We are making our kitchen and formal dining room one large room. Each room is 12x15 now, the kitchen currently has vinyl and dining room has hardwood. The hardwood is solid 2" wide, 5/16 thick facenail red oak, the same as the rest of the house. Condition is very good for 60 years old but we plan to have it refinished and possibly re-nailed to silence the squeaky areas. From what we can tell the sub-floor is also in good condition albeit squeaky in spots. It's 3/4 pine planks laid 90 degrees to the joists and the hardwood is 90 degrees to the subfloor.

I was thinking of picking up used hardwood of the same type for use in the kitchen. We would have the kitchen/dining refinished slightly darker than the rest of the house and maybe add some inlay accents where it meets the rest of the house. Is this a good plan?

Another option would be to pull the hardwood up in the dining room, renail and sand subfloor, then put down new 5/16. Cost of new 5/16 material is about $4/sqft so not terribly expensive and may give a better finished product.

Some have recommended that I use new 3/4 T&G hardwood and deal with the height difference since there is only one area where the floors meet. Can this be laid without issues on the plank subfloor?

Plusses ond minuses for the different options? We'd prefer not to use 5/16 or 3/8 floating floors like Pergo.

Thanks.

I have seen used top-nail flooring that has had the nails pulled through the bottom of the strips. This is not the best way to prepare it for another use. The tendency would be to lay it right side up, again. It will look good until it is sanded, ad then the old nail holes' putty will start to fall out of the old holes sine there are no nails under the old holes. It will start to look like a shotgun has blasted it with holes everywhere that will need putty to fill.
The correct technique for preparing the strips for re-use is to tap the nails back through the face of the strips and then use the reverse side to be the face.
Since the floor brads that were used to nail the flooring originally are diamond pointed, the wood will almost come together again when it is re-laid and sanded.
The old nail holes will practically disappear without much filler, instead of showing holes after being sanded.
Since the flooring will be different thicknesses depending on where it came from in the house it was removed from you will be sanding a lot of over-wood off just to get to the lowest thickness of your recycled flooring so you can have a flat floor.
If you can get new flooring for $4, it wholesales for around $2, it would be your best investment for blending in or extending your flooring.
I say that you can sand the top-nailed flooring as many times as you can sand a ¾ inch thick floor if it is installed correctly. It is nailed down with twice as many fasteners and both sides of the strips are nailed with a machine that really fastens the wood down.
You should be able to locate the floor joists where the sub-floor is loose and use a long 8d finish nail to secure any squeaks before the floor is sanded, filling with wood patch and then if you have nailed into the soft grain, the nail hole will blend in. You can toe-nail with two nails for extra holding grip.
Top-nailed floor lends itself to inlayed floor patterns well. You can use lots of different wood that only needs to be milled, or ripped to 5/16th inch or slightly thicker. Feature strips for rooms with borders come in walnut, Peruvian walnut (almost black), maple, mahogany and usually are only a partial width, not the whole 2 inches wide, mostly ¾ inch width. The border will be a feature of the architecture, usually the shape of the room, to highlight the shape or detail.
Good luck trying to find real floor brads, which are one inch long and 15 gauge
with a "diamond point", which as it fastens the flooring down, also spreads the fibers, tightening the boards together, and also splitting any end that is not as wide as it should be. The wood patch will hide small cracks and stay in position since the strips are nailed down tightly.
Forget about using recycled top-nailed flooring if it has nails pulled through the back unless you use it for a wainscot, or don't plan to sand it again.

You may want to re-nail the existing, but not to eliminate squeaks. In my experience with these floors, they do not seat as well when the subfloor is at 90 degrees to the hardwood.

You can test this easily after the first sanding—if you press the flooring between the nail rows with your index finger, you’ll see ‘give’ between the strips, in many different places. With the old finish in place, you wouldn’t notice this, but when the finish is gone, the looseness of the floor shows up.

You can also test it after putty has been troweled on the floor to fill up cracks. If we roll our sander over an area, just the weight of the sander will cause the filler to break out of the cracks behind it, when the floor is not properly fastened.

Some customers have us re-nail when these signs show up. I generally put the new nails between the existing rows, and I only put one new nail per strip, not two. This is enough nailing to correct the problem.

If we don’t re-nail, the floor generally stabilizes some when the new finish goes on. However, the troweled putty does not stay in the cracks, and we end up having to putty the cracks between coats of finish, which is a lot more time-consuming.

Most of the squeaks in your floor are coming from gaps between the subfloor and the joists, not the hardwood. If you have access to the joists, you can see this movement if someone jumps up and down on the floor.
Drive shims between the moving parts. It’s time-consuming, but you can do that yourself. If there is no access to the joists from below, then you’ll need to pull up strips of hardwood, and screw wood screws into the joists. Then you put the hardwood back down. These strips are not attached to each other, so it’s easy to remove them.

Thanks for your detailed replies.

I hate throwing away what seems to be good hardwood, which is why I hesitate on taking up the dining room floor. For < 200 sqft and the challange of getting the old and new wood to match, not to mention some piecework, it may be the right choice. The subfloor can be screwed down and new hardwood laid. Would you still go with new 5/16 for the kitchen or I should I look at 3/4?

The rest of the house I will keep the existing and address the squeaky areas. It may never be totally silent but there are are only a handful a spots we hear. This stuff holds up like iron. It's by our front door and we don't baby it at all, lots of traffic, wet shoes, etc... still looks great.

Is Waterlox a good choice of finish for 5/16? We won't be living in the house through the remodel so odor isn't an issue.

Just trying to do my homework first before getting a contractor here. Thanks again.

5/16th inch flooring in kitchens was common in the 1960's here in the Southbay.
I think it was the first type of flooring installed in kitchens. The flooring was bevelled planks which come in 3 to 8 inch widths. Each row had a small bevel that would fill with finish that tends to bridge the seam, making it water-proof. The correctly installed flooring did not and won't have gaps between the flooring boards, unless it gets flooded or someone starts watering a plant. The rows of nails will set the strips so their edges press together, so even though there are no tongue and groove, the edges press together and the boards move in unison. More rows of nails, with each row nailed within one half an inch of the edges of the strips, will both fasten down the strips and make them press together more firmly. One nail in the middle of a strip is not as effective as one nail on each side of the strips for a lasting quality. 2 inch strips laid correctly will have a no gap beginning as the flooring is tacked down every several row at a time, and then when nailed it will firm up from the pressure that a row of fasteners adds to the mass of the system. A small gap at butt-joints will be filled by the edges of the loose strips splitting, but also pressing against the edges of the strips that pass next to the minor butt-joint gap that has been filled by nailing. Depending on the sub-floor width of each plank, a row of nails in each row is the best fastening system, unless the sub-floor planks are wider than 1X8's.
If you have white oak flooring you have the better specie, but red oak works the same way. For a kitchen some people will prefer straight-grain and quarter sawn, which has a different look, but has different characteristics for wear and water resistance and is slightly higher in price. It will help to have a bundle of a wider plank to use near walls and against cabinets with a toe kick so a small rip would not be needed or the toe kick overhang would not need to be shimmed out to cover a small gap where a strip doesn't fill all the way to the cabinet base.
No expansion gap is necessary with the 5/16th inch thick flooring, so it can be installed "net fit". If the floor gets flooded and starts to expand, the brads that hold the flooring in place will fail in a spot because of the pressure that can develop and because it is a thin flooring, there will not be enough pressure to expand against walls or other "immovable" objects with detrimental force.
Where are you located? I hope you can find a good mechanic who can work with your flooring.

I am near Philadelphia. A lot of homes in this area have 5/16, built from the 20's into the 60's. I can only remember seeing it in 2" wide strips though. A wider plank would be nice in the kitchen but I haven't seen one available in any of the stores.

How are those floors holding up, in your experience?

I'm not worried about flooding water in the kitchen, that would be an insurance claim. For us, it's more likely for one of the kids to knock over a cup and just leave it there. Hard to imagine that 12 oz of water will cause issues for a properly finished floor. This is why I was looking at the Waterlox finish. Seems like it is easily repaired if damaged.

I hope I can find someone too! I'm going to be looking at GCs soon and will make sure I pick someone who's worked on this type of floor before.

For floor finishing you need to find a floor contractor. Some General Contractors have a floor specialist that they know and have had work done.
Lebanon Flooring in Tennessee makes all the widths, V-groove and square-edge.
It's my favorite flooring. It holds up well in kitchens, over a good sub-floor, the more brads the better. I also like to add a brad on each side plank where there is a butt-joint, which helps to keep butt-joints tighter with less splitting if one of the butt-joint strips is a little narrow.
Even with a square-edge top-nailed floor there is minimal water penetration cause the strips press together when it is nailed down with floor brads. We used to get brads in 50 pound boxes from Korea, but the distributor doesn't stock them anymore. At one point we got brads from a company in New York. I hope you can find a company with the Cavanaugh top-nailing machine for installation. A lot of the guys like to use pneumatic brad nailers, now.