CFA & GFA

Construction Floor Area (CFA) generally covers areas of a building that are to be constructed and are measured to the outside face of the external walls of the building and includes all lift shafts, stairwells, car park, plant rooms and the like. CFA is generally measured by QS for the purpose of estimation of the construction costs of a building

Gross Floor Area (GFA) (as defined under the Building (Planning) Regulation 23(3)(a)) is the area contained within the outer surface of external walls of a building measured at each floor level. GFA is generally measured by Architect for the purpose of building submission and referred in plot ratio (B(P) s18A - site classification, B(P) s19 - general provisions and 1^st Schedule of B(P)R refers).

GFA =  Site area x Plot ratio B(P)R s21 subject to site classification, also limited by permission in OZP and lease.
Site coverage B(P)R s20

For example, if the site area is 10,000 sq.m., site coverage is 50% and plot ratio is 10, it allows a 20 story building with 5,000 gross floor (“gfa”) area per floor.

GFA Concessions via "disregarded GFA" (covered under section 23(3)(b)/23A of the B(P)R), "exempted GFA" (covered under section 42 of the BO) and "bonus GFA" (covered under section 22 of the B(P)R).

 

(Extracted from http://www.news.gov.hk/)

Apart from the B(P)R, exemption of GFA or modification to Building Plan are as follows:
Buildings Ordinance
BO s31(1)
  To permit the following to project over a street:    

(a)     Window flower box

·     not projecting more than 500mm over street;

·     not having a width exceeding the width of the window opening;

·     the base is well above the floor level;
·     provided as amenity to domestic units;
·     designed so as not to drip water onto the street.
    Air-conditioning hood and platform
·     width is justified;
·     min. height is 2.5m above ground level;
·     drainage system for disposal of water generated from the A/C plant provided.
(b)     cladding walling provided for refurbishment of existing building subject to minimal projection is consistent with the fixing method used (but not more than 300 mm) and no resultant gain in floor area ;

(c)     transformer room door heads which do not fall within the criteria under B(P)R7, provided that no obstruction is caused to vehicular or pedestrian traffic ;

(d)     pedestrian bridges and other buildings required under the lease conditions, subject to compliance with the requirements of all interested departments (except in relation to any claims for GFA exemption or concession) ;
(e)     canopies not strictly in accordance with B(P)Rs Part II, subject to compliance with the requirements of all interested departments and that the canopy can serve its function of weather protection for pedestrians and subject to the width of the canopy not exceeding 3 m nor extending beyond the edge of the pavement ;
(f) architectural features to enhance genuinely the appearance of buildings provided they are not excessive and comply with the spirit of PNAPs 68 & 116 ;
(g)     installation of sheet piles under street subject to no adverse comments from Lands Dept, Highways Dept; Transport Dept. and other interested government departments and requirements, if any, from the above departments are compiled with.
Building (Administration) Regulations
B(A)R 14(3)
    To permit one set of submitted plans to be uncoloured
B(A)R 29(1A)
    To exempt plans submitted by charitable organizations from payment of fees for processing, subject to the building works being wholly for and directly associated with the charitable purpose.
    To exempt plans from payment of fees for processing of A&A proposals for upgrading/improving building or fire safety.
B(A)R 33(1)
    To permit exemption from obtaining prior approval and consent for amendments to building/drainage works for which the first consent has been given, on the condition that such amendments comply with criteria set out in PNAP 272 .

Building (Construction) Regulations

B(C)R 35

    To permit the level of an internal floor to be less than 150mm above the level of the external ground subject to compliance with the criteria for exemption laid down in PNAP 266.

B(C)R 49(1)   
    To permit the level of an usable floor area to be less than 150mm above the level of the adjoining flat roof subject to compliance with the criteria for exemption laid down in PNAP 266.

Building (Planning) Regulations

B(P)R 20 and/or 21
(a)     To permit existing party walls, common staircases and other party structures retained to be excluded from site coverage and plot ratio calculations, provided they are physically separated from the proposed new building at that particular floor level and no intervening space has any potential for infilling .
(b)     To permit the site coverage to exceed the limits laid down in the 1^st Schedule of B(P)R, provided the increase is for the purpose of upgrading the fire safety installation in existing buildings .
 (c)     To permit genuine green and innovative features under JPNs to be excluded from site coverage calculations if the criteria set out in JPNs are complied with .
  (Note: exemption from GFA calculation will be made under B(P)R 23(3)(a))
B(P)R 22(1)

    To grant bonus PR & SC in line with B(P)R 22(1) in return for corner splay not exceeding 4m x 4m with a height clearance not less than 3.3 m required by TD or HyD subject to compliance with the conditions specified by TD or HyD.

B(P)R 23(2)(a)
    To permit the existing private service lanes to be included in site area provided that the lane is not specifically required under B(P)R 28 and is not built in, over, upon or under.
B(P)R 23(3)(a)
(a)     To permit the exclusion of voids from GFA calculations where they appear at intermediate floor levels in the following cases:
(i) in cinemas, theatres, auditoria, school halls, sporting halls and auditoria of religious institutions, in front of galleries;
(ii)      in banking halls, outside mezzanine floors;
(iii)     in shopping arcades, in atria or around escalators;
(iv)    in bona fide hotels, club houses and commercial buildings, in prestigious main entrance halls over one storey high; and
(v)     void over prestigious main common entrance hall of domestic building;
(vi)    in front of cocklofts over ground floor shops, for single staircase buildings, subject to the cocklofts satisfying the following criteria:
(1)     they are constructed over ground floor shops, forming an integral part and within the curtilage of the ground storey;
(2)     they are used only as storage for the shops;
(3)     there is no sanitary provision in the cocklofts;
(4)     they are not at the same level as any adjacent staircase landing;
(5)     they are only accessible through the G/F shop;
(6)     a minimum clearance of 1.5 m is maintained across the front; 
(7)     all openings in the cockloft floor must be without full height enclosure but are defended with protective barriers not less than 1.1 m high; and
(8)     only one such cockloft is situated in any one shop.
In all such cases CBS should satisfy themselves that any subsequent conversion resulting in excess plot ratio is unlikely.
 Where there are no intermediate floors, high storey heights may be accepted where required by the intended use, as in squash and badminton courts and purpose designed factories with an identifiable client interest.
(b)     To permit suitably designed covered landscaped and play areas under the footprint of the domestic towers to be excluded from GFA calculations where there is no likelihood of abuse and that such areas do not exceed 5% of the total domestic GFA.
(c)     To permit filtration plant rooms for swimming pools to be excluded from GFA calculations subject to reasonable size (width of space between the plants and the wall of the room is less than 1.5 m) and installation of plants before OP application .
(d)     To permit the exclusion of recreational facilities referred to in PNAP 229 from GFA calculation.
(e)     To permit the exclusion of horizontal screens referred to in PNAP 116, covered walkways and similar passageways provided for the convenience of occupants from GFA calculations subject to the width of such screen, walkway or passageway not exceeding 2 m wide.
(f) To permit miniature logistic service room to be excluded from GFA calculation subject to:
l     not excessive in size and size not exceeding 8m² for a block size of 240 flats
l     the room is located in the common area adjacent to the management office or guard post
(g)     To permit counters, offices, stores, guard rooms, and lavatories for watchman and management staff to be excluded from GFA calculation subject to:
·     not excessive in size and size not exceeding 5 m² for every 50 flats per every block or for each block;
·     facilities are located in a common area or designated as common area in a Deed of Mutual Covenant.
(h)     To permit mail room not exceeding 60 m² in commercial and industrial buildings to be excluded from GFA calculation subject to:
·     not excessive in size
·     endorsed by Postmaster General
·     located in common area or designated as common area in a Deed of Mutual Covenant
·     building is centrally managed
(i) To permit refuge floors, which are required under the MOE Code, to be excluded from GFA calculations subject to the floor be suitably designed to comply with the FRC code .
(j) To permit lift shaft areas in domestic and composite buildings over and above 2.5% of the total (domestic) GFA to be excluded from (domestic) GFA calculation subject to:
·     the total areas to be excluded not to exceed 3.5% of the total (domestic) GFA; and
·     the criteria for exemption laid down in PNAP 207 are complied with.
(k)     To permit genuine green and innovative features under JPNs to be excluded from plot ratio calculations if the criteria set out in JPNs are complied with.
B(P)R 25(1)(a)
    (a)     To permit a portion of a service lane to count as open space as provided for by B(P)R 28(3) for lanes not required under B(P)R 28(1) ; and
    (b)     To exempt bona fide hotel developments from the provision of open space .
B(P)R 27
 To permit the intervening space between a cutting, including a toe wall supporting a cutting to be less than that specified in B(P)R 27 provided GEO raises no objection.
B(P)R 30
    To permit the omission, or reduction in standard, of natural lighting and ventilation in the following cases :
(a)     an ancillary office which does not exceed 30% of the GFA of the premises within which it is located (this is particularly relevant to small 'offices' associated with industrial premises);

(b)    shroff office serving commercial carparks;

(c)     management office and owners’ corporation/owners’ committee office;

(d)    temporary sales office and show flat;

(e)     kitchens in licensed premises; and
(f) in purpose-designed office buildings subject to the following principles and criteria:
(i) there should be recognizable reasons (structural, aesthetic, planning constraints, etc.) why the full standards required by the regulation cannot readily be met;
(ii)     the building should be of such a type, in terms of location, status, and size, that would lead to the inference that (except in times of emergency) office workers would normally be in an artificially boosted and controlled environment;
(iii)    plans should clearly show provisions for a central air‑conditioning installation to serve the whole building;

(iv)    most of the whole building, and most of each floor or occupancy unit, should have a reasonable provision of natural lighting and ventilation capable of ensuring that most of the premises can remain suitable for occupation even if the means for producing the artificial environment temporarily fail;

(v)     the Form BA 16 applications should indicate clearly in paragraph 2 what minimum standards of artificial lighting and/or mechanical ventilation are proposed to be maintained if the modification is given;
(vi)    the design of the building should not easily lend itself to division into a large number of separate units capable of occupation without any central management organization; and
(vii)   the plans should clearly quantify the deficiency proposed, expressed as a percentage of the regulation requirements.
Where the omission or reduction of natural ventilation is permitted, it shall be subject to:-
·    the submission of an assessment report confirming that mechanical means of ventilation to be provided in the building is capable of supplying fresh air at the rates stipulated in Annex 1 of PNAP 30.·    Plans and sections marking clearly the locations of the proposed fresh air intake to indicate the compliance of the requirements set out in Annex 2 of PNAP 30.
    For accommodation listed in (b), (c) and (d), fresh air supply requirement should be the same as that for ancillary offices set out in Annex 1 & 2 of PNAP 30.  Dual purpose industrial/office user premises, and industrial premises converted to office user, will be regarded as office user for the purposes of compliance with lighting and ventilation requirements.  For the avoidance of doubt these categories of premises are not 'purpose-designed office buildings'.
B(P)R 30(2)(a)(ii)
    In 'curtain wall' situations, in respect of ventilation only, to permit the area of openable windows to be as low as 1% of the floor area in commercial buildings, on the following conditions :
(a)    that the provision of openable sashes is equally distributed around the facade;
(b)     that an assessment report is submitted to confirm that mechanical means of ventilation to be provided in the building is capable of supplying fresh air at the rates stipulated in Annex 1of PNAP 30;
(c)   that plans and sections marking clearly the locations of the proposed fresh air intake is provided to indicate the compliance of the requirements set out in Annex 2 of PNAP 30; and
(d)     that the accommodation is designed so that all units are capable of receiving natural ventilation in the event of failure of the mechanical system.
B(P)R 31(1)(c) & (d)
(a)     To accept the layout of prescribed windows for the habitable rooms/kitchens of domestic flats with deficiency in horizontal plane provided that:
·     the “prescribed” windows facing wide permanent open space; and
·     it is satisfied that the standards of lighting and ventilation would not be prejudiced.
(b)    To accept the layout of prescribed windows for office or habitation with deficiency in horizontal plane provided that:
·     the room is provided with a window facing a RHP complying with the minimum dimensions stipulated in B(P)R 31(2);
·     the RHP has a longitudinal dimension of not less than 30m; and
·     there is ample open space for free flow of air with a minimum clear distance between buildings not less than 4.5m wide.
B(P)R 35A
    To accept non-provision of gas aperture in the following:
·   bathroom in domestic premises subject to the provision of shared hot water heater with other room and the hot water pipe from the said water heater is not greater than 12 m as required by Waterworks Regulation 19; and
·   shower room for recreational facilities subject to the provision of electric water heaters installed prior to OP application .
B(P)R 36
    To permit the omission or reduction, of natural lighting and ventilation to rooms containing soil or waste fitments in the following cases, provided good management is available :
    (a)     internal bathrooms in bona fide hotels;
    (b)     toilets/changing rooms in licensed premises and recreational facilities;
    (c)     in basements;
    (d)     in non-domestic buildings;
    Such modifications must be conditional upon:
·    The submission of an assessment report confirming that mechanical means of ventilation to be provided in the building is capable of supplying fresh air at the rates stipulated in Annex 1 of PNAP 30.
·    Compliance with the requirements set out in Annex 2 of PNAP 30 for t he fresh air intake.
·    The submission of plans and sections marking clearly the locations of the proposed fresh air intake shall be submitted except for a central AC system for B(P)R 36.
(e)     Bathrooms in domestic buildings subject to compliance with the criteria for exemption laid down in PNAP 219.
B(P)R 40
    To permit the omission of natural lighting to staircases provided proper management is expected (para.4 of PNAP 169 is relevant) subject to the provision of a permanent artificial lighting system with 30 lux min. lighting level backed up by an emergency lighting system providing a horizontal illuminance at floor level of not less than 2 lux.  The design of the emergency lighting system should comply with the Code of Practice for Minimum Fire Service Installations and Equipment .
B(P)R 41B
    To permit the non-provision of fireman's lift in A&A proposal subject to no adverse comment from D of FS .
B(P)R 41D
(a)     To permit the non-provision of turning space at the dead-end of the EVA subject to the F.S. appliances need not to reverse more than 30m for turning.
(b)     To permit the EVA at the run-in/out point to have a width of not less than 4.5m.
(c)     For domestic buildings not more than 3-storey and single family houses to which paragraph 5 of the MOE Code applies:
l     To relax para. 24.2(a) and 25.3(c) of the MOA Code to permit the width of the EVA to be not less than 4.5m
l     To relax the horizontal distance required under para. 24.2(e) and 25.3(c) of the MOA Code to a distance of 30m or more subject to the provision of enhanced FSI, including the provision of a hose reel or sprinkler system, as the case may be, to the satisfaction of FSD
(d)     To relax para. 25.3(c) to permit the width of the existing road serving as EVA for building re-development, other than industrial building, cinema and theatre, to have a width of not less than 4.5m
(e)     To relax para. 25.3(c) to permit the major façade having less than one-fourth of the total perimeter walls when the topographical features of the site make the compliance impractical subject to the following conditions:
l     The major façade served by the EVA shall not be less than the minimum distance between the two opposite side boundaries for Class A site within 10m from the EVA;
l     The requirements of para. 24.2(e) be complied with for Class B and C sites.
B(P)R 47(2)
    To permit the space left between the domestic building and the bottom of the retaining wall to be less than 1.5m wide provided that GEO raises no objection .
Building (Private Streets and Access Roads) Regulations
B(PS&AR)Regs (generally)
    To permit the modification of any regulation, subject to the agreement of and inclusion of any conditions imposed by the traffic authorities (HyD, CEDD and/or TD) .
Building (Refuse Storage and Material Recovery Chambers & Refuse Chutes) Regulations
B(RS&MRC&RC)R 7
    To permit refuse storage and material recovery chambers to have no external wall provided that:
·     there are planning restraints;
·     DFEH is satisfied that a refuse collection vehicle can gain access to the refuse storage and material recovery chamber when so required under B(RS&MRC&C)R 3; and
·     the location of the chamber will unlikely cause noise or sanitary nuisance.
B(RS&MRC&RC)R 10(2)(a)
    To permit doors to refuse storage and material recovery chambers to be situated other than in an external wall, provided that there is sufficient cross ventilation, that there are planning restraints making compliance impractical and that DFEH raises no objection .
B(RS&MRC&RC)R 19(2)(b)
    To permit vent pipes to be carried up to a lesser height in cases where the Hong Kong Airport (Control of Obstructions) Ordinance would otherwise be contravened, subject to their being so located as will not create a nuisance to any nearby occupancy.
B(RS&MRC&RC)R 23(1)
    To permit hoppers installed in industrial premises and markets to have a mouth opening exceeding the regulation maximum, subject to provision of suitable locking or other arrangement to safeguard against unauthorized access.
B(RS&MRC&RC)Regs (generally)
    To permit the modification of any other regulation for which a BC precedent exists in similar circumstances.  In the case of refuse storage and material recovery chambers, this would be subject to the agreement of and any conditions imposed by DFEH.
Building (Standards of Sanitary Fitments, Plumbing, Drainage Works & Latrines) Regulations
B(SSFPDW&L)Rs 5 & 8
    To permit less facilities than those required when recommended by the Licensing Authority.
B(SSFPDW&L)R 19
    To permit the discharge of flushing cisterns of watercloset fitment to be less than 9 litres provided that:
    (a)     the associated toilet bowls are compatible with the cistern;
    (b)    the flushing cisterns shall be the valveless syphonic type; and
    (c)     the syphonic action is sufficient for the wastes in the toilet bowls to be cleared effectively by a single flush.
B(SSFPDW&L)R 24(2)(a)
    To permit the internal diameter of a trap to a soil fitment to be less than 80 mm provided that:
    (a)     the fitment is of syphonic action;
    (b)     the internal trap diameter to be not less than 54 mm; and
    (c)     the fitment is within domestic, office, shop or industrial premises.
B(SSFPDW&L)R 31(1)
    To permit vent pipes to be carried up to a lesser height in cases where the Hong Kong Airport (Control of Obstructions) Ordinance would otherwise be contravened, subject to their being so located as will not create a nuisance to any nearby occupancy.
B(SSFPDW&L)R 48
    To permit drains or sewers to have a lesser fall, on condition that a minimum velocity of 750 mm/sec is achieved.
B(SSFPDW&L)R 50(3)
    To permit the provision of flexible joint for underground drainage pipework in reclaimed land subject to production of satisfactory test report demonstrating that the joint can accommodate the anticipated settlement.  
B(SSFPDW&L)Rs (generally)
    To permit the modification of any other regulation for which an established BC precedent exists in similar circumstances.

Main Reference:

• PNAP 13 - Calculation of Gross Floor Area and Non-Accountable Gross Floor Area - Building (Planning) Regulation 23(3)(a) and (b)
• PNAP 68 - Projections in relation to Site Coverage and Plot Ratio - Building (Planning) Regulations 20 and 21
• PNAP 116 - Amenity Features 
• JPN1 - Green and Innovative Building
• JPN2 - Second Package of Incentives to Promote Green and Innovative Buildings
• Parking - Hong Kong Planning Standards Standards and Guildlines (HKPSG)
• Food Hygiene Code (FEHD)
• Sustainable Development - Invitation for Response Document
• Building Plan Submission Review, Buildings Department