I am having my shower torn out and completely rebuilt.

The trademan who is doing this has installed a PVC liner 7 inches up
the sides of the shower from the and over the curb.

However, when he installed backer board over the PVC liner, he
installed screws into the backer board that were between 1.75 and 2.00
inches above the bottom of the liner where it rests against a sloped
subfloor, piercing the PVC liner at that point behind the backer board.


He intends to lay down a layer of mortar on top of the PVC liner to
create a sloped surface to lay the floor tile on. Thus, the height of
the screw holes (and the punctures in the PVC membrane) will be even
closer to the finished shower floor after the file is installed.

This trademan says that he installed a bead of caulk to prevent the PVC
liner from leaking where the screws penetrated the liner, but I am
extremely concerned that integrity of the PVC shower pan has been
compromised by the screws that pierce it.

It is my understanding that the PVC membrane should NOT have been
punctured at a point so low.

I would also like to know what would happen if the PVC membrane on top
of the curb is pierced by screws when backer board is installed on top
of the curb. Will screws piercing the membrane on top of the curb
create a potential for leaks as well?

What is the appropriate way to fasten backerboard when a PVC liner has
been installed?

Am I justified in being concerned about the potential for leaks?

Please respond ASAP as the trademan has not installed the tile yet, but
plans on doing so very shortly.

Thank you.