Crawl Space Vapor Barrier


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Old 07-13-15, 07:03 AM
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Crawl Space Vapor Barrier

My house is less than 2 years old but after previous bad experiences with crawl spaces I want to avoid issues. The current vapor barrier is not installed as I would prefer. There are gaps around the edges, not all the way to the corners etc.. Can I install a 2nd vapor barrier over the top of the current one or do I need to remove it?

Also, they put a lot of stone in certain area's of the crawl space. In one area there is a pile of stone and the vapor barrier stops before this area. What is the reason for the stones vs. vapor barrier?

Thanks!
 
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Old 07-13-15, 07:39 AM
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Welcome to the forums.

As long as the 'two' vapor barriers are in contact with one another, I don't see a problem just going over the existing with the new.

Erosion issue for the stones? Threw them there to get them out of the way?
 
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Old 07-13-15, 07:44 AM
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I don't know what the purpose of the stone was, unless it gave them a place to walk other than on the vapor barrier. Vapor barriers in a crawlspace need to be sealed 100% and usually up the walls a foot or so. I don't think you need to replace or cover what you have as you can patch and tape where needed. if patching isn't possible I would avoid a double layer to give ugly things fewer places to grow. Is your current plastic black, it keeps any light out.

Not sure where you are, but here is a radon map.
EPA Radon Risk Map for Virginia

Radon control and a sump pit are items often located under that vapor barrier.

Bud
 
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Old 07-13-15, 09:17 AM
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Thanks for the replies.

They used a lot of stone to just put on top of the VB. The downside is when I walk on it, I am pressing stone into the VB.. I just assume they dumped a lot of stone in one area and only used some of it. The VB was poorly done (IMO), it does not go to the edges and they used landscape staples to keep it in place.

I am a little concerned about putting one VB over the other because of anything that might grow between them.. but I guess if I have to deal with the mass of stones everywhere it would be just as easy to repair or replace it.
 
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Old 07-13-15, 10:52 AM
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Bud knows this stuff better than I do and he has concerns about the layers so I would first remove what's there now.
 
  #6  
Old 07-13-15, 01:18 PM
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Regular gravel or worse crushed stone will do exactly as you say, poke hole in the vb.

Let me back up for a moment. Moisture problems come in two forms, water and moisture vapor. Have you seen any indication that you are dealing with any water issues?

Moisture that finds its way in between two layers of plastic has no place to escape. It may come in by way of water pressure but must escape by way of evaporation or absorption, neither of which can occur when trapped between two sheets of plastic.

Is the amount of gravel too much to bucket out or bury somewhere where it is? It really doesn't have a good place above or below the plastic. If you needed and were building a perimeter drain and or sump pit, the gravel could find a useful home.

As a note, the rigid insulation board on the foundation walls is a benefit both summer and winter.

Bud
 
 

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