Before you finalize your building site, spend five minutes on FEMA's Flood Map Service Center at msc.fema.gov. Enter your address and look up your flood zone designation. This one check can save you from foundation requirements you did not plan for, insurance costs you did not budget for, and in some cases, a permit denial you did not see coming.

What the Flood Zone Designations Mean

FEMA designates flood zones based on the statistical probability of flooding in a given area. The designations that matter most for metal building owners:

Zone X (shaded and unshaded): Moderate to minimal flood hazard. Unshaded Zone X is outside the 500-year floodplain — the lowest risk designation. Shaded Zone X is within the 500-year floodplain but outside the 100-year floodplain. Most building projects in Zone X proceed without flood-specific requirements.

Zone AE: High flood hazard area. This is within the 100-year floodplain, meaning there is a 1% annual chance of flooding. Zone AE has a Base Flood Elevation (BFE) — the elevation to which floodwater is expected to rise during a 100-year flood event. Any permanent structure in Zone AE typically must have its lowest floor at or above the BFE.

Zone A: Similar to Zone AE but without a calculated BFE. The local floodplain administrator determines the required elevation.

Zone VE: Coastal high-hazard area with wave action. Very restrictive building requirements. Uncommon in the Mid-South.

Zone AO: Shallow flooding area, typically sheet flow on sloping terrain. Depth designations range from 1 to 3 feet.

What Zone AE Means for Your Metal Building

If your site is in Zone AE, you are not necessarily blocked from building — but you have additional requirements:

Elevation requirement: The finished floor of your building must be at or above the Base Flood Elevation. This typically means raising your slab or pad above the surrounding grade, sometimes significantly.

Permit requirements: Most counties require a floodplain development permit for any construction in Zone AE. This is separate from your standard building permit.

Flood openings: Enclosed areas below the BFE (like a crawl space or enclosed foundation) must have flood openings that allow water to enter and exit freely, equalizing pressure during a flood event.

Insurance: Flood insurance is typically required by lenders for structures in Zone AE. Even if you are paying cash, flood insurance is worth considering — standard property insurance does not cover flood damage.

The Elevation Certificate

If your property is in or near a flood zone, an Elevation Certificate from a licensed surveyor documents the elevation of your building relative to the BFE. This document is required for flood insurance rating and may be required for your building permit.

An Elevation Certificate typically costs $300–$600. If your site is in Zone AE, budget for it.

What to Do If Your Site Is in a Flood Zone

Option 1: Choose a different location. If you have flexibility on your property, look for a site that is outside the floodplain. Even moving 50–100 feet can sometimes take you out of Zone AE.

Option 2: Raise the pad. If your site is in Zone AE but close to the BFE, raising your concrete slab or gravel pad above the BFE may be all that is required. Get the BFE from FEMA's maps and have a surveyor confirm your existing grade elevation.

Option 3: Build to flood zone requirements. If you must build in Zone AE, work with your local floodplain administrator to understand exactly what is required. Requirements vary by county and by how far below the BFE your site sits.

Option 4: Apply for a Letter of Map Amendment (LOMA). If you believe your property has been incorrectly mapped into a flood zone, you can apply to FEMA for a LOMA. This requires a licensed surveyor to document that your property is actually above the BFE. If approved, your property is officially removed from the flood zone.

The Five-Minute Check

Go to msc.fema.gov right now. Enter your address. Look at the flood zone designation for your building site. If it is Zone X (unshaded), you are in good shape. If it is anything else, make a few phone calls before you order your building.

It takes five minutes and it is free. Do it before you do anything else.

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