Part 1
Category 1 buildings

• (1) that is neither an ancillary building nor an outbuilding; and

• (2) whose building envelope (whether the building is a new structure or an existing building) has a total risk score (calculated under Part 4) that does not exceed 12 for any external elevation; and

• (3) whose use (determined, whether the building is a new structure or an existing building, in accordance with regulation 6 and Schedule 2 of the Building (Specified Systems, Change the Use, and Earthquake-prone Buildings) Regulations 2005) is SH (sleeping single home).

Part 2
Category 2 buildings

A category 2 building is a building that is—

• (1) neither an ancillary building nor an outbuilding; and

• (2) neither a category 1 building nor a category 3 building.

Part 3
Category 3 buildings

A category 3 building is a building that is neither an ancillary building nor an outbuilding, and that is not a category 1 building, but is a building—

• (1) whose use (determined, whether the building is a new structure or an existing building, in accordance with regulation 6 and Schedule 2 of the Building (Specified Systems, Change the Use, and Earthquake-prone Buildings) Regulations 2005) is not SH (sleeping single home); and

• (2) whose building height is or exceeds 10 metres where—

  building height means the vertical distance between the upper surfaces of the floors of the building's lowest and highest storeys

  floor does not include a mezzanine floor or a rooftop area

  storey means a portion of the building between the upper surface of a floor (floor A) in the building and—

  • (a) the upper surface of the next above floor in the building; or

  • (b) if there is no next above floor in the building, the lower surface of the ceiling or roof above floor A.

Part 4
Total risk score

• (1) A total risk score for an external elevation on the building envelope of a building is calculated by using the calculation table in clause (2) and completing the following steps:

  • (a) for each specified risk factor, use the definitions of risk table in clause (3) to decide whether the risk severity is low, medium, high, or very high, and enter the applicable score; and

  • (b) copy the applicable score for each risk factor to the column whose heading is “Subtotals for each risk factor”; and

  • (c) add all the scores copied into that column to arrive at the total risk score for the external elevation.

• (2) The calculation table is as follows:

  Calculation table
  Elevation	Risk severity
  Risk factor	Low	Medium	High	Very high		Subtotals for each risk factor
  Wind zone	0	0	1	2
  Number of storeys	0	1	2	4
  Roof/elevation intersection design	0	1	3	5
  Eaves width	0	1	2	5
  Envelope complexity	0	1	3	6
  Deck design	0	2	4	6
  		Total risk score:

• (3) The definitions of risk table is as follows:

  Definitions of risk table
  Wind zone	Low risk	Low wind zone as described by NZS 3604:1999
  	Medium risk	Medium wind zone as described by NZS 3604:1999
  	High risk	High wind zone as described by NZS 3604:1999
  	Very high risk	Very high wind zone as described by NZS 3604:1999
  Number of storeys	Low risk	One storey
  	Medium risk	Two storeys in part
  	High risk	Two storeys
  	Very high risk	More than 2 storeys
  Roof/elevation intersection design	Low risk	Roof-to-elevation intersection fully protected (for example, hip and gable roof with eaves)
  	Medium risk	Roof-to-elevation intersection partly exposed (for example, hip and gable roof with no eaves)
  	High risk	Roof-to-elevation intersection fully exposed (for example, parapets, enclosed balustrades, or eaves at greater than 90° to vertical with soffit lining)
  	Very high risk	Roof elements finishing within the boundaries formed by the external elevations (for example, lower ends of aprons, chimneys, dormers, etc)
  Eaves width (1) (2)	Low risk	Greater than 600 mm for single storey
  	Medium risk	451–600 mm for single storey, or greater than 600 mm for 2 storey
  	High risk	101–450 mm for single storey, or 451–600 mm for 2 storey, or greater than 600 mm above 2 storey
  	Very high risk	0–100 mm for single storey, or 0–450 mm for 2 storey, or 600 mm or less above 2 storey
  Envelope complexity	Low risk	Simple rectangular, L, T, or boomerang shape, with single cladding type
  	Medium risk	Moderately complex, angular, or curved shapes (for example, Y or arrowhead) with no more than 2 cladding types
  	High risk	Complex, angular, or curved shapes (for example, Y or arrowhead) with multiple cladding types
  	Very high risk	As for high risk, but with junctions not covered in the rows of this table relating to roof/elevation intersection design and deck design (for example, box windows, pergolas, or multi-storey re-entrant shapes)
  Deck design (3)	Low risk	None, timber slat deck or porch at ground-floor level
  	Medium risk	Fully covered in plan by roof, or timber slat deck attached at first- or second-floor level
  	High risk	Enclosed deck exposed in plan or cantilevered at first-floor level
  	Very high risk	Enclosed deck exposed in plan or cantilevered at second-floor level or above
  Notes (1) Eaves width measured horizontally from external face of wall cladding to outer edge of overhang, including gutters and fascias. (2) Balustrades and parapets count as 0 mm eaves. (3) Deck— (a) means an open platform (which may be known as a balcony)— (i) projecting from an exterior wall of a building; and (ii) supported by framing; and (iii) that may be over enclosed internal spaces, or may be open underneath; and (b) includes an enclosed deck (that is, a deck (which may be known as a balcony)— (i) over an interior or exterior space; and (ii) that has an impermeable upper surface; and (iii) that is closed on the underside).