I just moved into a duplex and the tub (steel) not only creaks but I can feel it flexing under my feet when I'm standing in it, especially on the drain end of the tub. The duplex unit is about 10 years old, there is a crawl space under the house. I am a bit heavy - have been for years, but still I've never had a problem like this. Any advice?

I would consult the landlord about perhaps checking and making sure it is safe and that the problem is not structural or maybe reinforcing the floor just underneath the tub?

It may not be the floor per se, it is likely the tub was not set properly to begin with. The landlord or property owner would be responsible for this repair but flexing and creaking may not be considered as a needed repair for the LL. You can always ask them to fix it. A tub that has flex will likely leak at the drain pipe eventually.

Charlotte's on to something. However, it's not the floor that needs reinforcing, it's the tub floor itself that needs to be reinforced. At the time of installation the tub wasn't properly bedded. To bed anything but a cast iron tub you will have to puddle mortar of cement ubder the tub to support the floor. It could also be shored up with 2 X 4's or blocks. If it flexes near the drain you stand a very good chance of rupturing the drain seal under the lip. This will cause water to leak out under the tub. I would show this to the landlord and ask that the floor of the tub be reinforced. This will save him money in the long run. Good luck, Tom,

If your landlord does not do anything to stop the moving in the bottom of he tub here is my suggestion. If you are able to get under the tub, that is up around the tub area, I would get some of the foam that you squirt out and it increases in volume to fill up open spaces. It is used for around electric plugs and water pipes. This will support the bottom of the tub and stop the creaking. I hope.

Got to disagree with you letmetellu on two points. Tenants who do this sort of Mr. Fix It repairs are taking chances with someone else's property and would be held liable for further proper repair. Expanding foam should not be used under a fixture since it can actually raise a tub. If you read the can carefully they say to not use it between the rough frame and window frame or door frame, it expands and will cause the door/window to seize. Great Stuff has come out with a new foam made for doors and windows that does not expand like the original but it has no strong structural strength, it compresses.

If your landlord does not do anything to stop the moving in the bottom of he tub here is my suggestion. If you are able to get under the tub, that is up around the tub area, I would get some of the foam that you squirt out and it increases in volume to fill up open spaces. It is used for around electric plugs and water pipes. This will support the bottom of the tub and stop the creaking. I hope.

We don't recommend using foam. While it works for awhile the foam consists of mainly bubbles that will compress in time,( especially if you're heavy) and you're back to square one. Foam is good for insulation but not very good for bedding a tub. And it's a shame because it's such a easy repair. Regards, Tom

I just moved into a duplex and the tub (steel) not only creaks but I can feel it flexing under my feet when I'm standing in it, especially on the drain end of the tub. The duplex unit is about 10 years old, there is a crawl space under the house. I am a bit heavy - have been for years, but still I've never had a problem like this. Any advice?
I'm new to this so don't know how to respond to all the answers I got but want to say "THANKS!!" I was hoping to get an idea of what might be wrong before I approach the landlord just in case they try to minimize the problem. You all are lovely -- many thanks for the information!

letmetellu agrees: You must be using a different type of foam that what I do. Any time it has space to expand it will not lift, and is very strong.
All foam consists of bubbles, (that's why they call it foam), and bubbles compress over time when weight's pressing down. We've tried it. It's the easiest way to bed a tub or shower floor that there is. The only problem is that over time the bubbles compress and you're back to the same problem. Cheers, tom