I'm so glad I found this thread because I have a similar problem. We just bought our house a month ago. There's a window in the shower, above the tub. The previous owners had sealed the window shut with silicon caulk. I knew the grout would need touching up but this morning I tried opening the window to see how secure it was, and it opened right up. It wasn't even locked let alone sealed. There also is no extractor fan in there (having one installed this month) so now I'm really anxious that the wall is full of water. We can't afford a reno right now. Can anyone recommend the best stop gap solution to limit damage while we save up for a reno?

Even if you do decide to do the basket weave there, I think you will still find it lacking unless you have a window stool as that is what is really throwing it off for me. To fix it since you have very little space due to the crank, you might be able to build a faux window stool, but you'll need to remove the trim around the window no matter what as it is common for it to rest on the window stool. You could use a think piece of plywood, maybe 1/8-1/4" - not sure how much space you have and then rest it on a molding strip that would form the lip of of the molding and then trim the edge out in a think strip of molding. Going to show you a picture of how generally the pieces are put together. A true stool is at a minimum 1/2" thick when it rests on the window frame and I don't think you have the space. I think you can get the trim strip to adhere to the marble with construction adhesive, but realize this will ruin the marble in that area. You will need to remove and redo the casing on the sides though for the right propertions so it looks correct resting on the stool. I don't think you need to add an apron under the faux stool as the picture has it. That is often forgone when using tile or other materials as a backsplash.

417.5 Shower floors or receptors. Floor surfaces shall be constructed of impervious, noncorrosive, nonabsorbent and waterproof materials. 417.5.1 Support. Floors or receptors under shower compartments shall be laid on, and supported by, a smooth and structurally sound base. 417.5.2 Shower lining. Floors under shower compartments, except where prefabricated receptors have been provided, shall be lined and made water tight utilizing material complying with Sections 417.5.2.1 through 417.5.2.4. Such liners shall turn up on all sides at least 2 inches (51 mm) above the finished threshold level. Liners shall be recessed and fastened to an approved backing so as not to occupy the space required for wall covering, and shall not be nailed or perforated at any point less than 1 inch (25 mm) above the finished threshold. Liners shall be pitched one-fourth unit vertical in 12 units horizontal (2-percent slope) and shall be sloped toward the fixture drains and be securely fastened to the waste outlet at the seepage entrance, making a water-tight joint between the liner and the outlet. 417.5.2.1 PVC sheets. Plasticized polyvinyl chloride (PVC) sheets shall be a minimum of 0.040 inch (1.02 mm) thick, and shall meet the requirements of ASTM D 4551. Sheets shall be joined by solvent welding in accordance with the manufacturer’s installation instructions. 417.5.2.2 Chlorinated polyethylene (CPE) sheets. Nonplasticized chlorinated polyethylene sheet shall be a minimum 0.040 inch (1.02 mm) thick, and shall meet the requirements of ASTM D 4068. The liner shall be joined in accordance with the manufacturer’s installation instructions. 417.5.2.3 Sheet lead. Sheet lead shall not weigh less than 4 pounds per square foot (19.5 kg/m2) coated with an asphalt paint or other approved coating. The lead sheet shall be insulated from conducting substances other than the connecting drain by 15-pound (6.80 kg) asphalt felt or its equivalent. Sheet lead shall be joined by burning. 417.5.2.4 Sheet copper. Sheet copper shall conform to ASTM B 152 and shall not weigh less than 12 ounces per square foot (3.7 kg/m2). The copper sheet shall be insulated from conducting substances other than the connecting drain by 15-pound (6.80 kg) asphalt felt or its equivalent. Sheet copper shall be joined by brazing or soldering. 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. P2709.2 Lining required. The adjoining walls and floor framing enclosing on-site built-up shower receptors shall be lined with one of the following materials: Sheet lead; Sheet copper; Plastic liner material that complies with ASTM D 4068 or ASTM D 4551; Hot mopping in accordance with Section P2709.2.3; or Sheet-applied load-bearing, bonded waterproof membranes that comply with ANSI A118.10. The lining material shall extend not less than 2 inches (51 mm) beyond or around the rough jambs and not less than 2 inches (51 mm) above finished thresholds. Sheet-applied load bearing, bonded waterproof membranes shall be applied in accordance with the manufacturer’s instructions. P2709.2.1 PVC sheets. Plasticized polyvinyl chloride (PVC) sheet shall meet the requirements of ASTM D 4551. Sheets shall be joined by solvent welding in accordance with the manufacturer’s instructions. P2709.2.2 Chlorinated polyethylene (CPE) sheets. Nonplasticized chlorinated polyethylene sheet shall meet the requirements of ASTM D 4068. The liner shall be joined in accordance with the manufacturer’s instructions. P2709.2.3 Hot-mopping. Shower receptors lined by hot mopping shall be built-up with not less than three layers of standard grade Type 15 asphalt-impregnated roofing felt. The bottom layer shall be fitted to the formed subbase and each succeeding layer thoroughly hot-mopped to that below. All corners shall be carefully fitted and shall be made strong and water tight by folding or lapping, and each corner shall be reinforced with suitable webbing hot-mopped in place. All folds, laps and reinforcing webbing shall extend not less than 4 inches (102 mm) in all directions from the corner and all webbing shall be of approved type and mesh, producing a tensile strength of not less than 50 pounds per inch (893 kg/m) in either direction. P2709.2.4 Liquid-type, trowel-applied, load-bearing, bonded waterproof materials. Liquid-type, trowel-applied, load-bearing, bonded waterproof materials shall meet the requirements of ANSI A118.10 and shall be applied in accordance with the manufacturer’s instructions. P2709.3 Installation. Lining materials shall be sloped one-fourth unit vertical in 12 units horizontal (2-percent slope) to weep holes in the subdrain by means of a smooth, solidly formed subbase, shall be properly recessed and fastened to approved backing so as not to occupy the space required for the wall covering, and shall not be nailed or perforated at any point less than 1 inch (25.4 mm) above the finished threshold. P2709.3.1 Materials. Lead and copper linings shall be insulated from conducting substances other than the connecting drain by 15-pound (6.80 kg) asphalt felt or its equivalent. Sheet lead liners shall weigh not less than 4 pounds per square foot (19.5 kg/m2). Sheet copper liners shall weigh not less than 12 ounces per square foot (3.7 kg/m2). Joints in lead and copper pans or liners shall be burned or silver brazed, respectively. Joints in plastic liner materials shall be jointed per the manufacturer’s instructions. P2709.4 Receptor drains. An approved flanged drain shall be installed with shower subpans or linings. The flange shall be placed flush with the subbase and be equipped with a clamping ring or other device to make a water-tight connection between the lining and the drain. The flange shall have weep holes into the drain.

The photo I posted above is a bonding flange drain that was shown in one of Mr. Starykov’s articles on this subject. When I saw the orange membrane, I assumed it was a Kerdi drain. My post should just refer to bonding flange drains in general. Sorry for the confusion. I am a newbie re: shower pan construction. I‘ve just been doing a lot of research recently in order to avoid having my marble discolor due to water retention. I have read several discussion threads where specifically Kerdi drains + issue with water pooling around the drain have been discussed. These included comments by well respected professionals who would be able to identify a Kerdi drain. There is always is the possibility (probability??) that the dams around the Kerdi drains were caused by installation error. Anyone who spends even a little bit of time on Houzz looking at bathroom renovations knows all too well how often these shower pans are not built correctly! I think catbuilder has “nailed it“ in the above post - there may be (i) too much thinset used to set the drain, (ii) a dam that’s been created around the drain (drain wasn’t firmly set into the the thinset?), or (iii) a valley in the deck mud around the drain. Catbuilder clearly has quite a bit of knowledge re: shower construction/proper waterproofing methods. I do have a question for you - is the marble tile that you’re having an issue with the same as the marble installed previously without issues? There have been a lot of discussions about how the particular quality of the marble tile being installed may have some bearing on the rise in marble discoloration issues. There is a lot of marble being sold in the marketplace that is labeled as ”Carrara” but is actually not from Italy. My understanding is that the density/porosity of marble can vary quite a bit between different varieties. It also can vary somewhat in the same variety. If I hold up two of the Italian Carrara tiles I’ve recently purchased for my shower walls to a light source, certain tiles are much more translucent than others even though they were sourced from the same area. This would contribute to the amount of water being retained inside the actual stone. Then again, if you have a dam or birdbath around your drain, your marble tile is going to soak up some water regardless of type! I REALLY want a marble hexagon shower floor - but all of this is making me VERY ANXIOUS. I specifically decided not to purchase the standard Carrara hexagon mosaic tile that I really wanted since white marble tends to have more issues with this - but if my shower pan has any type of water retention issues, I still will wind up with discolored tile.