Hi All,

I have a 100+ year old house and the upstairs tub tends to leak over the side of the shower curtain and pool water on the upper corner of the floor near the tub. We try hard not to contribute to the problem, but it seems to be getting worse in the past five years or so. The tub has not noticibly shifted down in that corner, and there are no leaks downstairs on the ceiling, but the floor tiles in about a four by ten inch area around that corner are beginning to sink into the "rotten" wood under the tile. I lifted one up tonight (finally) and the wood (?) underneath is like crackly shredded paper. Do I need to have someone remove the whole tub and replace the flooring under the entire bathroom, or can they just replace the rotten area? I realize that any answer would be a guess, having not seem the problem; just don't want to pay for a whole bathroom re-do if this is fairly common and potentially easily fixable.

Welcome Lizz. What you are describing is what happens to plywood when it gets continuous intermittent exposure to water. The layers are delaminating as the glue falls apart. Only once that section of plywood is cut out can the subfloor be assessed. Will the tub fall through, no, it's not likely, it's supported by several joists. Your subfloor in a house that old is going to be plank boards unless the bathroom was gutted to the floor joists and redone within the last 40 years or so. I also would not be surprised if when you started removing more of the veneer layers to see a linoleum floor below. Old homes can be a cool archeological dig.

If you have an access panel for the plumbing behind the wet wall of the bath tub, you should be able to get a good look at the subfloor as well. If it's soft when you poke it with a screw driver, then you want to replace it. If you see holes as if some sort of boring insect has gotten to it, call an exterminator. Wet wood can attract them. If it's dry and solid, you have nothing to worry about. If you don't have an access panel, you can cut one and either repair the plaster wall or just frame out with some door casing and cover with a piece of paneling.

The correct way to fix the floor will depend upon how much height you have to build back up. Direct to plywood installation is a method that is not rated for wet areas, as you can see, but cement boards can't go directly on plank floors without first installing plywood. If you could do a bit more excavating and post some pictures or upload the pics to a photo sharing site like photobucket and then provide the links, we could provide more accurate repair info.

Thanks Bljack! What a great answer. That makes a lot of sense and makes me feel less like I am going to be plummeting down into my first floor kitchen next time I take a shower.

Unfortunately, there is no easy plumbing access (I can see where they just cut into the ceramic tile around the plumbing in the past). Also, the plumbing is on an outside wall, so I am not sure how much I can see if I look there. Maybe I can just pull up some of the degraded plywood and see what is under there. I should be able to see the subfloor that way, right?

Thanks again. I honestly wasn't expecting much but I really appreciate your expertise.