What "certified" storm shelter means
ICC 500, FEMA P-320 and P-361, and NSSA producer membership are three different things. Here's how to tell them apart.
There is no single "certified" stamp. Three different things get called certified. Here's what each one means.
ICC 500
The building standard for storm shelters, written by the International Code Council. It sets wind loads, debris-impact testing, and how the shelter is built and anchored. Many building codes and rebate programs require it.
FEMA P-320 and P-361
FEMA's design guides for safe rooms: P-320 for homes and small businesses, P-361 for community safe rooms. A FEMA safe room is designed for 250 mph winds and the debris that comes with them. Rebate programs often require P-320 or P-361.
NSSA producer member
The National Storm Shelter Association verifies a manufacturer's claim of meeting the standard. The maker sends drawings and debris-impact test results to an approved third-party engineering lab. The standard tornado debris test fires a 15-lb 2x4 at 100 mph. NSSA verifies the producer; it doesn't certify each installed shelter.
What to ask any installer
- Who makes the shelter, and is that maker an NSSA producer member? (Check the NSSA directory yourself.)
- Can I see the third-party debris-impact test report?
- Does the engineer-sealed drawing show the wind speed, occupancy, and usable area?
- Will you sign a Certificate of Installation? (Oklahoma's rebate requires one.)
- Will you help me register the shelter with local responders? (How registration works)
On installer profiles
Shelter installer profiles show: shelter maker, NSSA producer member (with the date we checked and a link), test report on file, and whether they can sign the Certificate of Installation. See the example shelter profile.
Sources: NSSA standards · NSSA homeowner info · FEMA P-320 (PDF) · FEMA building science FAQ
Last checked Oct 26, 2026.