I'm renovating a 1910 farmhouse and would like to tile the kitchen. The original flooring consisted of ship lapped 2x8 fir planks on the joists with finished 2x4 T&G fir flooring on top. At some point in the last 100 years someone layed orange resilient tiles over the fir flooring and then (presumabley) years later nailed down 3/8" OSB over it all and layed lino on that. Sheesh! I want to install tile in the kitchen and refinish the original flooring in the rest of the house. This weekend I'm hoping to strip everything down to the fir T&G, and then carefully pull it out and salvage it.
My question is: should I then pull out the planks underneath the flooring and start fresh, gluing and nailing T&G subfloor to the floor joists? Or should I just glue and nail subfloor over the original planks? I wouldn't mind salvaging the planks, they look to be mostly clear and would provide some nice material to rebuild the stair treads and window stools. Material like that just doesn't exist anymore. It would also mean though that I would probably have to double up the 3/4" subfloor to get the tile to the same height as the original flooring in the dining room, and cutting the planks out around the existing walls and such will be a serious pain in the butt.
I would pull the sub floor. Like you said they don't make wood like that anymore. You don't have to cut it exactly flush with the existing walls. Your first layer of OSB should be as close to the original thickness of the sub floor. Your 2nd layer will go up flush to the wall. That is how I would do it but I'm no expert.
Today is only yesterdays tomorrow, Now get to work!