Hello! New here, I've searched for similar topics, but found nothing -- here's my situation:

I'm levelling the floors in my condo (1920's Montreal walkup), and in the process I have to pull up all the hardwood. The place is ~1000 sq ft, and I've got roughly half of it off already. I'm guessing it's maple. The lengths range from 6" to 10'.

The wood was under linoleum and carpet for decades; it's mostly in good shape except for the high-traffic areas. It's not as much wear-and-tear, as that some of those boards warped with time. It's nailed down with cut nails. Every so often a board cracks or splits, but it's coming up pretty easy for the most part. I imagine I can salvage some 700 sq ft.

I was hoping to re-use the wood, less waste and cheaper that way. It seems like a lot of work -- all the nails have to be pulled, and I think the tongues and grooves need to be scraped / cleaned out. I test-fit a few together to see whether it would work, and it's hard to close the seam between boards. Nail gun splits the wood (but these are 2 1/2" nails with heads & the framing nailer is not hitting the exact spot above the tongue).

I'd like to estimate the likelihood of success before I take this on.

Has anyone here installed salvaged hardwood? Is this advisable? Horror / success stories?

Thank you!

Using recycled hardwood instead of new is a good idea. The wood may be old growth which usually has more growth rings per inch on average so the wood looks better, in my opinion. Once the nails are pulled you ought to stack the wood in piles by sorting the lengths by each foot of length, within six inches, plus or minus. This is how the wood came from the manufacturer in the old days and helps make it easier to lay the flooring, again. This way you will know how much of each length you have so you can make the joints spaced out evenly instead of using all long boards in one spot and short boards spread out evenly. Start rows with short boards and try to end with short boards, without using sort boards in the center of the room. You will need to cut out broken spots, but just because an end is cut off doesn't mean you can't use it. Put a nail close to the end where the T&G is missing.
I recommend using a professional floor fastening system, like a flooring stapler or cleat nailer. These help slam the boards together without any damage.
A carbide scraper sure helps clean the top of the groove where dirt and grit can keep the boards from sliding together.
Regular box type nails from a nail gun can work, but finish nails work through the tongue better. If they don't go all the way in, use a quarter inch punch to make your nails flush against the tongue side.

My only caution here is that you've said you have 1000SQFT in the condo to cover, but might only be able to reclaim 700SQFT of hardwood. If you need to tie in new material to finish the space, there will for sure be a noticeable difference where the two products meet. Not sure what you plan is for the other 300SQFT, but keep that in mind. If you purchased new pre-finished material, you can also do repairs down the line as replacement material would be readily available, and your material would also come with a manufacturers warranty.

Thank you for your replies.

Yes, the biggest problem is that there won't be enough wood to cover the entire area as Kris pointed out -- Maybe 30% is lost to damage, too worn to reuse, etc.

I took a few boards, pulled the nails, cleaned the tongues and the grooves, and did a little test on a loose piece of plywood to see how well it fits back together. The results were a little underwhelming to be honest. Some of the wood split when nailed, and it looked like it would take a LOT of sanding to get it flat.

Given how much extra work this would be for "okay" kind of finished product, I decided to get rid of the wood. Posted it for free on a couple of local classifieds sites, and it took a few days to get any response. A couple of people showed up to pick up some of it, and neither of them was planning to use the wood as flooring. So that also makes me think it was a good call to get rid of it.

To make a floor out of used flooring you need to do more work than using new material. If the floor has been sanded you will find lots of overwood when the new floor is laid. If you are determined and have the skills you will have an historic gem. I guess that you would need at least 10% more material and 25% more labor than new flooring.