Waterproofing Shower Walls before Tiling
Make Sure to Waterproof Shower Walls Prior to
Installing Wall Tiles
By Mark J. Donovan
It is important to waterproof
your shower walls prior to tiling them to prevent moisture and mold problems
behind them. To waterproof shower walls I prefer to use 15lb roofing felt
paper or plastic on the framed shower walls prior to installing a cement
backerboard. The felt paper or plastic acts as the moisture barrier and the
cement backerboard will not swell or decay if water comes in contact with
If not using cement backerboard on the shower walls, or if you neglected to
apply felt paper or plastic on the framed shower walls prior to installing
the cement backerboard, there are liquid waterproofing products that you can
Redgard, for example, is a liquid
waterproofing membrane product that you can apply to the shower wall
surfaces to form the moisture seal.
If using a cement backerboard and
you did not install felt or plastic behind it first, apply Redgard over the
cement backerboard after the seams have been taped and mudded with a thinset
mortar. Also, it is important to use an alkaline resistant tape when taping
the cement backerboard.
Redgard can be applied with a brush or roller. Typically you want to apply 2
to 3 coats of it and allow it time to fully dry prior to installing the
shower tiles. Thinset mortar can be applied directly over the Redgard for
attaching the ceramic tiles.
Redgard can also be used on
shower walls not constructed out of cement backerboard. For example it works
well over Hardibacker and Kerdi shower systems. As a matter of fact you must
use a waterproofing product over these surfaces to ensure that they do not
get wet. If they do they can eventually breakdown, unlike cement
Greenboard, plywood, or drywall should never be used as a shower wall
surface, even with Redgard. Any moisture penetration whatsoever could lead
to mold and mildew problems.
Also, never apply Redgard over
cement backerboard walls, if there is a moisture barrier already behind it.
This could lead to moisture being trapped between the two effective moisture
barriers and causing mold growth.
My Shower Pan Ebook for More Details: For a more detailed set of
instructions on building a shower pan, including pictures and a detailed
cross-sectional view of the make-up of a shower pan, see my “Shower Pan Membrane
information on tiling a custom ceramic tile shower, see the
How to Tile a Custom Ceramic Tile Shower Ebook
from HomeAdditionPlus.com. It provides detailed instructions for every
step in the process of tiling a custom ceramic tile shower and is loaded with
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