Plastic on OSB subfloor before carpet?

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  #1  
Old 12-04-09, 03:43 PM
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Question Plastic on OSB subfloor before carpet?

Hello. Hope I am posting this in the correct place.

I enclosed my carport (concrete floor). I laid down plastic then treated 1x4's and finally 3/4 T&G OSB all achored down with 3" tapcon screwes.

My question is should I lay down another layer of plastic on top of the OSB before the carpet is done??? My concern is that if there is an accident (dog, spilt something etc) or I steam clean the carpet there will be enough moisture from that to affect the OSB.

I would just do it, but I also dont if this would cause the OSB etc to not be able to breath etc.

Can someone offer some advice?

Thanks!
Carito
 
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Old 12-04-09, 03:57 PM
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No more plastic. The problem with enclosing a carport is there probably is not a footing or concrete stem wall to support the walls and roof, or stem wall to elevate the siding the required 6" from dirt or splash per code. An egress window is required as well as heat and ventilation if this area is to be living space. Check with your local building department for safety's sake. Garage conversions are normal, carport conversions are not.
Be safe, Gary
 
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Old 12-04-09, 03:58 PM
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You have infiltrated your moisture barrier by drilling holes in it, so it ain't worth much, now. In your home, there is no plastic on top of the OSB, so I would say if your house handles the moisture well, then so should your new install. I have seen modular homes with a layer of plastic on their subflooring, but it may be something to do with factory built units. My answer is not definitive, so others may have other advice.
 
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Old 12-04-09, 04:15 PM
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Thanks.There was a footing around the perimiter of the carport. It already had a roof over it. I simply filled in the side wall and front and rebricked.

I pulled the appropriate permits and have passwed everything. The area is also heated and cooled now. Ducts ran etc.

Wasnt aware of the issue with drilling into the plastic to anchor floor down since building inspector signed off on it.
My main concern has been with ensuring that if I steam clean the carpet etc that there isnt enough moisture for a length of time to swell the wood.

Would painting it with something help?
 
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Old 12-04-09, 05:04 PM
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There are a few questions you should have asked before you got to where you are, but I doubt you would want to start over .

I guess the best advice now would be not to create a double vapor barrier. The concrete has been drying for years to the open air. Now that path is blocked by your vb. If you install another vb or try to seal it with paint, you run the risk that if or when moisture gets in between, it would have nowhere to go and if it stays trapped, you know what comes next.

Best advice I can give now is to let it breathe as much as possible.

Bud
 
  #6  
Old 12-04-09, 05:36 PM
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Your VB you have down will trap moisture and will become moldy over time. Id remove it if you can.
 
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Old 12-06-09, 07:03 AM
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Originally Posted by airman.1994 View Post
Your VB you have down will trap moisture and will become moldy over time. Id remove it if you can.
Does moisture trapped between concrete and VB matter? The floor can't meaningfully dry into the concrete if the VB is gone, so as long as he doesn't VB the top any excess moisture can be dealt with.

As mentioned, a normal home has OSB and then carpet placed overtop without any water proofing. As long as you're proactive with spills and aren't doing them constantly this is ok and won't rot the wood out.
 
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Old 12-06-09, 09:10 AM
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Id say a normal home has carpet on to of concrete. No OSB!
Moisture will matter if it starts to pool.
 
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Old 12-14-09, 09:31 PM
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mold

That was what i was thinking to. Moisture is still going to come up thru the concrete. Unless you left the ends open after you put the 1x4's on. Mold is going to be your one true enemy.
You also mention that the city inspector signed off on it. Most of the time. They do not even look deep into those things.
 
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Old 12-16-09, 12:51 PM
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Originally Posted by airman.1994 View Post
Id say a normal home has carpet on to of concrete. No OSB!
Moisture will matter if it starts to pool.
I mean throughout the rest of the house; any two story home doesn't have a concrete subfloor on the upper level.

How much mold will grow in ONLY moisture? Does it not normally rely on food like wood or drywall?
 
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