My basement is smelly and humid, what can I do about that?

Jeff O.
Updated: July 21, 2020

I live in Sudbury Canada in a 1959 bungalow and the basement is always humid and the dehumidifier runs constantly. It also costs a fortune to heat. I was advised to insulate the top portion of the foundation (the top third) but the wall is not insulated at all. And on the bottom of the walls there is a white powder. According to what I am told, the problem is from excess moisture and probably due to french drains that aren’t working anymore. A contractor gave me a price for excavating the outside and replacing the drains but that is very expensive. Someone else told me to install a sump in the basement instead which would cost much less, will that do it? After fixing the problem I want to insulate the basement so I’m hoping for some advice. Thank you.

Responses (3)

Sarah Blair 4 years ago

Hi, I am reading everything about basements on your site and this answer confused me. I understood that isulating the basement (either with spray foam or EPS or XPS) acts as a moisture barrier, allowing the construction of interior walls that aren't as susceptible to mold. But here you seem to say that keeping the moisture out of the basement effectively keeps it in the concrete, and that that can damage the foundation. Like the person here, I live in a very cold climate. 

Mike Reynolds 4 years ago

Hi Sarah, concrete is porous and will continue to wick moisture from the ground if it isn't protected with a waterproofing layer of some kind, so almost every basement you've ever seen has concrete that is wet. It can lead to cracking so it is better to insulate from the outside and protect it from moisture, but  it isn't likely to crack to the point of causing structural problems. With a cinderblock foundation that is only held together by the mortar between joints it becomes a bit more risky.