kerdi board to drywall outside corner

Its a walk in neo angle job, no door, just a curb to step over. nice and clean! First Kerdi can be installed on drywall or cement board. Note: Water testing of the assembly 3. Schluter-KERDI-BOARD over wood or metal framing. Pay special attention to the consistency of the thinset. Schluter KERDI Outside Corner - 2 Units Brand: Schluter Systems 294 ratings $1540 Get Fast, Free Shipping with Amazon Prime FREE Returns Available at a lower price from other sellers that may not offer free Prime shipping. Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. Install KERDI-SEAL-PS pipe seals at showerhead, body sprays, etc. With this application from a wide knife, the joint areas will now be raised up nearly flush with the faces of the wallboard panels, and the tape should now be hidden under the compound. A special drywall sanding block can be mounted with fine-grit drywall sandpaper, and it accepts a threaded pole to allow you to easily sand high up on walls without a ladder. Tile ontop of kerdi board, apply schluter edge. I took like 2 months off over the summer and didn't even step in there as was on vacation/fishing/traveling. Ensure that its fastened to the wall. $14.31 $ 14. x 16 ft. 5 in. The tiles can be installed using Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or unmodified thin-set mortar once the bonding materials used to construct the partition have cured sufficiently to stabilize the assembly. This may be ensured by making holes in the KERDI-BOARD at the desired fastener locations prior to applying mortar spots. I realize I'm resurrecting an old thread, so if I should move this question to a new one, please let me know. Batch split images vertically in half, sequentially numbering the output files. The tiles can be installed immediately using Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or unmodified thin-set mortar. Tip: I wish I would have put RedGuard on the ceiling as well although I'm not sure if it would help with some of my staining issues from the water that accumulates up there. I am all ears though. This keeps the room looking simple and unified. When assembling material for creating this transition, make sure that you use the Kerdi band. However, when exposed to moisture, it wont stand a chance. This is where the glass will be installed. The mud is used to fill seams and other indentations in the drywall. 1. We are working on a similar transition. Calculate your building panels for a quick and easy waterproof installation. I had planned to remove the water lines from near the basement to avoid having stagnant water sitting in the pipe if I capped it below the subfloor. And the best way to do that is by cutting a small piece of the Kerdi board and fitting it on that seam. Knowing that the entire bathroom floor has been waterproofed. ncdu: What's going on with this second size column? Kerdi-Kereck-F Pre-Formed 90 Waterproofing Outside Corners (2-Pack) Kerdi-Band 7-1/4 in. Smaller tile such as 3x6 subway you would flash off with the flat side of a trowel prior to setting tile. Got sidetracked by a couple things but I'm about ready to sand and prime. DIYers often find this to be an easier method of finishing inside corners. I have a couple of outside corners that i have to deal with that transition from kerdi board to regular drywall. Note: If the bond between the thin-set mortar and substrate is questionable, additional mechanical attachment with the KERDI-BOARD-ZSD anchors or KERDI-BOARD-ZT washers and corresponding screws is required. Get it as soon as Friday, Mar 3. Most people get better results by dry sanding, which is relatively easy once you learn the technique of proper mud application. Butt vs Tapered Drywall Joints: Which Is Best? Sheetrock is a popular brand of drywall, which is why you often hear the name used interchangeably with drywall. Doing this also keeps the profile from 'walking' while the thinset cures up. Fasteners are installed after the thin-set mortar has hardened. You can run the final row of tile over the joint between the Denshield and of the drywall. Certainly not to that extreme just a example. Houzz Call: Have a Beautiful Small Bathroom? You dont have to be afraid of creating a Kerdi board to drywall transition. Connections between the niche and walls are made using KERDI membrane, applied with Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or unmodified thin-set mortar (mixed to a fairly fluid consistency, yet still able to hold a notch). Please call Schluter-Systems How do I install the prefabricated shelf in the Schluter-KERDI-BOARD-SN shower niche? So far you've dealt with I joists and wet shimming. @thisisnotadrill could you post that picture please. a. Not sure if you're in the PA/DE area but I opened an account with them and paid $5.99/sqft instead of the advertised price. Kerdi-Board panels, 2 pipe seals, 1 mixing valve seal, 1 - 5 in . However if installed on drywall it is only protecting one side. The floor is not as great as I would like, there's a little lippage between pan tiles and floor tiles but overall I'm happy. The colour is different. Tiles can be installed directly over KERDI-BOARD using the thin-set method. 1. Fasten all corners and limit fastener spacing to 12" (30 cm) o.c. Some pros add a little water to the mud before the final coat (but never more than the equivalent of one pint of water to a five-gallon bucket of mud). To avoid any risk of damage, keep the door a few inches from the transition. Corner bead consists of narrow paper flanges attached to an L-shaped metal bead. .read more Show Product Table Waterproofing 4.6 out of 5 stars 154. Place spots of thin-set mortar on the KERDI-BOARD panel or substrate in intervals of approx. I have one more finishing tile piece to put over the top layer of tile. 4. Seams can be constructed by overlapping the edges of the KERDI 2" (5 cm) using Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or unmodified thin-set mortar, or by abutting the edges and covering the joint with KERDI-BAND using Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or unmodified thin-set mortar. Step 3: Fit the Kerdi Band Tape on the Transition. When the process is done correctly, the wall surface will be perfectly smooth, the joints will be invisible to the naked eye, and the finished drywall surface will be ready for paint or a textured finish. Drywall tape is available in two types: paperand fiberglass mesh. Complete bathtub and shower base surround kit, Screws and washers for fastening KERDI-BOARD panels to stud framing, Waterproofing strip seals abutting joints of membranes and building panels, Vertically grooved building panel to create curved elements for tile, U-shaped profile for finishing partition walls and shelves, Angle profile used to stabilize KERDI-BOARD structures, Anchors used to stabilize KERDI-BOARD panels, Contact us: 888-472-4588 When framing a KERDI-BOARD-SN shower niche you will need to use the 90 How long do I have to wait before I can install tile on Schluter-KERDI-BOARD? Seamless waterproofing for 90 outside corners; Designed for Kerdi, Kerdi-Board, and Ditra applications; Preformed to simplify installation; View More Details; . The shower ceiling is hardibacker and the wall outside the shower is drywall. Yes uphill also. As long as the transition has been perfectly constructed, you can tile over it. Position KERDI-BOARD on the framing and press a washer into the board every 12 inches up the stud location. If you dont want to deal with transitions, that would mean you have to rip out all the drywall and replace it with Kerdi Board. Apply KERDI-FIX to the inside vertical surface of the KERDI-BOARD-ZC profile and slide the profile over the edge of the KERDI-BOARD, pushing it tightly against the panel. It is not necessary to tape the joints between drywall panels before installing KERDI. Can Martian regolith be easily melted with microwaves? b. RONDEC-CT and RONDEC-STEP profiles are installed with Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or unmodified thin-set mortar in conjunction with the tile. Then, after a light final sanding, your wall will be ready for primer or texture prior to painting. The only problem that would have occurred is if the seam had been left open. Fully embedded KERDI-BOARD Any board thickness suitable 1. In general, it is recommended that the tile be at least 5/16" (8 mm) -thick and extend approximately 1-1/2" (38 mm) beyond the fixture hardware on all sides. And lastly, just fewer tiles to hang. Hi - My wife wants tile in the shower . If you have found yourself in the above scenario, here is an in-depth guide on transitioning from Kerdi board to drywall. @thisisnotadrill i am about 3/4 through demo. @Charlie Baum thanks for the quick response! KERDI was developed as a waterproofing membrane to be used in conjunction with ceramic and stone tile coverings. How do I perform one on the Schluter-Shower System? The type of bonding mortar used to apply KERDI must be suitable for the substrate and must penetrate and engage the membrane fleece What type of thin-set mortar should I use when installing ceramic and stone tile over Schluter-KERDI? The size of your selected tile will determine if it's a issue that needs addressing. PDA. and KERDI-SEAL-MV at the mixing valve. Once the countertop is tiled and grouted, holes may be drilled through the assembly to fit the fixture-mounting studs. Choose a notched trowel to match the tile format, and back-butter the tiles, if necessary, to attain full coverage. From there, you can tile or paint over the transition and finish your project. 12" (30 cm). rev2023.3.3.43278. Fab Glass and Mirror Round Lighted LED Bathroom Mirror 39-in . Schluter Systems: Kerdi Board Shower Bench (Triangular 16"x16"x20") . 2. Manage Settings Calculate all your membrane requirements for your project. I am removing a jacuzzi tub and tiled surround. Here is how you should go about it. You can end your tile with cap / bullnose or a tile profile edge. These will be obstructions to smooth taping and mudding. With a 6-inch taping knife, apply a smooth, thin layer of mud over the joint. Immediately press the paper tape into the mud, centered over the joint. Woot. ; 3/4" (19 mm) for studs spaced at 24" (61.0 cm) o.c.1. Factory welded corners come with 8" legs in each direction, however, custom leg lengths can be ordered. 5.0 out of 5 stars 2. Charlie, I would still install cornerbead first to reinforce the corner. To learn more, see our tips on writing great answers. . The only slight lippage there is, and its not really noticeable is the bottom row where I couldn't use tile leveling clips due to the ledger board. Impact on that corner relying on the foam board is risky. when that is installed I will finish mud that bit of exposed drywall on the other edge and feather it right into the door casing. I would top it out at the height of the pony wall. Other than that, it's going well. do you recall the make/model of the floor tile? Where these surfaces will not accept a bond to Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or unmodified thin-set mortar, use KERDI-FIX to bond KERDI-BAND. 4. My floor tiles are 2" x 2"." - Lisa Jasper No - you can not use Kerdi Board on the floor. For inside and outside corners, adhere pre-formed KERDI-KERECK-F corners. There are two methods to seal KERDI to a bathtub. Waterproofing Strip: Customers also search. A 1/4" x 3/16" (6 mm x 5 mm) V-notched trowel or the Schluter-KERDI-TROWEL is recommended.. How do I seal Schluter-KERDI to a bathtub? How to finish tiling an outside edge for a shower? Making statements based on opinion; back them up with references or personal experience. No. [Archive] Kerdi board / Drywall outside corner Tile Forum/Advice Board. We and our partners use cookies to Store and/or access information on a device. Large format (any edge over 15") will not matter as the mortar setting bed will be thick enough. KERDI features a modified polyethylene (PEVA) core with non-wovenpolypropylene on both sides to anchor the membrane in the thin-set mortar. Sinks may be mounted on top of the tile or tiled-under using RONDEC or QUADEC profiles and corresponding sink corners. Waterproofing strip seals abutting joints of membranes and building panels, Waterproof, multifunctional tile substrate and building panel, Point drain with integrated bonding flange, Bonded waterproofing and vapor-retardant membrane, Single-component sealing and bonding compound, Contact us: 888-472-4588 Take care not to expose the tape. What I would be most scared off is the fact that no inside or outside corners appear to have been used. Yes, you can, but it will be expensive and time-consuming. Sheetrock is generally viewed as a quality product, and it comes in different forms, including moisture-resistant and sound-dampening panels. Sep 10, 2017 Generally your finish tile, whether bull nose or Kerdi strip will overlap onto the sheetrock, forming a seam of its own. Latex-modified mortars must dry for the polymers to coalesce and form a hard Why should I use the Schluter-Shower System? Therefore, cut a strip of Kerdi board and fit it into the seam. This grout joint is the location for the capillary break. Generally, Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or unmodified thin-set mortar is used. Choose a notched trowel to match the tile format, and back-butter the tiles, if necessary, to attain full coverage. Make sure its bonded and well attached to the drywall mud, and thats it. The other side with drywall should be moisture free. If there are any spots with torn paperon the drywall cut them off with a razor or other sharp tool. The best transition is to join the seams with a tin strip of Kerdi board, drywall mud, and Kerdi band. Yes. You dont have to worry about leaks when you create such a setup. While standard drywall comes in " and " thicknesses, greenboard is sold in " and 5/8 thicknesses. Cover the joints with KERDI-FLEX. Ideally, the paper surface of the drywall should not be broken (if so, it lessens the holding power of the fastener), but should be recessed just slightly below the surface of the drywall panel. It could be notched to eliminate any build up due to corner bead. (Wear a dust mask and eye protection while sanding.) i also gotta say i love how you matched the veining on the tiles that sit in the corner, just between the top and middle shelf :) it looks continuous! This can be achieved by sandwiching the panel between adjacent KERDI-BOARD panels, fixed building elements, etc. Remove any air pockets. It can be cut to length with tin snips, then simply pressed into a corner that has been coated with taping compound. 4. KERDI-BAND is also suitable for sealing connections to fixed building elements such as door and window frames. Keep the band approx. The corners are painted to match the straight pieces of Drywall Ceiling Transition to Drywall trim for a . Recovering from a blunder I made while emailing a professor. This is confusing since Kerdi Board has no Kerdi on it. INCREDIBLE. The selected screws must be of sufficient length to reach a depth of at least 3/4" (20 mm) in wood studs and at least 3/8" (10 mm) in metal studs. The process is often known in the building trades as taping and mudding. Very interesting. How do I connect Schluter-KERDI-BOARD to a bathtub? But it generally has to be installed under tile. Waterproofing with KERDI-BOARD Where waterproofing is desired, the joints and corners of KERDI-BOARD in the area must be sealed with KERDI-BAND using Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or unmodified thin-set mortar. But taping and mudding can be a frustrating job, so it's important to understand the process well. Water will migrate by capillary action through the grout and tile setting mortar. ".1) is is okay to use kerdi board instead of ditra on the floor? Drying time for taping compound will vary, depending mostly on humidity levels. I extended the Kerdi board on the corner already but it sounds like I may want to cut it back to the edge of the stud and redo the drywall pieces with a factory edge overlapping the Kerdi board if I want to try your method, right? If the transition features Kerdi board slightly overlapping drywall, it wont be level. We and our partners use data for Personalised ads and content, ad and content measurement, audience insights and product development. I'll have to look into this a bit more. For acid-resistant coverings, use an epoxy adhesive to set and grout the tile. A wet sander is a textured sponge designed to smooth wallboard joints without dry sanding. Using indicator constraint with two variables. Make sure that all nail or screw heads are driven down below the paper surface of the wallboard. Got back onto it in Sept. Next, scoop some mud into a compound tray. For showers and bathtub surrounds, KERDI must be carried to the height of the showerhead at minimum What size notched trowel should I use to install Schluter-KERDI? @Jonathan Gunnell Hey Jon! As a general rule, either paper or fiberglass tape will work for straight seams, but inside corners are best covered with paper tape. The Schluter-Shower System is an integrated family of products that together form a fully bonded, watertight assembly for tiled showers Can I use Schluter-KERDI in my steam shower? Calculate your building panels for a quick and easy waterproof installation. Schluter-KERDI-BOARD is a multifunctional tile substrate and building panel, which can also be used for creating bonded waterproofing assemblies with tile coverings. KERDI-BOARD should be stored flat. California Specification 01350 is referenced by various green building standards and rating systems. Get daily tips and tricks for making your best home. But its not recommendable because the transition wont be flush. Apply a corresponding piece of ceramic tile with thin-set mortar in the resulting space flush with the surface of the KERDI-BOARD. NOTE: (Not in the book) I have used expansion profiles such as Schluter BWA and set that into the sealant for a clean finish look instead of a sealant joint at the surface.. The exterior paper has a green tint to it helping to separate it from standard gypsum board, and leading to the product being known by most people as "greenboard." Greenboard Is Thicker Than Drywall. 2. 8. If you use both Kerdi board and drywall, the part with the latter material wont be heavily exposed to moisture. The membrane is subsequently cut to match the niche opening. 3. Then drill a single screw through the washer/KERDI-BOARD and into the stud. @thisisnotadrill Sorry, hope this time it works. To allow for greater movement, the center section of the KERDI-FLEX can be tucked into the cavity of the expansion joint prior to bonding. I really enjoyed the large format on the walls for a couple reasons. The excess weight of the door can make it weaker. The tiles can be installed immediately using Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or unmodified thin-set mortar. Use of KERDI-BOARD in non-bearing partition wall systems Minimum board thickness = 2" (50 mm)1. "thanks in advance :-) I know so little about this stuff, but when I watch videos (made by schluter-kerdi) everything looks so tidy and perfect - maybe that's not realistic'''" - Lisa Jasper It should look better than that and it's hard to tell but the wall stud spacing looks extreme and more than 16" I could not see if the screw heads where covered in the photos and in the one picture you can see that the screw and washer fitting where not covered. What's the difference between Sheetrock and drywall? is the contractor creating a waterproof schluter-kerdi shower? Thanks! To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Certain glass tiles may not be compatible with bonded waterproofing applications and/or may require special setting materials. And without using up more time, proceed to step three. The mortar must bond to the substrate and mechanically anchor the fleece on the KERDI-BOARD surface.3. KERDI-BOARD is adhered directly to base cabinets using the Schluter-KERDI-FIX adhesive. The corner bead will help strengthen the transition between these two materials. In general, unmodified thin-set mortar is a blend of Portland cement, sand, and water retention agents that is mixed with How far up the wall do I need to install the Schluter-KERDI? o_O Eventual floorplan will look something like this, with the chimney demolished and replaced with a pipe flue and the original entry repurposed back to a foyer again. I do love the schluter corner shelves. However, if you doubt your skills, you can always hire an expert contractor who will follow the above procedure and create a flawless transition between the Kerdi board and drywall. The pony wall will have tile on the inside of the shower, and the top. No, it wont. in tiled-under sink applications to distribute the pressure of the fixture hardware on the underside of the assembly. Then tile. Cut and remove the wallboard such that the niche will be supported on both sides by the studs or other wall framing. But with wet sanders, it can be quite hard to get perfectly smooth seams without waves and without dissolving and removing too much of the dried mud. So it appears I can use a schluter product as you mentioned or perhaps a bead of silicone in that break? Is there a solution to add special characters from software and how to do it, Styling contours by colour and by line thickness in QGIS. I think you may be misunderstanding my question. To wrap up your transition, apply the Kerdi Band tape on the seam. The tiles can be installed immediately using Schluter-SET, Schluter-ALL-SET, Schluter-FAST-SET, or unmodified thin-set mortar. Note: Please refer to the Walls and Countertops Profiles data sheet for additional information on profiles, including installation instructions. After I had finished with the tile, I taped the joint and applied joint compound over the backer board and it seems great. Normally you would get something like the picture below to cover the side of the tile. First, take kerdi band and wrap the four edges: Then take 4 outside corners (yes, OUTSIDE-- just use them "backwards") and install them like so: Now do the same thing in the back of the niche-- first wrapping the four sides with the Kerdi band, and then using four INSIDE corners: Fasteners are installed after the thin-set mortar has hardened.Note: See section Waterproofing on the use of KERDI-BOARD in bonded waterproofing assemblies. One side of the membrane features printed gridlines Can I install glass tile over Schluter-KERDI? Note: See section Waterproofing on the use of KERDI-BOARD in bonded waterproofing assemblies. Our thought is the transition to Kerdi board will be outside the shower door and we can get away with less than 2" of Kerdi band overlap. Cut and remove the KERDI-BOARD such that the niche will be supported on both sides by the studs or other wall framing. Pretty straight Forward except for having to wet shim the walls. Additional material may be removed from the underside of the KERDI-BOARD to allow installation of the fixture hardware. Waterproofing strip seals abutting joints of membranes and building panels, Rectangular shelf for prefabricated KERDI-BOARD-SN niche, Screws and washers for fastening KERDI-BOARD panels to stud framing, Waterproof, multifunctional tile substrate and building panel, Bonded waterproofing and vapor-retardant membrane, Point drain with integrated bonding flange, Contact us: 888-472-4588 For complete instructions refer to the Schluter website. It consists of an extruded polystyrene foam panel, with a special reinforcement material on both sides and fleece webbing for effective anchoring in thin-set mortar.KERDI-BOARD can be used in a multitude of interior applications. Where these two meet, what is the proper way to finish it so it's a nice corner? For finishing inside corners, consider using prefabricated corner bead. Regarding the corner bead, you can use one from any company. For paper tape or corner bead, first apply a thin layer of mud compound, then apply a folded strip of paper tape or corner bead, then cover the paper with a thin coat of mud. Please call Schluter-Systems Why should I use the Schluter-Shower System? For complete installation guidelines and warranty criteria for KERDI in showers, steam showers, and bathtub surrounds or KERDI-DS in steam rooms , please download the Schluter- Systems Shower System Installation Handbook and view the installation videos available below. Cookies collect information about your preferences and your devices and are used to make the site work as you expect it to, to understand how you interact with the site, and to show advertisements that are targeted to your interests. Im installing Schluter-KERDI over drywall in my shower. That's not exactly an answer but I hope it helps you decide. Work the KERDI into the mortar by applying pressure to the membrane with the flat side of the trowel (held at an angle) in smooth, diagonal sweeps. I made sure to keep the tile side completely clear of mortar. Spot-bonded KERDI-BOARDMinimum board thickness = 3/8" (9 mm)1. . This very light finish coat will likely be dry within an hour or two. 3. 2. Depending on which type of purple drywall you choose, a 4- by 8-foot panel typically costs between $15 and $60 (high-impact and sound-breaking options are available). Certain moisture-sensitive stones, e.g., green marble, or resin-backed tiles may not be appropriate for use in wet areas or may require special setting materials. KERDI shall be separated at existing expansion, structural, and flexible edge joints. I am going to put the schluter profile on the edge of the kerdi band but overlapping the exposed edge of the drywall. There's maybe a 1/4" of painted wall that rounds the corner before it meets up with the schluter edge. The possibility can be eliminated. Started 2 days ago. Part of the taping and mudding process includes sanding the dried compound (mud) to smooth the edges, For skilled professionals, sanding is minimal, but DIYers may find that sanding is surprisingly complicated and messy. The shower niche features a 1/2" (12.5 mm) -thick by 2" (50 mm) -wide integrated bonding flange and is available in 12" x 6" (30 x 15 cm), 12" x 12" (30 x 30 cm), 12" x 20" (30 x 51 cm), and 12" x 28" (30 x 71 cm) sizes. That is, sets equivalent to a proper subset via an all-structure-preserving bijection. 2. Schluter-KERDI-BOARD-SN is a prefabricated shower niche made of KERDI-BOARD that can be installed in both KERDI and KERDI-BOARD wall assemblies. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Most wall surfaces in new construction are made from drywallthin panels consisting of mineral gypsum sandwiched between paper faces. Continuing Education for Architects & Designers. It is designed to fill in the major gaps. Once cured, I pulled the nails and used kerdifix on the holes. Consult stone supplier and Schluter-Systems for more information. Tiles can be installed directly on KERDI using the thin-bed method. Do not install the door on this transition. Where these two meet, what is the proper way to finish it so it's a nice corner? A bearing plate must be provided for fastening fixtures (e.g., faucet, soap dispenser, etc.) These are usually pretty specific to the surroundings. You need to use a fiber mesh tape and a liquid waterproof membrane over the seams and corners any of the screwheads but the rest of the field is already waterproof and textured to except tile. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Following the process you used for either paper or fiberglass tape, finish the inside corners where walls meet. Apply the panels to the wall and firmly press them in place to ensure full coverage. I used the factory edge of drywall along the profile so to finish it, I perfectly taped the edge of the profile and just caulked that seam. Thank you, very kind words. Please refer to the Schluter-Shower System Installation Handbook for guidelines on waterproofing showers, steam showers, and tub surrounds.Limitations. You can find out more about our use, change your default settings, and withdraw your consent at any time with effect for the future by visiting Cookies Settings, which can also be found in the footer of the site. I am just not sure how to build this. You will know that the compound is dry when it all lightens to a uniform, white appearance. No. The shower ceiling is hardibacker and the wall outside the shower is drywall. Drywall comes up to the outside corner, and overlaps the raw kerdi edge. All joints of KERDI-BOARD panels must be sealed with KERDI-FIX or thin-set mortar. The previous-previous owners, on the other hand, didn't bother doing anything with the lumpy natural-stone chimney and just built around it, leading to perpetual roof leaks. Once you install KERDI over the drywall panels, they will be completely protected from the water and vapor in your tiled shower. Schluter-KERDI is a pliable, sheet-applied, bonded waterproof membrane and vapor retarder with limited crack-bridging capabilities. When using the KERDI-BOARD-SN prefabricated shelf, determine the desired height of the shelf and mark with a level line How to Tile a Niche with Schluter Profiles, How to install Schluter-KERDI-BOARD-SN Niche with KERDI Membrane, Schluter-KERDI-BOARD-SN Shower Niche within KERDI-BOARD Assembly. The transition should be strategically placed on the moisture-free side. You can even paint over it. The sanding dust, while not toxic, can irritate lungs and eyes, so it's important to wear a dust mask and eye protection while sanding. The walls were easier because I had tile wrapping around the corner so I just taped and thinset those and tiled overtop.

kerdi board to drywall outside corner 2023