Hello, I am in the middle of some renovations at a rental of mine. After exposing the ceiling I noticed that 3 of the joists are bowed about an inch lower than the others. This occurs directly below the bathroom tub.
The entire bathroom seems to have a double floor (not sure what to call it). Between the joists, planks have been added to hold what seems to be cinders. Not sure what this is for, but there is definately a lot of weight. These cinders are either part of the support for an old tile floor (house over 100years old), or someone suggested noise dampening. Anyone have any ideas.
Ok, so I'm thinking about removing the planks and cinders so I can sister up the "failed?" joists. After they are sistered, I was going to cut off the part that was hanging down - that way my drywall will have a true structure to hang from. Does that sound like a plan?
I just came across this site and read a bunch of posts. It's been very informative. Hopefully Someone will have some answers for me.
Maybe the joists were bent at install time or they dried to that shape? The joists should not be bowed unless they are rotten, or they are undersized and you have a really heavy cast iron tub. maybe these cinders have been retaining moisture and the upper part of the joists are rotten. That seems unlikely.
I have seen something similar in an old house in the UK where pumice (I think) was used as a method to decouple the tiles from the structure to avoid cracking.
Your joists are not bowed they are crowned. Bowed is side to side, crowned is up and down. Sistering new joists is a good solution; however to straighten them out all you would really need to do is attach (sister) 2 x 4's to the offending joists to flatten things out. As far a cinders go, I have never seen them used in a house, sounds like perhaps some good old yankee ingenuity.