Liquid waterproofing applied: last check before tiling

By Peter Wey and Dominik GrolimundLast reviewed August 10, 2026

Liquid-applied waterproofing is the only layer that keeps your bathroom watertight. Tiles and grout are not. Once tiled, you will never see this layer again — and a failure means ripping the bathroom open. Corners and shower drains are especially critical.

The most expensive defects in liquid waterproofing

Missing sealing tapes at corners and junctions

Internal corners, floor-to-wall junctions and door thresholds need embedded tapes. Liquid membrane alone cracks there.

Shower channel and drains incompletely sealed

Level-access showers stand or fall with the seal at the channel. Gaps there mean water damage under the finish.

Unsealed pipes and drains

Pipes for taps and drains need a sealing collar (glued moulded part around the pipe). If it is missing, water runs into the wall exactly there.

Waterproofing applied too thin or too low

Substrate showing through or insufficient height in the shower are typical causes of later moisture damage.

What to document and check now on the waterproofing

All wall surfaces in the wet area
Photograph the waterproofed surfaces completely, wall by wall. Ensure an evenly covering surface with no substrate showing through.
Corners, shower channel and junctions in detail
Photograph internal corners, floor-to-wall junction, channel and door area individually. A continuously embedded sealing tape must be visible in every corner.
All pipe connections with collar
Photograph tap connections, drains and pipe penetrations close up. Check if the collars fit tightly without visible gaps.
Waterproofing height in the shower area
Check and photograph if the waterproofing in the shower is applied clearly beyond the splash zone (at least above the shower head).
Briefly ask in writing before tiling begins
Ask by email if corners, channel and pipes are completely waterproofed. A written answer is later worth more than a verbal promise on site.