I've been searching the web and these forums for a good deal of time, and I can't find a solid answer on this... your opinions, expertise, and advise would be greatly appreciated!

My wife and I are purchasing a home built in 1930 in the Cincinnati area. The house has 3/4" oak hardwood that's about 3.25" wide -- tongue and groove, of course. There is no other subfloor underneath the flooring, which I suppose means the oak also serves as the subfloor, since it's what all interior framed walls are built directly on. The planks are perpendicular to the joists, which are 16" OC.

We'd like to install pre-finished hardwood in the home, but I'm at a loss as to how. I've read the suggested subfloor reading, but don't see anything that's suited to my situation. My concerns and assumptions (please correct me as needed):

If I lay directly over top of the existing oak, it would need to be perpendicular. This would not only make it less appealing visually, but would run the hardwood parallel with the joists (a no-no without additional plywood, right?).

If I remove the existing oak flooring and install new 3/4" plywood subfloor, I have no way to get underneath the interior walls and replace the current subfloor. So a certain amount of the existing planks would have to remain in place and I could patch up against them around walls.

If I lay 3/8" plywood over top and then install hardwood, it will cause problems with door thresholds.

I love a good challenge and I'm looking forward to the work, but I would sincerely appreciate any professional advice. Thank you!

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This doesn't have to do with my questions, but in case you're wondering why we don't refinish instead:

The house has hardwood laid over top of the original oak flooring in the kitchen, mudroom and hallway. There's a 3/4" transition strip going into the kitchen for this part of the house. In another area, they laid laminate floor on top.

The hallway with raised hardwood is part of an addition, which has plywood subfloor. There's also a section in the original floor that's filled with plywood where the basement steps used to be prior to the addition.

We're removing several interior walls to open the space up some more, and I don't know what the flooring will look like when that's done.

Lastly, there have been many electrical outlets and registers cut into the floors over the years, many of which I am properly moving as part of the renovations.

Me at my house? Sand and refinish no question about it, maybe even remove the other flooring in kitchen and mudroom to have the uniformity you want. Otherwise I would glue down a quality enineered 3/4" wood with a sufficient wear layer that can be refinished. You should not nail your new floor into the oak, the proper way would be to drill pilot holes and use small headed screws, so the oak doesn't split and creak.

I would also be inclined to try to refinish/repair existing (and hire a professional) - that probably costs less that the amount you're going to pay for new wood and I believe will avoid height issues.

BTW, another option if you install on top is to a diagonal.

Debbie Gartner aka The Flooring Girl
http://TheFlooringGirl.com
Westchester County, NY

Thank you for your responses. I will attempt to refinish as my first choice, but I'm still wondering what my alternatives are if it doesn't work out.

Is laying 3/8" plywood with 3/8" hardwood over top a viable option? What about going diagonal over top of the oak?

Here's an update in case anyone else comes across the same problem.

After removing the various flooring that's been added over the years, we've discovered that refinishing is simply not a viable option. There are enormous areas that would require patching in, and there's an entire room with asbestos tile and adhesive directly attached to the original oak floor.

I'm going to install 3/8" plywood over top of the entire oak subfloor and then install 3/4" hardwood on top of that, running perpendicular with the joists. I did talk to a pro installer who agreed this was the best option after looking at the home.

Ugh, asbestos is horrible to find. Seems like you have a good plan, glad you talked to a professional.

Just finishing up a repair job right now where the layers of the engineered wood are all delaminating, and that model flooring has been unavailable for years. It has just reminded me why we only install solid 3/4" sight finished flooring.

Old houses have this type of subfloor because they were likely built before plywood was invented. Usually the boards are pine (cheaper) and about 1" thick and have a range of widths from 3" to 6". There is absolutely no reason why your new floors cant be installed directly on top of it. When you pull up the plywood, if you find any broken or loose boards, be sure to fix them first.
I suspect your installer just has never worked on old houses much... Might actually be a warning sign for you!