Uniquely NZ
FEATURE
SECTION
A Code
to build by
The New Zealand Building Code was one of the first performance-based
building codes in the world. Unusually, it includes explicit performance
criteria for durability that all building elements must comply with.
BY NIKKI BUCKETT, ADVISOR – BUILDING SCIENCE, MINISTRY OF BUSINESS, INNOVATION AND EMPLOYMENT
This Building Code came into force in
A national building code
1992 after the passing of the Building Act
Because the industry wanted a coherent,
1991, which required the Code to address
national building control regime, the
the wellbeing, sustainable development and
Building Industry Commission was set up
safety and health of building users. These
in 1986 to determine appropriate legal and
requirements remained when the Building
regulatory provisions for building construc-
Act 1991 was repealed and replaced with
tion and maintenance across New Zealand.
the Building Act 2004, which added further
In 1990, the Commission produced a
controls including practitioner licensing and
report, Reform of Building Controls, which
accreditation of consent authorities.
recommended a new national performancebased building regulation system, designed
NEW ZEALAND’S performance-based
Modelled on the Norwegian Code
in accordance with the Nordic model. This
Our performance-based Building Code was
was brought together under a single Act – the
loosely derived from the Norwegian model
1991 Building Act.
and was New Zealand’s first countrywide
In 1991, the Building Act was passed, and
Building Code. Before this, both central
the New Zealand Building Code took effect
government and municipal authorities
in 1992. The Building Industry Authority
enforced building control legislation.
was established under the Act as the central
Building Code applies to all new buildings,
By 1979, there were over 60 Acts plus
government monitoring agency. Municipal
as well as all alterations and renovations to
a myriad of specific local bylaws related
authorities carried out building control func-
existing buildings. It allows flexibility and
to building administered by more than
tions under the Act.
encourages innovation by specifying the
19 central government departments, over
functional requirements and performance
300 municipal authorities and a variety of
Durability makes it different
criteria for building work as opposed to
other organisations, such as the New Zealand
The New Zealand Building Code differs from
prescribing how a building is to be built.
Fire Service.
the building codes of most other countries
Build 142 — June/July 2014 — 49
FEATURE
SECTION
Uniquely NZ
New Zealand
b y h av i n g e x p l i c i t
The perfor-
performance criteria for
mance-based
durability.
nature of the
Clause B2 Durability
Code enables new
requires structural
and innovative
elements – supports for
technology to
walls, floors, roofs – to
be incorporated
continue conforming to
as it becomes
the performance require-
readily avail-
ments of the Building Code
able through
for at least 50 years with
Alternative
normal maintenance.
Elements that are moder-
Methods and
updates to Acceptable Solutions.
ately difficult to access and replace, for
In 2013, the Acceptable Solution for
example, plumbing in subfloors or cladding,
fire escape paths was changed to include
have a minimum durability requirement of
photo-luminescent materials instead of
15 years with normal maintenance. Easily
just lighting solutions, and Australia has
accessible elements, such as surface coat-
followed suit.
ings, linings and services, have a minimum
Changes in 2012 mean professionals
durability requirement of 5 years with
are now able to use numerical modelling
normal maintenance.
to demonstrate compliance through the
Thi s means that building produc t
Verification Method for fire protection
manufacturers or importers of materials
(C/VM2), further encouraging innovation
must provide evidence that their prod-
in design and specification.
ucts will meet or exceed these durability
requirements in service, or specifiers and
More involved than prescriptive method
consenting authorities will be reluctant to
While it has taken time for Alternative
specify or approve them for use.
Methods and Verification Methods to be
It is particularly important to check that
taken up by the industry, many are now
imported products will perform in New
successfully using them as an alternative
Zealand’s climate and forms of construction.
to following prescriptive standards and
creating new solutions to old problems.
Advantages of performance-based
The slow uptake may be partly due to
Building Code clauses and standards refer-
the more involved process that includes the
enced are amended and updated over time
need to provide reasonable evidence that the
as political drivers, societal expectations
objectives of the Building Code will be met
and construction technology change.
by the proposed building work.
Before any change to legislative docu-
To facilitate this, engagement with the
ments, Acceptable Solutions or Verification
building consent authority from early in the
Methods are made, an assessment of costs
planning stage is important. Working
and benefits is carried out to ensure that
together helps to clearly define what needs
the outcome of the change is likely to have
to be done and what documentation needs
a positive benefit for New Zealand.
to be provided to achieve compliance.
50 — Build 142 — June/July 2014
Building
Code
Performance-based
one of first
Durability
5, 15 or 50 years
functional requirements
innovation
Acceptable Solution
Verification Method
B1 Structure
B2 Durability
C Protection from fire
D1 Access routes
E2 External moisture
E3 Internal moisture...