Once upon a time in a land not so far away … OK so actually this isn’t a fairy story. It used to be felt that tiling the walls of a tub surround or shower stall was enough to keep any significant moisture from getting in to the walls behind and causing any damage. It still amazes me today how often we see regular drywall behind the tile of a shower even in newer construction. As explained in one of our previous posts water does penetrate behind the tile over an extended timeframe and this can result in various forms of damage when that moisture reaches materials that trigger mould growth when damp, with the potential health concerns that this can present. Yucky to say the least!
Often we are being asked by clients to use the biggest tiles possible in their shower as they are concerned in part that more grout means more mould concerns … certainly if the installer uses inferior products combined with a lack of maintenance on the part of the homeowner then this is a valid concern. There is no such thing as a zero maintenance shower, but there are definitely options for lower maintenance. Just as most car owners wash their vehicle at least occasionally to keep it looking at its best, the same applies in terms of periodically resealing the grout or any porous tile to prevent it from staining.
Meanwhile back to the topic of water-proofing … There are several products on the market to address the waterproofing of a shower enclosure and some specifically for addressing concerns of vapour (for example in a steam shower). Some home owners opt for an acrylic shower stall (either the whole thing including the walls or perhaps just the shower base) so that they do not have to deal with maintenance or in-proper install concerns associated with tile & largely because of budget constraints, but this is usually considered a lower end approach from a purely aesthetic perspective. Nothing wrong with that as there is definitely a place for these products. There’s nothing quite like the look of a properly installed fully tiled shower stall though where quality products have been used. This is especially true if it’s in a master bathroom as opposed to perhaps the guest bath which is typically used less often … the latter is often where we would go with the acrylic shower stall option to save cost.
We specifically use the Schluter range of products for the vast majority of our custom tile shower stalls. This isn’t to say this is the only such solution, but it is one that is readily available in this area and liked by the building inspectors which is another important factor. All our staff are also certified by Schluter which is another key factor some inspectors insist upon. We like to keep up-to-date with their latest product offerings so that we can provide educated solutions for our clients. The Kerdi membrane covers the pre-contoured shower tray (integrating with a specially designed drain system), and extends up the walls of the shower stall all the way to the top of the tile (which in this case is right up to the ceiling). The membrane adheres to the backer-board via mortar & special pre-formed one piece corners are installed where the shower base meets the walls. Outside of the shower stall itself the walls do not need to be fully waterproofed, but we prefer to use DensShield here (ie. the grey wall surface in the top left of the photo) … not only does it have a built in moisture barrier for extra protection, but it is more structurally sound than drywall & has a slight texture surface for grip (which you want from a tile backer) and easier/faster to work with compared to concrete board which requires grinding tools to make holes and therefore generates far more dust.
Although the Schluter Kerdi waterproofing membrane and other components (pre-contoured tile-ready shower bases, drains, profiles, etc) are often available at some of the big box stores we recommend leaving this to the professionals … a few simple mistakes and the results can be pretty ugly (and expensive). We don’t mind educating home owners as we go as there’s no secrets in how this is done & we welcome questions as an informed client is typically a happy client.
Lastly a quick side note on which Schluter product to use under floor tile … their Ditra mat is an uncoupling product used to prevent tiny movements in the substrate (eg. plywood, OSB or concrete subfloor) from transferring to the tile and grout and causing cracks. It can be installed over hydronic or electric radiant heating and is compatible with all types of tile. This is not just for bathrooms but rather any interior floor where tile is to be installed.