Short answer
Your lender requires flood insurance when the house is in a high-risk flood zone, the zones on FEMA's map that start with A or V. Under Fannie Mae's rules, a detached garage or barn in the zone doesn't trigger it if the house is outside. If FEMA amends its map to take the house out of the zone, the requirement can be dropped. And a private flood policy can work instead of a federal one if its coverage is at least as good.
Is this only a coastal question?
No. Rivers, lakes and ponds have mapped flood areas too, and the Merrimack River runs past Manchester, Merrimack, Litchfield, Hudson and Nashua. Check any address on FEMA's Flood Map Service Center or the state's NH Flood Hazards Viewer before you make an offer. The flood zone guide walks through the basics.
What if only a garage or barn is in the flood zone?
Fannie Mae's Selling Guide (B7-3-06) looks at the main house first:
- If any part of the house is in a high-risk zone, flood insurance is required.
- If the house is outside but a detached residential building that's part of the loan, like a guest cottage, is inside, flood insurance is required on that building.
- If the house is outside and only a non-residential building like a detached garage or barn is inside, it isn't required on either one.
Your lender may still have its own rules, and you can always choose to buy coverage.
What if I think the map is wrong?
FEMA issues a Letter of Map Amendment (LOMA) when a home on naturally high ground was mapped into a high-risk area by mistake. Homeowners can request one through FEMA's Online LOMC system, and licensed surveyors and engineers can use FEMA's eLOMA tool. If FEMA approves it, send the letter to your lender and ask it to remove the flood insurance requirement for that building.
Can I use private flood insurance?
Yes, for Fannie Mae loans, if the policy's terms and coverage are at least equal to a National Flood Insurance Program (NFIP) policy and the insurer meets Fannie Mae's rating rules. Either way, coverage must be at least the lowest of the home's replacement cost, the most the NFIP offers, or the loan balance, and the deductible can't be higher than the NFIP's maximum. Get quotes from both during your inspection period.
What about a condo?
For an attached condo building in a high-risk zone, Fannie Mae requires the association to carry a master flood policy on the building. See the condo mortgage guide and condo documents to ask for.
Sources
- Fannie Mae Selling Guide B7-3-06, Flood Insurance Requirements for All Property Types
- FEMA, Change your flood zone (Letter of Map Amendment)
- FEMA Flood Map Service Center
- NH Office of Planning and Development, Floodplain maps and NH Flood Hazards Viewer
Checked November 2, 2026. Rules and dates change, so confirm current details before you rely on them.
General information only, not tax or legal advice. Program availability, eligibility and terms vary by lender and are subject to change and to underwriting approval. Not a commitment to lend.