After the Flood: Controlling Mold and Moisture

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1 Manitoba Emergency Management Organization Information compiled by Manitoba Energy and Mines After the Flood: Controlling Mold and Moisture Mold can affect your health and damage your home. Solving a moisture problem is often the key to eliminating mold. Homes that have been flooded need extra attention to prevent excess moisture. This fact sheet explains the steps you can take to get rid of mold and eliminate moisture problems in your home. Does your home have a problem? Mold is a common problem, even in homes that haven't been flooded. However, flooding can lead to more dampness and condensation than usual. If this excess moisture isn't controlled, it can create mold or make existing mold growth worse. MEMO has published another fact sheet entitled "Understanding Mold". It explains what mold is, why it is a concern, and how to determine whether your home has a problem. For a free copy, contact MEMO at or visit the Flood Recovery Information Office in either St. Adolphe, Rosenort or Letellier. How to get rid of mold Quickly destroy any mold you find to prevent it from spreading. Follow this three step process: Step 1 - Disinfect and clean surfaces: Kill mold by wetting it for 15 minutes with unscented household bleach. Next, clean away any dirt or debris on nearby areas using one part bleach in four parts water, plus a small amount of non-ammonia detergent. Finally, rinse the entire area with clean water. (Remember than both visible and hidden surfaces, such as inside walls, may need to be disinfected and cleaned.) Step 2 - Dry surfaces quickly: After disinfecting and cleaning, dry the affected area as soon as possible using fans, dehumidifiers or natural ventilation. A

2 moisture meter is recommended to determine whether materials are dry enough to be covered, enclosed or refinished. For information on how to obtain a moisture meter, contact the Flood Recovery Information Office in either St. Adolphe, Rosenort or Letellier. Step 3 - Take preventative measures: Most mold problems result from excess moisture. Unless you deal with the moisture problem, mold may continue to reappear. For more detailed advice, read CMHC's "Clean-up Procedures for Mold in Houses". Free copies are available from MEMO. Special precautions - Consider these precautions before you begin work to rid your home of mold: Relocate vulnerable individuals - If your home has a mold problem, and if you have a family member who is at an increased risk of health effects from mold, consult your family health care provider. It may be desirable to temporarily relocate these persons until the mold problem is solved. Use appropriate respiratory protection - For small patches of mold (up to about 0.2 square metres - two square feet), use an approved disposable dust mask. The mask or its package should state that it is ANIOSH-approved (TC-21C) for dusts and mists. "For larger areas (up to about one square metre - 10 square feet), use a full or half-faced respirator with a "NIOSH-approved HEPA filter". - These respiratory protection devices are available from safety supply stores and some building supply retailers. Areas with extensive mold growth (larger than one square metre - 10 square feet), should be left to qualified professionals. Protect your skin and eyes - For small areas, use rubber gloves and safety glasses or goggles. For larger areas, also use disposable coveralls and be sure to cover your hair. After you finish working or before you take a meal break, thoroughly wash your hands and any exposed skin. Ventilate the work area - Bleach is a harsh chemical. Ventilate the work area well and never mix bleach with ammonia - the fumes are toxic! Isolate the work area to prevent fumes, dust or mold debris from creating a problem elsewhere in your home. Vacuum with care - Vacuum cleaners can be helpful to remove mold and dirt that can support mold growth. However, ordinary household or shop vacuum cleaners do not trap fine particles and can increase mold exposure. A better alternative is to use either a central vacuum that exhausts directly to the outdoors or a vacuum equipped with a high efficiency "HEPA" filter.

3 Properly dispose of contaminated materials - Any material contaminated with mold, and especially porous materials such as drywall, ceiling tiles, insulation and carpet, must be double-bagged in heavy-duty plastic bags and disposed of properly. Solving moisture problems that can lead to mold Monitor your home's humidity levels - Knowing the level of relative humidity (R.H.) of the air in your home will enable you to judge whether it is too humid or too dry. Use a hygrometer to monitor the R.H. and how it changes throughout a typical day in different rooms of your house and over the heating season. Many older, dial-type hygrometers are inaccurate. More accurate, digital hygrometers are available from electronics stores and some building supply stores for about $30 to $40. For more information, refer to CMHC's fact sheet entitled "Measuring Humidity in Your Home" - contact MEMO for a free copy. Keep humidity levels within a healthy range - For optimum health and comfort, your home's relative humidity should be kept between 30% and 55% during the heating season. Higher levels increase the spread of mold and other indoor air quality problems. Lower levels aggravate respiratory infections and skin allergies. When the temperature drops below C outdoors, limit the indoor R.H. to 30%. Unless you have energy-efficient windows, higher levels will result in excessive condensation. Reduce excess moisture - Getting at the source of excess moisture makes more sense than having to rely on a lot of ventilation. Ventilation removes moisture, but also adds to your heating bill. Here are tips on reducing moisture sources: Slope soil away from the foundation and extend downspouts so they end one to two metres (three to six feet) away from the house. This will keep basement and crawlspace walls and floors drier. Cover exposed earth in crawlspaces or partial basements with heavy polyethylene, sealed at joints and edges, and weighted down. Cover open sources of water such as sump pits, aquariums, whirlpools, etc. Avoid drying clothes indoors. Vent the dryer to the outdoors. Operate bathroom exhaust fans during a shower or bath. Use a range hood exhaust when cooking. Make sure fans are vented to the outdoors. Don't use a humidifier unless humidity levels are below 30% R.H.

4 Do not dry firewood indoors. Use dehumidifiers wisely - Dehumidifiers are of limited benefit in winter, since they can only lower relative humidity levels to between 50% and 60%. However, running a dehumidifier in the basement during humid summer days can be effective at reducing condensation on foundation walls and floors. Install an effective ventilation system - If indoor relative humidity levels are high, and moisture sources cannot be reduced any further, increase ventilation rates. Ensuring adequate mechanical ventilation is especially important if you have a newer home or are reducing air leakage in an existing home. Many exhaust fans make a lot of noise but don't move much air. Replace these with more efficient, durable and quieter units to remove moisture from bathrooms and kitchens. Make sure the air is being exhausted to the outdoors and not into your attic! The best approach is to provide a balanced ventilation system with a heat recovery ventilator (HRV). An HRV provides continuous ventilation without wasting a lot of energy by transferring heat from the exhaust air to preheat the incoming fresh air. To find a qualified HRV contractor, look under "Heating Contractors" or "Ventilating Contractors" in the Yellow Pages. Additional points about ventilation: If your home has been flood proofed by raising it onto a new foundation, or if it has seen extensive repair work, the home needs lots of extra ventilation for several months. Construction materials, particularly wood and concrete, will be drying out. The interior of a home gains moisture in the summer and gradually releases it back into the air during the fall and early winter. This process is exaggerated if your home has been flooded. To speed the drying process, run exhaust fans longer and open windows on mild days in the fall and early winter. On mild and damp days in the spring, ventilation will not be effective at removing moisture. This is because the outdoor air is saturated and has little drying potential. During muggy summer days, the use of air conditioners can help. Be careful installing and using powerful exhaust fans. If your home has fuelburning equipment (i.e. furnaces, hot water heaters, boilers, fireplaces and wood stoves), powerful exhaust fans may, under certain circumstances, draw dangerous combustion gases into your home. If you suspect that this is occurring in your home, immediately ask your heating contractor or utility to investigate the problem. Keep the air circulating - Condensation and mold growth often occur in out-of the-way areas like closets, corners, walls behind furniture and unused rooms. Increasing air

5 circulation to these areas will warm the cold surfaces and lower local humidity levels, reducing the potential for condensation: Pull furniture and stored material (especially cardboard boxes) away from exterior walls and up off basement floors. Leave closet doors ajar; leave bedroom doors open as much as possible; undercut doors. Don't block warm-air registers or cold-air return grills. Open up drapes, curtains and blinds. Remove insect screens. Don't cut off the heating supply or close off unused rooms. Set the furnace fan to run continuously. This will use more electricity, but the expense can be reduced by installing a two-speed energy-efficient motor. Reduce uncontrolled air leakage - In the upper part of your house, air leakage from inside your home carries moisture into the attic and wall cavities. This can cause longterm, hidden deterioration. In the lower part of your house, air leakage from the outdoors can chill window frames and door sills, causing frost to form. Air leaking in from the soil can be a major source of moisture. It is a good strategy to reduce this uncontrolled air leakage and rely more on controlled mechanical ventilation for fresh air. Seal hidden openings into the attic, tighten the attic hatch, weatherstrip and caulk around windows and doors, gasket electrical outlets, caulk baseboards and seal the tops of foundations and open sump pits. For details about how to do this, refer to Manitoba Energy and Mines' booklet "Sealing, Caulking and Weatherstripping" - contact MEMO for a free copy. Add insulation to cold surfaces - Areas that are uninsulated or poorly insulated, such as exterior corners, the junction of the wall and ceiling, or foundation walls, can be improved with additional insulation. This may be expensive, but can be incorporated as part of a renovation. Don't forget to install an air-vapour barrier (usually polyethylene) on the room side of the insulation to prevent hidden condensation behind the insulation. If your basement walls are being excavated to repair cracks, consider insulating these walls from the exterior at the same time. This will keep the basement walls on the warm side of the insulation in winter reducing the potential for condensation. Exterior insulation has the added benefit of significantly reducing the potential for water leakage since the insulation acts as a drainage layer. Manitoba Energy and Mines has published several booklets about how to insulate a home: "Basement and Crawlspace Insulation"; "Wall Insulation"; and "Attic Insulation" - contact MEMO for free copies.

6 Upgrade or replace windows - Windows are usually the first place where you notice condensation, since they are the coldest surfaces inside the home. Replacing windows is costly and normally shouldn't be your first solution to a moisture problem: If your windows are still in good condition, consider installing interior storm window kits over the entire window and frame for the heating season. This effectively adds a layer of glazing, prevents air leakage, and brings the inner surface of the window closer to warm air currents. Condensation will be reduced or even eliminated, and heating bills and uncomfortable drafts will be reduced. Thin plastic "heat shrink" kits are inexpensive and widely available but have to be replaced each year. Other systems such as rigid plastic sheets, are much more expensive, but can be reused for years. If condensation is occurring between the panes of older unsealed windows (e.g. a permanent window plus a storm window or two single-glazed slider windows) try sealing the interior unit with weatherstripping or removable, strippable caulking. If condensation is occurring between the panes of sealed double or triple-glazed unit, the unit will eventually have to be replaced. If your windows are in poor condition, consider upgrading to high-performance windows that resist condensation and save energy. These windows often have special "low-e" coatings, "warm-edge spacers" and are filled with inert gases like argon. For tips about upgrading your existing windows, consult Manitoba Energy and Mines' booklet "Windows and Doors". If you are choosing new windows, refer to Natural Resources Canada's booklet "Consumer's Guide to Buying Energy Efficient Windows and Doors". Contact MEMO for a free copy of either booklet. Clean and maintain mechanical equipment - Humidifiers, dehumidifiers, air conditioners and air filters can be a source of mold growth. Regular cleaning has the added advantage of improving the equipment's efficiency. For advice on cleaning furnace humidifiers and replacing air filters, consult Manitoba Energy and Mines' booklet "Heating Systems". If your home is equipped with an HRV, see Natural Resources Canada's booklet "Operating and Maintaining Your Heat Recovery Ventilator (HRV)". Contact MEMO for a free copy of either booklet. Check fuel-burning equipment - If your house has high humidity levels and no obvious moisture sources, it is essential to have a heating contractor or your utility immediately check any fuel-burning equipment (i.e. furnaces, hot water heaters, boilers, fireplaces and wood stoves) to ensure that they are venting properly. A blocked chimney could mean that combustion products, including large amounts of water vapour, are spilling into your home. Along with this moisture comes dangerous

7 combustion gases such as carbon monoxide. For more information, refer to Manitoba Energy and Mines' booklet "Heating Systems" - contact MEMO for a free copy. This fact sheet is only an introduction to controlling mold and moisture problems in a flooded home. Contact MEMO for further information. Further reading There are many things other than mold or excessive moisture that can cause an indoor air quality problem in your home. CMHC's booklet "The Clean Air Guide" contains a stepby-step description on how to create and maintain a healthy indoor environment. Contact MEMO for a copy. Need more advice? If you feel that your home has a serious mold problem as a result of being flooded, or you need advice on eligible repair expenses, please contact MEMO in Winnipeg at or Many of the measures that solve moisture and mold problems also save energy and help to pay for themselves. If you need impartial, technical advice about what you can do to improve your home, call Manitoba Energy and Mines in Winnipeg at or Note: Portions of this fact sheet were adapted from Natural Resources Canada's publication "Moisture Problems".