Also known as: FEMA Wind Zone IV, Zone IV, 250 mph wind zone
How Zone IV affects what you buy
Almost all residential shelters on the market are rated to Zone IV by default because the manufacturing cost difference to drop to Zone III is minimal. The label still matters for FEMA grant paperwork and home insurance discounts.
Authority: FEMA P-320, FEMA P-361. Last reviewed 2026-06-07.
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