What is bathroom waterproofing?
Bathroom waterproofing is a flexible waterproof layer applied to the bathroom floor slab, usually a sunken slab, before filling and tiling, turned up the walls and taken to full height in the shower area. Pipes, floor traps and the junction with the door frame are sealed with reinforcing fabric and compatible sealants.
Because a sunken bathroom is filled with brickbat, lightweight concrete or other filling, any water that passes the tiles collects inside the sunk. The membrane must hold that water and drain it to the trap, otherwise it seeps out through the slab and walls.
Benefits
- Stops seepage to the flat below and adjoining rooms
- Pipe and floor-trap penetrations detailed to the membrane
- Wall upturns and full-height shower zones
- Ponding test before tiling, so problems are found before finishes
Common problems and applications
Problems it solves
- Damp patches and stains on the ceiling below a bathroom
- Wet walls and peeling paint in rooms adjoining the bathroom
- Swollen door frames and damp skirting near the bathroom door
- Leaks around floor traps and concealed pipes
- Water stagnating inside the sunken slab
Where it is used
- Bathrooms and toilets in apartments and villas
- Hotel rooms and hospital wet areas
- Office and mall washrooms
- Kitchens and utility areas
Our bathroom waterproofing process
Locate the source
We check whether the leak is from supply pipes, drainage, the floor trap, tile joints or the waterproofing itself, using water tests where needed.
Strip to the slab
For a failed bathroom, tiles and filling are removed down to the structural slab.
Prepare and detail
The slab is cleaned and repaired, pipe sleeves are sealed, coving is formed at the wall junction and the trap is fixed level with the membrane.
Apply membrane
A two-coat flexible membrane is applied with fabric at corners, pipes and the trap, turned up walls and to full height in the shower zone.
Ponding test
The sunk is filled with water for the test period and checked from below.
Filling and tiling
Filling, screed and tiles are laid without damaging the membrane, with epoxy grout in wet zones.
Materials and systems used
- Flexible cementitious membranes
- Two-component polymer coatings suited to sunken slabs and walls.
- Liquid PU or acrylic membranes
- For walls and high-movement areas.
- Reinforcing fabric and pipe collars
- At corners, pipes and floor traps.
- Epoxy grout
- For tile joints in showers and wet zones.
Products are selected from the approved specification. Coverage, thickness and curing follow the manufacturer's current data sheet.
Why professional waterproofing is important
Bathroom repairs are disruptive and expensive, because tiles, filling and fittings all come out. Most bathroom failures trace back to an unsealed pipe, a floor trap fixed after waterproofing, or a membrane damaged by filling material. These are avoided by sequencing plumbing before waterproofing and testing before tiling.
A professional contractor also tells you when the problem is a plumbing leak rather than waterproofing, so you do not pay to replace a bathroom that only needed a pipe repair.
Why choose us
- Diagnosis first
- We separate plumbing leaks from waterproofing failures before recommending work.
- Penetrations treated properly
- Pipes and traps are sealed into the membrane, not patched around.
- Tested before finishes
- Ponding test and check from below on every bathroom.
- Large project experience
- We have treated toilet blocks across multi-storey residential projects.
Read more about our team and how we inspect and record work.
Frequently asked questions
Can bathroom leakage be fixed without breaking tiles?
If the leak is through tile joints only, epoxy re-grouting can solve it. If the membrane or a pipe inside the sunk has failed, tiles and filling must come out to repair it properly.
How high should bathroom waterproofing go on the walls?
Typically at least 300 mm above floor level around the bathroom, and higher, often to the full shower height, in the shower area. The exact height follows the specification.
How long should a ponding test last?
A ponding test is usually maintained for at least a day, or as stated in the project specification, while the ceiling below is checked.
Do you also handle leaking bathrooms in new projects before handover?
Yes. We work on new construction and on snag lists before possession. See new construction waterproofing.
