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Schluter Home Additions & ADU: The Miami Owner’s Guide
If you’re planning a Schluter home addition or ADU in Miami, you’re looking at an installed range of $53,100 to $153,400 depending on square footage, foundation work, and the Schluter waterproofing and uncoupling systems specified. We stock and install Schluter-compatible membranes, profiles, and drainage components, and we can often begin the flooring and wet-area phases within a week of your materials arriving. Most Miami homeowners call us after a failed inspection, a leaking shower in an existing addition, or when a previous contractor walked away mid-job because they didn’t actually know how to detail Schluter systems correctly.
Schluter products don’t fail quietly. You’ll see it in cracked grout lines between tile and the KERDI membrane, or water staining on the ceiling below a second-floor ADU shower. In Miami’s humidity, even a small waterproofing gap turns into mold fast. Trevor Nash has walked onto more than one Coconut Grove ADU project where the tile looked fine from six feet away but the substrate behind it was holding water like a sponge. Give you a number first, then pick up the tools.
Which Schluter Models This Applies To
Schluter’s product line breaks into three families that matter for home additions and ADUs in Miami. First, the KERDI waterproofing membrane and board system, used in every shower, tub surround, and wet wall we build. Second, the DITRA and DITRA-HEAT uncoupling membranes that go under tile floors, preventing the cracks Miami slab movement causes. Third, the SCHLUTER-SHOWER SYSTEM profiles and drains, KERDI-LINE and KERDI-DRAIN, which are the most common point of failure when installed by someone who didn’t read the bonding requirements.
Identifying the right part comes down to what was originally installed. KERDI membrane is sold in rolls that are 3’3″ wide, and KERDI-BOARD comes in thicknesses from 3/16″ to 2″. If you have a shower pan, look for the drain grate style: a square KERDI-DRAIN grate versus the linear KERDI-LINE channel tells us exactly which bonding flange we need to match. Compatibility gotcha: older Schluter pans used a PVC bonding flange while newer ones use ABS. Mix the two and the solvent weld fails. That’s a mistake we’ve corrected in several Miami installations where a handyman “knew a guy” who could save the homeowner money.
We always recommend OEM Schluter components over aftermarket equivalents. Schluter’s fleece-webbed polyethylene membrane is engineered for a specific thinset-to-fleece mechanical bond. Generic waterproofing sheets don’t have the same fleece density, which changes how the thinset grips. When a $118,000 ADU is on the line, that $80 difference in membrane cost matters. Penhallow Remodeling Miami is an independent contractor and not affiliated with Schluter Systems, but we’ve spec’d their products long enough to know when an off-brand substitution is a bad bet.
Styles & brands we work with
Signs Your Schluter Home Additions & ADU Is Failing
- Water staining on the ceiling below a wet area. This usually means a seam in the KERDI membrane wasn’t overlapped the full 2 inches required, or the thinset wasn’t mixed wet enough to create the mechanical bond Schluter needs. Once water finds a gap, capillary action pulls it along the seam fast.
- Cracked grout lines running in straight rows across tile floors. Straight-line cracks point to an uncoupling membrane that wasn’t installed correctly, or no membrane at all. Miami’s clay-heavy soil expands and contracts with our wet season, and tile directly bonded to a slab loses that fight every time.
- Efflorescence or white crust at the base of shower walls. That’s mineral salts leaching out as water evaporates through the grout. It means the waterproofing behind the tile is catching water but not draining it to the KERDI-DRAIN the way the system intended. The fix is removing tile and re-detailing the pan-to-wall transition.
- Musty smell you can’t locate, especially after rain. In a Miami ADU built over a crawl space or on stilt foundations near the coast, humidity wicks up through the slab. A proper Schluter DITRA installation includes sealing the edges to create a vapor barrier. Skip that step and every humid day pushes moisture up through the tile assembly.
- Tile movement or hollow-sounding spots when tapped. Hollow spots indicate the thinset never bonded to the fleece, usually because the membrane was installed with mastic instead of unmodified thinset. Mastic can’t dry between a waterproof membrane and a large-format tile. It stays wet, eventually re-emulsifies, and the tile loses its bond.
See the difference
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AfterReplacement Cost & What’s Included
A full Schluter home addition or ADU construction in Miami runs $53,100 to $153,400, but the Schluter-specific component you’re addressing might be far smaller. If you’re repairing a failed shower waterproofing inside an existing addition, you’re typically looking at $5,310 to $14,160 for a walk-in shower re-do including demolition, Schluter pan and membrane, tile, and grout. A failed DITRA floor in one room runs $2,360 to $7,670 depending on the square footage and whether we’re matching existing tile or replacing the whole floor.
What drives the bigger number on a full ADU: foundation type (pier and beam versus slab matters in Miami’s flood zones), whether you’re converting an existing garage or building new structure, electrical and plumbing rough-in distance from the main house, and the tile and fixture level you pick. Every quote from Penhallow Remodeling includes a written line-item price before any work starts. That number covers demo, disposal, Schluter materials, labor, and the 365-Day Done Right Promise in writing. If a seam fails or a drain leaks inside one year, we come back and fix it at no charge. No service call fee, no re-inspection fee.
DIY or Call Us?
What you can safely check: whether your Schluter DITRA membrane edges are sealed with KERDI-BAND (peel back a corner of the baseboard to see), whether grout lines that were white are now yellowed or cracking, and whether any silicone at the shower pan perimeter has pulled away. Those observations help us diagnose before we even arrive.
What you should not attempt: removing tile from a Schluter waterproofed wall or pan assembly. The fleece layer on the membrane is fused to the thinset, and prying tiles off tears the fleece. Even a small tear compromises the waterproofing, and now you’re buying a full re-pan instead of a targeted repair. Same applies to modifying a KERDI-DRAIN bonding flange after installation. The solvent welds are permanent. One wrong cut and the cost goes up, not down. If you’re in Miami and you suspect a Schluter failure call us at (850) 988-7559. We’ll tell you over the phone whether it sounds like a quick diagnosis visit or a tear-out, and the estimate is free either way.
FAQs
Schluter waterproofing installed correctly should last 30 years or more even in Miami’s heat and humidity. What fails early is the installation, not the membrane, which is why we put our own 365-Day Done Right Promise over the top of Schluter’s own warranty. Call (850) 988-7559 if your shower is leaking and you want a straight answer on what it’ll take to fix.
No. Schluter waterproofing is a bonded system, and once water gets behind the tile, you cannot dry it out from the front. The tile has to come off far enough to find where the seam or corner detail failed, cut out the damaged section, and re-fleece the repair with KERDI-BAND. What you save by not re-tiling initially gets spent on mold remediation later if you wait. Estimates are free, call (850) 988-7559.
Most single-shower Schluter waterproofing replacements take 4 to 7 working days from tear-out through grout, including a 24-hour flood test before tile is set. A full ADU build with Schluter throughout runs 4 to 8 months depending on permitting and foundation work, not because of the Schluter phase specifically but because Miami’s building department queues are real. Call (850) 988-7559 and we’ll give you a written schedule before you commit.
We keep KERDI membrane rolls, KERDI-BAND, KERDI-KERECK pre-formed corners, DITRA membrane, KERDI-DRAIN and KERDI-LINE flanges, and mixing valves with Schluter shower valve seals on our trucks for Miami service calls. Specialty items like KERDI-BOARD thicknesses above one inch or custom profile lengths are ordered and arrive within 3 to 5 business days. We also work with KraftMaid, Cambria, and Silestone on additions that involve new cabinetry or counters, and can source those materials alongside your Schluter package.
Written by Trevor Nash, Owner, Penhallow Remodeling Miami at Penhallow Remodeling Miami, serving Miami and nearby areas.
