Building Regulations
About the Building Code
All new building work in New Zealand must comply with the Building Code. The Code sets out performance standards that
building work must meet. The Code is comprehensive and addresses many important aspects such as structural stability,
durability, fire safety, and means of escape, moisture control, ventilation and efficient use of energy.
Building plans and specifications are assessed by building consent authorities to ensure compliance with the Building Code
before a building consent is issued.
The Building Code is performance based. It does not prescribe how the building must be designed or constructed. It states
how the building and its various components must perform.
This provides the designer with a greater level of flexibility in that he/she is not restricted to certain products, systems or designs
but can remain innovative in his/her approach providing the final design meets the performance requirements of the Building
Code.
How is compliance assessed?
Compliance Documents
Compliance Documents (previously Approved Documents) are produced by the Department of Building & Housing and provide
one means of complying with the clauses of the Building Code. There are 35 Compliance Documents – one for each Building
Code clause. The key performance standards are:
B1 Structure
B2 Durability
C Fire Safety
D Access
E Moisture
F Safety of users
G Services and Facilities
H1 Energy efficiency
The Compliance Documents contain information on building materials and on construction details and offer various ways to
achieve compliance. They contain Acceptable Solutions that, if followed, mean that a building will automatically comply with
the Building Code. They also contain Verification Methods which provide the designer with a solid means of testing his design
to ensure that it will comply with the Building Code.
Buildings built to either the Acceptable Solution or Verification Method described in the Compliance Document are
automatically deemed to comply with the Code. They are sometimes referred to as “cookbook” solutions because they provide
a recipe for ensuring compliance.
Because Compliance Documents are published and endorsed by the Department of Building and Housing, designs based on
them must be accepted by building consent authorities as demonstrating compliance to the Code.
Alternative Solutions
Compliance Documents are however not mandatory. Alternative Solutions are for those situations where a non-generic
approach to design and construction is either desired or required. The Building Code, being performance based, allows for this
freedom for a building owner or designer to come up with a proposal that is different or out of the norm. The applicant would
need to determine which parts of the project are not covered by a Compliance Document. These parts will require an
alternative solution. The documentation for the proposed alternative solution must contain sufficient evidence to show that the
identified performance criteria of all relevant technical clauses of the Building Code have been met.
Insulation and the Building Code
H1 is the clause that spells out the minimum requirements for energy efficiency, of which insulation is a key component. The Acceptable Solutions and Verification Methods outlined in the Compliance Document H1 Energy Efficiency reference the New Zealand NZS 4218. This NZ standard contains tables which outline the 
minimum R values required for non solid construction, solid timber construction and solid construction (excluding timber), whilst also taking into account the different climate zones within New Zealand.
Changes to Building Code Clause H1 (Energy Efficiency)
From 31 October 2007, tougher insulation standards came into force for every home built in the South Island and North Island Central Plateau. This has meant the use of double glazing combined with more insulation in walls and roofs. By October 2008, all new homes throughout New Zealand will need to meet these new requirements. These new rules apply not only to all new homes, but also to all major extensions, to all multi unit apartments, and to any small building with a floor area up to 300m2.
The actual change to the Building Code is an increase in the stringency of the Building Performance Index (BPI). This is
reflected in a corresponding change to the H1 Compliance Document which updates the R values outlined in the referenced
standard (NZS 4218:2004 tables). The R values specified in NZS 4218:2004 have been increased significantly in order to
match the thermal performance required by the new BPI in the Building Code.
The purpose of this amendment is to lower power and gas bills and make homes warmer and more comfortable. It is
anticipated that due to the more stringent R value requirements on insulation and glazing that about 30% less energy will be
needed to achieve comfortable indoor air temperatures of between 16 and 20 degrees Celsius.
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How does insulation work?
An uninsulated or under-insulated house loses vast amounts of heat through the roofs, walls, floors and windows. Heat will
always flow from a warmer to a cooler space. In the winter, heat moves directly from all heated living spaces to unheated
attics, garages, basements and to the outdoors. Heat moves through interior ceilings, walls and floors – wherever there is a
difference in temperature.
To maintain comfort, the heat lost in winter is replaced by turning up the heating system. Likewise the heat gained in summer
is removed through the air conditioning or other cooling system. It costs money to heat or cool a house. Just to put it in
perspective, the annual cost of electricity & gas consumed by residential buildings nationally is currently about $2.3 billion.
The purpose of insulating is to slow down the transfer of heat. Bulk insulation like Bradford Gold segments and blankets work by
means of air entrapment (air is a poor conductor of heat). Bradford Gold traps numerous pockets of still air which provide a
resistance to the transfer of heat. An insulation’s resistance to heat flow is measured in terms of its R value (Thermal Resistance
value). The higher the R value, the more effective is the insulation at slowing down the transfer of heat, thereby retaining the
warmth within the home and reducing the amount of energy used for heating.
Insulating your home is the single most effective action that you can take to increase your comfort levels, save energy and
lower your power bills. A fully insulated home needs about half the heating that an uninsulated home requires.
In addition to this, the World Health Organisation recommends that a house have a minimum indoor air temperature of
16 deg.C. If a house is colder for long periods of time, condensation, damp & mould growth may develop. These can lead
to colds and other respiratory infections. Warm homes are healthy homes.
How much insulation do I need to comply with H1?
The minimum level of insulation needed to achieve compliance depends on a number of factors including climate zone,
house design, amount and orientation of glazing, construction detail, numbers of downlights and timber framing content.
Being a performance based code, designers and builders have the option of achieving compliance in a couple of different
ways. They can use the prescriptive R values outlined in the modified NZS4218 tables but only if the design satisfies certain
criteria. This is called the Schedule Method. If the conditions cannot be met, the calculation or modelling method can be
used. If the design is truly innovative or the ratio of glazing to wall area exceeds 50% the computer modelling method must be
used.
Wall and Ceiling Insulation
The following recommendations for insulating walls and roofs are based on the use of the Schedule method to achieve
compliance.
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Read MoreHeating Double Glazing |
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