DIYbanter - View Single Post

In article . com,
says...
Hi,
I had specified new "underlayment" to be put over the old 3/4" pine
board subfloor in a new 2nd story addition.

If it is a '*new* 2nd story addition' how can there be anything
*old* in the *new* addition? :-)

What our contractors
installed in our absence is regular 1/2" OSB sheathing material, not
specifically rated as underlayment. They screwed and glued it down very
well.

'Underlayment' is an ambiguous term. I have seen; 1/4" luan
plywood, 7/16" OSB, 1 1/2" light weight concrete, 2 x 6 T&G SYP,
3/4" T&G exposure I plywood, and ... 'underlayment'.

Underlayment and sheathing refer to the use of a material not the
type/size/physical-properties of a material.

After two weeks I already see swollen areas and chips coming
loose due to water being dragged in and left due to the construction.
Is OSB sheathing considered a reasonable underlayment for a carpet?

Millions of yards of carpet have been laid directly on OSB.

I expected plywood rated underlayment, with the top side sanded, not this
chunky stuff which is not even particularly smooth to begin with.

Expected or specified?