How much insulation does my home need?

The insulation requirements for buildings in Australia (and all other requirements) is governed by the Building Code of Australia (BCA)

The Building Code of Australia is produced and maintained by the Australian Building Codes Board (ABCB) on behalf of the Australian Government and State and Territory Governments. The BCA has been given the status of building regulations by all States and Territories.

The goals of the BCA are to enable the achievement and maintenance of acceptable standards of structural sufficiency, safety (including safety from fire), health and amenity for the benefit of the community now and in the future.

The BCA contains technical provisions for the design and construction of buildings and other structures, covering such matters as structure, fire resistance, access and egress, services and equipment, and certain aspects of health and amenity.

BCA is adopted through State and Territory Legislation – Building Acts and Regulations

To get a detailed explanation of ‘what is the BCA’ click here.

The regulations in the Building Code of Australia (BCA) that apply to home insulation are complicated. As well as determining specific R-value requirements for different parts of a home, they also contain requirements for ventilation, and various other related issues.

Climate Zones

For the purpose of insulation regulations, Australia is divided into 8 different climate zones. Each climate zone has its own particular insulation requirements.

Climate zone maps

You can find out more about the different climate zones on the climate zone map or on the ABCB website.

Which rules specifically apply to insulaton?

For your home’s insulation to be properly compliant, the building envelope must be constructed so that it satisfies:

  • Part 3.12 of the Building Code of Australia Housing Provisions (BCA)
  • AS/NZS 4859.1 – Materials for the thermal insulation of buildings
  • The manufacturer’s specifications, to ensure that the product performs as tested

What’s generally required in Australia?

The first step in meeting regulatory requirements is to determine what climate zone you’re in and what type of dwelling you need to insulate. This will determine the R-values required for different parts of your home.

These R-value objectives aren’t measured through insulation alone though; the whole construction is measured, taking into account additions to the R-value like the inherent R-value of things like brick walls, as well as subtractions caused by windows or any other thermal bridges that might exist.

This is why it’s so crucial to have the insulation labelled clearly and installed exactly to the manufacturer’s specifications and instructions. If you don’t, you may find that while on paper you meet the requirements, in reality your actual insulation is nowhere near as effective as what you’d calculated.

Having your thermal envelope independently assessed is important – you may not be able to obtain a construction permit if the building doesn’t meet the minimum ‘Deemed-To-Satisfy’ requirements. Likewise, there’s very little point paying for lots of insulation if it’s not going to do its job properly!

Required R values for walls, roofs and floors

Below is a table outlining the basic R value requirements for walls, roofs and floors. Note that there are many other requirements and exceptions to these figures, depending on the state, type of home and materials your home uses:

Climate zone:12345678
Roof / Ceilings
Direction of heat flowInwardsInwards/OutwardsOutwards
Very light coloured roofs (Absorptance ≤ 0.4)R4.1R4.1R4.1R4.1R4.1R4.1R4.1R4.1R6.3
Light coloured roofs (0.4 < Absorptance ≤ 0.6)R4.6R4.6R4.6R4.6R4.6R4.6R4.6R4.6R6.3
Dark coloured roofs (Absorptance ≥ 0.6)R5.1R5.1R5.1R5.1R5.1R5.1R5.1R5.1R6.3
Direction of heat flowInwardsOutwards
Direction of heat flowInwardsOutwards

(For a full and accurate understanding of what you need we recommend visiting the BCA website or talking to an insulation professional.)

Energy Efficiency

The objective of the Energy Efficiency section in BCA is to reduce the emission of Greenhouse Gasses.

Energy Efficiency is using less energy in buildings for heating and cooling. This can be achieved by:

        • Improving the performance of heating, cooling, lighting
        • Reducing the size of the services
        • Reducing the use of services

Energy, in the form of gas electricity and oil is used by building services for heating, cooling, lighting, ventilation and hot water supply.

The process of energy generation releases greenhouse gases to the atmosphere.

The 6 Star Energy Equivalence Rating of a building is determined by the design of its envelope or shell – roofs, walls, floors and windows.

The rating is out of 10 stars. Higher star rating means higher the energy efficiency and the comfort of the building.

An energy equivalence rating does not take into consideration a house’s fixtures and appliances, such as hot water systems, air conditioners, lighting and fridges.

Please click here for more information on Energy Efficiency.


Building Sustainability Index (BASIX) was introduced by the NSW Government in 2004 before the introduction of BCA Energy Efficiency requirements in 2006.

For NSW, BCA 2010 still refers back to BCA 2009 for Class 1 Residential Buildings
“For Class 1 and 10 buildings subject to BASIX, the BCA energy efficiency provisions of BCA 2009 as varied by the NSW Appendix are applicable.”

BASIX ensures homes are built to be more energy and water efficient.

BASIX is on-line program that assesses a house or unit design, and compares it against energy and water reduction targets. The design must meet these targets before a BASIX Certificate can be printed.

Every development application for a new home must be submitted to Council with a BASIX Certificate.

BASIX uses information such as site location, house size, type of building materials and fittings for hot water, cooling and heating.

For more information please click here to visit the BASIX website


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