The Building Code

The Building Code is a key building control mechanism in New Zealand and is contained in Schedule 1 of the Building Regulations 1992 (all but Schedule 1  The Building Code has been revoked).

As a performance-based regulation, the Building Code sets the performance standards that all building work must meet.

'Performance-based' means it does not prescribe how building work should be done but states how the building and its components must perform once the building work is complete. As such, it focuses on building outcomes and does not stipulate that any particular design, construction method or type of materials must be used to achieve a particular outcome.

In practice, this means there are many ways to design and construct a building while still meeting the requirements of the Building Code. This flexibility is intentional as it encourages the construction industry to develop innovative and cost-effective solutions.

Building Code requirements

The Building Code requirements are described in 35 technical clauses, such as B1 Structure, B2 Durability and so on, which must all be applied holistically to building design. For example, the weathertightness performance requirements for a cladding are contained in clause E2 External moisture, but the structural performance requirements of B1 Structure must also be applied to the design of the cladding.

Classified uses

The Building Code groups buildings into seven classified uses and imposes performance standards for each one:

  1. Housing
  2. Communal residential
  3. Communal non-residential
  4. Commercial
  5. Industrial
  6. Outbuildings
  7. Ancillary.

See Building Code clause A1 for more information.

Seismic resilience of structures

There are several sections of the Building Code that are relevant to seismic resilience. The most important of these is Part B, clause B1 Structure, which ensures the stability of the building’s structure. This clause is reproduced in full below.

B STABILITY

Clause B1 – Structure

Objective

B1.1 The objective of this provision is to:
 (a) Safeguard people from injury caused by structural failure,
 (b) Safeguard people from loss of amenity caused by structural behaviour, and
 (c) Protect other property from physical damage caused by structural failure.

Functional Requirement

B1.2 Buildings, building elements and sitework shall withstand the combination of loads that they are likely to experience during construction or alteration and throughout their lives.

Performance

B1.3.1 Buildings, building elements and sitework shall have a low probability of rupturing, becoming unstable, losing equilibrium, or collapsing during construction or alteration and throughout their lives.

B1.3.2 Buildings, building elements and sitework shall have a low probability of causing loss of amenity through undue deformation, vibratory response, degradation, or other physical characteristics throughout their lives, or during construction or alteration when the building is in use.

B1.3.3 Account shall be taken of all physical conditions likely to affect the stability of buildings, building elements and sitework, including:
 (a) Self-weight,
 (b) Imposed gravity loads arising from use,
 (c) Temperature,
 (d) Earth pressure,
 (e) Water and other liquids,
 (f) Earthquake,
 (g) Snow,
 (h) Wind,
 (i) Fire,
 (j) Impact,
 (k) Explosion,
 (l) Reversing or fluctuating effects,
 (m) Differential movement,
 (n) Vegetation,
 (o) Adverse effects due to insufficient separation from other buildings,
 (p) Influence of equipment, services, non-structural elements and contents,
 (q) Time dependent effects including creep and shrinkage, and
 (r) Removal of support.

B1.3.4 Due allowance shall be made for:
 (a) The consequences of failure,
 (b) The intended use of the building,
 (c) Effects of uncertainties resulting from construction activities, or the sequence in which construction activities occur,
 (d) Variation in the properties of materials and the characteristics of the site, and
 (e) Accuracy limitations inherent in the methods used to predict the stability of buildings.

B1.3.5 The demolition of buildings shall be carried out in a way that avoids the likelihood of premature collapse.

B1.3.6 Sitework, where necessary, shall be carried out to:
 (a) Provide stability for construction on the site, and
 (b) Avoid the likelihood of damage to other property.

B1.3.7 Any sitework and associated supports shall take account of the effects of:
 (a) Changes in ground water level,
 (b) Water, weather and vegetation, and (c) Ground loss and slumping.