# Subfloor vs Underlayment



## Mike Swearingen (Mar 15, 2005)

Yes, the T&G is the subflooring and the plywood is the underlayment.
You can remove the underlayment along with everything on top of it by sawing and prying it out in small sections.
You will need a circular saw with an old blade (you WILL hit nails), gloves, safety glasses, crowbar, pry bar, hammer, etc. to remove it. Adjust the saw blade to the depth of the plywood only, so that you don't damage the subfloor.
I usually don't cut more than a 2-foot or less section out at a time. 
Stagger the sheets of the new flooring, and glue and screw them down. If this floor is over an unheated basement or crawlspace, you need to put a vapor barrier of roofing felt down on top of the subfloor, overlapping the edges a few inches.
Good luck!
Mike


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## indignatz (Nov 15, 2007)

Thanks Mike. One question for you, what is the reason for gluing down the underlayment? Wouldn't that make it much more difficult to remove if I ever had to replace it again in the future?


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## New (Dec 1, 2007)

*1/4 inch underlayment OSB or plywood*

Have 1/2 inch subfloor. Plan to install 3/4 solid wood floor. Instructions call for 3/4 inch subfloor. Can I use 1/4 OSB as underlayment? With only 1/4 inch for screws does it matter OSB or plywood?


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## Mike Swearingen (Mar 15, 2005)

The purpose of using Liquid Nails or other construction adhesive is to prevent sqeaking of the flooring on nails. Almost all flooring will "give and buckle" a bit with swelling and shrinking of the wood.
It may make a little more difficult to remove later, but it is worth it for all of the years that it will be in place. 
Mike


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## Mike Swearingen (Mar 15, 2005)

new,
You can use OSB or plywood for underlayment, but if it were me, I would go with plywood. You will be screwing or nailing right through both layers of the subflooring, and plywood holds better than OSB IMHO.
Mike


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## ron schenker (Jan 15, 2006)

I would put those screws into the joists about every 6"


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