plastic sheeting over dirt in crawlspace

Hi, Planning on installing heavy plastic sheeting over the dirt in my crawlspac e (to reduce humidity in the overall basement area and house), but it's VER Y difficult to get around in there. I think I can manage to pull it over t he whole space, but sealing the sheeting to the foundation walls with acous tic caulk looks impossible due to restricted height down there. Is it still worth doing if I can't seal the sides off?
Other details: -House located in New York. -Not practical to air seal my floor from above or below, so I'm trying to s top humidity before it gets into crawlspace.
All opinions (and prior/current experience) GREATLY appreciated.
Regards, Theodore
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On Wednesday, March 11, 2015 at 8:40:24 PM UTC-5, snipped-for-privacy@yahoo.com wrote:

ace (to reduce humidity in the overall basement area and house), but it's V ERY difficult to get around in there. I think I can manage to pull it over the whole space, but sealing the sheeting to the foundation walls with aco ustic caulk looks impossible due to restricted height down there. Is it sti ll worth doing if I can't seal the sides off?

stop humidity before it gets into crawlspace.

I pinned my plastic down around the edges and seam taped at least 8-10" ove rlapped joints where ever the sheet runs happened to be. They do make seam tape for sheet plastic and it seals fairly well.
The pins were 5-6" long nails bought at a hardware store. They also have sh ort nails with 1" plastic caps used to hold down roofing felt. I removed t he plastic caps and pushed the long nails thru them. That made a wide head for the pins to hold down the ground plastic.
I put the plastic right up to the walls but pushed the pins down about 6-8" from the wall. This allowed me to fold the plastic back when I apply term ite treatment every 5 years.
I did this 22 years ago and it is still good. Well mostly good. A few mic e got under the sheet, ran around looking for a way out, and finally chewed a small hole on the plastic. A couple of 2" holes didn't make any differen ce in the humidity under the house. I thought the plastic ground cover woul d also be clean to crawl under the house on. Was for a while but then it h ad mouse turds and dust thru the vents while mowing. I now wear a full bod y painters suit when I go under it.
That's my experience. Hope yours works well.
Red
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On Wednesday, March 11, 2015 at 9:40:24 PM UTC-4, snipped-for-privacy@yahoo.com wrote:

ace (to reduce humidity in the overall basement area and house), but it's V ERY difficult to get around in there. I think I can manage to pull it over the whole space, but sealing the sheeting to the foundation walls with aco ustic caulk looks impossible due to restricted height down there. Is it sti ll worth doing if I can't seal the sides off?

stop humidity before it gets into crawlspace.

if the area is wet, better to first install a french drain in or around the area befor layin the plastic..
you might check out the harbor freight tarps.
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It's not that wet. Just trying to cut down on overall humidity and potential for mold in basement/crawlspace contiguous area. Basically wondering if I can't seal off the edges of the plastic, is it a futile effort or not?
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On Thursday, March 12, 2015 at 7:07:51 AM UTC-4, snipped-for-privacy@yahoo.com wrote:

area will get more wet once sealed with plastic. add the french drain first then seal.
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On Wednesday, March 11, 2015 at 9:40:24 PM UTC-4, snipped-for-privacy@yahoo.com wrote:

ace (to reduce humidity in the overall basement area and house), but it's V ERY difficult to get around in there. I think I can manage to pull it over the whole space, but sealing the sheeting to the foundation walls with aco ustic caulk looks impossible due to restricted height down there. Is it sti ll worth doing if I can't seal the sides off?

stop humidity before it gets into crawlspace.

I would think some kind of tape product would be better and easier than caulk to hold it to the sides. If it were me, not sure I'd even bother. If it covers the floor area and comes up 6 inches or so on the sides, I would think it's going to greatly reduce the moisture and the additional sealing at the edges probably won't make it that much more effective.
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On 03/12/2015 8:13 AM, trader_4 wrote: ...

+1
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On Thursday, March 12, 2015 at 10:16:19 AM UTC-4, dpb wrote:

cover as much of the area as practical and provide at least some ventilation above, it will make a big improvment.
Mark
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I've done something similar; didn't bother with the edges, just overlapped the seams (w/o any sealer). Has made a big difference.
If my experience is any guide, just covering the dirt is worth the effort. (My crawl space already had some minimal ventilation).
On 3/11/2015 6:40 PM, snipped-for-privacy@yahoo.com wrote:

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On Wed, 11 Mar 2015 18:40:16 -0700 (PDT), snipped-for-privacy@yahoo.com wrote:

Assuming this is a good idea at all (and I'm not acquainted with it) and that it's a good idea in your case**, I think so. I think you'll get most of the effect you would get if the edges were sealed.
How much headroom is there? After the plastic is down, maybe you can send a child in to do the sealing.

**In a north suburb of Indianapolis, we had a crawlspace that varied from a plantless swamp to a muddy mess, depending on how wet it was**. I went down there once when I was about 11 and I was so muddy coming out, everyone agreed, I'd never go again unless it dried out, and it never did. We never did anything about it, and the three of us never had any complaints that were related to humidity or anything else. We also didn't know what the humidity was, since no affordable close-to-accurate hygrometers existed then, if they even do now. (We did make apoint to open, from the outside, the louvered vents, about the size of basement windows, that existed, 4 or 5 of them, in the part of the foundation above ground. I think we opened them in the summer and closed them in the winter, but I could be wrong about that. My mother was never convinced it had any effect, but someone told her to do that. Not counting walking time, it took 2 seconds for each one.)
**It never rains in Indianapolis in the summertime.
What time of year does all this humiidty bother you?
After we all moved, I realized that that the water table was close to the level of the bottom of the crawl space. The city map showed a stream running through the yard of a house 3 doors away (300 feet), so there was probably a stream before the property was subdivided and sold for homes. His whole back yard was soaking wet a good deal of the year. One corner of our yard was like that for 3 months in the spring. This is just background. I don't think we could have changed that (without lowering the water table for 2 or 3 or more acres.)
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> What time of year does all this humiidty bother you?

Always. About 5years ago, we had placed a plastic bin full of old school p apers whose cover apparently wasn't sealed perfectly... and it became moldy /smelly and had to be tossed. So, we won't do that again even with these i mprovements, but I still want to cut down overall humidity coming up.
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On Thu, 12 Mar 2015 12:03:49 -0700 (PDT), snipped-for-privacy@yahoo.com wrote:

Then ignore all but the first five lines of my answe!
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Hi Theodore,

When we built our house in 2004, code required that we install 6mil plastic sheeting in the crawlspace. There were no stipulations that it needed to be sealed to the foundation, or that the seams had to be sealed. We simply overlapped seams about 6" or so and lapped the edges about 6" up the foundation (though as you would expect they just fall down and lay flat. :) ). The inspector climbed under our house on the final inspection and said everything looked good. We have not had any moisture issues.
A few things to consider:
You should have adequate ventilation for the crawlspace (there are code requirements for free vent space, but I don't recall them at the moment). You'll get rain and other moisture through the vents, some moisture will come through the foundation walls, and a small amount will probably come from the living space above. The vents let the crawlspace dry out before it permeates up into the living space.
You should slope the ground away from your home so rain and snow drain away from your foundation instead of under your house.
You should have a french drain around the outside of the foundation to carry away any ground water that does work it's way down along the foundation.
It can be tricky laying out the plastic sheets in a crawlspace, but it's doable with patience.
Good luck!
Anthony Watson www.watsondiy.com www.mountainsoftware.com
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