(08/30/17) BATON ROUGE, La. — A flood-damaged home requires special attention as soon as possible to avoid further damage and health hazards from molds, other fungi, algae and bacteria. Wetness and high humidity spur their growth within two to three days, so it’s important to act fast after a flood.
“In a nutshell, a wet house is soon an unhealthy house and eventually a rotting house. To make matters even worse, such secondary damage may be excluded from coverage on your flood and homeowners insurance,” said Claudette Hanks Reichel, LSU AgCenter extension housing specialist.
Mold and other fungi are bad for both the structure and the occupants. Mold is an allergen, a trigger for people with asthma, and some types of molds can produce mycotoxins. And decay-causing fungi grow in wood that stays wet for an extended period, causing it to lose strength, Reichel said.
“If your home was flooded, it should be cleaned and dried quickly and thoroughly to prevent mold and future damage by wood rot,” she said. Because floodwater may be contaminated with sewage or other biological pollutants, it’s advisable to disinfect safely, too.
Areas wetted by clean rainwater — for instance, from a leaking roof — may not need to be disinfected. All wet materials should be allowed to dry thoroughly before being covered or enclosed.
“A professional water damage restoration contractor with special drying equipment is the best and safest way to go. Yet, after a flood, many homeowners don’t have that option,” Reichel said.
For safety, wear protective clothing on hands, feet, legs and arms while cleaning up debris. Wear rubber gloves, goggles and a respirator with an NIOSH rating of N-95 or higher while handling flood-damaged or moldy items.
Homes built before 1978 could have lead-based paint. Disturbing lead paint creates a serious health hazard, so the gutting and restoration process can amplify the hazard.
If you hire someone to do work on your pre-1978 home, be sure the contractor is certified by EPA as a Lead-safe Certified Renovator, Reichel said. The website www.epa.gov/lead has information about lead-safe work practices and how to find a certified contractor.
Disinfectants should be chosen and used carefully because they pose a range of hazards, too. “Always read and heed warning labels and instructions,” Reichel said. “Commercial disinfecting cleaners need to be diluted and applied as directed to be effective.”
Bleach solutions, such as 1/4 to 1/2 cup liquid chlorine laundry bleach to a gallon of water, are economical, general-purpose disinfectants when used properly. But they can damage finishes, colors and metals and pose hazards to people, she said.
To be most effective, clean first, then disinfect as a separate step. Never use chlorine bleach in or near the air conditioning system. Never mix bleach with products containing ammonia or acids, which can produce toxic fumes.
Begin cleanup within 48 hours by removing wet carpets and padding. “You may be able to clean and salvage valuable rugs, but you should always replace carpet pads,” Reichel said.
Remove all wet fibrous insulation, even if the interior wallboard appears to be dry. Fiberglass, cellulose, open cell spray foam and other porous insulation will hold water and eventually cause mold and wood rot, so they must be replaced.
Also remove vinyl, laminate and other impermeable flooring to enable the slab or subfloor to dry. “Ceramic tile is a judgement call,” she said. “If fully adhered, it may be cleaned and retained.”
For wood floors, carefully remove a board every few feet to reduce buckling. It’s sometimes possible to salvage and restore solid wood flooring planks, but engineered wood flooring may not recover from warpage.
“A buckled wood subfloor may flatten out on drying,” Reichel said. “Be patient.”
Flush out the wall cavities and subfloors, then disinfect flooded surfaces. Allow the framing and slab to dry thoroughly before installing new insulation, wallboard and flooring. “Drying can take an excessively long time in our humid climate, so it’s crucial to dehumidify the space to speed the drying process,” Reichel said.
If possible, use dehumidifiers and fans. Try to maintain 30-50 percent relative humidity to pull moisture from wet materials. “If you can’t get dehumidifiers, run air conditioners and portable electric heaters at the same time to lower humidity,” she said. “Do not overcool the space because that can cause condensation, worsening the problem.”
Experts recommend waiting until wood framing dries to 15 percent or lower moisture content measured in numerous locations with a reliable moisture meter.
Refinish interior walls with gypsum drywall and latex paint to allow the walls to continue to dry to the inside. Never use (and remove any remaining) vinyl wallpaper, oil-based paint or other interior finishes that have a low moisture permeability.
Consider restoring your home with flood-hardy materials and assemblies that could withstand future flooding and need only cleaning, instead of replacement, Reichel said. Choose interlocking, removable solid vinyl tiles, decorative concrete finishes, ceramic tile with water-resistant mortar or removable room-size rugs, and elevate equipment and electrical wiring when feasible.
If walls have solid wood studs and sound structural sheathing, consider creating a “drainable, dryable wall” by insulating with rigid, closed cell foam boards cut to fit or closed cell spray foam to fill 60 percent of the wall cavity and finish with paperless drywall, leaving gaps behind the molding, Reichel said. After a subsequent flood, you could then remove moldings and flush out the wall cavity, avoiding having to gut and replace materials.
More detailed information on home cleanup, mold removal, repair, restoration and flood-proofing that are tailored for the Gulf region (including “23 FAQs – After Gutting Your Flooded Home” developed following the Louisiana flood of 2016) is available online at www.LSUAgCenter.com/LaHouse. Click on the Flood Recovery icon.
The comprehensive how-to guide “Rebuild Healthy Homes: Guide to Post-disaster Restoration for a Safe and Healthy Home” published by the U.S. Department of Housing and Urban Development is available as a free, online PDF and a free mobile app from the Apple and Android app stores.