Hello,

I would like to solicit some input from all of the experienced users. My home has 3/4" solid strip (looks to be Bruce) in some rooms installed directly on 19/32 OSB subfloor with staples. The joists are 16" on center. Installation is perpendicular to joists.

I would like to install additional hardwood in adjoining rooms, replacing carpeting. To achieve an even installation, would I be totally foolish to do the same thing? Or should I consider installing engineed floor of similar appearance, but lower thickness on top of an additional plywood underlayment? This might achieve the same total floor depth, but would obviously involve more expense.

Alternatively, I could install solid strip on some additional underlayment, but this would create a slight height difference. Also, I am wondering if identifying and installing the additional 1/4" plywood or other underlayment would really be justified or if matching the existing installation would be reasonable in most situations.

All installation is over a full basement or on the second floor.

Also, should I use a rosin or felt paper even though the original builder did not?

This would be my first DIY effort.

Thank you very much for any recomendations.

If the original flooring is performing fine and you are happy with it, I see no need to add more plywood. Keep in mind, these recommendations are "generally accepted guidelines and recommendations" by NOFMA and the NWFA. They may not apply to every situation, especially when trying to ad on to an existing floor.