Schluter Home Additions & ADU Nationwide

Schluter Home Additions & ADU: The San Antonio Owner’s Guide

We stock, specify, and install Schluter waterproofing and uncoupling systems for home additions and ADU projects across San Antonio, typically running $45,000 to $130,000 for a full addition and $90,000 to $220,000 for a complete detached ADU. Most owners discover a Schluter-related failure during a bathroom or wet-area addition when tile starts lifting at the edges, grout cracks along a transition, or water stains appear on the ceiling below. The most common root cause we see is an incorrect thinset bond between the Schluter membrane and the substrate, which is why we have our own installers use Schluter’s All-Set and exact trowel notch specs rather than whatever is on the truck.

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Which Schluter Models This Applies To

For home additions and ADU work, the relevant Schluter systems in San Antonio are almost always DITRA, DITRA-HEAT, KERDI, and KERDI-BOARD. DITRA is the orange uncoupling membrane we use under tile in kitchens, sunrooms, and ADU living spaces where slab movement matters, and DITRA-HEAT adds electric floor warming wires that clip into the membrane before tile goes down. KERDI is the waterproofing fabric for showers and wet walls, and KERDI-BOARD is the rigid foam backer that replaces cement board on shower surrounds and tub decks. The compatibility gotcha most owners miss: DITRA and KERDI are not interchangeable. DITRA manages lateral movement but is not waterproof at the seams unless you run KERDI-BAND over every joint, while KERDI is waterproof from the membrane itself. If you’re building an ADU with a curbless shower, we use KERDI with KERDI-BAND at every seam and KERDI-KERECK at the corners. If you’re tiling over a slab addition, DITRA with KERDI-BAND at the seams is the call. Aftermarket membranes exist, but we install the actual Schluter product, because the 10-year system warranty only holds when the membrane, drain, and thinsets are all from the same manufacturer.

Signs Your Schluter Home Additions & ADU Is Failing

• Grout is cracking in straight lines that follow the tile layout. This usually means the membrane was not bonded fully to the substrate, and the tile assembly is moving independently of the floor. In San Antonio slab-on-grade additions, slab movement shows up this way first.
• Hollow-sounding tile when you tap it with a coin. A properly bedded Schluter membrane sounds solid. Hollow spots mean thinset coverage was incomplete, often because the installer used a worn notch trowel or let the thinset skim over before setting tile.
• Water staining on the ceiling of the room below your upstairs ADU bath. This points to a gap in KERDI seam coverage or a pinhole at a corner. Water travels along the subfloor and finds the first opening.
• Shower floor tile is darkening around the drain. The KERDI drain assembly relies on a full bond between the fleece collar and the membrane. If the collar was not properly embedded, water seeps at the drain edge and the thinset stays wet.
• Floor feels warm near one wall but not the other in a DITRA-HEAT zone. This is usually a heating cable that was nicked during installation or a loose connection at the thermostat. Schluter’s continuity tests during install catch this, but many DIY projects skip the test.

Replacement Cost & What’s Included

For Schluter repairs inside a home addition or ADU in San Antonio, the typical installed cost ranges from $800 to $2,500 for a backsplash-area membrane patch, $3,500 to $10,000 for a tub-to-shower KERDI waterproofing replacement, and $4,500 to $12,000 for a full walk-in shower rebuild to Schluter spec. If the failure is in a DITRA-HEAT floor, expect $2,000 to $6,500 for membrane and cable replacement in a small bath, and more if tile demolition is extensive. Every quote from Elmstead Remodeling San Antonio is written before any work starts, and it includes the Schluter membrane, the correct Schluter thinset, seam banding, and the labor to demo and reinstall tile. We do not write estimates that grow after the crew arrives. The written price you sign is what you pay, and the work falls under our 365-Day Done Right Promise. If it’s not right, we make it right.

DIY or Call Us?

Pouring through old tile and membrane is not dangerous in the way garage-door springs or electrical panels are, but waterproofing failures are quiet and slow, and a single missed seam under a curbless ADU shower means pulling the floor again in eight months. If you want to know what you have, you can safely remove a floor register and peek at the tile edge to see if a Schluter membrane is present and whether it looks bonded. That’s a good first check. From there, we’d rather walk you through the findings and give you a written price than have you open up a shower pan on a weekend and discover the subfloor is wet and the joists below need attention. Call (432) 233-0976 and we’ll take a look before anything gets torn out.