Default <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>...
> >
> > Would there be any additional benefit to putting in a 1 or 2" layer of
> > sand under the vapor barrier? The downside might be if I ever needed to
> > pump out water the sand might making pumping difficult, I suppose. Any
> > comments?
>
> Under the vapor barrier, or over it?
> The only reason I can think of for putting anything at all under
> the vapor barrier is to level it out, and keep whatever is
> under it from poking holes in the plastic. The only
> reason I can think of for putting sand on TOP is to
> hold the plastic down, and protect it from whatever goes
> on TOP from poking holes in it.
>
> If you think for any reason you might ever get water under
> there, then you should slope the ground under there
> and put in a drainage channel like the bottom of a fish pond.

If the soil is clay and damp, the moisture is going to collect on the
underside of the vapor barrier. Sannd below the vapor barrier will
give it a place to collect.

I would suggest your moisture problem may begin outside the crawl
space. Is the ground in t(he area damp/ Does the surface tend to
direct run off toward the house? Does the roof shed water close to the
foundation?)

Tom Baker

Axial <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>...
> I hope the moisture is just from the crawlspace never having had enough
> ventilation; my neighbors houses, just 20-30 ft away on either side and
> the same age, both have very dry crawlspaces. My house has very wide
> eaves and the soil almost never gets very wet next to the foundations.
> All run-off is into drains, and the ground is sloped away. It's at the
> base of a hill, but there are berms with drainage across the hill.
>
> My thought was that sand would, as you suggest, give the moisture
> somewhere to collect, plus it might be a "vapor pre-barrier" before the
> plastic. If I have the sand put in and then plastic put down right after
> the mildewcide etc. is sprayed on, my theory is that maybe there will be
> less opportunity for musty mildew to grow under the plastic.
>
> Until the crawlspace has had a few months to air out with the new vents,
> I didn't want to go to the next step of looking at drains in there until
> I know that the cleanout & new vapor barrier didn't do the trick.
>
> Of course, I haven't the foggiest how I might get the sand in there or
> spread it ... maybe get a couple of large, low, garden wagons and drag
> them around with pulley & ropes. Is there some machine that could blow
> sand instead of bark mulch?
>
> Sheila

Your description of your neighbor's dry crawl space and the layout of
your property suggests a dry crawl spce. So,you are probably correct.
The moisture is surface moisture and given some time will evaporate.

I'd suggest digging down - say - six inches to see how wet the soil
is. If it's dry, give the surface a few days to dry off before you put
down the vapor barrier.

In my neighborhood, there are a lot of highschool kids looking to do
yard work. They don't seem to mind crawling around in small spaces,
but I have to choose the more careful ones.

If it were my crawl space, I'd put down the vapor barrier on the clay
and weight it down with some sand. That's what we've been doing for
Habitat houses and it appears to work.

Tom Baker