Flood Clean-up
ABCs of Flood Clean-up to
Reduce the Risk for Mold Growth
HEALTH CONCERNS
Vulnerable people and children should be out of the house while demolition is going on and until after mold has been successfully treated. Refer health questions to your physician.
Stachybotrys, a black mold, grows on drywall in flooded buildings and has been linked with pulmonary hemorrhage and death in infants up to 8 months of age – especially where there is someone who smokes in the house. Remove infants from an at-risk house. Never smoke in a house or car with children present.
Some common molds (such as Aspergillus) can grow in lung tissue, especially in immunocompromised individuals. Other exposed individuals can develop asthmatic or hypersensitivity reactions requiring hospitalization. Aspergillus and Penicillium molds are often green or white, but high levels of mold can be present on surfaces even when not visible to the naked eye.
If mold colonies are visible on drywall, there is high risk for much more hidden mold in wall cavities. When drywall is removed or other moldy materials disturbed, magnitudes more mold particles can be released to the air.
TIMING
The best approach is to remove wet contents and building materials within 24-48 hours, before mold can grow.
If wet materials have not been removed within 24-48 hours, assume that mold has started growing. If funds allow, call in mold professionals to properly and safely deal with contaminated materials and remediate the building. If needing to do the work yourself, carefully observe safety precautions.
Contact your homeowners insurance company. Check with the health department regarding registering with FEMA, if applicable. You may find useful information at www.policyholdersofamerica.org, a non-profit site aimed at helping homeowners with their homeowners insurance companies.
PREPARATION FOR REMOVAL OF WET MATERIALS
Rule out concerns with lead and asbestos prior to disturbing building materials. A small bulk sample can be sent for assessment to a laboratory, such as American Westech, 4359 Linglestown Road, Harrisburg, PA 17112, 717-661-9700, asbestos or lead, $15-20.
If test results are positive, consult with your health department or a lead or asbestos certified contractor regarding options. Lead and asbestos clean-up are similar to mold clean-up.
Seal off the floor above the flooded area to protect it from construction dust and mold particles.
Improve ventilation to the attic as needed. If moisture is trapped in the attic, mold will grow. After a few weeks, check for white or green fuzz where the rafters meet the sheathing or for a dark sheen on the sheathing (roof deck).
MAKE SURE ALL CONTAMINATED MATERIALS ARE REMOVED.
Many times, mold industry personnel go by what is visible. That is, if they don’t see mold, it’s not there. This is not always the case. You can have high levels of mold that are not visible to the naked eye. Follow the path of the water. If water got into wall cavities, under kitchen cabinets, behind built-in shelving, or under flooring, the chances are good that hidden mold will grow. Remove these materials and treat for mold.
Another alternative is to do further testing. Either call to arrange for an on-site assessment or send tape samples (see Testing section of www.mold-control-on-a-budget.com) for microscope examination.
It’s helpful to ask the question, “Why WOULDN’T mold grow there?” If there was water and cellulosic material, and the area couldn’t dry out promptly, the chances are high for mold growth. Common sense is once again a useful quality.
PERSONAL SAFETY
Wear a respirator labeled either P100 or N95 to protect lungs. These respirators are locally available from a home supply store. Breathing will be easier with a respirator that has a cut-out-like section at the nostril area. Make sure the respirator fits snugly.
Check with your physician before respirator use if you have a heart, lung or other health condition of concern.
Wear goggles and other protective gear as needed.
HEPA VACUUM
The vacuum cleaner with the best filtration for capturing mold spores and dust is one labeled “HEPA,” preferably a canister model. A life-time HEPA vacuum cleaner with an industrial strength motor is the Nilfisk GD 930 (about $600 on-line). Use for mold clean-up and for routine housekeeping.
Huge numbers of mold particulates may be released during demolition. Those particulates need to be captured by HEPA vacuuming, damp dusting, and use of a room air purifier. If funds allow, call in mold professionals for this clean-up. They have better equipment than a homeowner.
Mold professionals typically use negative pressure. That is, a commercial-size room air purifier is set up in the work area. This “air scrubber” draws in dirty air, filters it, and discharges it through a hose to an exterior window or door.
Because room air is discharged, the air pressure is reduced. It becomes “negative.” Make-up air flows from cleaner areas of the house into the work area. The direction of air flow from clean to dirty to exterior keeps mold particles from escaping into cleaner areas of the house, thus preventing “cross-contamination” to cleaner areas.
In a do-it-yourself job, you probably wouldn’t have a negative pressure machine, but you can still seal off the dirty work area from the cleaner parts of the house. You can use a HEPA vacuum cleaner and maybe a portable room air purifier to help clean the air. After demolition, cleaning up mold spores becomes a numbers game. The more cleaning, the lower the number of stray spores and other mold particulates in the space.
Tiny mold spores can take 4-8 hours to settle down in dust. Thus, if you have your HEPA vacuum cleaner plugged in and ready to go at the entry to the work area in the evening, wait until morning and then gently vacuum from the entry. Sneak up on the spores. Avoid unnecessary air agitation. You don’t want to be vacuuming while the spores have already been stirred up and are floating up above the vacuum cleaner.
Vacuum before, during, and after demolition and cleaning. Capture as much construction dust as you can at all stages of the project.
SEWAGE
If sewage was part of the flood mixture, the basement and the first floor (if affected) should be disinfected. A least toxic product, Benefect, is available from www.benefect.com. A mild chlorinated bleach solution (1 cup per gallon of water) can also be used, but according to test results, Benefect performs better (see supporting documents at www.benefect.com).
Chlorine is harmful to lung tissue. When chlorine is in contact with organic matter, carcinogens are released.
SAFETY FOR ELECTRICAL & HVAC SYSTEMS
Before starting demolition, have a licensed electrician check wiring and appliances that have gotten wet. Boilers and hot water heaters, etc., may require replacement.
If water has gotten into a furnace, AC unit, or ductwork, have the system checked by an HVAC (heating, ventilation and air conditioning) contractor prior to using it. The unit may need to be replaced, while the metal ductwork and any remaining parts can be cleaned at the end of the remediation project.
Review the brochure on duct cleaning from the U.S. Environmental Protection Agency. Go to www.epa.gov/aiq and then search on “duct cleaning.”
Use only a pleated media filter, such as 3M Filtrete. Do not use the inexpensive fiberglass filter or electrostatic or electronic filtration.
Flexduct cannot be adequately cleaned and should be replaced. Fiberboard-lined ductwork should be replaced.
If water did not get into the HVAC system, do not run the AC. Seal off the vents and returns with plastic sheeting to reduce the risk for infiltration of contaminated air and dust.
If a pleated media filter has been used since installation of the system, the pleated media filter may have protected the system from mold. Cleaning may not be required. If other types of filters were used, cleaning of the entire system is recommended.
From a health standpoint, the main purpose of the filter is to protect the AC coils from dust. The coils are the place of condensation, so if the coils are dirty and wet, mold will grow. A pleated media filter (looks like an accordion pleat) protects the coils from dust.
Make sure the pleated media filter fits snugly, so there is no air by-pass.
REMOVING WET POSSESSIONS and BUILDING MATERIALS
Bag and discard wet porous materials. Wet clothing can be washed, unless it is moldy.
Moldy materials, whether possessions or building materials, should be wrapped in plastic sheeting prior to discarding, to protect neighboring houses from mold particulates.
If carrying moldy materials through cleaner parts of the house, first wrap the moldy materials in plastic sheeting. Put down plastic sheeting or drop cloths to protect floor surfaces.
Discard wet upholstered furniture, mattresses, and rugs and other porous wet materials (cardboard boxes, books, papers, pictures, etc.).
Remove wet drywall, paneling, insulation, and flooring.
CONSIDER THE HOUSE SHEATHING
An area of concern is the sheathing (plywood under the siding). If it has gotten saturated with water, mold will grow on the hidden side under the siding. Talk to a contractor about your options for accessing (for cleaning and encapsulation) or removing sheathing. If the sheathing cannot be removed from the inside, siding has to be removed to reach it.
If the sheathing gets moldy, gases from the growing mold may later infiltrate the living areas and contribute to symptoms in susceptible persons.
If you are stuck financially and absolutely, absolutely cannot attend to removing siding or sheathing, eventually you may be able to tolerate the house by installing an ERV (energy recovery ventilator), which will improve air exchange and ventilation in the house.
ERVs are good for virtually all houses, for air exchange, but they should NOT be considered substitutes for mold removal.
A good source for purchasing ERVs and other energy-related appliances is the non-profit Energy Foundation Incorporated, www.efi.org.
AFTER WET MATERIAL IS REMOVED
Examine remaining building materials for signs of mold. If discoloration is present, HEPA-vacuum visible mold to remove loose material. Do not use a power nozzle, because the power nozzle does not have a HEPA filter.
HEPA vacuuming is very important, not only in mold clean-up but for routine cleaning.
Dry wet building materials with dehumidification. Be wary of fans, because if mold is present, fans will blow it around.
TREAT MOLDY AREAS
After HEPA-vacuuming, wipe small areas of discoloration with Borax solution (1 cup per gallon of water), followed by IMMEDIATE wiping semi-dry with a clean dry rag. Do NOT leave wetness on surfaces, because the more wetness, the more mold growth.
In this inspector’s experience, wiping with Borax solution works better than wiping with chlorinated bleach.
Wiping with 10% bleach solution is likely to be ineffective. Using much stronger solutions can be harmful to lung tissue, plus it releases carcinogens to the air.
ENCAPSULATE WOOD SURFACES
Reduce the risk for re-growth of mold by sealing all remaining wood and wood products with an encapsulant, such as lime-based Caliwel (www.alistagen.com), Zinsser’s PermaGuard, or Fosters 40-20. If the product label has an EPA registration number, it contains a pesticide, even if only lime.
Caliwel is a least-toxic product. Lime kills mold on contact and protects the surface afterwards, without use of chemical pesticides (mildewcides).
PermaGuard is a clear, low-VOC (low odor) product designed to seal studs and sill plates after cleaning. It contains a mildewcide.
Fosters 40-20 is a common industry encapsulant that contains a mildewcide.
Or, search out another encapsulant. Be cautious about using “green” products that may not stand the test of time in protecting wood surfaces. A product can make a satisfactory cleaner but not be a long-term encapsulant. The term “mold resistant” may be virtually meaningless.
Encapsulants don’t last forever. If there is another flood, all bets are off.
As a point of information, even conventional paint contains a pesticide, a “mildewcide.” If it didn’t, in a coastal area mold would grow. One client wanted to use a healthier paint in his basement on Long Island. Within two months, the paint was covered with Penicillium mold.
If you are on a tight budget, use old-fashioned whitewash as an encapsulant. Wear a respirator and gloves, and mix the lime and water outside. (Search on-line for “whitewash + recipe.”) Whitewash may have a limited effective lifespan.
Encapsulate crawlspace ceiling joists and subflooring, followed by installation of fresh insulation between ceiling joists.
CLEAN CONCRETE
Mold typically doesn't grow on concrete, but it can grow on the dirt that settles on the concrete. HEPA-vacuum. Brush off with Borax solution. This is a homeowners' maintenance job. If desired, apply a moisture retardant. Take steps outside to reduce water infiltration, such as extending downspouts, cutting back vegetation 1-2' from the foundation, improving the grading.
POST-REMEDIATION MOLD TESTING
Have surfaces and air tested to confirm that mold has been eliminated and that air levels of spores are within satisfactory limits.
RECONSTRUCTION
Consider whether a basement at risk for future flooding should be finished.
Use mold-resistant building materials, such as cement backerboard (WonderBoard) or Dens Armor drywall (Georgia Pacific), and composite base molding.
A PLAN FOR A CONTROLLED INDOOR ENVIRONMENT
Consider installation of an ERV (Energy Recovery Ventilator – discounted at www.efi.org, Energy Foundation Incorporated).
Use a portable-size dehumidifier from ThermaStor in the basement. (www.thermastor.com).
Use a quality room air purifier, such as IQAir or a HEPA-purifier from E.L. Foust, upstairs.
The result would be:
Fresh filtered air (warmed in the winter; cooled in the summer)
Low relative humidity – minimizing mold growth and dust mites
Low level of particulates in air for breathing
In the summer, if you want to open windows and bring in fresh air, just turn off the system temporarily.
FOR MORE INFORMATION, read further at www.mold-control-on-a-budget.com
For mold assessments and drawing up of remediation guidelines, call
EnviroHealth Consulting, Inc.
888-735-9649
By May Dooley, M.S., CMC (Certified Microbial Consultant)
9-2011
EnviroHealth Consulting, Inc., 1-888-735-9649
Mold and other environmental inspections available in
Connecticut - Maryland - New Jersey - New York - Pennsylvania - Virginia - Washington DC and other areas
may@createyourhealthyhome.com.
Updated 9-2011
