Mold Inside Walls

There are two general ways to check for mold growth inside walls. One way is to open up walls in areas below the known roof leaks or other leaks. That can be done from the inside or the outside.

The easiest approach is to open a hole at the base of the wall, in the interior Sheetrock between the studs in an exterior closet wall, if one exists. Otherwise, the interior Sheetrock of an exterior wall must be cut open near the base of the wall.

Then the wall cavity can be visually inspected for the existence of mold. An advantage of this approach is that you can see whether the mold is active or inactive, and whether or not it is widespread. Small amounts of black mold in walls often occur naturally and are not uncommon.

Unfortunately, this approach is destructive, and you may need to open several holes to be certain of whether or not there is black mold in the walls.

Of course, the holes will have to be patched and repainted. You can sometimes gain access to the wall cavities by removing pieces of siding, but opening the walls from the outside is usually more expensive and more destructive, since some of the siding must be removed and later replaced (hopefully without being damaged in the process), and the building paper or house wrap and sheathing must be cut open.

Another less destructive approach is to hire a mold specialist, who can sample the air inside the wall cavity by inserting a sampling probe through small openings.

Air is drawn from the wall cavity through the sampling probe and onto a filter, so that mold spores and fungal fragments in the sampled air are captured on the filter. The filter samples are then analyzed in a laboratory to determine the levels and types of mold in the air inside the wall cavities.

While an expert can tell the difference between the two types of mold, the type of mold that is found within walls is often the same as that found outdoors, and may not be as likely to cause health problems.

We strongly suggest removal of carpeting that was soaked with water even if you do not see mold in the carpet, carpet is designed to hide the dirt and mold.