The noise is typically from movement.
Floor of bathtub creaks.
The tub flange moving against the wall the tub drain plumbing maybe rubbing against the subfloor.
If you re doing a full remodel and can see the bathroom floor framing from the room below you can usually see where the floor moves and squeaks when someone walks on it.
I know it s not the floor boards since the rest of the bathroom is silent.
Yeah it sounds as if they removed the structural support.
The tub creaks a lot and there is a great deal of vertical play when standing and moving around.
This could be due to new construction under the tub.
I think the floor was not prepped correctly.
Rarely is this the case.
It was about three years old.
Then fill the holes with wood filler.
With no water each footstep in an empty tub loads and unloads the floor of the tub thus the movement.
Bigjaylow nj i recently installed a new acrilic tub in my bathroom.
Squeaking in an acrylic tub when weight is placed on the floor of the tub can be due to the tub flexing or bending.
Occasionally if the floor joist are spaced two far apart to properly support the sheeting then floor creaking may occur.
Since the first shower in it i continuously hear a loud creaking as i move my feet all over the base.
Or if separating floor from subfloor is causing the creak drive two nails at opposite 45 degree angles into joists which you can locate with a stud finder.
One tile has a hairline crack now.
The grout in an a joining bathroom cracked also after squeaking in winter.
The tub does appear to be level so i don t think that s the problem.
The four year old tile floor in our bathroom started squeaking during winter after four years and stopped squeaking in summer.
Screws will normally do a much better job of holding the.
I need to fix it.
Loaded with water the water weights the tub down thus no movement.
The majority of sub flooring issues can be corrected by adding screws in the areas where the creaking is occurring.
A few well placed screws can eliminate the squeak.
Is this from humidity.
Using your power drill make a pilot hole through the subfloor then a smaller pilot hole into the finished.
Driving short screws through the bottom of the subfloor through the bottom of the finished floor can alleviate the noise.
This can potentially weaken the tub and lead to cracks and splits in.
It doesn t seem to be such an issue when it s full of water and i m sitting down i suppose the weight is more evenly distributed.