Hi,
Lots of info here, its all good. My question, want to install 3/4 in red oak hardwood. The subfloor is? Hard to tell from the markings but made in Canada in 1994 and it says waferboard? Is this safe, ok to nail into, will my floors buckle. I have heard mixed reviews from installers here.
Thanks for the responses.

Most likely, it is a type of OSB. Waferboard is slightly different than OSB but similar. NOFMA has stated that OSB is acceptable as a subfloor to nail to. I have installed flooring to OSB for 15 yrs and never had a floor fail because of it. It is not my favorite subfloor material so I would recommend using flooring staples, 15gauge x 2" leg x 1/2" crown, as the fasteners instead of cleats.

Thanks for the quick response. "the expert here told me not to worry, it was good to go, but didn't even look at it. The boards are screwed into the joists so wondering if that is norm, or because of the type of board.
Thanks again.

another question, if it is stapled in, can that be done with 3/4 inch thick strips?

Yes.