Page Title

Cleaning and Repairing Flood-Damaged Walls, Ceilings and Floors

Text

REMOVING MOISTURE, CLEANING AND REPARING

Be prepared to let flood-damaged walls, ceilings and floors dry for several weeks. If restoration work is completed before proper drying, mold and mildew will continue to grow. The result may be structural damage to your home, the need to repaint walls or replace new wall coverings, and discomfort or illness to family members who have allergies.

GETTING THE MOISTURE OUT

Remove all water as soon as possible from your home. Also remove furnishings that are water soaked. Once water is removed, the next step is removing moisture that has been absorbed by wood, plaster and other materials.

If the weather permits, open doors and windows to remove moisture and odors. If the outside humidity becomes greater than inside, close things up; likewise, close up the house overnight if temperatures drop and moist air might otherwise be drawn indoors. If windows are stuck tight, take off window strips and remove entire sash. If doors are stuck, drive out door hinge pins with a screwdriver and hammer, then remove.

Consider using dehumidifiers to speed up drying when outside humidity levels are high. If possible, rent commercial dehumidifiers, which remove three to four times more water than home models. When using dehumidifiers, shut windows and doors. If there is severe flooding in your home, consider hiring a contractor for water removal. Some companies can dry homes in less than a week with commercial dehumidifiers and air movers.

WALLS AND CEILINGS

Wash out mud, dirt and debris as soon as possible with a hose and mop cloth or sponge.

Start cleaning from the top floor or upper limit of flooding and work downward.

Remove wallboard, plaster and paneling to at least the flood level. Wallboard acts like a sponge when wet. If soaked by contaminated floodwater, it can be a permanent health hazard and should be removed. If most of the wallboard was soaked by clean rainwater, consider cutting a 4- to 12-inch-high section from the bottom and top of walls. This creates a "chimney effect" of air movement for faster drying. A reciprocating saw with a metal cutting blade works well, but use only the tip of the blade and watch out for pipes, ductwork and wiring.

Plaster usually does not need to be replaced, though it will take a very long time to dry.

Some paneling may be salvaged if allowed to dry slowly. You also should remove and dispose of any flood-damaged insulation, which will hold water for months after getting wet.

Sections

More About Drying and Repairing Walls

Walls must be dry from the inside out before restoration, repainting or recovering can begin. Even when walls feel dry to the touch, the material inside the wall may be wet. Drying the inside of the walls may take weeks or even months. The total drying time will depend partially on the amount of dry air that can circulate through the studding and different wall materials.

Plaster and paneling can often be saved, but you still need to get air circulating in the wall cavities to dry the studs and sills. Wallboard soaked by dirty floodwater will need to be replaced. If the wallboard was damaged by clean rainwater, consider cutting a 4- to 12-inch-high section from the bottom and top of walls. This will create a "chimney effect" to speed up drying time. A reciprocating saw with a metal cutting blade works well for this task, but use only the tip of the blade and watch out for pipes, ductwork and wiring.

Guidelines for Wall Coverings and Insulation

Remove drywall, laminated paneling and plaster at least to the flood level. Warping above the water level often occurs with drywall and paneling, so more may need to be removed.

Plaster walls can sometimes be adequately drained by removing the baseboard and breaking out plaster and lath at the bottom of the wall. Later the baseboard can cover the opening.

Some paneling may be salvaged if allowed to dry slowly. Remove the baseboard from paneled walls and pry off the individual sheets. Prop them against the wall to dry. Don't allow them to dry in sunlight, which may cause warping.

Remove vinyl-covered wallpaper. It will restrict drying within flood-damaged walls.

Water-soaked insulation should be removed and replaced. It can hold water for months, causing odor and decay problems. While wet it has little insulation value.

Consider wainscoting as a restoration option if flooding is no higher than 3 feet above the floor.

Patching Plaster

Do not attempt to repair plaster until walls and inner walls (studding and insulation) are completely dry. If walls were flooded extensively, you may need to wait four to six weeks, or even several months, before attempting repairs.

Drywall compound is the preferred method for patching plaster. It comes in a variety of types with different drying times, shrinkage characteristics and consistencies. Read labels to select the type you need.

Repairing Exterior Siding

Dry wall cavities from the inside if possible. (See previous section.)

Remove small section of siding to check conditions on the reverse side. If crevasses are filled with silt, remove siding to water level and clean. Silt left in crevasses will trap moisture, causing mold, decay and peeling paint.

Check for cracked or warped siding. If only a few boards are warped or cracked, replace them individually.

Checking Sheathing

Sheathing is the material between studding and finish siding. Depending upon the type of sheathing, replacement may or may not be necessary.

Wooden boards should dry slowly and some will warp. Re-nail warped areas after they dry. Replace those that are too badly warped to salvage.

Sheathing board is usually absorbent and difficult to dry. Replace any that is disintegrating or separating.

Plywood will probably separate and must be replaced. Marine plywood will not warp or separate, but is generally considered too expensive to use in residential construction unless the building is subject to frequent flooding.

CLEANING SURFACES

Thoroughly wash and disinfect walls, ceilings, exposed wall cavities and studs.

Use a good disinfectant to prevent mildew build-up. One cup of chlorine bleach mixed with a gallon of water works well. For a soapier cleaning solution, add a half cup of mild detergent. Wear rubber gloves.

If walls have already dried, work from the floor to the ceiling to prevent streaking. (Dirty water splashed on dry walls may be absorbed and become almost impossible to remove.) Overlap sections, cleaning the ceiling last.

FLOORS

Before the house has dried out, scrub floors and woodwork with a stiff brush, plenty of water, a detergent and disinfectant. Carpeting soaked by contaminated floodwater should be removed and discarded unless it can be sanitized at a commercial facility for a cost substantially less than replacement. Vinyl flooring and floor tile may need to be removed to allow drying of subfloor.

Wooden floors should be dried gradually. Sudden drying could cause cracking or splitting. Some restoration companies can accelerate drying time by forcing air through the fluted underside of hardwood floorboards.

ONCE FLOORS HAVE DRIED

Assess whether your floors can be repaired, replaced or recovered. Consider your time and budget as you make any decisions. If hardwood floors are damaged beyond repair, you may want to forego the cost of replacement and instead cover them with carpeting, vinyl or linoleum. Or you might lay a new floor over the old, rather than replace it.

Plywood subfloors may have delaminated (separated) from excessive moisture, causing buckling. Sections may have to be replaced or have new plywood nailed over them. Consult a contractor for this work.

If buckling or warping has occurred, drive nails where the floor tends to lift or bulge. This will prevent further damage. Badly warped hardwood floors usually can't be repaired. Warped, wide pine board flooring, however, will often flatten out after it has thoroughly dried.

Plane or sand floors level. Do not refinish until thoroughly dry.

More About Cleaning Floors and Woodwork

After wood floors have been covered with wet mud and dirt, they need to be cleaned, flattened and possibly replaced.

Cleaning. Before the house dries out, scrub all woodwork with a stiff but nonabrasive brush, plenty of water and a non-sudsing detergent to remove mud and silt from corners, cracks and crevices.

Floodwater may accumulate in partitions and exterior walls. Drain these areas as quickly as possible of insulation and structural materials. Remove the baseboard and drill holes between studs a few inches above the floor. After the insulation and frames have dried, replace the baseboard.

Use your regular cleaning product for a final, thorough floor washing. If refinishing is necessary, wait until moisture has dried from wood framing, between walls and floors, and backs of trim. This may take several months. Consult an experienced professional for refinishing, or follow instructions on standard brands of finishes and varnishes for household use.

Flattening. Wood floors probably will be buckled, but if it's not too late, remove a board every few feet to reduce buckling caused by swelling. Leave them alone to dry. Dry wood as fast as possible without aggravating shrinkage or deformation. Open windows and door wide enough to give good ventilation on dry, non-humid days. Maintain a temperature of 50 degrees to 60 degrees Fahrenheit or higher in the house.

Sections of subfloors that separate must be replaced to avoid buckling. When floor coverings are removed, allow subfloors to dry thoroughly, even though it may take several months.

In vinyl floors with wood subflooring, the floor covering should be removed so the subflooring can be replaced. With concrete floors, removal isn't necessary except to hasten drying of the slab.

Loose tiles may be replaced individually if the floor hasn't been soaked. If water has seeped under sheet flooring, remove the entire sheet.

After the house is dry, there are several possibilities for renovating the floors. Some of the buckled flooring may be pounded into place with nails. Some humps may be removed by planing or sanding. Heavily planed floors may never be used uncovered, but a smoothed old floor can serve as a base for a resilient hard-surface floor covering.

Mold is a common problem with wet wood. Badly molded wood must be replaced. Clean moldy floors, woodwork and other wooden parts by scrubbing with a mild alkali, such as washing soda or tri-sodium phosphate, using four to six tablespoons for each gallon of water. Rinse well with clear water after scrubbing with alkali and allow the wood to dry thoroughly. Then apply a mold-resistant finish.

To remove mold stains or mold from unpainted wood surfaces, wash with warm soapy water. If stains remain, add one-half tablespoon of tri-sodium phosphate or four tablespoons of borax to each gallon of warm soapy water. Dry by rubbing with an absorbent cloth.

If mold has grown into the wood under paint or varnish, the finish must be removed. Scrub the wood with an abrasive cleaner, then wash with a solution containing four to six tablespoons of tri-sodium phosphate and one cup of household chlorine bleach for each gallon of water. Sand the wood and bleach any remaining spots. Several applications of household bleach may be needed. Then wash the surface with a weak ammonia solution—two tablespoons of ammonia per quart of water. Finally, rinse the wood well with clear water. Let wood dry thoroughly and apply a wood preservative before repainting or refinishing.

Source: Lois Warme, Iowa State University Extension art and design specialist

REMOVING MILDEW

To remove surface mildew on walls or ceilings, use a mildew surface cleaner (available at paint stores) or: scrub the mildew with household detergent, then scrub with a solution of one-quarter cup bleach to 1 quart water. Rinse well with clean water. Once fully dry, apply a coat of paint containing an anti-mildew agent.

To remove surface mildew on floors and woodwork, use a phosphate cleaning solution such as powdered automatic dishwashing detergent or trisodium phosphate (4 to 6 tablespoons to a gallon of water), available in hardware stores. Rinse with water, and when dry, apply a mildew-resistant finish.