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.

If I wish to erect light-weight canopy for sun-shading or for protection against falling objects, do I need consent and approval from the BD?

Owners intending to construct new building or make alterations and additions to existing buildings are required by Buildings Ordinance to appoint an authorized person to coordinate and supervise the works and also if so required, a registered structural engineer. The authorized person appointed will follow up the application for approval and consent from BD.

If I wish to erect storage cabinets on the roof of my property, do I need approval and consent from the BD? 

Prior approval and consent from the BD are required for erecting prefabricated structures including mobile houses and man-size storage cabinets on the main roof, podium roof or open yard of a building. It is because large storage cabinets occupying space will likely contravene the floor area limitation and other building regulations.

However, storage cabinets at such locations are generally not subject to immediate enforcement action when:-

• the cabinet does not exceed a height of 1.5 metres nor the parapet wall, 

• the cabinet does not affect the structure of the building,

• the fire escape route is not obstructed, and 

• the drainage system is not affected

If both residential units do not contain any green balcony or utility platform, and the building works concerned in merging the adjoining units does not involve removal of structural elements and the alteration works involved do not contravene any provision of the Buildings Ordinance and allied regulations, no enforcement action will be taken by the BD as the alteration works concerned comes under the category of exempted building works.

However, if the residential units contain green balconies and utility platforms, immediate enforcement action by the BD will be taken as long as the merging of the units lead to contravention of 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 any alternation works for merging the units and make formal application for approval and consent from the BD if necessary.

Generally, industrial buildings carry higher risks in terms of fire and other hazards because of industrial activities and storage of hazardous goods or materials. Many unauthorized structures on rooftops, flat roofs, yards and lanes of industrial buildings are of flimsy construction or built by combustible materials. They may be used for storage purpose or other uses without fire protection, which may cause serious fire risk, health hazard and environmental nuisance.

To improve building safety of industrial buildings, BD will issue removal orders and take enforcement action in clearance operations to require removal of these unauthorized structures.

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.

Unauthorized 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 unauthorized 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.