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Do you need to waterproof shower walls before tiling?
Great question!

Prior to 1960 the average house didn’t have any “showers stalls”, only bath tubs with surround walls. Those walls were built with concrete plaster just as the rest of the house. On top of that plaster was added a second ½” layer of concrete plaster called “mud bed”  in which the tiles were embedded and on the edges finished off with a rounded piece of tile called mud cap (hence the name).Here it shows the backside of a plastered wall. The concrete plaster locks in the wooden lath.

The disadvantage about the concrete plaster though, it soaked in the moisture through the grout lines. Once inside the wall, the wood frames soaked up the moisture from the wet concrete and through lack of fresh air started to deteriorate the studs, also known as stud rot.

Later on when drywall or gypsum boards were generally recognized, the so called “green board” replaced the plaster, with the promise of being mold and water resistant.

Little did they know (or much did they ignore) that the green, water resistant paper layer is a cellulose product and mold just thrives on cellulose! As soon as the water penetrated the water resistant coating, the mold had a free for all, feeding of the paper and the gypsum.

In 2006 changes were made to the International Residential Code or “IRC” that no longer recognized moisture resistant, paper faced drywall (green board) as a suitable tile backing material in wet areas such as tub and shower surrounds. Instead, a cement-based backerboard (Durock, Wonderboard,Hardiebacker) or other approved moisture-resistant tile backerboard product (for example: DensShield from Georgia Pacific) must be specified to meet IRC requirements (also referred to as Building Code).

Typical Mold damage

So: back again to CONCRETE!

Through high customer demand and new innovations in technology, Tile supply manufacturers came up with a waterproofer in liquid form. It’s an elastomeric product (liquid rubber) similar to elastomeric paint for exterior walls.

Just like the elastomeric paint this waterproofer can be rolled on or brushed on.

Today there are dozens of different products on the market in dozens of different colors.

Waterproofing your walls may cost you a little more, but it will save you thousands down the road.



One for the storybooks:

A few years ago I met up with a customer to quote him on remodeling his master bathroom. He lived on a Golf course, right behind the eight hole. He had a beautiful stucco home with a master bathroom bigger than some people’s living room and a vaulted ceiling 10’ high.

The bathroom was located at the outside corner of the house with a walk in shower right at the very outside corner. As we walked towards the bathroom I wondered what could possibly be wrong, after all it’s such a nice home.

Well, I found out really fast, construction was already under way. The whole bathroom was torn to shreds, walls ripped open vaulted ceiling gone and the corner shower wasn’t even there anymore. When the man saw my jaw drop he explained that because the shower walls, which were the outside corner of the house, had stud rot, it compromised the structural integrity.

He ended up with lifting up the roof, tearing of the stucco façade and reframing the corner of the house, costing him upward of $20.000.

PS: Remember the red colored shower walls from above? This is the finished shower.



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