Updated 2026-10-10 ยท by Seepwise
Short answer: Hacking (re-screeding) renews the failed membrane and is what HDB describes as the most effective fix for ceiling leaks; it needs a permit and takes days. Non-hacking (PU injection) seals the specific cracks the water travels through without opening the floor; it is faster and less disruptive but does not replace a membrane that has failed across the whole wet area.
Seepwise writes these guides from HDB, MND and BCA sources and published Singapore price data; each claim links to where it comes from.
Side by side
| Hacking (re-screeding) | Non-hacking (PU injection) | |
|---|---|---|
| What it does | Removes tiles, screed and old membrane; lays new ones | Injects resin into the crack or joint the water uses |
| Fixes a failed membrane | Yes | No |
| Disruption | Noise, dust, bathroom out of use for days | Minimal, no hacking |
| HDB permit | Generally needed for hacking | Not for hacking |
| Ponding test | Yes, 24 hours or more before tiling | Not applicable |
| Best for | Membrane failure, renovation, long-term fix | Localised leaks, warranty or rental limits, a stopgap |
HDB calls re-screeding the most effective solution for ceiling leaks (HDB); permit rules for hacking: (Hometrust).
How to decide
- Is the leak localised? A dye or ponding test that shows water travelling along one crack or joint favours injection.
- Is the membrane old? Older flats where HDB notes membranes and screed have worn down favour re-screeding.
- Can you hack now? In a new flat inside the warranty, report to HDB instead. In a rental, injection may be the only option.
- How long must it last? If you plan to stay for years, renew the membrane.
Costs in context
Published 2026 contractor guides put a toilet waterproofing package (membrane, screed, ponding test) at roughly S$800 to S$2,500, with hacking and disposal S$800 to S$1,500 per bathroom (Triton, PRDT, Hock Star). Injection is priced by the length of crack treated after inspection.
Bottom line
Injection for a localised, confirmed leak path; re-screeding for a membrane that has failed. Any honest specialist will tell you which one your leak needs. Request an inspection.
Want this checked at your home?
A specialist calls you back to book an inspection.
Request received.
A specialist will contact you on the number you gave. If water is near electrics, switch off that circuit at the distribution board and keep clear until then.
More questions
Which lasts longer?
Re-screeding, because it replaces the membrane. Injection lasts well on a localised crack but cannot renew a failed membrane.
Which is cheaper?
Injection usually costs less up front. Re-screeding costs more but is the long-term fix when the membrane has failed.
Can I try injection first?
Yes, if the leak path is confirmed and localised. Ask what happens if the leak returns.