Double Waterproofing Layers?
Trying to understand why the big manufacturers all call for double waterproofing layers in their guides and diagrams; but residential work seems to ignore it or recommend against it. For example see these: https://usa.sika.com/dam/dms/us01/o/SikaTile_R613_Ceramic.pdf https://www.laticrete.com/~/media/a59e3ce3ccb2420797803b5c8a0038c0.ashx https://www.laticrete.com/~/media/826c925015b44eeea20000d9b0451ff0.ashx Etc. What I haven't seen many options for are drains that work with these multiple layer setups. Infinity Drain offers one:https://fergusonprod.a.bigcontent.io/v1/static/10082929_11255759_specification I've also found Kessel (though I can't see a US distributor listed for them). See the diagram labeled "Waterproofing using two membranes" on this page https://www.kessel.com/topics/waterproofing-with-membrane So basically I'm looking for more info on what drains are commonly used for these setups in the US. And also why we don't see this type of setup used as commonly in residential waterproofing. Context: planning a remodel (due to leaky pipes that I've capped for the time being) on a second story bathroom; stick framed house; right over the kitchen. This is the kids bathroom; and while they are 1 and 3 today; I know my childhood bathrooms probably only survived because they were concrete floors and CMU walls... So I'd like to take the extra effort and expense to make certain the bathroom stays structurally intact and dry for the next 30 years.
Hah. Found another drain vendor that talks about the double setup. Compotite. I have a vague recollection that someone (maybe TileCoach? though I've watched so many videos from so many people I can't be certain) mentioned that brand as something they used to use more in the past. Unfortunately, they only have linear right now - though they note square/round as "coming soon". https://compotite.com/product/compotite-linear-drain-system-drain-bodies/ https://compotite.com/wp-content/uploads/2024/03/Compotite_LinearDrain_Brochure_sm.pdf But this comes back to my initial questions around the dual layers; and how this runs counter to the "common knowledge" that dual layers lead to rot and mold and such from "trapped moisture".