Mold growing inside our home

Asked March 7, 2018, 10:06 PM EST

Hi, we discovered mold growing along the walls and ledges by our windows on the inside of our house. We are curious whether there might be any pathogenic species in the mix. I realize you would need specimens collected to perform a positive ID, but in the absence of a specimen, do any of these jump out to you as potential pathogens? More info: this grew sometime between November 2017-March 2018 (we hadn't raised the blinds in that period so never saw the colonies til yesterday). We live in Salem and the windows with the growth are west-facing.

Marion County Oregon

1 Response


I'm sorry to hear about your mold problem. Window sills are a common place we see mold. The good news is, this is a pretty simple fix.

I actually don't recommend testing for mold species since it is found naturally in the air. As for your question about identifying pathogenic species, I can't do that visually. Historically there has been a concern over 'black mold' but the truth is that a lot of mold is black, but not pathogenic. The other consideration is that this is actually a very small amount of mold. The bottom line is that if you have mold or mildew, you need to remove it. Based on where it is growing, I am going to guess that the window gathered condensation during the winter, and the water collected on the base of the window and along the sides. Mold/mildew loves drywall, which is why you are seeing it there as well.

First step is the clean the area. If you are concerned about breathing in spores, wear a face mask. Also, I recommend using a spray bottle of half water, half vinegar and thoroughly wetting the area before scrubbing; that keeps the spores from flying around. Once the area is wet, you can clean off the fungus. Make sure you remove it all. The vinegar/water solution will both remove the fungus as well as kill off the spores.

Once the area is clean, let it dry thoroughly. In your photographs, it looks like the caulking around the window has failed. Remove that, clean any traces of mold/mildew, and once the area is dry, re caulk around the window. This will help prevent cold air entering and causing condensation.

I would suggest leaving the blinds pulled up about an inch in the future, so that you can see if condensation is collecting. If it does that, just wipe away the condensation as often as you can. You can also clean around the window with the half-vinegar/half water mixture to help prevent mold growth.

I hope this helps,