On 20 May 2016, a giant rooftop of Chan Tai Ho Hall at the City University of Hong Kong (the “University”) came crashing down without warning, injuring three people in the hall. It is believed that the grass-covered roof, spanning 1,400 square metres, was overloaded which led to the collapse eventually.

The accident highlights the risk of overloading rooftops with plants and soil and calls into question the lack of government supervision of green rooftops. The legality of green rooftops also arouses public concern as the University admitted that no building plans of the structures had been submitted to the Building Authority for prior approval.

The law

According to section 14(1) of the Buildings Ordinance (Cap. 123) (the “Ordinance”), approval and consent from the Building Authority must first be obtained before carrying out any building works. Failure to do so constitutes a breach of the Ordinance. The term “building works” is given a wide definition as “any kind of building construction, site formation works, ground investigation in the scheduled areas, foundation works, repairs, demolition, alteration, addition and every kind of building operation, and includes drainage works”.

Nevertheless, this does not mean that each and every building work has to be subject to the Building Authority’s prior approval. Some exemptions are provided in section 41 of the Ordinance, in particular, section 41(3) states that where the building works do not involve the structure of the building, the approval and consent required under section 14(1) of the Ordinance will be dispensed with.

Are green roof projects exempted building works?

There is a hot debate as to whether green roof projects should be regarded as exempted building works. Some are of the view that no formal submission to the Building Authority is required so long as the green rooftops are constructed in accordance with the relevant building laws and regulations. While placing of flower pots or laying of soil can be outside the scope of section 14(1) of the Ordinance, those green roof projects involving demolition, alteration and addition of structures or drainage systems ought to be bound by the Ordinance.

In fact, this issue has already been dealt with by the Court of Final Appeal in Mariner International Hotels Limited & Anor v Atlas Limited & Anor FACV 3/2006. The Court noted that two requirements had to be satisfied for section 41(3) to apply:

  1. the building works must not involve the structure of a building; and
  2. the building works must be in a building.

For building works on the roof of a building, the Court of Final Appeal held that such works could not fall within the section 41(3) exemption because (i) those works added to a building involved its structure if the works served a structural function or were capable of affecting the integrity of the structure; and (ii) building works on the roof of a building were not “in” the building.

The Court also noted that the Ordinance should be construed purposively and that the exemption under section 41(3) had to be construed narrowly because one purpose of the approval scheme of the legislation was to protect the public by subjecting the matter of structural acceptability to the scrutiny of the Building Authority.

Actions to be taken

The current regime relies heavily on owners taking initiative to submit plans for approval if they intend to carry out building works which involve the structure of a building. In other words, the government is in the dark if the owners skip such formalities, whether intentionally or not.

Adding greenery may be too much for a roof to bear, compounded by laxity over the submission of building plans for structural changes, both the government and the owners should be more proactive to avoid any other collapse incidents.

The government has been promoting rooftop greenery but it has not provided sufficient measures and guidelines to regulate the quality and safety of such green roofs. The government should consider revising the wordings of the Ordinance to make it clear that any alteration on the roof of a building is not exempted under section 41(3) of the Ordinance. Meanwhile, the Building Authority should remind owners to submit plans for new structures.

As for the owners, the construction of green roofs usually involves the installation of drainage system, which can be an Achilles’ heel. If the system is not installed properly, it can result in water gathering on the roof, leading to dangerously high loading which can jeopardise the structure of the building. Even if there are no structural alterations, the plants and soil also add weight to building structures and put an extra load on the roof. Therefore, for prudence sake, owners should engage an Authorised Person (e.g. a building surveyor, a structural engineer or an architect) to conduct a site inspection to determine whether a building work belongs to a structural work and submit the relevant building plans to the Building Authority for approval where necessary.

For enquiries, please contact our Property Department:
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Important: The law and procedure on this subject are very specialised and complicated. This article is just a very general outline for reference and cannot be relied upon as legal advice in any individual case. If any advice or assistance is needed, please contact our solicitors.
Published by ONC Lawyers © 2016