Old House Journal
EXCAVATING for GOLD
The floor in the downstairs bath of our 1908 Foursquare was our first project. The dingy tile was badly scratched and cracked and we found it concealed heart pine underneath. The 1 ½" square tiles had been installed with glue over a substandard plywood layer, without an isolation membrane. A patched area around the toilet had subsided so much the floor dipped and the toilet rocked.
Demolition (of tile, plywood, and a feltand-glue layer) dropped the height of the floor by almost an inch. We lowered the toilet flange by the same amount, cutting out the old one below the floor and splicing in a new stub. We framed in reinforcement lumber directly below the toilet and around the waste line. The floor is now fully supported.
Several of the pine boards were too far gone. Still, there was enough sound wood to proceed with a bundle of heart pine from a local supplier. New boards were slightly different in thickness from our old tongue-and-groove; we made it work by adding shims underneath.
A few boards needed to be narrower to fit into the layout. We ripped a few to about 2" wide, then cut a new groove on the side. We laid the boards, weaving new with old, face-nailing into joists rather than blind-nailing; we’d fill holes later.
Tar from the felt/tar-paper layer had turned some old boards almost black. We decided to hand-scrape that to avoid clogging a sander. Next, because the room is small, we used a belt sander and random orbital sander rather than renting equipment. We began with 40-grit paper, sanding with the grain on old boards and on the diagonal across new boards, which flattened the floor but left marks on the wood—removed with final passes of finer grit paper, going with the grain; we used a sandpaper belt cleaner. After filing nail holes, we sealed with a preferred waterbased finish: Pallmann Pal-X 325 sealer.