Durability
The Building Code sets the required durability standard for building work. Clause B2 Durability aims to ensure that buildings are durable enough so that all other objectives of the Building Code are satisfied throughout the life of the building without needing reconstruction or major renovation.
Required durability periods for building elements
To comply with the Building Code, building elements must, with normal maintenance, continue to satisfy Building Code performance requirements for the following periods (or the specified intended life of the building, if shorter).
The life of the building, being not less than 50 years, for building elements:
- that provide structural stability to the building (for example, floors, walls, and fixings)
- that are difficult to access or replace
- for which failure to comply with the Building Code would go undetected during the building's normal use and maintenance.
The life of the building, being not less than 15 years, for building elements:
- that are moderately difficult to access or replace (for example, the building envelope, exposed plumbing in the sub-floor space, and in-built chimneys and flues)
- for which failure to comply with the Building Code would go undetected during the building's normal use, but would be easily detected during maintenance.
The life of the building, being not less than five years, for building elements:
- that are easy to access and replace (for example, services, linings, renewable project coatings, and fixtures)
- for which failure to comply with the Building Code would be easily detected during the building's normal use.
Assessing building product durability
Designers and builders recommend the use of building products based on their opinions that those products will meet Building Code durability requirements. In assessing the durability of building products, regard should be given to:
- appraisals
- history in use
- manufacturers' technical literature
- reputation of the manufacturer
- the product's warranty (which may be provided by the manufacturer).
A building consent authority may be satisfied that a product complies with Clause B2 Durability despite there being no product warranty. Although a product warranty can be considered (for example, if the manufacturer is willing to replace its product for a period equal to its required durability), a warranty cannot be the sole criteria for assessing durability.
Warranties do not ensure durability
The existence of a product warranty does not mean the product will necessarily be durable or last for a certain number of years. Rather, a warranty only helps to repair or replace the product when there are problems, or to compensate for any damage. Additionally, a warranty for several years is worthless if the company offering it goes into liquidation.