Shower Liner
A shower liner is often a rubber like mat that goes beneath the shower tile on the floor. I have had clients call me though to install a shower liner and what they meant was a shower surround. This is made of a few different materials and surrounds the shower. Sometimes with a thin acrylic sheet that gets set to the wall with PL700, other times the surround is part of the shower with either a two piece shower or three piece shower. These ones are thicker and get screwed to the shower base or shower pan. From there just like a one piece shower enclosure you level the shower and screw to the wall.
Other types of shower liners or shower surrounds are made from granite. These look very nice, but remember the thickness of the granite prior to doing your shower plumbing.
Most shower liners are made from CPE or PVC. The CPE type is a little easier to work with. The rubber mat lays on top of a layer of mortar then has mortar on top and then the tile. When done properly these last a long time.
Do I need a Shower Liner?
I have been to many peoples places to do a shower repair only to find that what is wrong is the shower is leaking from the base. When this happens there is not much you can do but replace the tile and either install or properly reinstall the shower liner. Again, when this is done properly you should have many worry free showers in your future.
There is a new shower liner out now that has an orange rubber mat that works in conjunction with a Styrofoam floor. I have only seen this done once. The finished product looked great, but I have no idea how long it worked for.
With a tub surround make sure you cut the hole for your shower faucet in the proper place. Whether this is a one piece, 2-3 piece, or shower surround, or shower enclosure, you will want complete accuracy when cutting the hole for the shower faucet and shower head. The same thing is true if you are installing granite. If you are doing a diy tiles surround then this won't matter as much. At least then if you mess up all that is lost is one or two tiles.
I hope this article was helpful, if you need a plumber or a handyman check the contractors section. Good luck with your shower liner.