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Ridgerunner

crawl space recomendations

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.I am trying to improve energy efficiency in my house.

I live in central Va. with summer temp. 95 degree +, winter low 15 to 30 degrees.

I have brick ranch home 2500 sq ft. Built in 1973. Heat pump located in attic.

Attic is well insulated.

Crawl Space , vented, no insulation, powder dry, no mold, outside entrance, no ground vapor barrier. Located in the crawl space is the water pressure tank.

I like the idea of sealing the crawl space, trying to insulate between the floor joists would be difficult due to electrical, plumbing, central vac, tel, tv cables, etc.

I was a telephone installer for years and spent a great deal of time under houses, I never saw a vapor barrier I liked, they either had water puddles or terrible dampness under the barrier. I had a crawl space at another location and a termite inspector recommended I put down a vapor barrier on a dry dirt crawl space, a year later I had a damp dirt crawl space that had rusted stored bicycles, lawnmowers, and other stored metals. OK enough about vapor barriers, I think they draw moisture.

I am open to suggestion, recommendation, and comments.

Thanks , Richard

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.I am trying to improve energy efficiency in my house.

I like the idea of sealing the crawl space, trying to insulate between the floor joists would be difficult due to electrical, plumbing, central vac, tel, tv cables, etc.

I am open to suggestion, recommendation, and comments.

Thanks , Richard

Vapor barriers SHOULD have moisture underneath them. They are stopping the mositure at the barrier.

If you are planning a sealed and conditioned crawl space system, one of the major components is a totally sealed vapor barrier on the floor extending up the sides of the walls, piers and columns about a foot. The joints would be taped.

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.I am trying to improve energy efficiency in my house.

I live in central Va. with summer temp. 95 degree +, winter low 15 to 30 degrees.

I have brick ranch home 2500 sq ft. Built in 1973. Heat pump located in attic.

Attic is well insulated.

What does "well insulated" mean? Is it at least 12" of cellulose or 15" of fiberglass?

Crawl Space , vented, no insulation, powder dry, no mold, outside entrance, no ground vapor barrier. Located in the crawl space is the water pressure tank.

I like the idea of sealing the crawl space, trying to insulate between the floor joists would be difficult due to electrical, plumbing, central vac, tel, tv cables, etc.

I was a telephone installer for years and spent a great deal of time under houses, I never saw a vapor barrier I liked, they either had water puddles or terrible dampness under the barrier. I had a crawl space at another location and a termite inspector recommended I put down a vapor barrier on a dry dirt crawl space, a year later I had a damp dirt crawl space that had rusted stored bicycles, lawnmowers, and other stored metals. OK enough about vapor barriers, I think they draw moisture.

I am open to suggestion, recommendation, and comments.

Thanks , Richard

Vapor barriers don't "draw moisture." They stop it from evaporating into the air. Right now lots of moisture from the ground is evaporating into your crawlspace air. That's why the ground is "powder dry." Right now, the crawlspace vents are helping to carry away that moisture in summer. In the winter, you're losing so much heat through the floor that you're elevating the temperature down there and lowering the relative humidity. It all works ok, but the successful conditions are being driven by heat loss. That's not a great thing these days.

If you merely seal the vents, you'll have moisture problems. All of the water that's presently evaporating from your soil will humidify the air in the crawlspace and, without vents, it'll get very damp down there.

If you want to go the route of a sealed crawlspace -- which is a good idea in your climate -- you'll want to install a nearly perfect vapor barrier to completely cover the soil, place insulation around the perimeter stemwalls, and totally seal off your foundation vents.

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Thanks for responding guys, I read some information on sealing a crawl space, I was hoping for a different answer. Going the 20 mil barrier route, from what I have read is an expensive way to go. Since it was so dry under the house I thought maybe there was another alternaitive. I always hated the black plastic under houses mainly because I had a hard time seeing snakes, and was almost bitten more than once. If you know of a good site that can give instruction for a do it yourself person I would appreciated your imput.

Thanks again

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Get the 20 mil polyester hi-low density sandwich, fiber reinforced material. You can get it in white which brightens up the crawl a bit, and gets away from that black plastic look. (I don't like the black plastic look either.)

Seal the VB to the foundation with caulk, Tremco is OK, or any other poly compatible caulk. You might have to use termination bars/strapping to secure the VB. Seal all seams.

There's some discussion of caulks somewhere in here; run a search and I know you'll find it.

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Depending on different factors such as cost, amount of moisture, desired durability, these factors will all play a role in determining the thickness of your vapor barrier and the material used.

20 mil thick barrier would be great but if your ground is as dry as you state it might be overkill. There is very little difference between 6 and 20 mil plastic when you are blocking moisture. I would go with the thicker plastic for durability and long life if there isn’t a huge price difference, the thicker the better. All you are trying to do is block the ground moisture from rising into the wood and causing a fungus to grow. The minimum I would go with is 6 mil plastic. This plastic should last many years and is pretty durable.

Another factor to take in to consideration is your termite bond. If you have a chemical termite treatment the chemical is applied around the foundation piers and walls. If you fasten plastic to the walls and piers you will create a bridge for termites to use where there is no chemical applied. Seams kind of farfetched I know but it’s not and I’ve personally seen it happen. That’s also what your termite company is going to say when you find an infestation and damage.

If you want a completely sealed moisture barrier go with the 20 mil barrier sealed at every seam and the foundation walls/piers. If you want a vapor barrier then a 6 mil plastic lapped 3 foot at each seam set back 6-8 inches from foundation wall or pier will work great.

If you decide to install the barrier yourself measure the area and cut the plastic outside. Then label it, drag it under the house and spread it back out leaving you with a clean neatly cut barrier. You can pin it down with garden pins or tape/mastic the seams often enough to join all pieces of the barrier together.

I wouldn’t recommend insulation unless you are going to maintain it and it’s installed properly. You must ensure all holes leading to the crawlspace are sealed to prevent animal activity.

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Mil = one thousandth of an inch

Millimeter = much more than one thousanth of an inch

WOW. I feel pretty dumb for not realizing that. If I would’ve thought about it yeah that would be really thick. HAHA thanks for the correction. I made changes to my post.

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The advantage of the thicker plastic is its resistance to puncture if you are going to have people crawling around down there, as is often the case. Another component of the sealed systems is often dehumidification.

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