Thinset follows the substrate instead of flattening it
Thinset mortar, dryset mortar, and drybond mortar are the same material: cement, finely graded sand, and a water-retention compound so the cement can hydrate. Tile set this way is stuck with a thin layer, typically not greater than 3/16 inch. A 3/8-inch notch trowel leaves about that thickness after the tile is pressed in. Minor height tweaks are possible. The method is not for leveling. The tile follows the substrate.
Polymers and the standard numbers
ANSI A118.1 defines unmodified thinset. Polymers added to the cement are often called latex-Portland cement mortar, even though many of today's polymers are acrylics rather than latex. ANSI A118.4, A118.15, and A118.11 set minimum performance for those modified mortars. The polymers are used for freeze-thaw resistance, flexibility, and adhesion. Some are formulated to be waterproof or elastic enough to act like an anti-fracture layer.
Speed has a cost in movement
Thinset work is less expensive and usually faster than a mortar bed. Because the tile bonds directly to the substrate, variation and movement in that substrate show up in the tile.
Source
Fetched 2026-10-11 from Tile Council thinset FAQ. The sentences above follow that page. They are not a contractor promise.
Related notes
- Tile notes index
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- ANSI tile standards cited by the Tile Council exclude OSB
- Backsplash photos
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