# Vapor barrier for floor



## guyod (Mar 2, 2008)

Hey Guys :

I need a vapor barrier to stop the cold and humid air from coming up from my damp, floods often, dirt floor basement. Half is about 6' the other is 2' high. The house is very humid inside its 60% +. With the heat blasting it goes down a little. I dont want to get any mold or mildew in the house(was an issue when i got the house). I have 4 mil plastic. I want to put that on the subfloor under the flooring Just beacuse it would be the easiest. But i think that would cause more mold. and if something spilled it would be wet for days. The other option is to staple it under the floor joists but i still have some plumbing and electrical to deal with plus i would like to insulate it just dont have the money for that right now. Anyone have any thoughts?

PS you can save the stop the flooding speech I just got done replacing all the floor joists and replaced most of the foundation. I will get to that soon enough. I just need to get the family moved back in the house first.


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## glennjanie (Mar 2, 2008)

Hello Guyod:
The vapor barrier on the subfloor is a good shot. When you get to the flooding problem you will probably cure the mold problem.
Glenn


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## inspectorD (Mar 2, 2008)

I hate moisture problems... 
The plastic on the sub floor will cause many issues with the vapor transfer getting stuck, so to speak.
You need the plastic is where it will condense under the floor joists. It is best on the floor of the crawlspace and run up the walls to just below the sill plate. Then secured to the concrete wall at that spot with a flange of sorts. Basically check out your masonry supply stores for a sealing flange, usually a metal piece with rubber gasket which basically seals the moisture under the plastic envelope.
The professionals use 6 mil poly, the 4 mill punctures to easily when you move across it later.
The basics are the wood and anything cellulose based belong in the heated and controlled part of the house, above the plastic.  The rest stays outside the plastic.
I hope this makes some sense, you can always go to www.buildingscience.com for the really long explanations under "crawlspaces"...or follow my basics. 
Good luck under the house....I dislike crawlspaces too.

PS..please where your respirator....it's worse than you think under there.


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## guyod (Mar 3, 2008)

Thanks for the replies. That should work for the crawl space enough it even flooded in there to but securing it to the sill should keep it in place. I can't do that in the basement section though need to walk on it


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## inspectorD (Mar 3, 2008)

If you can afford it...the box stores have a raised floor finishing system. We put the plastic down first ,then these 2 foot square plywood and plastic rippled pieces lock in with each other. I think they are about $4 a section though.


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## guyod (Mar 3, 2008)

i seen them, never though of using them on a dirt floor....something to think abou...... but the next big rain they will be floating. need to fix that first.


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## guyod (Apr 30, 2008)

I about to put down hard wood floors and am faced with this question again. i ended up stapling plastic to the bottom of the floor joists and it helped alot. 

I seen at home depot a couple weeks ago a vapor barrior for hardwood laminate and i think regular hardwood designed to go under it. seemed to be only 6 mill plastic in 6' width. so should i use this or can i just get away with sheet plastic or should i stay away from both and my plastic and eventually  insulation with paper.


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## TaskBoy (May 14, 2008)

Have you folks heard of a product by Custom Building Products called RedGard?

http://www.custombuildingproducts.c...actureMembranes/RedGard.aspx?user=diy&lang=en

It's widely used and has good reviews.


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