FEMA and ICC 500 shelter standards, in plain English

Not every "storm shelter" is built to the same bar. There are real standards, and a good installer can show you that their product meets them.

The documents

• FEMA P-320, Taking Shelter from the Storm: FEMA's guide for homeowners and small businesses, with safe room designs and planning advice.
• FEMA P-361: FEMA's design criteria for residential and community safe rooms. FEMA calls a room built to it a "safe room."
• ICC 500: the ICC/NSSA Standard for the Design and Construction of Storm Shelters, the building-code standard. P-361 points to it for test procedures.

What they require for a home tornado shelter

• 250 mph design wind speed. FEMA recommends residential safe rooms be designed for 250 mph no matter where in the country they are.
• Debris impact testing. Walls, roof, and door must stop a 15-pound 2x4 board hitting at 100 mph on vertical surfaces and 67 mph on horizontal surfaces like the roof.
• A tested door assembly. The door, frame, and hardware must be tested together. FEMA warns that if the installed hardware isn't identical to what was tested, the door may fail in a tornado.
• Anchoring. The shelter has to stay put. That means a foundation or slab designed for the loads and anchors installed the way they were tested.
• Space. At least 3 square feet per person for a one- or two-family home (FEMA P-320).

Questions to ask any installer

• Has this exact model been tested to FEMA P-361 / ICC 500? Can I see the test report?
• Is the door and hardware you're installing the same assembly that was tested?
• How will it be anchored, and is my slab or soil adequate for that?
• For underground units: how do you handle groundwater, sealing, and uplift on my lot?
• Will you pull the permit? (Jonesboro has a storm shelter permit.)
• Are you a member of the National Storm Shelter Association, or is the manufacturer?
• What's the warranty on the unit, the door, and the installation?

Labels like "FEMA approved" get used loosely. FEMA publishes criteria; it doesn't certify individual products. Ask for the test documentation instead.