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What are the Building Consequence Classes?


Technical Guidance Document A, 2012 (Building Consequence Classes 2.2)

Consequence Class Building type and occupancy

Class 1 - Single-occupancy house not exceeding 4 storeys, Agricultural buildings, Buildings into which people rarely go, provided no part of the building is closer to another building, or area where people do go, than a distance of 1.5 times the building height

Class 2a Lower Risk Group - 5-storey single occupancy houses, Hotels not exceeding 4 storeys, Flats, apartments and other residential buildings not exceeding 4storeys, Offices not exceeding 4 storeys, Industrial buildings not exceeding 3 storeys, Retailing premises not exceeding 3 storeys of less than 1000sqm floor area in each storey, Single-storey educational buildings, All buildings not exceeding two storeys to which the public are admitted and which contain floor areas not exceeding 2000sqm at each storey

Class 2b Upper Risk Group - Hotels, flats, apartments, and other residential buildings greater than 4 storeys but not exceeding 15 storeys,Educational buildings of more than 1 storey but not exeeding 15 storeys, Retail premises greater than 3 storeys but not exceeding 15 storeys, Hospitals not exceeding 3 storeys, Offices of more than 4 storeys but not exceeding 15 storeys, All buildings to which the public are admitted and contain floor areas exceeding 2000sqm but not exceeding 5000sqm

Class 3 - All buildings defined above as Class 2 Lower and Upper Consequences Class that exceed the limits on area and number of storeys, All buildings to which members of the public are admitted in significant numbers, Stadia accommodating more than 5000 spectators, Buildings containing hazardous substances and/or processes


  1. For buildings intended for more than one type of use, the consequence class should be that relating to the most onerous type (i.e. of greatest risk).

  2. When determining the number of storeys, basement storeys may be excluded provided such basement storeys fulfill Consequences Class 2b Upper Risk Group requirements.