I have an 1890's that someone had glued 1970's shag carpet to oak hardwood floors. Also had a maple hardwood floor in the kitchen with several layers of linoleum glued down with the black adhesive. After trying sanding, adhesive remover, paint stripper and scraping someone told me the solution that does work! It will sound counterintuitive but you mix a strong solution of TSP cleaner in a bucket of hot water. Then mop this solution onto the floor keeping it wet for 40 min or so. The TSP solution will turn the glue to mud which can be easily scraped off. When nothing else worked, this took care of the problem. If you leave the oak flooring wet too long, it can warp, but I used this method in 3 rooms and then was able to sand and finish and they turned out beautiful. The maple floor cleaned up beautifully as well! Attempting to sand the glue mess off the floor will fill up sandpaper sheets almost immediately - the TSP method works!!

Do you have a photo? What are the conditions like in the room? Heat/AC running? Sounds like you might have a lot of renovations going on, so perhaps the conditions haven't been constant, and the humidity in the air could have caused the previously installed wood to cup. If so, restoring the conditions should allow the floor to lay down again.

Crawlspaces require SPECIFIC venting/cross venting and a vapour barrier over the raw earth. The HVAC not running sounds like the culprit. This is a builder's Oopsa. The center of the planks will tell you the DIRECTION of the moisture. If the center of the plank is sitting LOWER than the edges (like yours are = "cupping") then the centre is pointing DOWN....That means the BOTTOM of the planks are WETTER than the top of the planks. Just like yours are showing. That indicates that something BELOW the plank is causing issues with the wood. And that often comes from what it is SITTING on...like damp plywood that was never acclimated/dried properly before install (ahem....HVAC needs to be on and at living conditions for plywood to become "dry enough"). IS the HVAC running yet???? Do you have a humidistat added to your HVAC? It is *possible this can be corrected - over time - by EXTREME regulation of indoor living conditions. But it be prepared that even THAT won't help. Sadly wood GRABS moisture MUCH MUCH faster than it lets it go. So it may only take 3 weeks for wood to grab all that unconditioned moisture (no HVAC, no dehumidifier, no A/C, etc), but it could take MONTHS to let go and settle down. And you will never know if it works until many many months have passed. Wait for the Inspector to give you some hints and tips. But the builder made a massive mistake by installing hardwoods in an unconditioned space. Massive, massive mistake. That is flooring installing 101. A decent flooring installer would have told the builder to "call me when the HVAC is in" and would have walked away (which is why builders don't like using these "decent" guys - they have too much knowledge). Keep us posted on the Inspector's report.

The floor will tell you what will happen. A stable, rigid plank, floor sitting over something soft(er) will do one of two things: 1. It will continue to bridge over the squishy stuff and continue to 'work' for years and years and years. OR, 2. It will sink or bounce with each footstep and eventually the edges will begin to break (this is click flooring or tongue and groove hardwood). These breakages will cause the floor to separate and show BIG gaps (big enough to see the black stuff underneath). You can't miss it when a rigid floor starts to fail. Since you won't know what you have until it 'happens' (or does not happen...which ever), I suggest you live with it for as long as possible. The old saying, "If it ain't broke, don't fix it" comes to mind. That being said, there are personalities out there that CANNOT handle the idea of 'something' coming (or not coming). They just cannot deal with a question mark. If you or someone in your family falls into the CANNOT DEAL category then go ahead and start making plans to deal with this floor sooner rather than later. This would be for the comfort of the HUMAN rather than the 'health' of the floor. I would live with it for as long as it 'works'. All the while saving $100/month to get decent enough savings to tackle anything that comes along with a new home (or new to you). You would be AMAZED at what pops up in the first 5 years of homeownership. I've been there...put on a new roof. Updated wiring and dealt with plumbing issues...all in side 4 years. Thanks to the 'Bank of Dad' I was able to wiggle my way out of the rabbit hole.