John excellent article.
I was up early today and waiting for my latest version of ITunes to download and update and flipped through my pile of mail. I stumbled upon a great article written by William (Bob) Sturrock titled "Moisture Control". The article can be found in the TTMAC (Terrazzo, Tile and Marble Association of Canada) Hardsurfaces magazine (2012 + Vol 21 + Issue 2).
William Sturrock works for Laticrete International and has over thirty years in the business. More info on William Sturrock here. The stat or fact that 90% of all waterproofing problems involve 1% of the installation area is such a great bit of information. It should be common sense but it is so easy to miss a failed corner or pin hole. Yet another reason to flood test those showers!
William mentions that moisture accumulation in wall cavities is more frequently caused by water vapour from the shower side and not from the effects of exterior rain fall and snow. Detailing the exterior wall is key to a successful installation.
We are building a steam shower right now and I choose to build it with the Laticrete Hydro Ban system. This will be my first project using Hydro Ban and I'm doing so for a number of reasons. Number one I never quoted a full Noble Seal TS installation and only found out that the shower I'm building is in fact a steam shower when I saw the plumber installing the steam line! Number two - I believe that one of my mentors prefers this approach to steam shower construction. I will need to wait till next year before Donato releases his next paper to find out for sure - for sure.
With a Hydro Ban steam shower the use of Hydro Ban is only part of the equation. You need to use a vapour barrier behind your cement backer board to build a proper Hydro Ban steam shower. This 6mil poly blocks vapour from getting into the wall cavities and condensing as liquid in the stud bays. Here in Vancouver there is a lot more to the equation since we also need to keep the insulation inspector happy. The rain screen inspector happy and on and on.
Each stud bay should have slight gaps (in the exterior sheathing facing) to facilitate air movement (via convection) inside the wall studs. Insulation should be placed properly and meet R20 so it needs to be 2"x6" Batt or two pound spray foam at least 3.25" thick. Now if you have used spray foam you should still use poly in this steam shower to seal the wood and framing members from vapour migration.
I took a ton of pictures and can upload them to show the poly being used in the shower build.
The tips William shared for a successful steam shower build are as follows.
- Make sure you consider the steam showers operating temperature. All materials should work well at this temperature.
- Try and keep all components of the steam shower in one family.
- Get 95% contact with your setting material
- Respect the manufactures cure times for each layer!!! (I think this is where most failures come - people rushing the jobs)
- Drains need to drain from the surface and subsurface
- Room for expansion and movement need to be considered.
Last edited by johnfrwhipple; 10-30-2012 at 07:09 AM.
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Always get construction advice double checked by your local city hall. Flood Test Every Shower - Every Time.