Mold and Moisture
In order to grow, mold spores need a comfortable environment, food, and moisture. If left undetected or untreated, mold can lead to negative health effects such as allergic reactions, respiratory infections, and more. This checklist is to be used as a guide to inspect and investigate your home for signs of excess moisture and mold growth.
When investigating possible mold issues, you may disturb contaminated areas and, in doing so, further spread contamination into the rest of the home. This poses a serious health risk to those with compromised immune systems, asthma, or allergies; therefore, before conducting a thorough mold investigation, you may want to consult your doctor or hire a professional. If you choose to conduct this search yourself, please use appropriate personal protective equipment (PPE) as recommended by the EPA.
Basement / Crawl Space
Inspect ceiling, joists, and stairs for mold growth.
- Check the indoor humidity levels with a moisture meter or humidistat. Humidity levels should be maintained below 60% If over 60%, you should consider using a dehumidifier. If you have a dehumidifier, be sure to empty and clean the drip pan regularly. Optimal humidity levels are between 30-50%
- Look for peeling paint, imperfections, and discoloration as this may indicate moisture. If present, locate the source of moisture, eliminate it, and dry the area. Dry areas within 24-48 hours.
- Inspect the floor for foundation cracks. Keep in mind that they may lead to the exterior, so check inside and out.
- Check that the sump pump is functioning properly and the floor drain is intact. (A sump pump is found in some basements or crawl spaces, and it is used to pump water away from the house).
- Inspect your crawl space for moisture leaks and ensure that it is properly sealed. At a minimum, there should be a 6-8 mil. plastic, or vapor barrier covering the soil.
Exterior / Yard
- Make sure all gutters and downspouts are intact, free of debris, and that they direct water away from the house. The downspouts should extend 6–10 feet from the foundation.
- Check for signs of water pooling on the roof or around the foundation. If present, this indicates that water is not properly draining from the roof.
- Check the slope and grade of the house to ensure that the ground slopes away from the house. The slope should be about 6 inches of 6–10 feel. The slope helps direct water away from the foundation.
- Inspect the siding and exterior paint for peeling, chipping, or bubbling paint. Also, look for visible signs of mold growing on the house.
- Inspect the roof for missing or curling shingles that could lead to indoor leaks. You may need to hire a professional to inspect the roof.
- Check that the flashing around doors, windows, joints, etc., is in good condition (flashing is a type of material like aluminum or stainless steel, used around joints on roofs, walls, windows, doors, and chimneys to prevent water penetration).
- Check that the outside dryer vent is not blocked or filled with debris. Also, ensure that it vents to the outdoors and not the crawlspace, attic, or indoor space.
- Make sure lawn/outdoor sprinklers only spray water onto the grass and not the house.
- Check to see that any plantings around your foundation are not overwatered. If you have too many plants around the foundation, you may need to remove them.
Floors, Ceilings, Windows, and Walls
- Inspect ceilings and walls for discoloration, sagging, bowing, or wet spots. If you have a dropped ceiling, lift up the tiles and inspect the cavity.
- Check for condensation or moisture on the windows or walls. Condensation may be a sign of high indoor humidity.
- Look for moisture leaks or peeling drywall around window frames.
- If concerned about mold beneath the carpet, lift a corner of the carpet and inspect the underside for visible mold.
- If you have vinyl wallpaper, look behind it for mold.
- If you have mold in your closet, it may be caused by poor ventilation. You may need to increase the airflow, which can be done by leaving the door open. Also, if the closet is full, remove about 1/3 of the contents to increase circulation.
Kitchen and Bathroom
- Inspect the caulking, grout, and tiles for damage. Repair if needed.
- Check for plumbing leaks around sinks, tubs, refrigerators, dishwashers, and showers.
- Check the exhaust fan suction with a piece of toilet paper. With the fan running, place a single sheet of toilet paper in front of the fan. If the paper stays in place while the fan is on, then the fan is working properly.
- Check to make sure the kitchen and bathroom fans vent to the outside and not the garage, attic, or other interior space.
- Make sure everyone in the household turns the bathroom fan on when showering or bathing. If there is no fan, then they should open the window for ventilation.
- Check for mold or musty smells in cabinets, drywall, and all wood materials. You may want to hire a professional who will use a moisture meter to check moisture levels.
- Clean and empty the refrigerator drip pan.
- Check for moisture damage, leaks, and proper ventilation. Ensure that exhaust ducts direct air to the outside.
- Make sure soffits on the underside of the eaves or overhand of your roof are not blocked. These provide ventilation or air flow in your attic.
- Inspect the walls, joists, and insulation for any musty smell or visible mold.
- If not present, install a water heater drip pan. Empty and clean it regularly.
- Have your heating and cooling systems serviced by a professional twice a year. Check the coils for visible mold.
- Check water heater and washing machine water lines for plumbing leaks.
- Make certain your dryer vents to the outside of your house and not the garage, crawlspace, attic, or other interior space.
Other things that may be contributing to the humidity in your home include large quantities of plants, large aquariums, hanging laundry inside to dry, or using an unvented heater or gas logs.
Remember . . .
Anywhere you smell a musty, earthy odor or see excess moisture, there is the potential for mold growth. If you find either, take immediate action. First, find the source of the moisture and then fix the problem. Remove contaminated items and clean with soap and water. Then, speed dry. Generally, there is no need for a mold test. Once you identify the source of moisture and fix it, that should resolve the problem.
This publication was adapted with permission from: Mold and Moisture Checklist, by Pamela R. Turner, PhD and Lindsey Bailey, MEd, University of Georgia Extension.
Publication date: April 4, 2022
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