Tile and Finish Setting over Receptors
What this domain tests
Finish work over a receptor must preserve drainage and not damage the membrane. Concepts: mortar selection (polymer-modified thinset appropriate to the substrate), slope maintenance through the tile layer, drain integration, movement joints, and curing before flood testing or use.
Traps
- Applying tile with a thick bed that flattens the slope - the finished surface must still drain.
- Using mastic or an unmodified thinset where the substrate or membrane requires modified mortar.
- Tiling tight to the drain without accommodating the strainer height, leaving a lip that ponds water.
- Omitting movement joints at changes of plane, leading to cracked tile or debonding.
- Grouting before the setting material cures, trapping moisture under the tile.
Rule of thumb
Check slope after tile is set, using a level and a straightedge from the drain to the farthest corner. If water would stand, the finish is wrong regardless of how good it looks.
Worked example
A finished shower ponds at the perimeter. The setter used a 3/4 in. mortar bed to level out uneven tile, flattening the preslope. Correct diagnosis: the finish layer destroyed the slope. The fix is to reset the tile to follow the sloped substrate, not to add a surface drain or drill weep holes.