ROOF WATERPROOFING
Roof Waterproofing: Even the Government Says This Is on You
Quick answer
Roof waterproofing (coating-type or membrane/felt-type, replacing the waterproofing layer) is Designated Exempted Works Item 29 under the Buildings Department's Minor Works Control System — no registered minor-works contractor required, though it explicitly excludes any work that removes tile or screed layers (that scope needs a registered contractor). Just as important: seepage caused by rainwater penetrating a roof is normally not a case the Joint Office can act on as a public-health nuisance — the government's own guidance is to hire a building professional. For a top-floor flat, private roof waterproofing is usually your main route to a fix.
Regulatory scope (verified against the Buildings Department page)
Designated Exempted Works Item 29 covers installing or replacing a roof-surface waterproofing layer, coating-type or membrane/felt-type only — it explicitly excludes any work that lays or removes a tile layer or screed layer. In practice: pure coating/membrane surface renewal doesn't need a registered minor-works contractor, but any work that opens up tile or screed layers does (falling under Minor Works classes 1.62 / 2.34). We match the scope of your job to a partner holding the matching registration.
Pricing
| Item | Reference price | Note |
|---|---|---|
| Exposed-oil surface coating | from HK$130/sq ft | Published operator rate; actual price depends on area and substrate condition |
| Full removal (incl. tile/screed removal) | from HK$260/sq ft | Involves tile removal — requires a registered minor-works contractor |
| 800 sq ft whole roof (surface coating) | from approx. HK$140,000 | Estate/village-house scale reference, per-sq-ft basis |
| 800 sq ft whole roof (full removal) | from approx. HK$260,000 | As above |
| Small top-floor patch repair | HK$3,500-7,000, or injection pricing | For a localized patch, not a whole-roof job |
These figures are compiled from published operator pricing, not our own invoiced data. Actual quotes depend on substrate condition, building height and drainage design — we always assess on-site before quoting.
Warranty
Market convention scales warranty with system tier: coating-type work typically 5-7 years, full-removal work up to 10 years, with the overall market spread at 2-10 years. Warranty terms should state trigger conditions in writing — we spell these out before you book.
Top-floor flat leaking? Send a photo on WhatsApp to arrange an inspection
Our WhatsApp and phone hotline are launching soon — please use the form below in the meantime and we'll reply as quickly as we can.
Frequently asked questions
Can the Joint Office handle a leaking roof?
Rain ingress through a roof is normally outside the Joint Office's scope — the government's own guidance is to hire a building professional. If you're a top-floor owner, private roof waterproofing is usually your main route.
Does roof waterproofing require a registered contractor?
Pure coating/membrane surface renewal is a designated exempted minor work and doesn't require one. But if the job involves removing tile or screed layers, it must be done by a registered minor-works contractor — we match your scope to the right registration.
Surface coating or full removal — which do I need?
It depends on the condition of the existing waterproofing layer. If the substrate is sound and just aging, a surface coating is usually enough. If seepage has reached the structural layer or the tile/screed is deteriorating, a full removal and rebuild is needed. An on-site inspection is the only way to tell for sure.