I pulled up the tile in my bathroom and discovered that the sub-floor was partially rotted near the bathtub, under the toilet. Based on the tile/mortar, it looks like whoever did this floor last mortared over/into the already damaged subfloor to cover up the fact that it was damaged. It looks, from what I can tell, that the damage goes under the wall.
My questions are:
- What's the ideal way to cut out the damaged section? The parts I can get to, I would just use my circular saw with the depth set properly, but for the edges along the tub insert and the wall, (especially the tub edge, which runs perpendicular to the joists), how would I get close enough? I've heard reciprocating saw and toe-kick saw suggested by a few people I know.
- Do I need to worry about the damaged subfloor that goes under the wall? If so, how would I go about removing/replacing the damaged subfloor there?
Best Answer
Your plan to use your circular saw with the table set to depth is good. Even if you were to cut tight to the wall and tub, you still aren't getting all the damage, so a short distance out is fine. Personally I'm not a fan of joints right at walls and tubs anyway. I'd rather have an offset.
When you do the repair, float lumber under the remaining damage, with construction adhesive between, wherever possible to support it.
The fact that the damage extends under the wall probably isn't a serious concern if you haven't seen any significant side effects, such as settling or floor damage in the adjacent room. I'd be fixing whatever you can reasonably access and calling it good. It'll be a far cry better than what you have now.
FYI, a "toe kick saw" is actually called an "undercut saw".