Flood Resistant, Fire Resistant Homes that are Healthy

I’ve been giving a lot of thought lately to flood resistant, fire resistant houses. My neighborhood in Austin, TX experienced a 100 year flood, last year. Though my house was spared, over 100 other homes in my neighborhood were not so lucky. Surrounding areas experienced significantly more flooded homes. So watching the costly and inconvenient renovations that followed really got me thinking. Is it possible to make a water resistant home, and why we’re at it, fire resistant? And, I’d like to keep it healthy.

R-Guard via Prosoco

R-Guard via Prosoco

So I started looking into the premium products that could make this possibility a reality. In terms of water resistance there are many obstacles to overcome. So I decided on Prosoco’s Cat5, a fluid applied air and water control layer that can be applied via paint roller (and some hand tooling) to the exterior of a home, instead of your typical house wrap. Cat5 and it’s R-Guard family of products create a monolithic skin that has been tested to withstand 150 mile hurricane force winds in a controlled laboratory setting (hence the name Cat5).

Let’s cover the entire vertical wall structure with this membrane, even connecting it to our concrete slab foundation. Essentially we are putting a gasket like seal around all of our door and windows frames along with any other penetrations in our exterior wall assembly.

Outswing Doors via Marvin.com

Outswing Doors via Marvin.com

Then we would should reverse the swing of our exterior doors to swing out, using the potential water’s force as an ally to snug tight our door seals in the event of a flood. In terms of addressing our water proofing weak-links in this assembly (the openings), we’d start with Passive-house rated exterior doors and windows, providing us the best weather seals available residentially, and work our way up from there. Exterior outlets and the electrical panel should be raised to 48″ as well. Now, I know this isn’t a perfect flood plan, but it’s a start that could at very least prevent a lot of damage, and help mitigate homeowners’ and insurance companies’ risks alike.

Magnesium Oxide  Sheathing from China

Magnesium Oxide Sheathing from China

What about the fire resistance portion? Let’s start with using Magnesium Oxide 4′ x 8′ sheets for the interior and exterior sheathing, floor decking, roof decking, and even MgO soffits. Roxul Insulation is both fire and water resistant, so lets put it in the walls. That pretty much covers it right?

Roxul Insulation via Pittsburg Insulation

Roxul Insulation via Pittsburg Insulation

Oh, yeah I just remembered insulated concrete walls already have many of the desired attributes of this assembly, though I’d figure this assembly to be somewhat more cost effective. Even if we incorporated the concrete walls, we could still swing the exterior doors outward, raise the exterior outlets up to 4′, and use the Cat5 to water proof the concrete.

Please keep in mind my entire hypothesis is only theoretical at present, and probably full of flaws (specifically leaky exterior doors). That said, I do believe fire resistant “submarine like” homes are both desirable and achievable, all while simultaneously promoting energy efficiency, durability, and indoor air quality.

Doug Cameron is a Healthy, High-Performance Builder & Remodeler with EcoSafe Spaces in Austin, TX.

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