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Q
:
I smell a musty/moldy smell in my living room. I can narrow down the area of the smell, but can’t seem to find the source. Any suggestions? — Debbie, Kentucky
A:
If you can smell it but can’t see it, it must be inside one of the living room walls or under the living room if you have a crawlspace. If the living room is on the south or southwest side of your house and you have brick or stone veneer, it is likely that rain water has gotten into your wall particularly from wind-driven rains. If such is the case, the moldy/musty odor will be the strongest on breezy days.
Locating mold in a wall is difficult. Most professionals drill holes in such walls and collect mold samples to determine whether mold is present, the dominant mold types and its relative concentrations.
Typically I use a non-destructive approach. I typically look for electrical outlets on the external wall. I take the plastic plate off and then use my odor detector (my nose). I often detect the presence of mold odors in external walls using this technique. It works best on a slightly breezy day when the wall is under positive pressure. It also works best if the infestation is near to the electrical box. If it is distant, you may not be able to detect it.
Mold infestation of exterior wall cavities is also common under windows, particularly windows subject to condensation and those that have been poorly caulked. Caulking is intended to prevent water from entering wall cavities. If it was poorly applied or maintained, water easily enters the wall around the window where infestation takes place.
The presence of mold growth in cavities of external walls is not that unusual. Common causes are water intrusions around poorly caulked windows (as mentioned) or through brick veneer that has been poorly installed or has developed settling cracks.
In the first case the area around the lower part of the window will have to be opened from the interior wall side. Heavily damaged/infested wood materials will have to be removed and replaced. In older homes this will likely include the replacement of the entire window unit. Timbers that appear to be structurally sound but are nevertheless mold-infested should be treated with one to two coats of polyborate containing paint (such as that distributed by Foster Products). Care should always be taken to protect oneself from excessive mold inhalation exposures by using an NP-95 respirator and from spreading mold spores all over the house (remove infested materials and then wrap them in polyethylene plastic before removing them from the house, cover floor and other horizontal surfaces with polyethylene plastic in work area, etc).
Water intrusion through brick veneer can vary from a minor remediation project (removing/treating infested wall materials associated with a settling cracks, and repair of such cracks) to a major one in which brick veneer has been installed in violation of code requirements. In such cases wind driven rain water may have entered wall cavities resulting in significant mold infestations and elevated mold levels. Defects include the absence of weep holes, inadequate gap between brick/mortar and wall materials, and the absence of a water impermeable barrier between wall materials and brick veneer. The only permanent solution in this case is to remove the brick and have it reinstalled properly. This is currently being done in the case of hundreds of homes constructed by a major developer in the greater Indianapolis area.
