Humidity in crawl space

[logan97]

new construction. north and east side of crawl space is bermed into the ground. south and west have numerous foundation vents.6 ml plastic on the ground. The north and east sides have heavy humidity in the form of water condensation on the plastic. How can I correct this.
I do not have any plastic or insulating foam on any of the vertical walls in the space.

 

[fixitman123]

I would close all vents winter and summer. From what I understand, in the summer , warm moist air is drawn to the color air under your home and the moisture condenses. I keep all my vents closed and don't have moisture problems anymore. Try it, if it doesn't work you might need to have the crawl space sealed.

 

[boomer1025]

maybe put a fan on the south and/or west side and blow the air through and out the north and west sides

 

[dave1949]

I think encapsulated, sealed and conditioned crawlspaces are what is recommended now.
Crawl Space Encapsulation Method | Energy Vanguard

If it is not done correctly, it can also cause problems. If you search on encapsulated crawl space [or problems] there is a lot of info. I suppose local climate has a lot to do with the approach needed.

I would say that needing to insulate, seal and condition (heat-cool-humidity) a crawlspace is putting a lot of effort and funds into an unusable space and that doesn't make a lot of sense in most cases. If the house is located somewhere that a 6 mil vapor barrier can be rolled out on the ground with decent venting in the walls, call it good and no problems arise, that's different.

 

[4570Man]

I would highly recommend the encapsulated craw space. I will never have it the other way again. If you do it yourself it isn't terribly expensive.

 

[logan97]

6 ml on the floor and walls then insulate. close all vents. is this your suggestion ? Thanks much

I would highly recommend the encapsulated craw space. I will never have it the other way again. If you do it yourself it isn't terribly expensive.

 

[s219]

Normally an encapsulated crawl also has an HVAC supply/return (easy to do if your ducts are already in the crawl) or a dehumidifier. You can't just seal it up, there also needs to be some sort of conditioning. I agree it's the best way to go. However, you can also try improving the ventilation in your crawl first, maybe by adding a blower to move the air. If that's enough to keep the humidity low, it might be all you need. The lack of vents all around could be what's really the issue, and a blower can tip the balance.

I had a regular vented crawl in my last house, and of course we get 70-100% humidity all summer long. Never had issues there at all, probably due to the good ventilation.

 

[4570Man]

6 ml on the floor and walls then insulate. close all vents. is this your suggestion ? Thanks much

Mine was 8 and some 12 inch block and then brick so no need to insulate. I have done this on two houses. One was a new constitution and we didn't put in any vents. The other was a rock house and I removed the vents and rocked the hole. I don't remember what kind of plastic it was. It was a material made to to that with. I can maintain about 55% humidity year round.

 

[4570Man]

The brick on the outside is solid, but they did put vent holes in the block. I insulated the joist and vent holes, and put in two air vents. Before we did it the joist were starting to mold because the humidity was so high. Now it is probably drier than the rest of the house.

 

[DKCDKC]

Built my new home in 2001 with an encapsulated crawl-space. I have small HVAC vents there to refresh the air, and have never had any problems. Only people who have been critical were the exterminator people who said it would cause fungus, but they'd be happy to pre-treat for $1,000 to stop it. Didn't do it.

A key thing for those doing this is to seal the plastic on the floor - tape seams and seal against the walls. Otherwise it will pull in some moisture. And you check it over time as you have to access the space to make sure the access doesn't lead to tears and such.