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

Anonymous Feb. 8, 2017, 10:22 a.m.

I live in Sudbury 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 (1)

Ecohome Nov. 15, 2017, 10:28 a.m.

Your problem of high heating cost would definitely be helped solved by insulating your basement. According to the Canada Mortgage and Housing Corporation (CMHC), this part of the home is typically responsible for more than 30% of heat loss.

It sounds like you do have problems caused by excess water infiltrating your basement walls, probably by capillarity, which creates an efflorescence (white stains) on your walls. That occurs when water around an unprotected foundation saturates the concrete (or cinder blocks if that’s what you have), and when it evaporates to the inside it leaves mineral compounds on the wall.

The use of a dehumidifier will not solve the problem of capillary water, it will only act to regulate and reduce moisture in the air, but that’s still better than doing nothing. Insulating your basement from the inside could in the long run only hide the problem. Over time, the wall could start to weaken and crack due to the amount of moisture, particularly after you insulate it since it will now probably freeze.

A sump pump is also a great thing to have, but it only deals with rising water tables or interior flooding from washers or water heaters, so it won’t solve your problem either.

From our understanding of your problem, unfortunately what we would consider a lasting solution would be to proceed from outside the home as you’ve been recommended. If you do proceed with exterior excavation and repair, don’t stop at just the French drain. You would be wise to treat your walls with a waterproof coating and include a drainage mat (dimple membrane) that will protect your porous foundation walls from absorbing moisture from the ground.

Be sure to consult professionals, and getting a second onsite opinion is a good idea. See our pages on durable basement renovations for more information.