Wall and Ceiling Mold

To check for wall and ceiling mold look to the corners at ceiling level and follow the corner of the wall to the floor. Look for a brownish stain or blistering of wallboard or wallpaper. If the damage is found on the first floor, mold from ceiling leaks may be from a bathroom pipe above. Ceilings and walls directly beneath the roof are vulnerable to staining and mold growth due to concealed roof leaks.


Ceiling Mold

If the damage were found upstairs in your home, it would suggest a leaking roof, a rotted dormer or possibly an HVAC condensation line backup. Examine the attic or the floor above the stained area. If you are doing mold inspection look for wetness, dried water stains or for newly installed wood that might indicate where a leak had been repaired. To check if a leak has been successfully repaired, but a stain persists, mark the perimeter of the stain with pencil — once a leak is repaired, the stain should not expand. Any further spreading of the stain would indicate either that the leak had not been properly repaired, or that a new leak or soaked insulation was present.

If the water stain is found on a wall or ceiling without attic access, an exploratory hole will have to be cut through the drywall to examine the space inside for wall or ceiling mold. Be sure to take precautions to avoid breathing in disturbed particles that could potentially contain asbestos or insulation materials. If you hire a professional mold inspector to access the situation, they can drill a much smaller hole to test with a probe, resulting in less damage to the property.

How Water Damages a Ceiling

Water always flows down and always follows the path of least resistance. When water flows onto a ceiling from above, it looks for the easiest way to keep going down. With drywall, this is usually where two panels of drywall meet. The water drips through the gaps in the seams. With plaster, it is usually the place where the water pools up. It saturates the plaster then drips right through. It soaks up the water, changes color and ceiling mold results.

a corner with wall and ceiling moldWall Mold

Wall mold tends to grow where there are inadequately insulated exterior walls, particularly where the conditions are coolest: close to the floor (because cold air sinks) and in outside corners.

Unheated closets, where one or both walls face the outside, can also be a problem. Clothing stored in moldy closets can get contaminated with spores from the dust, and if the clothing is in contact with the cold wall, mold can begin to grow in the fabric itself.

If you have a closet where mold grows, you can buy a small warmer, but be sure it’s safe and was manufactured for such use (clothes should not come into contact with heating elements). You can also install a louvered door to the closet or insulate the exterior walls. If you are building a new house with corner closets that have exterior walls, be sure a component of the heating system warms the closet.

Since mold usually grows indoors in the dust on painted surfaces, rather than in the paint itself, inhibitors added to the paint are not necessarily useful. Be very careful NOT to paint with exterior mildewcide intended for outside use as these products may off-gas low levels of potentially toxic vapors.

Cleaning surface wall mold

Circulate the air in the room to prohibit mold growth on walls by running a fan or opening windows. Run a dehumidifier to circulate air and lower humidity levels further prohibiting mold growth. Run an air conditioner to circulate air, lower the temperature, and lower humidity levels if possible

After you have hampered the mold growth, and fixed the issue that was causing the moisture for the mold to grow, thoroughly clean the wall. It’s recommended that you use a strong thistle scrubbing brush and hot sudsy water, either with bleach mixed in or Trisodium phosphate.

Allow the wall to dry thoroughly after washing.

Refer to our mold removal page more info on cleaning wall and ceiling mold. Health Canada has some helpful recommendations for removing a preventing mold.