### Building (Planning) Regulations 《建築物(規劃)規例》

25. Space about domestic buildings
(1) (a) Every domestic building on a class A or B site or on a class C site shall have within the site an open space at the rear, or partly at the rear and partly at the side, at a level of not less than 150 mm below the floor of the lowermost storey in accordance with the Second Schedule:
Provided that where the Building Authority considers it necessary for proper and equitable development or redevelopment of an adjacent site, he may require the provision of more open space than that specified in the Second Schedule. (G.N.A. 97 of 1962; L.N. 82 of 1963)
(b) The open space provided pursuant to subparagraph (a) shall be such that no part of the building which bounds on such open space at any level shall be within 1.5 m, measured horizontally, of a line drawn vertically from a point in the boundary of the open space immediately opposite thereto. (L.N. 33 of 1966)
(2) No part of any domestic building shall be erected within 1.5 m of the rear boundary of the site. The open space so provided shall be counted as part of the open space required under this regulation. (L.N. 33 of 1966)
(3) No existing domestic building which has an open space of equal or less area than that required by this regulation shall be altered in such manner as to reduce the existing amount of open space.
(4) No existing domestic building which has a greater area of open space than that required by this regulation shall be altered in such a manner as to reduce the area of open space to less than that required by this regulation.
(5) Where any open space or area is at a level more than 600 mm below an adjoining open space, safe parapet walls, railings or fences shall be provided by the person creating the difference in levels.
(6) Access shall be provided to every open space.
(L.N. 294 of 1976)

26. New buildings on existing street less than 4.5 m wide to be set back from centre line of street
Where the width of an existing street in front of any new building is less than 4.5 m, no part of such building shall be nearer to the centre line of the street than 2.25 m.
(G.N.A. 83 of 1959; L.N. 294 of 1976; L.N. 144 of 1978)

### Building (Planning) Regulations 《建築物(規劃)規例》

27. Cuttings
(1) No building shall be built to abut against a cutting, including a toe wall supporting a cutting.
(2) A clear intervening space or area of a width of not less than 1/4 of the height of the cutting shall be left between such building at ground floor level and the toe of the cutting.
(3) Such intervening space or area shall in no case be less than 2.5 m in width. (L.N. 294 of 1976)
(4) For the purposes of this regulation the height of the cutting shall be deemed to be the height measured on a vertical line drawn from the toe of such cutting, and extending from the finished ground or concreted surface to a point where it meets a line drawn downwards at an angle of 30 degrees with the horizontal from the top of the cutting.

28. Service lanes
(1) In addition to any open space required under regulation 25 every domestic building shall be provided with a service lane at the rear or side of such building:
Provided that a service lane shall not be required—
(a) where a public lane not less than 3 m wide or a street already exists;
(b) for detached and semi-detached buildings;
(c) where exempted by the Building Authority.

(2) Every such service lane shall be accessible from an existing street but where such access is not immediately possible, this regulation shall be deemed to have been complied with if access would be obtained in the event of future development or redevelopment of other lots within the block. (L.N. 159 of 1990)
(3) The alignment, width and levels of every such lane shall be decided by the Building Authority who may grant a modification of regulation 25 when a lane exceeding 1.5 m in width is required.
(L.N. 54 of 1969; L.N. 294 of 1976)

28A. Access facilities for telecommunications and broadcasting services
Every commercial building, industrial building, residential building (other than a building for the residence of a single family) and hotel building shall be provided with access facilities for telecommunications and broadcasting services in accordance with the design requirements as may be specified by the Building Authority from time to time.

29. Lighting and ventilation
Every storey of every building used or intended to be used for the purpose of an office or for habitation shall be provided with effectual means of lighting and ventilation. 
(G.N.A. 83 of 1959)

### Building (Planning) Regulations 《建築物(規劃)規例》

30. Lighting and ventilation of rooms used or intended to be used for habitation or as an office or kitchen
(1) Every room used for habitation or for the purposes of an office or as a kitchen shall be provided with natural lighting and ventilation. (G.N.A. 97 of 1962)
(2) Such natural lighting and ventilation shall be provided by means of one or more windows which shall be—
(a) so constructed that—
(i) the aggregate superficial area of glass in the window or windows is not less than one-tenth of the area of the floor of the room; and
(ii) the windows can, to an extent at least equal in the aggregate to one-sixteenth of the area of the floor of the room, be opened in such manner that the top of the opening of each window is at least 2 m above the level of the floor or, in the case of detached and semi-detached buildings, at least 1.9 m above the level of the floor; and (L.N. 294 of 1976)
(b) such that not less than the area required by subparagraph (a)(i) (hereinafter referred to as the prescribed window) faces directly into the external air.
(G.N.A. 83 of 1959)