Hi,

I want to install solid hardwood on my second floor which used to have carpet. After carpet removal I was surprised to see that the subfloor is half plywood half OSB. The OSB is a little higher than plywood (probably by 3/32).

Could you give me some ideas how to deal with this situation? Or is this a problem at all?

Thanks in advance!
bike2work

I would pull out the OSB if possible or reseath the whole thing. You dont want to risk going over two different wood substrates, but then some people do. You also could fasten and glue it down, but again, in order to do that you should be going over an underlayment, not the original subfloor.

Hi Stephen,

Thank you for your reply.

So you think two different substrates would be a problem? I have never come across this but I am novice.

I was thinking sanding or padding with felt. Are these something I should not do?

Thanks.

When I am up against wood underlayments or subfloors that are not flat I use an electric hand planer.

I see a miltitude of issues going over different wood substrates. Just like going over wood to concrete. Totally different animals.

I would agree w/ Stephen and add that the plywood is a better subfloor and the nails will hold in better.

Debbie Gartner aka The Flooring Girl
http://TheFlooringGirl.com

Well I'll add to the mix. I wouldn't be concerned with it as long as it's a good quality OSB. However, considering it was covered with carpet, perhaps it's a much older version that does not have good holding capacity. Is it marked with any tell tale signs of the type?

Thank you all for your replies!

Don't risk it using OSB. OSB absorbs moisture differently and swells more and could cause serious problems down the road.

Get some more CDX and be done with it