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-   -   crawl space vapor barrier help (http://www.diychatroom.com/f19/crawl-space-vapor-barrier-help-109515/)

Eddie Bear 07-03-2011 01:16 AM

crawl space vapor barrier help
 
I just bought my first house. (FYI)
Its a single level ranch with a crawl space.
The crawl space has some type of clay.
No signs of mold. The crawl space has two outside wall vents.
The A/C drains in to the clay so I plan to install a condensation pump.

There is a plastic vapor barrier down there but it has many holes and covers about 60-70% of the soil/clay. (the crawl space is about 26'x41')

I want to install a new vapor barrier.
Here is the question, Can I install the NEW vapor barrier OVER the OLD one?

My thinking is that moisture will get trapped in between the layers THEN cause mold.

The photo shows the condition.
http://i876.photobucket.com/albums/a...ear2/photo.png

Ron6519 07-03-2011 06:25 AM

I'd clean out all the garbage(old barrier included) and put down a new barrier that covers the whole floor.

Eddie Bear 07-03-2011 10:15 AM

Thanks Ron.
That's what I though. There is garbage down there (old shoes, tile, pipes).

Is it bad to have the barrier over the cast iron drain pipe?
That's how it is now. I a little worried about tampering with pipes that old. (I have that kind of luck)

Eddie Bear 07-03-2011 10:26 AM

OK, then about the mil of the plastic. Between 4, 6 and 10 mil, 10 would be best right?
I see 20'x100' 10 mil online for $119 (Home Depot its $199).
Is the higher the mil, the thicker the plastic?

AGWhitehouse 07-03-2011 02:28 PM

You can cover the pipe and yes the higher the mil, the thicker it is.

Ron6519 07-03-2011 04:02 PM

Six mil is the standard in vapor barrier thickness.

jklingel 07-04-2011 02:30 AM

I'd only spend the money on 10 mil if you were planning on using the crawl space frequently. Be sure to run it up the walls, secure it, and caulk it w/ a compatible caulk, something like Tremco acoustical caulk.

Gary in WA 07-04-2011 08:36 PM

As we don't know your location, only run the plastic up the concrete walls 6", to inspect for termites.http://www.termiteinstitute.com/cont...-hot-zones.asp
You may need to take special precautions if in a radon zone: http://energy.cr.usgs.gov/radon/rnus.html

Gary

John_W 07-04-2011 11:06 PM

Clean it out for sure. You are breathing air that comes from your crawl space.

Gary has a good point about radon. If you have to mitigate for that, the quality of the plastic and the way it is installed will be more important.


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