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LC Urgent Q2: Immediate follow-up actions on the collapse of a roof with green vegetation

Following is an urgent question by the Hon Starry Lee under Rule 24(4) of the Rules of Procedure and a reply by the Acting Secretary for Development, Mr Eric Ma, in the Legislative Council today (May 25):

Question:

On the 20th of this month, the entire roof of the Chan Tai Ho Multi-purpose Hall at the City University of Hong Kong (CityU) collapsed abruptly, injuring three persons.  There are comments that CityU carried out works to cover the roof in question with green vegetation early this year, thus putting an additional load on the roof, and the vegetation thoroughly soaked by the rain in recent days had added further load to the roof.  As a result, the roof, which was mainly built on a metal frame structure, collapsed due to overloading.  CityU indicated that as the contractor responsible for the greening works considered that the works would not affect the building structure, CityU had not applied to the Buildings Department for an approval for undertaking the works.  In this connection, will the Government inform this Council:

(1) whether it knows the current number of buildings in Hong Kong the roofs of which are mainly built on metal frame structures and covered with greening vegetation, as well as their geographical distribution; whether it will immediately inspect the roofs of those buildings to ensure their structural safety; if it will, of the details, if not, the reasons for that; and

(2) whether it will immediately formulate guidelines to require that approval must be obtained from the Buildings Department prior to undertaking any rooftop greening works the coverage of which exceeds a prescribed area; if it will, of the details; if not, the reasons for that?

Reply:

President,

As mentioned in my reply to the Hon Chan Hak-kan's question just now, generally speaking, greening works at rooftops should pose no risk to safety if the roof loading has been evaluated by building professionals and that there are proper maintenance and repairs.  In view of this roof collapse incident, relevant departments will ascertain through various channels any green roof of large areas in the territory that might have been carried out without prior evaluation by building professionals.  Immediate actions will be taken against any such case found.  In particular, the Buildings Department (BD) has disseminated information to schools and will issue a circular to the building industry on the relevant matters.  The BD and other relevant departments will shortly arrange a series of briefings for school administrators and relevant stakeholders.

My reply to the two parts of the question is as follows:

(1) On private buildings, the BD has not compiled statistics on the number and locations of buildings in Hong Kong the roofs of which are built on metal frame structures and covered with greening vegetation.  On Government buildings, as I mentioned in my reply to the Hon Chan Hak-kan's question, according to the record of the Architectural Services Department (ArchSD), among the Government facilities of which it is responsible for maintenance, greening facilities installed over long-span metal structures are found in the Ping Shan Tin Shui Wai Swimming Pool, the Victoria Park Swimming Pool, the Sai Kung Tseung Kwan O Government Complex, and the New Wing of the Ko Shan Theatre.  The ArchSD has finished inspection of the facilities, all of which were found in normal conditions.

(2) The scope of greening work is wide-ranging, and their extent and nature can vary greatly.  A categorical answer that fits all circumstances cannot be given to the question of whether carrying out roof greening for private buildings amounts to building works that require the prior submission of plans for BD's approval.  It is also hard for the BD to lay down hard-and-fast rules to cater for all situations in an exhaustive manner.  As I mentioned when replying to the Hon Chan Hak-kan's question just now, if the greening is of a substantial scale, the relevant owner should consult authorised building professionals on matters such as roof loading.  The professionals will advise the owners on the need for seeking the BD's consent for the works.  Generally speaking, if the greening works at rooftops involve the demolition, alteration or addition of structures or drainage systems, or even involve changes in the gross floor area or structural members of the building, the greening work concerned will be subject to control under the Buildings Ordinance (the Ordinance).  According to the Ordinance, any person who wants to carry out any building works in private buildings, unless such works meet the requirements of exempted works or are qualified to be carried out as minor works under the simplified procedures of the Minor Works Control System, should appoint an authorised person to submit plans (including structural plans showing the calculations of roof loading capacity) to the BD for the latter's approval and consent for works commencement in accordance with section 14 of the Ordinance, before such works can commence.  In view of this roof collapse incident, the BD will examine the need to provide the industry with further guidance on whether roof greening works require its prior approval.
 
Ends/Wednesday, May 25, 2016
Issued at HKT 19:43

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