A Guide to Hawaiian Floodproofing: How to Meet FEMA Standards

A vast ocean sits before numerous homes on a Hawaiian island that have had floodproofing.

Consider the Base Flood Elevation When Floodproofing

An expanse of water can be seen stretching straight all the way back to the horizon.
  • Elevate the lowest floor in a residential building
  • Do the same for a non-residential building or have it dry floodproofed to the BFE
  • Construct anything below the BFE with flood damage-resistant materials
  • Avoid having a basement extend below the BFE

Check to See If You Need a FEMA Elevation Certificate

A man is sitting in front of his laptop looking up whether he needs a flood elevation certificate.
  • The owner’s name and address
  • Data from a FIRM that presents the NFIP’s flood zone and elevation
  • GPS coordinates
  • Adjacent grade elevation
  • Elevation for the lowest horizontal structural support
  • The utility equipment/machinery’s lowest form of elevation

Use Flood Damage-Resistant Materials Below the BFE

Blueprints for floodproofing lay strewn about on top of a wooden piece of furniture.

There Are Several Material Classes, Though, So Choose Your Material Carefully

  • Class 1 — These materials are not at all suitable for flood damage resistance. In fact, they have no resistance to damage from clean water (such as potable and gray water) or even moisture. As a result, you’d typically use them only in dry spaces.
  • Class 2 — Similar to Class 1 materials, Class 2 materials are also not a great defense against clean water damage. However, they can handle moisture. So you’re more likely to use them in dry spaces that might experience infrequent water vapor and seepage issues.
  • Class 3 — One level above the previous two classifications, Class 3 materials can resist clean water damage. But that doesn’t mean they are flood damage-resistant. It’s true they can handle being submerged in clean water during periods of flooding. And they can even survive the wetting and drying process that’s a part of that. However, the owner may not be able to get them cleaned up, which can leave the material covered in harmful pollutants.
  • Class 4 — Once you get to Class 4 materials, you’re at the flood damage-resistant stage. With Class 4 materials, you get items capable of resisting damage from the wetting and drying process of flooding. And the owner can successfully clean them after flooding. They still aren’t very durable, however, when it comes to resisting damage from moving water. Still, they can be submerged in floodwaters for interior spaces without any special waterproofing protection.
  • Class 5 — The best for floodproofing, Class 5 materials are highly resistant to floodwater damage. That means they can survive the wetting and drying process and damage from moving water. The owner can also successfully clean them after flooding to remove most harmful pollutants. Because of this combination of advantages, it’s a type of material permitted to be used for partially enclosed or fully outside spaces that may be fully exposed to flooding.

For the Least Amount of Risk, You Might Want Waterproof Concrete

Minimize Your Risk Even Further with Kryton Expertise

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