Schluter ALL-SET Calculator
Schluter ALL-SET eliminates the modified vs unmodified dilemma. Calculate exact dual-layer bags (under and over DITRA/KERDI) with official Lifetime Warranty compliance.
Room Area & Assembly Layers
Finished Tile Type
Always use the flat side of your trowel to firmly skim mortar into all DITRA square cutback cavities BEFORE combing the notched ridges on top.
Coverage estimates are planning figures calculated under TCNA standards and ANSI specifications. Actual mortar consumption may vary based on substrate flatness, troweling technique, tile back profile, and jobsite environment.
How This Tool Calculates Your Results
Complete mathematical transparency with formulas, standard assumptions, and variable definitions.
Schluter ALL-SET calculation math:
Schluter ALL-SET Dual-Layer Cross Section
Schluter ALL-SET functions as both the substrate anchor and the tile setting bed.
Schluter ALL-SET Coverage Rates by Layer & Trowel
Direct data from Schluter Systems Technical Data Sheets.
| Application Layer | Trowel Specification | 50 lb Bag Coverage | Water Ratio | Slake Time |
|---|---|---|---|---|
| DITRA Substrate Bedding | DITRA Trowel (11/64" × 11/64" Square) | 150 – 175 sq ft | 5.2 – 5.5 Qts (Fluid) | 10 Minutes |
| KERDI Wall Bedding | KERDI Trowel (1/8" × 1/8" Square) | 200 – 250 sq ft | 5.2 – 5.5 Qts (Fluid) | 10 Minutes |
| 12×24 Tile Over DITRA | 1/2" × 1/2" Square Notch (Cavities + Bed) | 35 – 38 sq ft | 4.8 – 5.2 Qts (Stiff) | 10 Minutes |
| Standard Tile Over DITRA | 1/4" × 3/8" Square Notch (Cavities + Bed) | 42 – 48 sq ft | 4.8 – 5.2 Qts (Stiff) | 10 Minutes |
Schluter Lifetime Warranty Checklist
Ensure complete system compliance for Schluter's full Lifetime Warranty.
Common Field Schluter Projects
54 sq ft (Half DITRA Roll)
Requires 1 bag under DITRA + 2 bags for 12×24 tile over DITRA = 3 bags total.
150 sq ft (Full DITRA Roll)
Requires 1 bag under DITRA + 5 bags for tile over DITRA = 6 bags ALL-SET total (300 lbs).
300 sq ft (2 Rolls DITRA)
Requires 2 bags under DITRA + 10 bags for tile = 12 bags ALL-SET total (600 lbs).
5 Fatal Schluter ALL-SET Installation Mistakes
Common blunders that void Schluter's Lifetime System Warranty.
Combing notched ridges directly over DITRA without first using the flat side of the trowel to fill the square pockets traps large air pockets beneath the tile, leading to cracked tiles under point loads.
Under DITRA, the mortar must be mixed slightly fluid (5.5 quarts water) to wet out 100% of the fleece anchoring fibers. A stiff mix will not penetrate the fleece, causing the membrane to peel up.
Schluter ALL-SET contains specialized dry polymers that require 10 minutes to dissolve into solution. Skipping slaking results in poor workability and premature surface skinning.
Stepping directly on freshly bedded DITRA with boots displaces the wet mortar beneath the fleece, creating sunken ridges and hollow spots. Always kneel on plywood boards to spread your weight.
Schluter ALL-SET Polymer Chemistry & Engineering Manual
Why Schluter engineered ALL-SET, ANSI duality, and the Lifetime System Warranty protocol.
1. Resolving the Historic Modified vs Unmodified Dilemma
For decades, tile setters struggled with mortar selection over uncoupling membranes. Standard modified thinsets require air drying to cure, but setting impervious porcelain tile over impervious plastic DITRA prevents air exposure, trapping moisture and delaying cure times for weeks. Traditional unmodified thinsets cure chemically without air, but lack bond strength to dense porcelain. Schluter engineered ALL-SET with advanced polymers that achieve complete chemical hydration in vacuum-sealed conditions between porcelain and plastic.
2. ANSI A118.4T, A118.11 & A118.15T Triple Qualification
Schluter ALL-SET is independently certified to three major ANSI specifications:
- ANSI A118.4T: Modified cement mortar with thixotropic anti-sag properties for vertical walls.
- ANSI A118.11: Exterior-glue plywood bond rating for subfloor deflection resistance.
- ANSI A118.15T: Ultra-high shear bond strength for heavy commercial traffic and thermal stress.
3. The Schluter Lifetime System Warranty
Using competitor mortars over DITRA or KERDI reduces warranty protection to a standard limited warranty. However, using an unbroken Schluter assembly—Schluter substrate primer + DITRA or KERDI membrane + Schluter ALL-SET mortar + Schluter KERDI-DRAIN—qualifies the installation for a Lifetime System Warranty covering all materials and professional replacement labor.
Frequently Asked Questions
Practical answers backed by TCNA Handbook recommendations and ANSI specifications.