# Questions on Underlay for subfloor over crawl space



## Danrad (Oct 31, 2014)

Hi, We are second owners of a 11yr old house built over a crawl space. There has never been any moisture issues in the crawl space  and we use it for storage. We are pulling up the old glued down commercial carpet and will put down Golden Select ash laminate with a foam backing. We are doing the work in sections. The carpet has pulled up very easy leavening all the glue on the plywood subfloor. The glue is slightly Tacky but even. I was considering putting a underlay that has a moisture barrier since I am unsure if one was installed under the gravel floor in the crawl space when the house was built. Good idea or not? Also if I use the underlay does the old glue need to be scrapped off? Lastly will there be a friction problem between the  underlay and the flooring?

 Ty for the thoughts and help Dan


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## nealtw (Oct 31, 2014)

Welcome to the site. The vapour bearer for the crawl space is usually on the surface and you should have one. That has nothing to do with floor of the house. The subfloor plywood is considered the bearier of the wood structure. I would scrape the glue off as you don't want lumps under your floor.


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## Danrad (Nov 1, 2014)

Ty Neal for the reply. I will clarify about the vapor barrier. Since there is no vapor barrier visible in the crawl space I was thinking of putting and underlay with vapor barrier between my subfloor and the laminate. The laminate does have a foam back attached already.
Ty for the imput - Dan


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## nealtw (Nov 1, 2014)

The idea of a vabour barrier is to stop the moist wet air in the house from mixing with cold  air outside causing condensation. Your subfloor does that. The vapour barrier in the crawlspace it there to stop moisture in the ground from entering that space, these are two different issues. No matter what you do with your floor you still need to cover the dirt in the crawlspace.


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## bud16415 (Nov 1, 2014)

The idea of a laminate floor is it is a floating floor and needs to be able to expand and contract. You leave a gap all around the edge for that. The first one I did was before the backing pad was attached to the plank and you rolled down a plastic sheet with tiny foam balls in the center of two sheets of plastic. The foam was the pad. If the old glue is tacky on your job I would put down the plastic or paper so the floor can move. It will also help with installing it as you won't want the strips sticking when you slide them in place. 

I'm not a pro and pros may be along to help. I have done a dozen floors at most and that's my two cents. 


Sent from my iPhone using Home Repair


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## Danrad (Nov 1, 2014)

Hi, ty bud and neal for the advice  will follow through on the suggestions. FYI another flooring installer said to try Baby powder (non cornstarch type) sprinkle around and then broom it across the floor. Took all the tackiness out


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## nealtw (Nov 1, 2014)

You just need to make sure the floor can move as it expands, if it can't move easily I have seen where it expands and the stays in the new spot and pull joints apart when it contracts.
Putting plastic or wax paper uinder shouldn't hurt anything, my point before was just don't think of that as a barrier for the crawlspace.


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