Safe Rooms (this section still under construction)
While a home might be built to the latest building codes, that doesn’t ensure that it can withstand the strongest hurricanes. The purpose of a safe room is to provide a space where a family can seek refuge that provides a highest level of protection. Safe rooms can be built in one of several places in the home either during original construction or as a retrofit to an existing structure.
- Atop a concrete slab-on-grade foundation or garage floor.
- An interior room on the first floor.
Safe room designs are based on wind speeds that are rarely encountered in the US. Those built below ground level provide the greatest protection, but a safe room built in a first-floor interior room also can provide the necessary protection. Safe rooms should not be built in an evacuation zone, since they cannot protect against rising water.
To protect its occupants, a safe room must be built to withstand high winds and flying debris, even if the rest of the residence is severely damaged or destroyed. Consider the following when building a safe room:
- The safe room must be adequately anchored to resist overturning and uplift.
- The walls, ceiling, and door of the shelter must withstand wind pressure and resist penetration by windborne objects and falling debris.
- The connections between all parts of the safe room must be strong enough to resist the wind.
- Sections of the exterior and interior residence walls that are used as walls of the safe room, must be separated from the structure of the residence so that damage to the residence will not cause damage to the safe room.
Basement or In-ground Safe Room Storm Shelters:
In new construction, one or more regular basement walls can be reinforced to use as shelter walls if they do not contain windows or other openings. The shelter must have a special ceiling that resists penetration from debris above. Below-ground safe rooms must be designed to avoid accumulating water during the heavy rains common in hurricanes.
Slab Foundation Safe Room Storm Shelters:
For new construction, the slab is poured thicker at the spot where a concrete shelter will sit. If the safe room is being built within an existing slab home, it might need to be of wood frame construction instead of concrete. An alternative is to build a concrete shelter adjacent to the exterior of the home.
Storm Shelters in Homes with a Crawlspace:
In homes with crawlspace, the safe room must have a separate foundation. Placing it inside an existing house would require cutting out a portion of the floor, filling in the grade and installing a new foundation. It may be more practical to build an exterior shelter.
Multi-task Your Safe Room:
Your safe room needn’t be a space that’s only used in a storm. It can function as a walk-in closet, bathroom, storage space or other room until it’s needed for shelter.
Steel Safe Rooms:
One supplier provides the option of a two-person or five-person tornado safe room made with 10 gage, galvanized steel panels, reinforced with 2 1/2" x 2 1/2" x 1/4" angle iron. The top is manufactured from 1/4" steel plate to be crush resistant from any falling objects. It has been tested to withstand wind loads of 450 mph and to withstand the 100-mph projectile test. The units have also passed gun shot tests from several types of weapon.
The five-person room is 91" long x 30" deep x 55" high. It has room for two adults and 3 children and one or more pets. It is anchored with 21 special concrete anchor bolts giving it a total of 147,000 lbs of holding power.
Modified Steel Safe Rooms:
Another steel version is a factory manufactured, modular kit, ready for assembly in a home or garage. Its impact and fire-resistant construction provides an easily accessible, architecturally finished tornado or hurricane shelter for construction in the home. This safe room has passed testing at the Wind Science & Engineering Research Center at Texas Tech for missile impact resistance at tornado velocities. This included resisting the impact of full sized automobiles being dropped from 30 feet above the roof. It comes complete with an approved tornado-proof door, welded air vents, frame, structural adhesive, connecting and anchoring hardware.
This safe room is constructed of cold formed, steel plate modules that are bonded with a structural grade, high-strength, one part adhesive to create a strong, solid, impact resistant wall. Walls and roof are erected on a tubular frame constructed of 14 gauge steel tube and attach to the frame with screws in precision laser-cut holes and structural adhesive provided with the unit. Pre-punched holes in each module provide a continuous path for electrical conduit in walls, floor and roof.
Kevlar Safe Rooms:
The DuPont StormRoom is reinforced with DuPont KEVLAR. It is specially designed to endure wind speeds of up to 250 miles per hour and was tested for repeated hits from 12-foot, 15-pound two-by-four pieces of wood shot out of a cannon at 100 miles per hour. Chemically-set anchors help resist the wind uplift. Delivered completely finished, setup on a level site takes 3-4 hours.
Concrete Safe Rooms:
Concrete safe rooms can be built in place or precast. Both require a sufficiently thick reinforced slab. A built-in-place safe room is typically constructed from concrete block with all cells reinforced with steel and poured. Ceilings can be built with steel reinforced concrete or with an engineered wood design. Steel impact doors are typically used. If incorporated into the home itself, separation joints are built into the walls and floors. In the walls, these joints are covered over with the same exterior home surfacing allowing the safe room to blend in with the home.
Precast concrete are constructed from precast concrete panels that are assembled in place and anchored to the slab. They are typically tested to withstand 250-mph winds and 100mph windborne objects. Some have exterior and interior finishes of stucco in a range of colors. Concrete safe rooms are often difficult to retrofit into an existing home.
Wood Safe Rooms:
Due to challenges of adding a concrete or steel safe room to an existing home, a wood frame safe room might be preferable. The walls of a wood frame safe room are not as heavy and therefore don’t require a thickened slab. The wood frame safe room can be created from an existing room, such as a closet or bathroom or built as a new room in an open area of the house such as a garage. If modifying an existing room, the walls of that room must be completely removed and replaced with walls/ceiling resistant to wind and impact that are structurally separated from the house structure. Wood frame safe rooms are built to withstand 140mph windload.