Why should I use a shower vapor barrier?

The quick answer to this question is that a shower vapor barrier provides you with an extra layer of protection against internal and external damage from water, leaks, condensation, mold and mildew. From the outside, the barrier keeps condensation and water leaks where they below, outside the shower. Conversely, the vapor barrier keeps the sub wall – the wall behind the fancy tiling and such  – from being damaged by the added effects water, soap and other caustic chemicals. Quite frankly, the shower vapor barrier will probably save you thousands over its lifetime. Properly installed, the shower vapor barrier can be as important as a well-placed shower curtain or bath towel.