Bathroom waterproofing
Failed bathroom waterproofing lets shower water seep through the floor slab, causing stains and drips below or damp walls next to the bathroom. Repairs range from injecting sealant into the leaking spot to hacking up the floor and laying a new membrane, and prices vary widely between methods.
Typical price
$450–$3,800per bathroom, depends on methodTypical job time
1 day for injection; about 1–2 weeks for hack and redo
Estimate, confirm on WhatsApp
Signs to look for
- A stain, drip or peeling paint on the ceiling of the flat below, under your bathroom.
- The leak below gets worse after showers and eases when the bathroom stays dry.
- Damp or bubbling paint on the wall outside the bathroom, near the door or kerb.
- Grout that stays dark, cracked or missing, especially around the floor trap and corners.
- Loose, cracked or hollow-sounding floor tiles.
Common causes
- A waterproofing membrane that has aged or cracked over the years.
- Cracked grout and gaps where tiles meet the wall, the floor trap or pipes coming through the floor.
- Renovation that disturbed the original waterproofing, such as changing floor tiles without relaying the membrane properly.
- A membrane that was not taken up the walls or over the kerb, so water escapes at the edges.
- Hairline cracks in the screed or slab under the tiles.
Before you call
Safe things to try first
- Keep the bathroom floor dry for two or three days and ask your neighbour below whether the drip stops. If it does, the leak is linked to water on your bathroom floor.
- Do a meter test with every tap off. If the meter stays still, a supply pipe leak is unlikely and waterproofing is the main suspect.
- Check the grout and silicone around the floor trap, shower area and kerb. Re-grouting can slow minor seepage but will not fix a failed membrane.
Stop and call if
- Water is dripping into the flat below, or near light fittings.
- The ceiling below is sagging or plaster is falling.
- Floor tiles are lifting or the floor feels soft underfoot.
What we do
- 1Confirm the source with a meter test and a controlled water test on the bathroom floor, to rule out supply pipes first.
- 2Find where water is getting in: grout lines, the floor trap, wall-to-floor joints, the kerb or pipe openings.
- 3Explain the options and their costs: injection into the leaking area, a membrane coating over the existing floor, or hacking the floor and laying a new membrane before re-tiling.
- 4Carry out the agreed repair. For a hack-and-redo, the new membrane is taken up the walls and over the kerb. HDB's guideline for HDB flats is that it turns up at least 150mm at walls and kerbs.
- 5Do a ponding test before tiling: flood the floor, leave it for a set period, often a day or more, and check below for drips.
- 6Check with the neighbour below after the repair, once the slab has had time to dry out.
How much it costs
Most bathroom waterproofing jobs in Singapore cost $450–$3,800 (per bathroom, depends on method). This is an estimate; the final price is confirmed on WhatsApp or on site before work starts.
- Injection repair$450–$950
- Membrane coating over the existing floor$500–$2,000
- Hack, re-waterproof and re-tile the floor$1,500–$3,800
- Full toilet redo$5,000–$8,000
HDB, condo and landed
HDB
Hacking bathroom floor tiles is renovation work under HDB's rules, so use a contractor on HDB's Directory of Renovation Contractors and check whether a permit is needed. New flats have a 5-year ceiling-leak warranty, which is void if the floor tiles are changed or the waterproofing is tampered with, so check before renovating.
Condo
Check the by-laws and get management approval before hacking. Leaks into the unit below are settled between owners under the strata framework, often with the MCST's help, not under HDB's rules.
Landed
You own the whole structure, so there is no cost sharing with neighbours. Check roof, balcony and planter box waterproofing too, as they fail in similar ways.
Bathroom waterproofing: common questions
How do I know it is the waterproofing and not a pipe?
If the water meter stays still with every tap off, and the leak below only shows after the bathroom floor gets wet, waterproofing is the likely cause. A pipe leak runs all the time and moves the meter.
What is a ponding test?
After a new membrane cures, the floor is flooded with a few centimetres of water and left for a set period, often a day or more. The ceiling below is checked for drips. Tiles go down only after it passes.
Can I just re-grout instead?
Re-grouting and resealing tired silicone can slow minor seepage and is worth doing anyway. It will not fix a membrane that has failed under the tiles.
Does injection waterproofing need hacking?
No. Small holes are drilled along the grout lines in the leaking area, sealant is injected under pressure, and the holes are sealed. It is quicker and cleaner than hacking but treats that area only.
How long before I can use the bathroom again?
After injection, often the same or next day. A hack-and-redo needs time for hacking, membrane curing, the ponding test, tiling and grout curing, which together usually take one to two weeks.
Get a price for bathroom waterproofing
Send a photo or short video, your home type and postal code. We reply with a price range and the earliest slot.
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