Safe room size calculator
Enter how many people will shelter. We show the minimum floor area FEMA and ICC 500 call for in a home safe room.
Minimum usable floor area: 12 sq ft
That is 3 sq ft per person for a residential tornado safe room. A room about 4 × 4 ft would work; more space is more comfortable for long hurricane stays.
Minimums from FEMA P-320 and ICC 500 for residential safe rooms. Rebate programs usually require the shelter to meet these standards and be installed by an approved contractor.
How safe rooms are sized
FEMA’s guidance for residential safe rooms (FEMA P-320, built to the ICC 500 standard) sets a minimum usable floor area per occupant: 3 square feet per person for tornado safe rooms and 7 square feet per person for hurricane safe rooms, because people may need to stay inside much longer during a hurricane. Wheelchair users need more room.
State rebate programs typically require that the shelter meet FEMA P-320 or P-361 and ICC 500 and be installed by a qualified contractor. See your state’s program on our state pages and read ICC 500 and FEMA P-320 in plain English.