Flood Vents and Flood Openings on a Raised Home: What Counts and Why It Matters

Flood vents, which FEMA calls flood openings, are permanent openings low in the walls of a crawlspace or the enclosed area under a raised home that let floodwater flow in and out on its own, so the water pressure on both sides of the wall stays equal. FEMA sets minimum standards for them, and openings that meet the standards can also earn a discount on NFIP flood insurance.

I'm Dennis Mark Interdonato with The Dennis Mark Group. A raised home near the water in Monmouth or Ocean County may sit above a garage, a storage area or a crawlspace, and the vents along the bottom of those walls deserve a closer look on a showing. As a former New Jersey home builder and residential remodeler, I give clients a construction-level read on the house, and these openings are worth reading closely.

What do flood openings do?

FEMA's Technical Bulletin 1 (March 2020) explains that the requirements are meant to equalize hydrostatic forces, the pressure from standing or slow-moving water, on walls, to prevent damage to or collapse of the building. They aren't meant to address fast-moving water, wave impacts or debris. The bulletin covers buildings in Zone A on FEMA's maps; Zone V has its own elevation, foundation and enclosure requirements.

What are the minimum requirements?

The NFIP regulation the bulletin quotes, 44 CFR 60.3(c)(5), requires that fully enclosed areas below the lowest floor in new construction and substantial improvements be designed to let floodwater in and out automatically. The design either has to be certified by a registered professional engineer or architect, or meet these minimums:

• At least two openings
• A total net open area of at least one square inch for every square foot of enclosed area
• The bottom of every opening no higher than one foot above grade

Openings can have screens, louvers, valves or other covers, as long as water still flows in and out automatically. Building codes call for openings on different sides of each enclosed area, and FEMA recommends spreading them around the perimeter.

What doesn't count as a flood opening?

Technical Bulletin 1 lists measures FEMA has determined don't satisfy the requirement:

• Standard foundation air vents that can be closed by hand, unless they're permanently disabled in the open position
• Air vents with detachable solid covers meant to be put on by hand
• Vents that open and close with temperature, unless they're also designed to let floodwater in and out automatically
• Devices with covers that only open when water rises on one side of the wall
• Windows below the base flood elevation
• Garage doors without openings; the gaps around a garage door don't count toward the net open area either

The bulletin also explains that net open area means the permanently open part of an opening, so grilles, fixed louvers and faceplates reduce it.

What are engineered openings?

Openings with moving parts should be certified as engineered openings, according to the bulletin. For flood insurance, FEMA's October 2025 NFIP Flood Insurance Manual accepts two kinds of documentation: a certification from the design professional, with their license information, signature and seal and a statement that the openings will automatically equalize the flood loads, or an International Code Council Evaluation Service report for the specific make and model, along with proof of how many were installed and which model.

How do flood openings affect flood insurance?

FloodSmart lists flood openings among the building characteristics that shape an NFIP premium, and its mitigation discount includes proper flood openings (FloodSmart). FEMA's manual says the discount can apply to a building in any flood zone with an enclosure or crawlspace, if every enclosure below the elevated floor meets three requirements: at least two openings on at least two exterior walls, the bottom of each opening no higher than one foot above the higher of the exterior or interior grade or floor below it, and at least one square inch of net open area for every square foot of enclosed area.

The bulletin warns about the other side too: if the openings aren't compliant, the floor of the crawlspace or enclosure is treated as the lowest floor for insurance rating, which can mean a higher premium. More on pricing is in what sets the cost of flood insurance.

What does the elevation certificate record?

The elevation certificate records the square footage of the enclosed area, measured from the outside, the number of permanent openings within one foot of the adjacent grade, their total net open area, and whether engineered openings were used. The bulletin says comments should be added when engineered openings are used, so a local official or insurance agent doesn't mistake a compliant enclosure for a noncompliant one. See what is an elevation certificate.

What can the space under the home be used for?

Under the NFIP regulations, enclosed areas below an elevated building are allowed only for parking, building access and storage. The bulletin lists features that aren't allowed below the base flood elevation, including appliances, heating and air conditioning equipment, ductwork, plumbing fixtures and materials that aren't flood damage-resistant. Some towns have owners sign non-conversion agreements when they issue permits for these enclosures. If the space under a home you're considering has been finished, ask the town about it before you make an offer. The rest of the paperwork for a lifted home is in buying a home that has been raised.

What should you look at on a showing?

• Count the openings and note which walls they're on.
• Note how high they sit above the ground, inside and out.
• Check that they're clear, not covered, blocked or closed.
• Look for labels or paperwork on any engineered openings.
• Compare all of it with the elevation certificate.

Then hand the certificate to your insurance agent. When you're ready, search waterfront homes, see how I approach waterfront homes, read how I help buyers, or start with what your home is worth. Selling to buy on the water? See selling and buying at the same time.

Frequently Asked Questions

How many flood vents does a house need?

Under FEMA's minimum standard, at least two, with one square inch of net open area for every square foot of enclosed area, unless an engineer or architect certifies a different design.

Do regular foundation vents count as flood vents?

Not if they can be closed by hand, unless they're permanently disabled in the open position, according to FEMA's Technical Bulletin 1.

Does a garage door count as a flood opening?

No. FEMA says garage doors without openings don't meet the requirement, and the gaps around them don't count toward the net open area.

Can flood vents lower my flood insurance?

They can. The NFIP's mitigation discount includes proper flood openings, and engineered openings with the right documentation.

This is general information, not legal, insurance, engineering or lending advice. The town's floodplain administrator decides compliance, and your insurance agent rates the policy. Sources checked October 12, 2026.

About the author

Dennis Mark Interdonato is a REALTOR® and Master CDRE® who leads The Dennis Mark Group at Keller Williams Realty Ocean Living in Point Pleasant, NJ, helping buyers and sellers throughout New Jersey make their next move, with Monmouth and Ocean County as home base. Read more about Dennis Mark.

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