You have to put down a vapor barrier against the soil and seal it to keep the moisture out of the crawlspace and home. Then, you can use the right kind of insulation. You want to be sure and do a moisture test before proceeding with choosing the type of flooring that will work in your home. And you also want to be sure to use your AC in the summer, and potentially a humidifier in the winter to keep the moisture levels relatively stable. And I agree with the others. Without a doubt, it's a moisture issue causing the problem. You now have to play detective to find out what's caused the elevated humidity issues.

Since my husband and I recently went through this DIY, I can make a few suggestions, although we didn't refinish, we installed unfinished rustic inexpensive red oak floors ourselves and finished them. I don't know anything about removing a wax finish, maybe someone here can advise or you could try a different hardwood flooring forum. For the sander we rented a U-sand, which is a floor sanding machine that is supposedly made for the DIY'er. It worked great, got right up to the edges and was really easy to use. I don't know how well it would perform for refinishing, as that involves more sanding. For the stain and poly, we went with the professional grade stuff. It was so worth the extra money as the products were much more forgiving to work with, and I think will have better long term durability. We went with the Bona products which are designed for hardwood floors. We`used the Bona Drifast stain, which is an oil modified stain that dries quickly. The stain is very rich looking and was wonderful with any accidental overlap. We mixed a couple different colors for a custom stain color. We went with the new Bona waterbased Traffic HD in the extreme matte finish and I love it. I think the traffic HD has one of the highest durability commercial ratings. A matte finish will hide more imperfections and scratches than a shiny finish. Although it says extreme matte, the finish does have a slight shine with a very natural wood look, it looks great with our rustic grade floors. I've never seen a poly finish like it, it's so velvety smooth and natural looking. It's sheen is in between Bona Naturale and Bona Traffic Satin HD. The water based polys I believe are more durable than the oil base and this one is meant to go on top of Bona's oil base stain. The Bona waterbase poly also had very little fumes that disappeared with in a couple days. It has a separate catalyst (hardener) that has to be added and then you have 4 hours once you add the hardener in. We were concerned at first, but with the T-bar applicator, we were able to get one application done in about 45 min-1 hour (650 sqft+ stairs). We have two dogs who like to race around the house and hate to have their nails clipped, I have yet to see a scratch, this finish seems to be wearing like iron, I am so impressed. We applied the stain, waited 48 hours, then applied the first coat of poly, the next day we buffed it, wiped down with a damp cloth, let it dry and then applied the second coat and let it fully cure. We bought the T-bar poly applicator, which worked out well. We also bought the Bona Mixer bottle, so we could mix smaller batches when we needed to and didn't have to mix up a whole bottles worth. This was 7.00 well spent as we mixed up a gallon and a half for each application. For wood filler we tried Woodwise floor filler, and Timbermate, I thought the Timbermate performed a little better, but both products were much better than anything at Lowes, or Home Depot. The waterbased wood fillers are great because wiping off excess with a damp rag is fairly easy, even after it's dried. Plastic putty tools should be used with the waterbased fillers as some metal scrapers can discolor the filler. Since the Bona products are professional grade, we bought them through a company that sells to the general public and professionals. Their business is mostly an online store, but people can come in and buy products from them locally. Since they were local for us we got to talk to them in person. They were great, they took the time to answer all our questions each time I stopped in for products. I found them extremely knowledgeable and very caring, their how to videos on their website were also helpful. Floor Mechanics Online Store We spent about 1,750.00 total for 1,000 sqft of very rustic red oak flooring, Pneumatic floor nailer, moisture meter, sander/buffer rental, and finishing products. It was some work, but worth it for site finished, solid hardwood flooring. Good luck with your son's floors.

I know this is an old thread but I felt the need to reply. We used Bona Traffic 5 years ago using spice brown stain followed by the Satin poly HD 2 part system. I remember back then it stated the darker color allow 12 hour dry time which we did. Then we applied two coats of finish. I recall that it took longer then 2 weeks to fully set and get solid but eventually it did and worked out great. Fast forward we got a new house. Great wood floors. Again we refinished them using the Bona HD traffic 2 part system in semi gloss. We used a lighter finish this time which stated on the stain can stated to allow 2-3 hours drying time in normal humidity. So this time around we followed the instructions and allowed 3 hours for the stain to dry on a lovely 75 degree sunny day. I did not go heavy on the stain and I would use a dry cloth to buff out the excess as I went along. Everything looked great. We have experience with the sanding so we spent roughly 10 hours using the different grits down to the 100 grit as the final step as instructed. Floors were lovely and down to the bare unadultured wood. We then vacuumed them and got every last bit of dust off using special footies as to not contaminate the floor with our feet. We could not have followed the instructions more perfectly. In fact we researched for a week and spoke to a floor refinishing company just to insure we did things 100% correctly. Well here we are now, 12 days in and I can scratch this off with my nail in many places. I am not talking just a scratch in the wood, but a peeling of the top coat scraping down to and exposing bare wood. I am sick to my stomach. The floor will not last. It is supposed to be strong like for a gym. This would not hold up to a room of infants. We luckily were finishing in a vacant home so nothing was placed on the floor for 10 days. It's not even worth moving all of our heavy furniture and starting over so I am going to put laminate floors over top of this and be done with it. I called Bona and they told me that they suggest 8 hour stain drying time. Well then why the heck would you state on your product 2-3 hours? Human error on my part? I think not I did everything that Bona said. Disgusted with the product. I should have used a cheaper oil base from the big box store. Biggest regret of my life. Perhaps Bona stored the product in a cold warehouse? Maybe it was a faulty batch with bad hardener? I have no idea but it behaves like something that did not have hardener. However I checked the unused bottle the next day and it was solidifying in the jug. Something failed and I can't understand what because I followed Bona instructions to a T.

"Tom Silva replies: You can do it either way. My painting contractor, Jim Clark, wants to be last so doesn't have to repaint baseboards that have been splotched with stain or ployurethane, or nicked by a sander. Besides, even the most careful flooring contractors inevitably leave a film of dust everywhere, he says. My flooring contractor, Pat Hunt, sees things a little differently. He prefers to be last because floor finishes take a while to fully cure, so he doesn't want anyone walking on them even when they're covered with protective tarps. He also says it's pretty common for other contractors to damage or spill stuff on a finished floor. The way he figures it, it's much easier to touch up paint than a floor finish. As the general contractor, I sometimes have the flooring finisher go first, and sometimes I let him go last. It all depends on what's best for the project schedule. I have that kind of flexibility because I know Clark and Hunt will put a lot of effort into protecting the other guy's work." https://www.thisoldhouse.com/ask-toh/what-comes-first-wall-painting-or-floor-refinishing