Mongoct/Live Wire Oak, Thanks for the replies. Here's a photo I took right after the hot mop was done. You see it terminates at the outer half wall surface with a 'lip' maybe 1" tall (I didn't measure it so just guessing). So that centered tile in the entry sits above that and during a normal shower the water line (water that splashes over the drain to the door) doesn't go past about halfway the thickness of those half walls or doesn't go past the glass door that's centered between those half walls. So if I understand what you're saying about the capillary break, the tiler should've physically separated the thinset/mud under the entry area tile by creating a physical divider barrier to separate it from the thinset/mud under the rest of the tiles on the bathroom floor? I'm picturing a thin vertical layer of sealant (or membrane) from the bottom of the tile surface through thinset all the way through the mud down to meet the hot mop 'lip'? That would then form a barrier and force the water that gets under the tile to stay in the pan and go back towards the drain. I'm still trying to get a feel for how much water could be sitting under my bathroom floor (worst case) or if it's limited to a few areas of damp thinset due to wicking that are showing up as dark grout spots (best case?). Relative to the amount of water that seems to be making it down the drain, how much water are we talking about that could be wicking out through the thinset/mud/grout? 10%? 20%? 50%? How long does it take for the water that eventually sits on the concrete slab to evaporate or absorb into the slab itself? And what damage would this cause long term assuming the water never makes it to any wood?

I've looked at many baths but haven't studied that aspect, mainly was looking for tile. I was hoping maybe someone would have some real life experience. I know I don't want a doorless shower for the draft aspect, however in the bathroom in my new home before the remodel, it had one of those cheapie all in one showers where there was space above the shower (not fully enclosed) and I didn't feel drafts from above. However it was a lower ceiling in there.

Almost every state has adopted the International Residential Code to some extent. http://www.iccsafe.org/gr/Documents/stateadoptions.pdf Some are not statewide. Some have adopted the UPC and not the plumbing section if the IRC. About 33 states use the International Plumbing Code. About 10 states use the Uniform Plumbing Code. http://www.tests.com/State-Plumbing-Codes-License UPC 2012, 2015 408.5 Finished Curb or Threshold. Where a shower receptor has a finished dam, curb, or threshold it shall be not less than 1 inch (25.4 mm) lower than the sides and back of such receptor. IN NO CASE shall a dam or threshold be less than 2 inches (51 mm) or exceeding 9 inches (229 mm) in depth where measured from the top of the dam or threshold to the top of the drain. Each such receptor shall be provided with an integral nailing flange to be located where the receptor meets the vertical surface of the finished interior of the shower compartment. The flange shall be watertight and extend vertically not less than 1 inch (25.4 mm) above the top of the sides of the receptor. The finished floor of the receptor shall slope uniformly from the sides towards the drain not less than 1⁄4inch per foot (20.8 mm/m), nor more than 1⁄2inch per foot (41.8 mm/m). Thresholds shall be of sufficient width to accommodate a minimum 22 inch (559 mm) door. Shower doors shall open so as to maintain not less than a 22 inch (559 mm) unobstructed opening for egress. IPC 2012 SECTION 101 GENERAL [A] 101.2 Scope. Exception: Detached one- and two-family dwellings and multiple single-family dwellings (townhouses) not more than three stories high with separate means of egress and their accessory structures shall comply with the International Residential Code. IRC 2012 LATEST CODE CYCLE SECTION P2709 SHOWER RECEPTORS P2709.1 Construction. Where a shower receptor has a finished curb threshold, it shall be not less than 1 inch (25 mm) below the sides and back of the receptor. The curb shall be not less than 2 inches (51 mm) and not more than 9 inches (229 mm) deep when measured from the top of the curb to the top of the drain. The finished floor shall slope uniformly toward the drain not less than 1/4 unit vertical in 12 units horizontal (2-percent slope) nor more than 1/2 unit vertical per 12 units horizontal (4-percent slope) and floor drains shall be flanged to provide a water-tight joint in the floor. http://publicecodes.cyberregs.com/icc/ansi/2009/a117p1/icc_ansi_2009_a117p1_6_sec008_par024.htm ANSI A117.1 (accessible) LINK current code 608.6 Thresholds. Thresholds in roll-in-type shower compartments shall be 1/2 inch (13 mm) maximum in height in accordance with Section 303. In transfer-type shower compartments, thresholds 1/2 inch (13 mm) maximum in height shall be beveled, rounded, or vertical. EXCEPTION: In existing facilities, in transfer-type shower compartments where provision of a threshold 1/2 inch (13 mm) in height would disturb the structural reinforcement of the floor slab, a threshold 2 inches (51 mm) maximum in height shall be permitted. The above exception is stating that there is no excuse to not have 2" between the top of the drain and the top of the curb or floor, whichever comes first. A curbless shower isn't even an ADA requirement, and therefore is not an excuse to circumvent other codes. VIDEO http://www.access-board.gov/guidelines-and-standards/buildings-and-sites/about-the-ada-standards/guide-to-the-ada-standards# Illustrated guide explicitly saying curbless showers are not allowed. http://www.countyofnapa.org/WorkArea/DownloadAsset.aspx?id=4294980783  Effective 7/1/2015 (NOT OUTDATED) DESIGN SPECIFICS http://www.iapmo.org/Documents/CPC%202013%20Supplement%20effective%207115.pdf  They make flexible rollover dams for those that really NEED it. You may also get a code variance if you NEED an ADA compliant bathroom, but you can not just pick and choose which part of the code you want to follow. If you get a variance for an ADA reason, the whole bathroom better be ADA compliant, complete with grab bars, fold down seats, large turning radius, ADA sinks and toilet, and access all the way back to the parking lot. If you think that any or all of the pictures on Houzz are code compliant, you are mistaken. Whether an inspector chooses to enforce the code is a totally different matter. Some places have no enforcement, and others let the fox guard the hen house by letting architects inspect their own work. Mr Wiffle can argue with the code all he wants, but to say that the codes don't require the 2" rise between the door and the drain is clearly wrong.

Is your father in a wheel chair or are you anticipating the need? I ask because I have some experience dealing with elderly parents, their friends as well as some very senior neighbors. In my experience most seniors are not in wheelchairs except when they need to go a long distance. In other words, as long as they have a 24/7 caretaker by their side, they are using a walker to get around inside their homes. Also they are capable of stepping over a low curb with assistance for balance. As others have posted, it might make more sense for you to use your master bath for bathing your parents and turn the powder room into a toilet and sink area since accessibility to the toilet is far more important than a shower - e.g. when my father was in the last year of his life with a 24/7 caretaker, he had to urinate frequently versus taking a shower. While a senior can't easily walk over a tub/shower combination, there are actually seats that swivel and so a caretaker can get a person into a tub and then shower him/her with a hand held attachment. The other alternative is to turn the tub/shower in your master into a nice shower which you will then enjoy. I recently remodeled my condo with an eye to aging in place. There was certain stuff I couldn't do but such as enlarge the bathroom but I swapped out the tub/shower for a larger shower with a lower curb and grab bars at the entrance and along the long side. I also had a bench installed with its own hand held next to the shower so either I or my caretaker can hose me down while I am sitting if it comes to that LOL. Although my bathroom is relatively narrow, I can use a walker to get to the toilet and swing the walker around once I am at the toilet. I tested that with a neighbor's walker. I did also install a grab bar by the toilet and also a Toto washlet. The washlet is actually an aging in place accessory as I have friends who became unable to wipe themselves easily because of hip or shoulder issues or even arthritic hands.