as they vary in thickness. Some are thinner by design specifically to make it easier to construct a curbless shower. The use of an ANSI A118.10-compliant, thin, load-bearing waterproofing mem- brane directly below the shower floor tile – instead of a traditional shower pan membrane underneath a mortar bed – results in a lower profile system without sacrific- ing functionality. Bonding flange drains and linear drains also offer reduced thickness of the shower base, in many cases requiring no more than 3/4” (mortar bed or pre- formed pan) at the thickest point, whereas a traditional clamping ring style drain, such as those shown in many TCNA Handbook meth- ods, (e.g. Method B415) requires a 1-1/4” to 2” mortar bed. Thus, for the tile contractor to be able to deliver a curbless shower, the specifics of how the shower will be constructed must be deter- mined at the outset so their dimen- sions can be incorporated into the building's rough-in plans. This is much earlier than is often the case, which highlights the importance of advance planning when it comes to curbless showers. Another piece of the puzzle is drain location. In many cases linear drains and bonding-flange drains can be located in various plac- es within a shower compartment – at any of the shower walls, at the shower entrance, or mid-floor. Perhaps more important than its impact on the required floor recess, ideal drain location is critical to how the shower water will flow and drain. Effective draining – versus aesthetic preference – should drive TECH TALK –––––––––––––––––––––––––––––––––––––––––––––––––––––––––– Diagram of a shower base constructed of a topically-waterproofed mortar bed (bonded to concrete) and a bonding- flange drain, recessed to facilitate a curb- less shower entry A single sloping plane is possible with a linear drain, which gives a streamlined appearance and allows large tiles to be used; just be sure the tile layout on the walls will facilitate the non-level floor perimeter. 68 TileLetter | March 2019