When researching flood protection, you will likely encounter two terms: wet floodproofing and dry floodproofing.
They describe different approaches to managing floodwater, and choosing between them requires more than deciding whether you would prefer to keep a space dry.
How wet floodproofing works
Wet floodproofing intentionally allows floodwater into designated spaces. Flood openings help water enter and leave automatically, reducing differences in water pressure across the walls. The approach also involves preparing the space for water exposure. FEMA’s wet floodproofing guidance
How dry floodproofing works
Dry floodproofing uses a designed system to resist water entry. Depending on the building, that system may include sealed walls, protected openings, flood shields, and measures to manage seepage.
It also requires attention to the loads imposed on the structure. Keeping water outside does not remove the pressure it places on a building.
FEMA’s dry floodproofing guidance addresses qualifying nonresidential buildings and nonresidential portions of mixed-use buildings in specified flood hazard areas. It is not a general substitute for required elevation of residential buildings. Systems that require deployment also need operational planning, maintenance, and trained personnel. FEMA Technical Bulletin 3
Which approach fits your property?
Start with your building’s use, flood zone, elevation, and local requirements. A garage beneath an elevated home and a commercial building may call for very different solutions.
Before comparing products, have a qualified professional establish which approach is permitted and appropriate. That decision gives your project a sound starting point.
If flood openings are part of your plan, visit the Flood Solutions Info Center for product and installation resources.
