Water Leaking From the Rooftop or Flat Roof? Who's Liable in Hong Kong

Water starts coming through the ceiling of the flat below, and tracing it up leads to the rooftop or a flat roof. The natural next move is to go to the top-floor owner; if that goes nowhere, the next move is the Owners' Corporation. And more often than not, both sides say the same thing: "not my problem." The top-floor owner says the roof's waterproofing is a common part and the corporation is responsible for it; the corporation says the roof was assigned to the top-floor owner for exclusive use long ago, so it isn't theirs to fix.

This standoff isn't usually either side lying — it's because rooftop liability genuinely splits into two separate questions: who owns the roof, and who is responsible for maintaining it, and those two answers don't always belong to the same person. This guide walks through how to read a building's Deed of Mutual Covenant, whether a waterproofing layer counts as a common part in law, and what to do — and who to pursue — when it's genuinely unclear.

Why Does a Rooftop Leak End Up With Nobody Taking Responsibility?

Unlike a leak from a private unit above, a rooftop or flat-roof leak typically involves more than one party by its very nature — it might be the roof's own structure or waterproofing layer deteriorating, or it might be damage the top-floor owner caused themselves by building an extension or altering the roof. That built-in complexity is exactly what lets the top-floor owner and the corporation point at each other.

This article covers leaks originating from the rooftop or flat-roof structure itself, seeping into the top-floor unit or the unit below — a different scenario from other water-leakage articles on this site. Our guide to leaks from a private unit above covers a dispute between two private units; our guide to common-area pipe leaks covers pipework that is unambiguously a common part, with no exclusive-use question attached. What this article specifically addresses is the three-way pull that happens when the roof's ownership may already sit with the top-floor owner, but liability for the leak can still land back on the corporation.

Check the Deed of Mutual Covenant First — It Decides Who You're Pursuing

A Deed of Mutual Covenant (DMC) is the legally binding document that sets out every owner's, tenant's and management company's rights, duties and responsibilities for the building — including which areas are common parts and which are an individual owner's exclusive or private area. Getting rooftop liability right starts with checking the DMC, not guessing from instinct.

If the DMC assigns the roof to a unit owner, that roof area can be included ("入契") in that owner's title at purchase, making it part of their own property with a right of use. Conversely, if the DMC treats the roof as a common part, it belongs to all owners collectively. This single question decides who you should even be approaching first — if the roof was never assigned to anyone, go straight to the corporation and skip the exclusive-use argument entirely.

You can check the DMC yourself at the Land Registry, or instruct a solicitor to do it for you. A DMC will often also specify whether the owner with exclusive use of the roof carries an attached maintenance obligation — that clause, more than the roof's assignment itself, is usually what actually decides who has to pay for repairs.

Even If the Roof Is Assigned to the Top-Floor Owner, the Waterproofing Layer May Not Be Their Responsibility

This is where most people get it wrong. Even where the DMC grants the top-floor owner exclusive use of the roof, that doesn't automatically mean everything on that roof becomes their personal property.

It depends on whether the leak's source is the waterproofing layer: if that layer was installed for the whole building (i.e. it protects not just the roof but the structure of the building beneath it), a Lands Tribunal case (LDBM249/2000) ruled that even where the roof itself is assigned to an individual owner for exclusive use, the waterproofing layer remains a common part of the building — the roof being carved out as exclusive-use area does not change the common nature of the waterproofing layer itself. In other words: ownership and maintenance liability can be two different answers under the law.

Applying that principle, the split generally runs like this:

Source of the leak	Who's generally liable
The roof's original waterproofing layer deteriorating or failing (installed for the whole building)	The Owners' Corporation
Damage the top-floor owner caused themselves — an extension, an alteration, or their own renovation work on the roof	The top-floor owner
A common facility on the roof (e.g. a water tank, a shared drainage pipe) failing	The Owners' Corporation

Under the Building Management Ordinance (Cap. 344), the Owners' Corporation must keep common parts and corporation property in good and usable repair, and must comply when a public officer or public body lawfully requires work on common parts. That statutory duty doesn't disappear just because the roof has been assigned to a particular owner — if the source really is the waterproofing layer itself, "the roof is theirs" isn't a defence the corporation can hide behind.

Can't Pin Down the Source? The Joint Office Can Help

Visual inspection alone often can't confirm the source, let alone whether it counts as "installed for the whole building." The safer route is to report it to the Joint Office for Investigation of Water Seepage Complaints (call 1823 or submit online).

The Joint Office contacts the complainant within 6 working days of receiving a report, conducts a site inspection, and carries out systematic non-destructive testing to identify the source — the rooftop is one of the common sources it deals with. Its role is to investigate and follow up on the nuisance the leak is causing; it does not decide who owes you compensation. Its findings, though, can become important evidence for whatever claim you pursue afterwards.

If the Joint Office's conclusion remains ambiguous — or even points to both the common-part waterproofing layer and the top-floor owner's own alteration — you don't have to gamble on picking one side. Where the evidence genuinely doesn't point clearly to a single party, you can name both the top-floor owner and the Owners' Corporation as co-defendants, and let the adjudicator weigh the evidence from both sides.

Evidence to Prepare Before You Pursue a Claim

Whether you end up negotiating a settlement or filing at the Tribunal, having your evidence in order is what gives you leverage:

Evidence type	Recommended approach
Joint Office findings/notices	Keep the original and a copy, especially any part linking the source to the rooftop waterproofing layer or to the top-floor owner's own alterations
A copy of the relevant DMC clauses	Especially the clauses on exclusive use of the roof and any attached maintenance obligation
An independent surveyor's or plumber's opinion	To help establish whether the source is the ageing waterproofing layer or damage from the top-floor owner's own alterations
Photos/videos of the leak	Record continuously from the day it's discovered, with dates and times
Repair quotations (2–3)	Itemising materials and labour, to support your claimed amount
Written correspondence with the corporation/top-floor owner	WhatsApp, email or letter screenshots, dated, especially anything acknowledging the source or promising follow-up

For how to turn this evidence into a hearing-ready bundle, see the Small Claims Tribunal evidence preparation guide; if you want to send a formal demand letter before filing, there's a template in the demand letter guide. One of our published case notes describes a successful claim for a ceiling leak left unrepaired for three years — a different kind of leak (a private-unit dispute, not a rooftop one), but the same underlying lesson: what an adjudicator actually weighs is the record you can produce showing the other side knew, or should have known, not who tells the better story.

Negotiation Failed? Filing at the Small Claims Tribunal

If the top-floor owner or the corporation keeps stalling or refuses to repair or compensate you, and the loss (including losses already incurred and reasonably anticipated) is HK$75,000 or below, you can consider filing a claim at the Small Claims Tribunal.

Before filing, it's worth sending a formal demand letter clearly stating the amount claimed and a deadline, and keeping proof it was sent. If the other side still ignores you, you can go in person to the Tribunal registry to submit Forms 1 and 2 and pay the filing fee — fees are tiered by claim amount: HK$20 for claims up to HK$5,000; HK$40 for HK$5,001–$25,000; HK$70 for HK$25,001–$50,000; HK$120 for HK$50,001–$75,000 (fees are set by subsidiary legislation and may change — check the Judiciary's latest published schedule before filing).

Where the evidence clearly points to a single party, name that party as defendant (the top-floor owner's name, or the corporation's official registered name, typically "The Incorporated Owners of [Building Name]"); where the source is still unclear, you can name both as co-defendants. At the hearing, the adjudicator will consider the Joint Office's findings, the DMC's terms, photographic evidence and repair quotations in deciding liability. If you'd like someone to walk through checking the DMC and preparing your filing with you, see what our filing assistance service covers and how it's charged; if your situation matches a different water-leakage scenario, our water leakage case overview may be a more useful starting point.

Note that general civil claims for property damage must generally be brought within 6 years from the date the cause of action arose — so it pays to preserve evidence and act early. Even a successful judgment isn't automatically enforced — if the other side still doesn't follow through, you'll need to apply for a writ of execution yourself; see how to enforce a Small Claims Tribunal judgment for the details.