What is the best way to reduce humidity in a basement?

Robert J. Pierson
Updated: Aug. 25, 2020

We live in Bellingham WA and our basement was built in the 70's. It has high humidity (70-80%RH) although I don't see any visible damp anywhere. The washer/dryer are down there - the dryer vent is fully sealed, there is no actual ventilation in the basement apart from the drafts. There is a sink, the hot water tank with drain off and furnace, and one small window that stays closed to keep the black widow spiders out ever since I sealed it all with double foam strip!

So - as we want to use the space in the basement, what are the suggested steps to reduce the humidity? What should we put on the uninsulated floor as a covering that won't go moldy/smelly like the carpet has (and we're on a budget, and have next to no headroom.)

I appreciate there's no perfect solution - but I wondered whether we would be better getting a continuous drain dehumidifier, a HRV or ERV ventilator unit, or simply put a decent fan one side of the house and a vent or two with bug screens in on the other through the pony wall - bearing in mind our ambient external humidity is often quite high due to being near the coast?

Thanks for your help - Ecohome is a great source of tips and info for older home maintenance!

Responses (2)

Robert J. Pierson 4 years ago

Hi Frank, I would second the dehumidifier route, and as your climate isn't generally too cold I would recommend adding some cross ventilation too - preferably linked to a humidistat - this video I found explains it: https://www.youtube.com/watch?v=BOBSn-Jt074