What kind of mortar do should I put under a fiberglass shower pan to make it feel firmer underfoot.
Manufacturer (American Standard) says I do not need an underlayment,but it is optional.
I know to place plastic over the mortar to prevent it from adhering to the underside of the pan.
Also,how much of the stuff and where to buy it would be great to know also.
It is a 60 by 32 pan.