We have an old 1930's handymans house and are slowly refinishing it. In the mudroom we just recently pulled up the old vinyl sheet tile and found that the floor was made of standard old boards which someone had "insulated" by placing sheets of newspaper over, back in the 40's. I talked to a friend because I have my heart set on placing in groutable 12" square vinyl tile, and he suggested rather than trying to repair the boards and level it all with floor leveler, that I should just go over it with 1/4 " plywood. My question is, should I do anything to the boards before I lay down and start screwing in plywood? I'd rather not have them slowly rot from beneath, or cause an issue because I didn't protect the boards.
Re: no subfloor
t &g boards were what was used for sheating floors, walls and roofs back in the day before plywood. putting down subfloor is fine. no worries of rot as long as theres no leaking water.
only thing i would do first is pick up some 2 " screws and screw the boards down to the joists first then go with 3/8" underlay as opposed to 1/4". 3/8" is stronger and much better suited to tile. you want to stiffen up the floor as much as possible before tiling over to prevent cracked grout and tiles popping up from floor movement