PVC liner has been an approved shower pan membrane since the 60's. The advantage of shower pan liner is its flexible, so it can handle movement. It is used in high rises for this purpose and also for reasons of ease of access where hot mop kettles can't fit, or fire codes that prevent hot mop shower pans from being applied in that particular building.
The disadvantage of this material is that it seems to be the #1 choice for handymen who have never installed a shower pan before, and it is installed incorrectly very frequently. When replacing your shower pan, make sure your contractor is very familiar with the type of shower pan he is installing. This is especially true with PVC shower pan liners.
If you have any further questions on shower pan liners, need one installed, or just need to purchase some, feel free to call us at (800) 313-1548.