I bought a 100+ plus house and to my horror, under the carpet was not the strip hardwood floor we expected, but particleboard. Not OSB, not plywood - particleboard (which I just learned would need to be replaced anyways with plywood if new flooring going on top).
BUT! Under the particle board are very old wood planks! They're 5" t&g douglas fir (I think) and they look like they've never been sanded once. There's an old varnish or shellack finish (except for in the middle of the room where a rug must have been) so they where not installed as just subflooring.
They're awesome! But.. they're plenty soft, gaps as big as 1/4", plenty of damage and splinters, tons of nail holes, a large section by the front door was replaced with pine, etc. And here's the biggest problem maybe: there's no subfloor underneath them!
However I don't think they're worn badly at all and we're intent on restoring and using them, even if that means pulling them up and flipping them over to the unused side. It's only in one small room -- about 300 sq ft -- but it's the living room and the heart of the house. And we're on a major budget and new flooring is expensive, less sustainable than reclaimed, and not as cool :).
What do you recommend? Should I sand them with a drum sander or just a DA sander? Or would a DA sander catch splintered edges and rip out large sections? What finish do you recommend? Poly or a hard wax like rubio monocoat? What about wood filler? Any other tips??
Thanks! (BTW, I will NOT accept NO for an answer!)
[UPDATE: we sanded finished them: http://dannix.net/lib/abode/floor ]