On 07/11/2015 8:42 PM, Casper wrote:
I am curious if anyone has put vinyl plank flooring over osb.

Recently we removed sheet vinyl from two rooms to find it was laid
over osb and not glued down. It was there for almost twenty years,
flat as a board and no issues. I was surprised it wasn't glued. Since
the subfloor seems like new, I am trying to decide if it really needs
any further underlayment.

Thoughts on this?

One of the floating HDF/Laminates with the recommended underlayment will
be just fine. That'll typically be like 8 mm thickness for the flooring
and another 2mm for the underlayment for 10 mm (just over 3/8") total
installed thickness.

You could _probably_ get by with simply a layer of heavy paper if this
is above grade with finished floor underneath rather than bare crawl
space so there's really no moisture issue but as Leon says,
"manufacturer rulez" is the real answer.

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