Could be almost anything. If you're going replace the thin slat florring anyway, then have at it and remove the stuff; you will then reveal what you have beneath it and be able to decide if it is worth restoring. I have done many restorations and there was only one floor that was DOA. Sounds as if your house has had lots of "remuddling" over the years; it's amazing what a DIYer with poor vision can do to nice architecture.

Its like putting a lid on a can of liquid. You do have a moisture problem. Could be something as simple as putting a layer of visqueen under your crawlspace. Your getting moisture and until you find the 'problem' your flooring will continue to have the same problem.

Ha, I saw this earlier and came back to write pretty much what Hollysprings said. So, yeah--that. We have doug fir subfloors too, but they were definitely not designed for prime time (original blueprints called for cement tile--sadly long gone!) It was a really common subfloor wood in the West in the early 20th century because it was so inexpensive. A couple of other thoughts: - Fir is beautiful (many of our neighbors have refinished their fir floors) but it is very soft. One neighbor has a large dog and another has a young child; both floors have taken a beating (the dog floor in particular). That's the primary reason we covered ours back up. Better to keep it safe for someone who might want it in the future! I agree that I don't think it would be easy/possible to get it to tan; fir tends towards orange/red. You can stain it but it looks strange (I think, at least--our new-old fir door has a light tan stain of some sort that is supposedly helping to even the grain where there was some variation, but I think just makes it look yellow on top of the reddish fir tones...bleh). - If you like linoleum, you might look at Marmoleum Click; this is what we chose specifically because it doesn't get glued down, so someone could take it up in the future and refinish the fir. Don't know how their colors compare to Armstrong's, though. We do have another neighbor who laid sheet Marmoleum on the fir, so it can be done but obviously not if you want to preserve the floor for refinishing later. If it's already painted, though, it may not be in great shape underneath. (Ours is a mess and would require some board replacement to refinish; possible but $$. The original builders took no particular care in nail placement or matching grain since it wasn't intended to be used as a finished floor.)

I recall that there is a particular type of flooring that should NOT go under the cabs - floating floor installations? I believe it has to do with the need for the planks to move. The best idea, of course, is to read the directions that come with your particular flooring. You can always use plywood the same thickness as your floor under your cabs and then bring the rest of the floor up to the edges of the cabs. The spaces under the 'fridge, stove, and dishwasher should be finished to the wall. The theory there is that those appliances will be replaced before you replace your flooring. Originally our house had 1971 vinyl tile (probably asbestos) in the entire house. We put down new sheet vinyl, maybe twice, and eventually engineered hardwood. As predicted, dealing with the dishwasher got to be a nightmare as it was then lower than the current floor. The counters were also a little low, but I kinda liked that. While doing the reno, it was fun to see all the flooring of years past and hearing ourselves say, "Oh, I'd forgotten about that floor! When did we do that?" It's nice to now have the flooring be all at one height, that being the same height as the base of the cabinets. I'm also very much enamored of our current bamboo flooring :-)