Speedy Jim wrote:
willshak wrote:
SNIP

When my shower stall and tub/shower enclosure were installed, they put
a bed of wet concrete in the spaces before setting the units in place,
thereby giving the fiberglass bases more support.


Yes! The cement bed is essential to give the base support.
It doesn't need to be concrete w/aggregate; a "sand mix"
is adequate.

They didn't put anything under our fiberglass tub and it creaks like you
wouldn't believe. Good thing I never use it and my wife doesn't weigh much.