Will adding insulation to the exterior walls help get rid of mold on the inside?

Updated: Feb. 15, 2022

The house was built around 1958.  It has aluminum siding. It has little to no insulation in the walls. About 15 years ago I tried to get sprayed in insulation put in the walls. The company told me they couldn't because the 2x4s were the wrong way and the foam didn't have room to expand.  The interior walls that touch the outside keep getting mold on them.  I keep cleaning with bleach, but it keeps coming back. Someone told me if take of the siding, put insulation, and put new siding that the mold would go away.   Is that true?  If not, what would be the best way to fix this problem?   Over the years it is getting worse. 

Responses (3)


live near cleveland oh.

Mike Reynolds 2 years ago

Code for Cleveland seems to be R20 for walls. Typically we recommend insulating more than what code requires as that is a minimum, but I'll leave that for you to decide, can you go as thick as 4 inches? As mentioned, if you're going to the effort and cost of removing all the siding I'd want to take advantage of it and not do just one inch.

In your case since you have no insulation at all it's safe to put foam on the outside, and anything over 2 inches will be a vapor barrier, which is fine since you currently have no insulation at all. 2 inches would be good, 3, 4, even 5 inches would be better if you can, but, do what you can.