I have what appears to me to be a very strange tub problem. Over the past few years i had noticed my floor near the outside edge of the tub getting soft and rotting out. I thought it was due to water running out of the corner of the shower curtain and through cracked away cauld but it appears to be caused by something else.
I began to tear out the floor and i was amazed how soaking wet the sub floor was. I removed about a 2 foot section of sub floor that butts up to the side of the tub in the front lower corner., The wood was soaked through the vinyl, and two layers of plywood. My house has a crawl space so i can inspect the plumbing fairly easily although it is somewhat boxed in around the front of the tub.I figured i had a plumbing leak so i spent a whole day looking at all possible pipes and fittings. Every time i ran the shower, the subflooring would seep water in the front right corner. After checking all the pipes and drain i could not find a leak. From the crawl space i could see the front center area of the tub bottom and it was perfectly dry. The rest of the area is covered with sub floor so i cannot see the front edge of the tub.
Next, I removed the 4 inch ceramic tile that runs along the top edge of the tub, thinking that maybe water was running down the inside of the tub. The tub is an Americast, probably 15 yrs old, and does have a lip along the that is nailed to the wall. while i did find some trapped water in the lip, it did not appear to be causing a problem.
I then thouht maybe i had crack in the tub floor but could not see anything. I finally decided to unscrew the drain even though the connection underneath the tub was perfectly dry.
when i unscrewed the plastic tub drain fitting from inside the tub, water began to flow out of what appears to be the edge of the drain hole. the water did not come from the drain,but woud have been flowing down the drain if was still attached. Hard to explain because it does not sound possible. It was as if the inner wall of the tub, if there is such a thing, was holding water. I would guess that at least a half gallon to a gallon of water came out of the material. It continued to drip for a long time. I had put a bucket in the crawl space to catch the water.
when i am in the crawl space looking up, I cannot the long edge side of the tub due to a joist running just under the edge of the tub. I can see lots of wet wood under the tub area, mostly to the front and the right half running long ways down the tub.
I wonder if water somehow got into the material of the tub floor and possibly rusted out the front right corner of the tub floor,from the bottom side.
While i can replace the drain pipe and fitting, making a new seal,I'm thinking that something else is wrong.
Is there any expert out there who can explain this?? Again, it is an Plain old Americast tub, nothing fancy.
thanks for any help or ideas.