I am having my shower torn out and completely rebuilt.
The trademan who is doing this (and who has done exceptional work for
me in the past) has installed a PVC liner 7 inches up the sides of the
shower and over the curb.
However, when he installed backer board over the PVC liner, he
installed screws into the backer board that were about 1.75 to 2.00
inches above the bottom of the liner where it rests against a sloped
subfloor, piercing the PVC liner at that level 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 by the time the tile 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
still 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 to the bottom of the pan.
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 this create create a potential for leaks as well?
If screws should not pierce the PVC vinyl membran, what is the
appropriate way to fasten backerboard over a PVC liner? Does one just
not fasten the backer board to the wall at the the bottom or what?
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.
As I wrote above, this trademan has done superb work for me in the
past, but this is the first PVC shower pan he has ever installed and
it's possible he may not be fully aware of all the details to follow in
installing one that is absolutely leak proof.