Hi-
We have a house built in the 1930's in Arizona. We recently had water damage in the kitchen and the water restoration company had to take up all of our old kitchen flooring tiles. This revealed that the kitchen also has the same oak flooring as the rest of the house! The floor throughout the house is nailed across 1 foot separated joists with no subfloor. there is a small 2 ft high crawlspace under the house. the oak flooring is tongue and groove and is 2 1/4 wide and 3/4" thick. it looks like red oak.
We dont really have issues with the floor in the rest of the house, it has held up pretty well no squeaking or bouncing.

We would like to refinish and use this flooring. Unfortunately there are some areas where the wood is not in good condition. Maybe about 3- 4 sqft total out of a 90 sqft kitchen would need replacement.

during this renovation we had a contractor remove and save similar flooring which had tile on it from the bathroom, so we do have some replacement pieces, but they were not very careful, and some is damaged & some is not in good condition due to being in a wet environment.

Im wondering whether I can use newly manufactured flooring and just place over joists to match, and whether that will be strong enough. Some of the flooring will be under cabinets, so an exact color match is not necessary, but I want it to be strong enough

Thanks!

As long as you get the right species of oak repairing with new wood will probably be stronger than what you have if it is old growth. Old growth oak which has growth rings close together is not as dense as wood that has wider growth rings. Most oak trees that are harvested today are managed to be harvested before they reach a large diameter which will have more growth rings per inch. With more growth rings per inch there will be more big pores from Spring growth when the tree is trying to get all the leaves out and draws more water through the larger pores. The Summer wood, or late wood has all the strength of the lumber. Wider growth rings will give stronger flooring.
When laying flooring over sleepers you need to cross over 2 sleepers with each board. This means that you need to use at least 2 nails for each board.

Another option may be to swap out the flooring from closets (since you said the oak is throughout the house) for the kitchen, if it's in better condition than the flooring from the bathroom.

Thanks! so you are saying that I can use matching new oak, and not worry about its strength, even if installation says it should be over plywood? Thanks!

Thanks. this is a very good idea. There are two closets in the house.. I know for sure that one of them has the wood in it. Not sure about the other as a previous owner put carpeting in it.. will check. The condition of the wood is good there, great idea.

I think it is silly to remove closet wood when you may buy flooring to match at a distributor. To even get one board from a closet it would take me over an hour to remove base board and the last row installed against the wall, which may not be full width and then replace the base board. The salvaged flooring may not have the T&G at the ends of the boards. You would still need to buy replacement wood to go in the closet to replace however many rows you salvage.
Flooring is usually sold in 18 square foot bundles. You may have some short boards that you would not be able to use over sleepers, but it used to be common to nail hardwood over sleepers. New wood flooring has the same dimensions as older wood, the T&G should fit together, so if you do not have structural problems occurring in your existing flooring, use the same design for the replacement flooring, unless the sleepers are rotted out and will not give support.