Flooded Wall Considerations


AUTHOR: Tyler LeClear Vachta

POSTED: November 19, 2019

The system is easy enough that a homeowner can do the prep work, install the Sure Cavity rainscreen on their own, and then have spray foam contractor come in to do the insulation.

MTI helped me through the mess of cleaning up after the flood, and I highly recommend their solutions to anyone trying to rebuild after a flood.” –

Joseph P

Houston, MN

Areas That Need to Be Addressed

Moisture Concerns

Floods are not the only moisture concerns that walls face. The reality is that no veneer (brick, stone, siding, stucco) keeps out all moisture. The small amount of moisture that gets past it needs to be drained and dried or it can lead to dangerous mold and damage to building materials. A continuous, vented rainscreen air gap behind the exterior is a best practice approach to preventing incidental moisture issues. The rainscreen gap created by Sure Cavity® is an integral component of the drainable, dryable flood resistant wall. In a future flood the Sure Cavity® will allow the exterior wall to dry out.

Structural Considerations

Most framed exterior wells have plywood, OSB or gypsum sheathing to resist racking, but once flooded these water sensitive materials are removed from the inside. Replacing the sheathing from the inside is an impractical retrofit, but 2lb density closed cell spray foam can be used in the stud cavity to resist racking in the wall assembly and provide a water tolerant insulation.

Addressing Mold

Mold is a serious health concern in flooded areas that requires proper personal protective equipment and mitigation. Paper faced drywall, wood based materials and other organic materials are food sources for mold and need to be removed after a flood.  Apply a paint-based fungicide to walls, studs and insulation surfaces to kill mold and pre-treat for mold in future floods.

See How To Do A Rainscreen Retrofit

Frequently Asked Questions

Are There Other Considerations For Floor Recovery? Where Can I Find Other Resources For Flood Recovery And Mold Removal?

Take a chance to learn from people who have been through floods before. Following Hurricane Katrina and other flooding events the Lousiana State University Extension and LaHouse Homeowner Resource Center have partnered with Building Science Corporation to develop and disseminate resources for homeowners. Browse the LaHouse Homeowner resources.

Will The Rainscreen Retrofit Prevent Future Flooding?

No. The rainscreen approach is a building science best practice to prevent entrapped moisture problems under normal conditions. Many brick veneers were constructed without the proper air gap behind the brick for drainage and ventilation. Without a rainscreen air gap normal weather conditions lead to a buildup of moisture in the wall system and structural deterioration as well as mold issues.

How Can I Reduce the Impact of Future Flooding?

If you can’ elevate your home or move it out of the flood plane, using this rainscreen retrofit technique along with “wet floodproofing” approach for your interior renovation will result in a wall system that is drainable and dryable. Using flood hardy materials reduces the time and resources required to rebuild after a flood.

Wet Floodproofing Resources

Do I Need To Plug Weep Holes During a Flood?

No. Unless your home is a submarine the exterior materials along with doors and windows are not watertight and will succumb to the flood waters. Standing water in contact with brick walls (or other veneers) will inevitably enter the structure and plugging weep holes will not improve the situation.

What Types of Insulation Can I Use?

Use insulation that is water tolerant, such as closed-cell insulation in spray foam or rigid foam panels. Closed-cell insulation will not absorb water and may not require removal in a future flooding event.

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Call 1-800-879-3348 or contact us.

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