Shelter types and standards
The main types
- Garage in-ground: a steel box set into a cut in the garage slab. Common in newer suburbs.
- Outdoor in-ground: buried in the yard, away from the house; check drainage and the city permit first.
- Above-ground safe room: steel or concrete room anchored to the slab, easier for anyone who can't manage stairs (Tulsa Planning Office: Install a Storm Shelter).
How big should a storm shelter be?
The Tulsa Planning Office suggests at least 3 square feet per person, plus room for pets and supplies (Tulsa Planning Office: Install a Storm Shelter).
Standards
- FEMA P-320 covers residential safe rooms; P-361 covers community ones (FEMA P-320 (2025), FEMA Safe Rooms).
- Ask for ICC 500 testing paperwork for the exact model (Tulsa Planning Office: Install a Storm Shelter).
Water table
On about 52% of Tulsa County's mapped land, soil stays wet within about 6 feet of the surface for part of the year (FoundationSoils Tulsa County soil summary (USDA SSURGO, data as of Oct 13, 2026)). Ask in-ground installers how they handle water.
Newer guides: Tulsa storm season checklist · SoonerSafe rebate status for 2026
Ratings and limits to know
FEMA's criteria call for a residential safe room to resist 250 mph winds and a 15-pound 2x4 board hitting at 100 mph. FEMA does not test or certify shelters; the National Storm Shelter Association runs a seal program, so ask for test reports or that seal (FEMA P-320, Taking Shelter From the Storm (2008), hosted by NWS).
FEMA calls the door the most vulnerable part of a safe room, and describes its own in-ground design under a house slab as practical only for new construction (same source). Prefab garage units are a different product sold for existing slabs; have the slab checked before one is cut in.
Last checked Oct 23, 2026.
Related: shelter costs and permits and registration. When you are ready, request a quote.