What insulation is in my house?
Written by a registered architect for Dudils.
For a NSW house approved since BASIX began, its BASIX and NatHERS certificates list the insulation it was approved with: the R value in the ceiling, the walls and sometimes the floor. Search the address on the BASIX lookup to read it where the council published the certificates, before you open a wall or lift a ceiling sheet.
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Where can I find out what insulation my house was built with?
Start with the BASIX certificate, which lists the insulation for the roof, ceiling, walls and floor, and the NatHERS certificate, which lists the construction the star rating assumed. Both are filed with the approval for the house, and the guide to finding a BASIX certificate covers where. The builder's handover documents and the construction drawings may say more, such as the brand of batts.
What does the R value mean?
The R value measures how well a material resists heat passing through it, and a higher number insulates better. A certificate states the R value the insulation in each part of the house must reach, so it tells you the level the house was approved at, not the brand or the product.
Can I check the insulation myself?
In the ceiling, usually yes. From the roof space access hatch you can see the batts or loose fill, and most batts are printed with their R value. Walls are harder: the usual way to look is behind a power point cover plate, with the power turned off at the switchboard first, or ask an electrician.
In an older house, do not disturb loose insulation in the roof until it has been checked for asbestos.
Does the certificate prove the insulation was installed?
No, it shows what was approved. The certifier inspects the work at set stages and must be satisfied the BASIX commitments were met before issuing the occupation certificate, but no record shows the insulation is still in place years later. For the ceiling, look in the roof space.
Why does it matter before I renovate?
It tells you where an upgrade gains the most. If the ceiling already has the R value the certificate lists, topping it up gains less than insulating a wall or a floor that has none, or replacing single glazed windows. A renovation costing $50,000 or more also needs its own BASIX certificate.
What else do people ask?
Does BASIX list wall insulation?
Yes. The BASIX certificate lists the insulation for each kind of external wall as well as the ceiling, roof and floor, and the NatHERS certificate lists the wall construction its rating assumed.
What glazing does my house have?
The NatHERS certificate lists each window's frame and glass with its U value and solar heat gain coefficient (SHGC), and the BASIX certificate lists the glazing it commits to. A lower U value loses less heat through the glass, and a lower SHGC lets in less of the sun's heat.
Where does this information come from?
This guide explains how BASIX and NatHERS work in general. A certificate records the design that was approved, and your home may differ from it. Nothing on this page replaces advice from your certifier, engineer, lawyer or your own designer.