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Frequently asked questions

Unauthorised Building Works

The following measures are adopted to monitor and verify new UBW :

  1. Aerial photos are used to identify new UBW on rooftops.
  2. Record photos of buildings are kept for verifying the status of new UBW.
  3. Results of enquiries and circumstantial evidence.

Yes, prior approval and consent from the BD are required for erecting prefabricated structures including mobile houses and man-size storage cabinets exceeding 3m3 in volume or 2m in height, or construction of glass houses on the main roof, flat roof or open yard of a building. You should appoint an authorized person to submit building plans and to coordinate the building works, and a registered general building contractor to carry out the works after obtaining BD's approval and consent. Such works cannot be carried out by a registered minor works contractor. Any person contravening the above requirements may be subject to prosecution and/or disciplinary action under the Buildings Ordinance. Any such structures constructed in contravention of the above requirements are unauthorised building works which would be subject to enforcement action by the BD.

While prefabricated cabinet not exceeding 3m3 in volume and 2m in height may be erected on the main roof, flat roof or yard of a building, the building owners should ensure the general stability of the cabinet and observe the following requirements:

  1. the cabinet does not adversely affect the structure of the building;
  2. the fire escape route or refuge area of the building is not obstructed; and
  3. the drainage system of the building is not adversely affected.


If physical alteration to the approved green balcony and utility platform is found, immediate enforcement action under the Buildings Ordinance would be warranted when the alteration works is being/has been carried out in the following situations:

  1. without prior approval and consent from Buildings Department (BD); or
  2. contravention of the provisions of the BO and allied regulation is identified if the simplified requirements under Minor Works Control System is being adopted.

Removal of the partition wall between two adjoining units having green balconies and utility platforms may involve structural elements which lead to contravention to the BO. The alteration works involved may also lead to contravention of other provisions of the BO and allied regulations such as the exemption criteria for green balconies and utility platforms in the building concerned. The owners are strongly advised to consult an authorized person before commencement of the removal works and make formal application for approval and consent from the BD if necessary.

Property owners with financial difficulties may apply for loans under the Building Safety Loan Scheme administered by BD to cover the cost of the required works for compliance with the removal orders.

Unauthorised roof structures in industrial buildings should not be converted into domestic use which is incompatible with the use of the buildings. Under the current policy, the Housing Department would not make rehousing arrangement to the affected occupants as a result of BD's enforcement action against unauthorised roof structures used for habitation in industrial buildings. Nevertheless, BD will liaise with the Housing Department to arrange bedspaces in the transit centre for those in urgent need of accommodation. Besides, the affected occupants may also approach the Social Welfare Department for assistance.

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