FLOOD VENTS: If you’re considering elevating your house, chances are pretty good that you live in a special flood hazard area (SFHA). By “special” they (FEMA) mean that your house gets rocked by a flood every now and again and therefore requires a homeowner to adhere to strict FEMA building codes. Once your house is elevated, the foundation will continue to be subjected to an occasional pummeling by floodwater. In effort to eliminate the destructive force from a flood, flood vents will be added to the foundation walls.
WHAT IS A FLOOD VENT? Simply put, a flood vent allows for a free flow of flood water in and out of a home’s foundation walls. They serve to equalize the pressure on both sides of the foundation walls, decreasing the chance of significant damage.
So while it may seem counterintuitive to welcome the flood water in, it’s the best way to protect your foundation in the long run. These vents are placed around the perimeter of the house near the ground, but can easily be blended into the surrounding landscape.
This style of flood vent is only appropriate for hydrostatic pressure resulting from slow moving/rising water. Homes located near the ocean or a fast moving river would be subjected to hydrodynamic forces and would therefore require an entirely different foundation system (break-away walls or an open foundation with the house built up on pylons).
These vents are an important part of the National Flood Insurance Program regulations that apply to all new build, repair of substantially damaged homes and substantial improvement of existing homes in SFHA’s. Flood insurance rate maps (FIRMs) put together by the NFIP determine which properties are located in a SFHA based on base flood elevations. Confused? Let’s try an acronym you may be more familiar with instead …
SUMMARY: Install flood vents around the perimeter of your elevated home or your foundation walls may by S.O.L. with subsequent flooding events.