Crawl Space Help: Tricky Situation


Old 01-27-14, 06:52 PM
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Crawl Space Help: Tricky Situation

I have what I believe is a tricky crawl space of an old 1907 home in Richmond, VA with a dirt floor. It is currently slightly vented with a 1" x 2" gap in the brick foundation every 8 feet apart or so.

The hard part is at the front of the home there is about 12" of space between the dirt floor and the floor joists but as you move toward the back of the home this space goes down to about 4" between dirt and floor joists for the last 1/4 or more (we live on a hill so the dirt floor follows the natural grade outside the house).

I would love to encapsulate but am not sure what it would take to be able to seal that last section. On the other hand, there is not much space to properly install insulation between floor joists. I have currently be sealing around the rim joists with rigid foam as much as I can.

I am wondering if sealing as best I can, putting down as much vapor barrier as I can (hopefully 10 mil wouldn't rip with me crawling around on my stomach everywhere), and possibly dehumidifying (it is currently around 73% humidity in there) would be of any benefit or whether that may just cause more problems and I am better to insulate between floor joists with rigid foam where I can and give up the rest as a lost cause.

Any advice would be greatly appreciated!
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Old 01-29-14, 04:33 PM
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At least for the section that is only 4" high, I would look into filling it with cement. It might be cost prohibitive to do all of it that way.
Old 01-30-14, 04:27 AM
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I hate houses like yours. There is no easy way to do anything. Best and possibly least expensive, especially if you want to do some upgrading, is to cut an access hole or two in the floor in the back where there is least room. Then you can use sticks to push out plastic or other membrane. It's not perfect but any area you cover will help reduce the humidity.

As a plan B for vapor barrier you can just work from the front where you have better access and roll strips back, pushing them with rods or sticks. Lay out the plastic outside and cut into strips of a manageable width and leave them several feet longer than your house. Go under and roll them out, overlapping them about a foot or so. Telescoping paint roller handles can work well. If your crawl space is relatively free of debris a child's remote controlled 4x4 truck can work surprisingly well. Use it like a bulldozer to push the roll to the inaccessible part of the house. Tie a light rope to the truck to pull it back in case it gets stuck or the batteries die.

I don't think insulating the floor is a reasonable option. It can be done but I don't think you'd be up for the work or willing to pay someone to do it. If your floor joists run front to back you can start where you have more room and dig trenches back along the joist bay creating an access tunnel. As you can imagine it is very hard, slow work (lots of labor = expensive). Since you have so little room in back you may need tunnels every couple joist bays to provide access to install insulation. Personally I'd say live with what you've got or move. The house has gone a hundred years without insulated floors. The vapor barrier is doable though and that would help limit rot, mildew growth and insects.

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