@nikki1307 - I'm sorry to say but you needed to have the vapour barrier in the crawlspace BEFORE the floor was installed. Sorry but this is not the fault of the flooring installers. A General Contractor (who is INSTRUCTED to investigate the crawlspace and correct it prior to flooring being installed) could have caught this. Now that this has happened, you will need to get the vapour barrier over the earth in the crawlspace QUICKLY. The garage space is another problem. Garage "slabs" (concrete normally) rarely have vapour barriers installed under them. Therefore the concrete in the garage will be allowing water vapour through at a rate that is ALMOST as bad as the crawlspace. When applying vapour barriers to a CEILING in a garage, you will need some help. The one thing we try to avoid is a "double" vapour barrier. That's a bad situation. You will want to contract a moisture remediation company (when you deal with the crawlspace) to help with the garage ceiling. As for what the wood will do "after" the moisture has been dealt with, it will take TIME. Lots and lots of time. You will apply the vapour barriers (possibly a dehumidifier in the garage to help you if you can't get a vapour barrier on the ceiling....wood does NOT like plastic sitting next to it) and then wait. The wood will correct a LITTLE bit...maybe 25% - 50% better. It takes a LONG TIME for wood to LOOSE moisture. Almost TWICE as long as it takes it to GAIN moisture. So if this has been going on for 4 years....you can almost certainly double that time to lose it. I would give it a few years (like 2) and then look to see how much the wood has corrected. You don't want to do ANYTHING to it until you are CERTAIN that the change in appearance is "finished" changing. Once you have waited another 2 years (or so...it isn't set in stone) you can then go ahead and have it sanded and refinished. Once it has STABILIZED (this is SUPER important) then the chances of it changing and cupping again are VERY slim.... Until another moisture issue pops up. Then all bets are off - of course.

Thanks for the tip. Would a leak like that cause the entire floor to cup? Could it be possible that the floor was poorly installation? Honestly I don't remember when the cupping started to occur. Anyhow, a home inspector is a good place to start. I appreciate your input!

It takes several months and the wood still may never "relax". But you can't jump in and sand until all the excess moisture is gone from the floors. Keep checking with a meter is all you do at this point. Someone needs to be checking the MC on the bottom side of the subfloor and also the joist. Is there any thick plastic covering the soil?

I suspect you will regret bamboo. I have stranded bamboo in a kitchen and I wouldn't put it in a bath. If you really don't have the money to truly fix the deflection, use a small mosaic tile, hexagon or penny-round will probably work best. Use a masonry board or a uncoupling membrane and then adhere the tiles with a flexible thin set. I prefer Laticrete 254, but if you have to do the big box store, Flex bond from Home Depot isn't bad. Then use a decent flexible grout. The Mapei flexcolor is a solid product. If your floor is flexing enough to break those tiles then you have much bigger problems. Eventually the grout might work loose but you should have quite a while before that becomes a real problem. ETA: Check my advice on the johnbridge forums if you would like. You can literally paste my advice to your problem over there and get opinions from professional tilers who will put their name and experience right there in their signature.