Toilet & Bathroom Waterproofing in Singapore

Toilet waterproofing stops water from your bathroom floor and walls seeping into the slab and the unit below. Depending on the damage, it's done with a no-hacking treatment (nano sealant or PU injection) for minor seepage, or full re-waterproofing, where tiles are removed and a new membrane is laid, water-tested and re-tiled.

Last updated November 2026

Why bathrooms leak

Every bathroom has a waterproofing layer, a membrane, under the screed and tiles. Tiles and grout aren't waterproof on their own. Over the years, that membrane can crack or break down, especially at the weak points:

• The floor trap: the joint between the trap and the floor is the most common leak point
• Wall-to-floor corners: where the membrane is folded up the wall
• Pipe penetrations: where water and waste pipes pass through the slab
• Grout and tile joints: grout becomes porous with age and lets water through
• Shower area: the most water-exposed zone, especially without a proper kerb or screen

Once water passes the tiles and finds a gap in the membrane, it soaks into the concrete slab and appears as a stain, bubbling paint or drips on the ceiling below.

Is it your bathroom or a pipe?

Not every bathroom leak is a waterproofing problem. A leaking concealed pipe causes damp patches even when nobody showers. A waterproofing failure usually gets worse after the bathroom is used, and dries out when it isn't. A simple test helps: avoid using the bathroom for a day or two and see whether the stain below dries. We confirm with a water test on the floor before recommending any work.

Option 1: No-hacking treatment

For minor seepage through grout and tile joints, the bathroom doesn't have to be torn up. Two common no-hacking methods:

• Nano / penetrating sealant: a clear coating applied over clean, dry tiles and grout. It seals the pores and hairline gaps water passes through. See nano waterproofing.
• PU injection: polyurethane resin is injected through small holes into specific cracks or gaps, where it expands and seals the leak path.

Pros: fast (usually about a day), no dust or debris, cheaper, no HDB hacking permit needed.
Limits: it can't rebuild a membrane that has completely failed. If the leak is widespread or has been going on for years, it may only be a temporary fix.

Option 2: Full re-waterproofing (with hacking)

When the original membrane has failed, the long-term fix is to replace it:

1. Remove old tiles and screed down to the slab
2. Repair and prepare the surface, paying attention to corners, pipes and the floor trap
3. Apply a new waterproofing membrane, turned up the walls
4. Water test (ponding test) to prove the membrane holds before anything covers it
5. Screed and re-tile

Pros: the lasting solution, and a chance to update your tiles.
Limits: takes longer, costs more, the bathroom is out of use during the work, and HDB flats need a renovation permit.

Nano vs full re-waterproofing at a glance

	No-hacking (nano / PU)	Full re-waterproofing
Best for	Minor seepage, specific cracks	Failed membrane, long-running leaks
Time	Usually about a day	Several days (membrane cure + water test)
Mess	Minimal	Hacking dust and debris
HDB permit	Not needed	Needed
Cost	Lower	Higher

HDB owners: rules to know

• Hacking bathroom floor or wall finishes in an HDB flat needs an HDB renovation permit.
• Newly completed BTO flats have a 3-year restriction on removing bathroom finishes, so no-hacking methods are the option during that period.
• For a leak into the flat below, responsibility is usually shared between both owners, unless the upper flat's renovation caused it. Read our ceiling leak guide.

What affects the price

• No-hacking treatment or full re-waterproofing
• Bathroom size and number of bathrooms
• Replacement tiles chosen (for full re-waterproofing)
• Whether the ceiling below needs repair or repainting
• Extra work: floor trap replacement, shower kerb, pipe repairs