Is your HDB toilet leaking? Straightforward comparison of PU injection and full-hack waterproofing — real costs, pros and cons, and how to choose.
Waterproofing conversations in HDB toilets always start the same way: “Can’t they just inject something from inside?” Sometimes yes, sometimes no. The right method depends on where the leak is coming from.
Polyurethane injection targets active leaks by drilling small access holes and pressurising sealant into the gap. Cost typically $300–$600 per toilet for the no-hack approach.
Best for: seepage through tile joints, minor cracks, and cases where you want minimum disruption. Works best when the waterproofing layer is still mostly intact underneath.
Hacking means removing floor and wall tiles, stripping to the substrate, re-doing waterproofing membrane, then retiling. Cost generally $1,200–$3,000+ depending on tile choice and toilet size.
Best for: extensive membrane failure, recurring leak after injection, or if you’re already renovating anyway.
A good contractor should do a water test first (wet the toilet floor above, observe the lower unit). That simple test tells you whether the leak is surface-level or structural. If they quote a method without testing, get a second opinion.
PU injection warranties are typically 3–5 years. Full waterproofing warranties are often longer, sometimes matching the HDB lease expectation. Keep records and photos; disputes are easier with evidence.