Rainscreen & Weeps Post Flood Retrofit
Outdated construction practices created risky conditions for moisture damage and mold growth. Building professionals have noted that many of the homes affected by the 2016 & 2017 floods lack the necessary mechanisms to drain everyday moisture from walls.
The signs of moisture intrusion can remain hidden from the casual observer for years. Moisture intrusion into a wall system leads to a loss of structural integrity, rot, and mold. According to the Environmental Protection Agency, mold is a leading cause of allergies, asthma and other respiratory complaints.
The EPA advises that “the key to mold control is moisture control.”
Homeowners working to clean up after the flooding are encouraged to partner with a qualified contractor to discuss issues that affect the long-term health of the home and its occupants.
MTI is here to help.
Retrofitting a Brick Veneer Rainscreen
Plan A: Design a resilient building outside of the flood plain with a predictable rainscreen drainage plane so that when moisture enters a wall system it has a path to exit and will not come into contact with materials that could rot, mold, or deteriorate in the presence of moisture. MTI has hundreds of new construction wall details from common to complex in its HyperSpecs detail drawing library.
Plan B: Add those important moisture management features to an existing building. If the exterior of the structure has been removed many of the Hyperspecs detail drawings can be referenced when restoring the building. When the interior of a structure has been mucked out, and the cladding is visible from inside the restoration is possible using a detail like the one below.
Fixing It From the Inside - After Gutting a Flooded Home
In a brick veneer restoration from the interior, the goal is to protect the interior from moisture intrusion by adding the Sure Cavity™ rainscreen drainage plane. Weeps must be drilled in the bed joint mortar at the lowest point of the system to allow bulk moisture to exit the system and ventilate the cavity. Spray foam insulation can be used between the studs and the brick wall to restore some stability where the sheathing has been removed. Filling the remainder of the cavity with foam insulation (either spray foam insulation or rigid boardstock panels) increases R-value, protects the drywall from moisture and provides some additional structural strength.
FAQ - Frequently Asked Questions
Are There Other Considerations For Floor Recovery?
Where Can I Find Other Resources For Flood Recovery And Mold Removal?
This guide is NOT comprehensive. 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 This Prevent My Home From Flooding In The Future?
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?
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
- Low Country Rx: Wet Floodproofing (JLC)
- BSD-111: Flood and Hurricane Resistant Buildings (Dr. Josepth Lstiburek - Building Science Corp)
- Wet Floodproofing: Reducing Damage From Floods (LSU Ag Center)
- Wet Floodproofing Requirements - Technical Bulletin 7-93 (FEMA)
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?
Consider using 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.