Crawl space ventilation

[sheslostcontrol]

Have a cement-floor crawl space in a 1940s house. This room is very humid and currently has no ventilation (smells musty). It has my furnace, hot water heater and washer/dryer (which does vent to outside). I have a dehumidifier and the bucket fills once every day or two.

My question is about foundation vents.. I saw a powered vent online last night and wondered if that would be a good solution to keeping the humid air out of the crawl space?

Or do I skip the powered vent and put down 6 or 10 mil poly? I will be walking on the floors a lot so that is why I was thinking about the powered vent.

 

[banzaitoyota]

go read buildingscience.cm lots of good info on crawl space ventilation

 

[lawfarm]

I think you'd do better to run a dehumidifier down there, instead of venting it. Outside air in GA will be very humid in the summer anyhow, and with a powered vent, all you'll be doing is drawing outside air into your house to compete with your heat in the winter, and your AC in the summer.

I had a similar problem in my last house (over 100 years old). Running a large dehumidifier completely eliminated the problem.

 

[jake00]

how large of a dehu? I have a humid basement, I run a dehu, but i'm not sure its large enough.

 

[GTO]

Google "Crawl Space Ventilation"
you will see the fans that fit into your crawl space vents.

IIRC Nothern Tool sells them.

 

[lawfarm]

how large of a dehu? I have a humid basement, I run a dehu, but i'm not sure its large enough.

I run a 70 pint model in my basement, but I have it set on a timer (3 hours on, 3 hours off). I used to keep it set at 50%, and it would run a LOT. I had mine drain into one of my sump pump pits.

 

[oldcpecdr]

I built an apt for my Dad out of the 2 car attached garage ( and I got to build my new shop ) . The floors were raised about 30 inches off the old concrete garage floor and it was humid and musty in the summer heat....after two years installed powered vent fan in rear foundation wall and intake in front wall...controlled by humidistat....works well here on Cape Cod, in Ga you better ask around..BUT flawless here for six years now...about a hundred bucks back then and an easy self install....