed to withstand extreme winds and the wind-driven debris that comes with them. A drywalled, 2x4-framed room is no match for a 2x4 traveling at 100-plus miles an hour, even if it’s in the middle of a house. “Force 5” tornadoes or C5 hurricanes (the two most serious storms) can pack winds of more than 200 mph-enough to blow a well built house right off its foundation. So a safe room can pay off, especially if you live in a vulnerable high-windzone area. (See Fig. A, to find the wind zone you live in.) It won’t cost a fortune, either. A little elbow grease and $1,000 worth of materials will all but guarantee your family’s injury-free survival in any storm that comes down the pike.
Effective Designs
All safe-room designs, even for rooms inside the house, are engineered to provide a room that’s completely independent of the house structure and bolted down to a concrete slab. In addition, the room has a tough, impact-resistant shell to protect occupants from the wind-blown debris that accounts for most storm fatalities and injuries.
Click image to enlarge.
A free booklet published by FEMA (Federal Emergency management Agency) gives explicit construction information for building variations of safe rooms (see the Buyer’s Guide). It offers many designs to consider, depending on the design of your Home and local building practices and materials.
We show a wood/steel design, but other equally effective designs use poured reinforced concrete, reinforced concrete block, fiberglass and welded solid steel (you’d have to hire a contractor or buy a kit to construct these styles, however). Another option is a prebuilt one piece steel or modular cast concrete unit that can be dropped into the ground or into a Home under construction. (Kit prices start at $4,000. See Buyer’s Guide) Even if the house disintegrates around the safe room in the teeth of a tornado, you’ll be snug and safe inside (but scared to death!).
Safe rooms are still embryonic in design, but the room on pages 10 and 11 is the sturdiest, most DIY-friendly design we found. It’ll fit in most basements, large garages or even outside on a separate slab, for people who live in slab-on-grade homes or mobile Homes. For outside locations, build the structure as shown and add a roof and siding.
The sandwich skin of the walls and ceiling has two layers of 3/4-in. plywood oriented in opposite grain directions. The plywood absorbs most of the impact of flying objects, and a layer of 14-gauge steel on the “safe side” (interior side) of the room further blocks debris. The skin can be applied to either the inside or the outside of the studs as long as the steel sheeting faces inside the room.
When possible, install the sandwiched skin on the outside surface of studs. Construction will be easier because you’ll be able to run wire and install electrical boxes without cutting through steel. Plus, you’ll be able to fasten an optional cosmetic layer of drywall to the plywood on the outside and to the studs on the inside. We had to install the sandwich on the inside surfaces on the two walls facing the concrete block and on the ceiling because those areas were inaccessible from the outside. On the ceiling, we glued 1x2 furring strips to the interior-mounted steel to hold the drywall screws.
