Discalimer: I'm clearly no expert . . . It seems to be builders' preference. My tiler was used to doing Durock for commercial applications--stronger, more vandal-proof. I dislike Durock's "crumbly" edges (warranted or not), so I chose Hardibacker instead. It's easy to cut. Unlike Durock, however, Hardi wicks water easily (even though it's "waterproof," it's not vapor-proof, like a Kerdi, Tyvek, or other vapor/water-proof membrane. Hardi just doesn't warp or get damaged by water). That in mind, installed correctly, I'm sure all of the available commercial cementboard products do their job satisfactorily. I did my guest bath in Hardibacker with a Tyvek vapor barrier between the Hardi and the studs. However, in the master bath shower, I really want to do a Kerdi shower. The Kerdi system seems like the best system for no-worry, never-leak membrane systems. The peace of mind will be well worth the $400-$500 in materials cost (which I think is trivial in light of the cost of all the other materials, fixtures, and labor you're about to invest in). Just my novice opinion . . . I'll let the real experts chime in now.

tobik5 asked: "is it true, that :"the manufacturers of Wonderboard and Hardiebacker require a vapour barrier behind the substrate, whereas the makers of Durock and Permabase do not"? Manufacturers will often tell you simply how to best install their product. They'll tell you that a certain framing schedule is needed to back the boards, they'll tell you haw many fasteners should be used to attach the boards. What they often don't tell you is how to use their material within a certain system, in a shower, for example. There are a couple of reasons. One is liability. With national, state, and local codes, building code may vary throughout the country, even from town-to-town. So often times the manufacturers will write nothing specific and only write installation generalities. Or they might wrote "consult your local building code" or "consult a knowledgeable professional". The other is that there are so many variables in shower systems out there. A manufacturer can't reprint their literature for every permutation that can be thought up. Example, before topical membranes became common, pretty much every manufacturer wrote to "install 6-mil poly or lapped tar paper behind the cement board in a shower", because that's how showers were built. When topical membranes became popular, people followed the 6-mil poly advice because the installation instructions said to do so. But then they installed a topical membrane on the face of the cement board too. So things change. And with the rapid rate of change manufacturers have responded by simplifying. A lot of them will tell you just how to install their product, but not how to incorporate their product with installation options "A", "B", or "C".

"One question--I've Redgard isn't ok. But, maybe it is. If we go the RedGard route, are you saying you would use that with a kerdi or laticrete drain, then? (I know nothing about drains. Sort of assumed the plumber did that)." RedGard is a fine topical membrane. RedGard is sold through Home Depot, so there is a chance that any naysayers out there might be using the product without reading the directions. Just sayin'... Now that being said...personally, I prefer Hydroban, but that's me. If you use RedGard on a shower floor, use a 2-part clamping drain and the "Divot Method". If you use Hydroban, then you can use Laticrete's HydroBan flanged Drain, or Schluter's flanged Kerdi Drain. I think the flanged drain method with Hydroban is superior to the Divot Method with the clamping drain and RedGard. "And, then, regarding the use of spectralock to "ensure" waterproofing... I'm paranoid about mildew/mold and rotting out the boards (mostly the great big beam that has replaced our former exterior wall with this addition and over which our shower would span). Any suggestions on how to optimally protect that beam? " A properly applied topical membrane gives the best protection from leaks. The topical membrane with the flanged drain will give you the best installation in terms of minimizing moisture penetration below the tile. With minimal wetting below the tile, there is less chance for mildew. Ventilation within the shower is paramount. Not just the fan, but the ducting needs to be properly set and sized. But that's another story for another day. So if mildew is a concern, then I highly recommend a topical membrane, the flanged drain with HydroBan approach, which is what we've been discussing, or a Kerdi drain with Kerdi membrane. Your shower is not a steam shower, so the Hydroban will be sufficient and probably less expensive. "(and the tile--will I need something like that orange decoupler stuff on the floor to prevent cracks from any movement?)" "Orange decoupler stuff", I'm going to assume that is a reference to Ditra? If you need that, yes, it goes on the bathroom floor outside the shower area. Whether you need it or not can depend on your floor structure and what type of tile (porcelain or natural stone for example) you are using. " Linear drain at the shower threshold..." Some locales do not permit a trench drain at the shower entry threshold due to flow-over issues. Sudsing from soap or shampoo can cause water to sheet right over the drain and puddle in the non-membraned/protected areas of the bathroom floor. If the entire room is made into a wetroom, not all portions of the room need to be sloped. And even if the floor area around the toilet is sloped, the toilet should still be set level. Another option would be to use a wall-mounted toilet.

I have been blessed to live in a beautiful island state where the ocean is a key part of our daily lives. But all of you, regardless of address, has a responsibility to the planet. Whether you believe Earth came to us in a big bang or was given to us by a loving creator, it is our choices that will shape it for future generations. 1. The fact that Styrofoam is lightweight and floats, means that over time a great deal of Styrofoam has accumulated along coasts and waterways. It is now considered the main component of marine debris. Styrofoam is manufactured by using HFCs, or hydrofluorocarbons, which have negative impacts on the ozone layer. Styrene is also known to be toxic to the reproductive system. The brominated flame retardants that are used on Styrofoam are also causing concern, and research shows that these chemicals have negative environmental and health effects. Combined with the fact that all the scraps and waste of this Kerdi-Board material will be sitting in landfills for hundreds of years because it takes so long to biodegrade. 2. The laminate (waterproofing) that Kerdi is made from is polyethylene. The same plastic that the grocery bags are made out of. Which are now outlawed in Kauai and Maui counties. There are many ways plastic is bad for our environment. From its manufacture to its disposal, polyethylene emits toxic compounds. During the manufacturing process dioxin and other persistent pollutants are emitted into the air, water and land, which present both acute and chronic health hazards. During use, polyethylene products leach toxic additives. When polyethylene reaches the end of its useful life, it can be either landfilled, where it leaches toxic additives or incinerated, again emitting dioxin. The world's "great garbage patch" can be found floating between Hawaii and San Francisco. This garbage patch is estimated to be twice the size of Texas and thousands of pounds of our discarded trash, mostly plastics. These materials have no business being pumped into our economy and homes. Large corporations make up lies about the impact the production of such materials has on our earth and it's inhabitants. I will have no part in increasing the use of these materials. Not when mortar methods are and have been available to us for generations. It is only laziness that breeds the use of these products. They, in no way, lead to a better finished product.