What is the best way to reduce humidity in a basement?
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!
The cheapest and more effective way to remove humidity from a basement is without a doubt, a continuously operating dehumidifier. Select one that is sized to manage the amount of space you have, and try to keep it about 40% RH. If you don’t already have a heat recovery ventilation system, you may want to look into that as well.
A house that old probably has nothing to protect the foundation from moisture, so the source of the moisture is not something like a washing machine, it is the porous concrete floor and walls absorbing moisture, which then migrates inwards. Your basement is basically a damp box. Covering the floor (if it is currently bare concrete) will help somewhat.
One flooring option we really like, but that isn’t the cheapest unfortunately is marmoleum (see link below). We don’t often recommend vinyl as a building material, but given your limited budget and limited head room, we suspect you’re going to end up with something like that anyway so we would point you towards either Lowes or Home Depot since both those retailers have made a commitment to only stock vinyl flooring that contains no phthalates.
The brands to avoid are, unfortunately, those that show a ‘recycled content’ label, as they can contain post-consumer plastics from electronic equipment such as computers. Phthalates in vinyl flooring are toxic to both the planet and humans, particularly small humans that may crawl on the floor then stick their grimy little fingers in their adorable little mouths, or your mouth on occasion too J
With a bit of price shopping you should be able to find something in the $1.50 - $1.75 USD per square foot range in a click together style, there are also some that have an adhesive backing that will stick right to the floor. Below are some links to help choose products as well as how to finish your basement if you do decide to do some more work on it.
Why are Basements Moldy? How to Fix & Prevent Mold in Homes
Preventing mold when you insulate your basement
Marmoleum : A healthy and non-toxic green flooring product
The Difference Between an HRV and an ERV
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