Pre-FIRM vs. Post-FIRM Buildings: Why Your Build Date Matters for Flood Insurance

A Pre-FIRM building was built before its community's first Flood Insurance Rate Map (FIRM) took effect, often with no requirement that it be built above flood level. A Post-FIRM building was built on or after that date, under codes that generally required the lowest floor to be at or above the Base Flood Elevation. The distinction has nothing to do with the building's age in years and everything to do with which set of construction rules was in place the day it was built.

Here is what a FIRM date is, why it changed how buildings got built, and how it shows up on a flood insurance quote.

What "FIRM" Actually Means

A Flood Insurance Rate Map, or FIRM, is the map FEMA produces for a community showing flood zones and the Base Flood Elevation. Every community that participates in the NFIP has a FIRM, and most have had more than one as flood studies get updated over time. The date that matters for Pre-FIRM versus Post-FIRM status is the date the community's first FIRM went into effect, not the date of the most recent map.

That first FIRM date varies by community. Two houses built in the same year, in neighboring towns, can land on opposite sides of the Pre-FIRM/Post-FIRM line simply because one town's first flood map took effect earlier than the other's.

Why the Build Date Changed Construction Requirements

Before a community had a FIRM, there was no flood zone, no Base Flood Elevation and no federal requirement tying construction to a flood level. Buildings went up at whatever elevation made sense for the lot, the foundation and the budget at the time.

Once a community's first FIRM took effect, new construction and substantial improvements in the mapped flood zones generally had to meet floodplain management requirements, most importantly that the lowest floor be built at or above the Base Flood Elevation. That single requirement is the main difference in how Pre-FIRM and Post-FIRM buildings tend to sit relative to flood risk.

• Pre-FIRM buildings were built with no elevation requirement, so the lowest floor can sit well below, at, or above the Base Flood Elevation purely by chance.
• Post-FIRM buildings were built after the requirement existed, so the lowest floor was designed, at a minimum, to meet it.

How Pre-FIRM and Post-FIRM Status Affects a Flood Insurance Quote

An underwriter uses Pre-FIRM/Post-FIRM status as one input among several, not as a standalone verdict on a property. In practice:

• Pre-FIRM buildings often get more underwriting attention, because the lowest floor's actual elevation relative to the Base Flood Elevation is unknown until it is measured or an elevation certificate is produced.
• Post-FIRM buildings often move faster through underwriting, because the construction requirement at the time of the build gives the underwriter a starting assumption to work from.
• An elevation certificate affects a Pre-FIRM building's quote more than a Post-FIRM building's, because it replaces an unknown with a measured number. Sterling does not require an elevation certificate to quote, but one can change the picture for an older building.

Step-by-Step: How to Find Your Building's FIRM Date and Status

Step 1: Find Your Community's Name as FEMA Uses It

Flood maps are issued by community, not by individual address, so you need the city, county or unincorporated area name FEMA uses for your location.

Step 2: Look Up the Community's Flood Map History

The local floodplain administrator, usually part of the city or county building or planning department, keeps the history of FIRM effective dates for the community, including the date of the first map.

Step 3: Compare That Date to Your Building's Construction Date

If your building's certificate of occupancy, tax record or permit predates the community's first FIRM effective date, it is Pre-FIRM. If it was built on or after that date, it is Post-FIRM.

Step 4: Check Whether an Elevation Certificate Already Exists

A Pre-FIRM building with an elevation certificate on file gives an underwriter a measured answer instead of an assumption. Ask the local floodplain administrator, the prior owner, or your lender whether one was ever produced.

Common Mistakes with Pre-FIRM and Post-FIRM Status

• Assuming "old house" automatically means Pre-FIRM. It depends on the community's specific FIRM date, not a general sense of the building's age.
• Using the current flood map's effective date instead of the first one. Status is based on the community's first FIRM, even if the map has been updated several times since.
• Assuming Post-FIRM means no flood risk. It means the building was built to a code that accounted for flood risk, not that the risk is gone.
• Skipping the elevation certificate question on an older building. It is often the single piece of information that moves a Pre-FIRM quote forward.

Pro Tips from Sterling Flood Underwriters

Ask your local floodplain administrator for the FIRM history, not just the current map. Most keep a record of every effective date going back to the community's first map.

Send what construction records you have, even partial ones. A permit date, a certificate of occupancy, or a tax record showing year built all help establish Pre-FIRM or Post-FIRM status.

Get a Quote

Not sure whether your building is Pre-FIRM or Post-FIRM, or what that means for your situation? Sterling's underwriters work with both every day. Get a flood insurance quote from Sterling Flood.

Frequently Asked Questions

What does "FIRM" stand for?

Flood Insurance Rate Map, the map FEMA produces for a community showing flood zones and the Base Flood Elevation.

Is a Pre-FIRM building harder to insure?

Not necessarily. It often means more underwriting questions, because the lowest floor's elevation relative to the Base Flood Elevation is not established by the build date alone.

Does Pre-FIRM status ever change?

No. Pre-FIRM and Post-FIRM status is set by the building's construction date relative to the community's first FIRM and does not change later, even when the map is updated.

Do I need an elevation certificate if my building is Post-FIRM?

Sterling does not require one to quote. For a Post-FIRM building, the construction-era requirement already gives the underwriter a starting point, though a certificate can still help.