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banpei 05-31-2012 01:20 PM

High humidity in condo
Hello all, I've done all I can to try and fix this, so I really hope someone here can throw another idea at me.

I live in the first floor of a two story condo in San Francisco with a crawlspace underneath. We've been having really high humidity (65-70%) and it's starting to affect our clothes and give them a damp, musty smell.

First we thought the shower steam wasn't getting ventilated, so I tried replacing the bathroom fan during a renovation. But after a month of not using the shower and no lowering of the humidity, I realized it wasn't that.

Second I tried just getting a dehumidifier, but it didn't seem to do much.

Third I tried laying a 1 mil plastic mylar sheet in the crawlspace to try and trap the moisture. The ground underneath is mildly damp in places, and it seems to get a bit of circulation down there, but not a lot. After 5 days with the sheet, no change.

So...I'm fresh out of ideas, and I smell like my grandma's closet. I need help. I checked the upstairs neighbor's condo, and their humidity was ~40%, so it's just me. Outside humidity was 40%. Could I try spreading a desiccant in the crawlspace under the tarp? The thing is, I don't know if the ground is that wet to cause a 70% humidity.

raylo32 05-31-2012 03:02 PM

Not sure what you mean by the dehumidifier "didn't work". Was it broken? If not then by definition it was pulling water out of the air and maybe you just need a bigger one. Can't help on the possible source... none of it sounds very plausible to me that your humidity would be so much higher than the prevailing air mass in your area.

banpei 05-31-2012 03:11 PM

Thanks for the response, and by "not working", I meant, it draws water out of the air, but the change in humidity is negligible, plus when I turn it off, the humidity stays the same. There is water being drawn out, as I have to empty the basin, but...the humidity just isn't going away.

beenthere 05-31-2012 08:13 PM

Usually need thicker then 1 mil. Seal the crawlspace from both the outside air, and from your living area. then run that dehumidifier.

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