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jsingband
Crawl Space Rehabilitation

I have a damp, unused crawl space and the heat is escaping from the basement through to the first floor den. I want to dig out the crawl space and use for storage or a kids hideaway/play space. How can I insulate, dig out and waterproof/vapor proof the area safely and economically?

Timothy Miller
Re: Crawl Space Rehabilitation

Hire a good contractor!
So you want to dig down lowering the crawlspace an then store stuff an kids in it- would be swell if it were not already damp. Some places are better left not to store or play in...

Reducing the dampness, is there plastic on the soil? If there is is the plastic sealed to the foundation walls? If not get 6 to 10 mill and seal it to the walls this stops more moisture from coming up into your home. Consider insulating the floor joist bays an build the kids a play storage house with the kids in your back yard.

dj1
Re: Crawl Space Rehabilitation

I really don't understand why you would want your children playing in a crawl space full of spiders, black widows and other insects/pests.

When my elder son was about 12 he was beaten by a spider. It was not an easy and pleasant experience.

But if your mind is set on digging, don't outdig your footings.

California_Cookie
Re: Crawl Space Rehabilitation
dj1 wrote:

When my elder son was about 12 he was beaten by a spider. It was not an easy and pleasant experience.

My goodness! It sounds like an AWFULLY big spider!! I'd be wary, too!!

;)

hollasboy
Re: Crawl Space Rehabilitation
jsingband wrote:

I have a damp, unused crawl space and the heat is escaping from the basement through to the first floor den. I want to dig out the crawl space and use for storage or a kids hideaway/play space. How can I insulate, dig out and waterproof/vapor proof the area safely and economically?

I live in Texas where basements are rare, but crawl spaces are common in older homes. I had a similar problem with my crawl space...it smelled nasty, was muddy when it rained and dusty when it didn't, and gave access to pests like spiders and mice. Furthermore, I found all sorts of mildew growing on the underside of my floor where the humid exterior air contacted my the subfloor of my air conditioned home, and caused condensation.

So I dedicated a lot of time reading and researching what to do with it. It turns out there are a lot of smart people who are now questioning the wisdom of existing building codes that require ventilation of crawl spaces. Also, they are starting to advocate lining the crawl space with a vapor barrier, then sealing off the space from the atmosphere. I found an up-and-coming company that does this type of work. They spent a week under my house. They first dug out a perimeter trench, put in a porous pipe with an automatic sump at the low corner that pumps water to the outside. Then they backfilled the trench with stone, and covered the whole crawlspace with a thick vapor barrier mat, cutting and taping around each pylon and the perimeter concrete brick ledge. Then they sealed off any and all vents and holes to the space from the outside atmosphere (this also stopped all pest infiltration points). Finally, they put in a dehumidifier to keep the air down there nice and dry.

I immediately noticed that my house no longer had that characteristic "musty old house" smell. Also, during rainfall I hear the pump taking all that water out away from under my house, which will help prevent foundation movement. I installed a wireless thermometer and hygrometer down there so I can monitor conditions, and there is never more than a 5 degree temperature difference between the crawl space and my living space, both in winter and summer. The earth is a very effective insulator - the only part exposed to the exterior is the 18" high outer concrete wall that is about 18" thick. Stopping air flow made the biggest difference.

ed21
Re: Crawl Space Rehabilitation

Not really practical to dig out much of a crawl space usually. The foundation doesn't usually go down very far and can't dig below the top of the footing. Even going that far might compromise the foundation without extra reinforcing.
The floor joists can be insulated. A vapor barrier can be put down. Crawl space encapsulation companies seem to be growing field of contracting.
Ps. DJ- you can keep those big spiders in SoCal. I don't want to have to carry a baseball bat with me just to go in my crawlspace.

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