Insulation 

Based on the construction type and details of your development, along with the climate zone your dwelling is in, BASIX lists the construction that you have selected and calculates the R-value of insulation that is required to be added to each construction element. 

Insulation of construction material (R-value)

BASIX calculates the inherent thermal resistance of the floor and wall systems that you selected.  This can be seen in the table following the description of the construction. This is simply for information purposes. It does not include the R-value of any additional insulation.

Concrete slab on ground R-value is not calculated as no insulation will be required underneath it and therefore there is no need to provide the R-value of the slab. 

Ceiling and Roof R-values are not calculated as they are treated separately by BASIX to ensure there is foil under the roof when the colour is Medium or Dark.
 

Additional Insulation required (R-value)

This is the amount of insulation that must be added to the floor, wall, ceiling or roof (if required).  This value depends on the climate zone.  

The value is not in 0.5 increments as some types of insulation do not come in 0.5 increments. If, for example, an R-value of 0.8 is required to be added, and you intend to use bulk insulation batts, you will need to use R1.0 batts.  Other insulation products may have an R-value of exactly R0.8.

R-value ‘including construction’

For complex construction or foil insulation, BASIX provides the option of meeting the R-value of the construction plus any insulation.   This is sometimes called ‘total system R-value’ where ‘system’ means the wall, floor or ceiling/roof construction system. 

Complex Construction

The R-value of construction material is based on typical construction.  If you have atypical or complex construction the R-value of the construction material may be higher.  If you can demonstrate the higher construction R-value with evidence to the building certifier, you can comply with the R-value including construction and thereby reduce the R-value of additional insulation. 

Selecting ‘Other/undecided’ wall type

Because BASIX does not know the R-value of your wall, you will only be presented with the R-value including construction option.  You will need to provide evidence to the certifying authority that the wall and insulation meet this value.

Foil insulation products

Foil products generally only display the R-value including construction or total system R-value of their products, e.g. the total R-value of foil within a wall or ceiling and roof.  They do not display the added R-value because the R-value can only be calculated when the foil is tested within construction.  Follow the instructions below to work out what foil products comply with the requirements. 

Floors – ignore the added R-value requirement.  Choose a foil product that meets the R-value including construction.  You need to do this for the required direction of heat flow (i.e. up/winter or down/summer) as the performance can be very different. 

Walls – ignore the added R-value requirement.  Choose a foil product that meets the R-value including construction.

Ceilings and Roofs

This will also be displayed on packaging as a total system R-value of the foil plus the ceiling and roofspace.  BASIX, however, separately assesses the insulation requirements of roofs and ceilings.  This is not done as a total system R-value to avoid additional ceiling insulation to be installed instead of foil under the roof where required – they do not perform the same functions and foil will have greater benefit for comfort in bedrooms at night. 

For roofs, simply match the type of insulation shown in the table.   

For ceilings, subtract the R-value for your construction, from the total system R-value of the product for the required direction of heat flow. The difference must be greater than the additional R-value required by BASIX.  Ignore the Roof insulation in this calculation.

Further information

For more information on insulation products go to the following websites:

The Aluminium Foil Insulation Association (AFIA) - http://www.afia.com.au/

The Australian Cellulose Insulation Manufacturers Association - http://www.acima.asn.au/

The Insulation Council of Australia and New Zealand (ICANZ) - http://www.icanz.org.au

See also:

What is new or altered floor?

What is new or altered wall?

What is new or altered ceiling (with roof above)?