Unauthorised Building Works: What a Hong Kong Renovation Can and Cannot Do

The Buildings Department defines unauthorised building works as any additions or alterations inside a building, and building works outside it, carried out without the prior approval of the Building Authority. Two further categories are easy to miss: small-scale building works that are designated as minor works but did not follow the simplified requirements of the Minor Works Control System, and addition and alteration works carried out inside a building not involving structure but which do not comply with building standards.

That third limb is the one owners rarely expect. Works can involve no wall, no beam and no column, and still be unauthorised because the result falls short of a building standard.

The works the department says are most frequently found are worth reading with a renovation in mind: air-conditioner supporting frames, canopies, flat roof structures, rooftop structures, flat subdivision, signboards, structural alterations, and drainage misconnections. Several of those are ordinary renovation requests.

The department is also explicit about where responsibility sits. Owners have the responsibility to ensure their premises are free from unauthorised works and should, in their own interest, arrange for their demolition. For works in common areas, the owners' corporation or co-owners should coordinate demolition between themselves.

The picture is less restrictive than the word 僭建 suggests. Hong Kong sorts domestic works into three tiers, and most of an ordinary flat renovation sits in the least onerous one.

• Exempted works, no approval and no professionals required. The department names plastering, laying tiles and the repair or replacement of sanitary fitments. It also states that the removal of non-structural partition walls is generally considered exempted building works, which can be carried out without obtaining prior approval and consent.
• Minor works, notification instead of approval. Erecting non-load-bearing brick walls, and erecting or altering supporting frames for air-conditioning units and drying racks projecting from external walls, run through the Minor Works Control System. The work is done by a prescribed registered contractor following the procedure, and it is the failure to follow that procedure, not the work itself, that turns it into an unauthorised work.
• Works needing approval and appointed professionals. Where the structure of the building is involved, for example the removal of a structural wall, beam or column, the owner is required to appoint an authorised person and a registered structural engineer.

Two cautions belong with that list. First, the exemption for partition walls depends on the wall actually being non-structural, which is a question answered by the approved plans, not by tapping it. Second, an exemption under the Buildings Ordinance is not consent under your deed of mutual covenant. The management office and the statutory process are separate gates and neither substitutes for the other.

Enclosing a balcony or utility platform. This is the most common and the most misunderstood. Balconies and utility platforms are granted their exemption on conditions, and the department states that enclosing such features above the parapets by windows, glass panels, grilles, solid walls or the like would breach the condition of the exemption and result in a contravention of the Buildings Ordinance. The glazing contractor who says everyone does it is describing a habit, not a permission.

Drainage alterations. Drainage misconnection sits on the department's own list of frequently found unauthorised works, and for alterations to a toilet, bathroom or kitchen and the associated drainage works, the department should be notified before commencement and after completion. Moving a toilet or relocating a kitchen sink is not a free decision; it is a notifiable one.

Removing walls without checking what they are. Removing a non-structural partition is generally exempted. Removing a structural wall without an authorised person and a registered structural engineer is a different thing entirely. The decision therefore rests on the approved plans, which is why we obtain and read them before promising any layout change, rather than deciding on site with a hammer.

Flat subdivision also appears on the department's list, which is worth noting for anyone renovating with letting in mind.

This is where secondary summaries mislead by omission. Failing to comply with a statutory order is a criminal offence, and the department states the maximum penalty as one year's imprisonment and a fine of HK$200,000, together with a further fine of HK$20,000 for each day the offence continues.

That daily figure is the part routinely left out, and it changes the arithmetic completely. Real outcomes show it compounding: in a single prosecution reported in May 2024, ten owners of five village houses in Tai Po, Tuen Mun and Yuen Long, with rooftop or ground-level unauthorised structures ranging from 28 to 80 square metres, were fined more than HK$450,000 in total, the largest individual fine being HK$180,160.

Two consequences matter as much as the fine:

• The department does the work and bills you. If an owner does not comply, the department instructs government contractors to carry out the demolition and subsequently recovers the full works cost from the owner, plus supervision charges and a surcharge.
• The order is registered against the property. The order is recorded at the Land Registry, and where the property is mortgaged, the financial institution is notified. This is the consequence owners feel most, because it surfaces at exactly the wrong moment, during a sale or a refinancing.

Enforcement is risk-based rather than comprehensive, and the numbers are larger than most owners assume. In a Legislative Council reply of 13 May 2026, the Development Bureau described a risk-based approach that gives priority to works posing an apparent threat or imminent danger to life and property, and stated that the department issues in the order of 7,000 to 10,000 removal orders each year and removes more than 20,000 existing unauthorised structures annually.

The same reply is candid about backlogs. In the south-west New Territories region, 129 removal orders relating to higher-risk unauthorised works remained overdue as at March 2026, with 46.5 per cent of those overdue by three years or less.

The practical reading for an owner is neither panic nor complacency. A long-standing structure may sit untouched for years, and then become urgent the moment it is reported, the moment the building comes up in a large-scale operation, or the moment you try to sell.

Here is where most coverage goes wrong, so it is worth being precise. In December 2024 the Development Bureau proposed amendments to the Buildings Ordinance along three lines: speeding up building inspection and repair, rationalising the policy on unauthorised building works, and enhancing building safety. On unauthorised works the proposals would:

• Distinguish minor works connected with daily life, the bureau's examples being drying racks and supporting frames for air-conditioners or canopies, from serious works such as unauthorised basements, enclosed rooftop structures and podium or backyard structures.
• Consolidate three existing urban validation schemes into one integrated scheme, under which owners could retain minor works meeting specified dimensions, the examples given being canopies, supporting frames for air-conditioners, enclosed balconies and signboards, after a one-off or regular validation, with a grace period of three years from implementation.
• Raise penalties. For serious unauthorised works the maximum would rise from HK$200,000 and one year to HK$300,000 and two years, and to HK$600,000 and two years on a subsequent conviction. For minor works a subsequent conviction would carry up to HK$400,000 and one year.

None of that is law. These remain proposals following a public consultation, and the timetable has already moved: the December 2024 papers targeted introduction of the bill in the first half of 2026, while the Development Bureau's Legislative Council reply of 13 May 2026 states the bill will be submitted in the second half of 2026. Any article telling you that enclosed balconies can now be validated, or that a three-year grace period is running, is describing a proposal as though it were in force. Until the bill passes, the current law is the law, and the current law is the penalty set out above.

Unauthorised works attach to the property, not to the person who built them. A buyer who completes on a flat with an existing unauthorised structure inherits the problem, and if an order is later served it is served on the current owner. This is why the department's registration of orders at the Land Registry matters so much in practice: it is the mechanism by which a previous owner's shortcut becomes a present owner's condition of sale.

Practical sequence before you commit to a purchase and a renovation budget: obtain the approved plans for the unit and compare them with what is physically there, ask your solicitor to check the Land Registry for any registered order, and treat anything on the department's frequently found list, rooftop and flat roof structures, enclosed balconies, canopies, subdivided layouts, altered drainage, as something to price rather than assume away. If the plan is to renovate anyway, this survey is work you were going to do regardless; doing it before exchange is simply cheaper than doing it after.

Nearly every unauthorised work created during a renovation comes from one of three places: nobody read the approved plans, nobody ran the notification the Minor Works Control System required, or somebody treated an exemption condition as decoration. None of those is a design failure. They are coordination failures, which is why they are avoidable.

What that looks like in practice on our projects: obtain the approved plans before any layout is promised, so structural walls are identified on paper rather than discovered behind a finish. Establish at survey stage which items are exempted, which are minor works requiring a prescribed registered contractor and the proper notification, and which need an authorised person and a registered structural engineer. Handle the deed of mutual covenant and management office consents on a separate track from the statutory ones, because clearing one has never cleared the other. And treat the balcony, the utility platform and the drainage as the three places where a client's reasonable request and the Buildings Ordinance most often disagree, so the conversation happens at the drawing stage rather than after the glazing is installed.

We should be straight about the limits of that. Nobody can regularise existing unauthorised works for you, and any firm that offers to make an order go away is offering something it cannot deliver. What a design and build team can do is make sure your renovation does not add to the problem, tell you honestly what is already there before you spend money on top of it, and carry the coordination of drawings, notifications and consents as part of one programme rather than leaving them scattered between trades.

If you are weighing up a flat with structures you are unsure about, or planning a layout change and want to know which parts are exempted before you fall in love with the drawing, send us the floor plan and a few photos. We will tell you which category the works fall into and what the process actually requires.