Frequently asked questions
What is the best insulation to use?
This depends on three factors:
- what is being insulated (e.g. ceiling, wall)
- for what purpose (e.g. thermal comfort or noise reduction)
- the climate where you live.
These factors will determine the R-value of the insulation you choose. The R-value is a measure of the material's resistance to heat flow, and therefore its performance. The higher the R-value, the greater the resistance to heat transfer, and the greater the energy savings.
Will possums or rats eat my insulation?
No insulation is pest proof. Wool, polyester and cellulose fibre insulation should all be treated to prevent them from being eaten by pests.
Which way do you put reflective foil insulation, silver side up or blue side up?
The silver side goes down. The shiny surface will only let around 5% of the heat radiate through and the other 95% will go back to the roof or external wall.
I have down lights and I want to insulate the ceiling - what should I consider?
No form of insulation can be placed over down lights - this creates a heat build up and a subsequent fire risk. 25mm gaps must be made around down lights, therefore holes must be cut in batts and non-flammable restraints put in place for loose fill insulation. It is possible to purchase downlight guards, which are placed over each downlight in the ceiling and enable you to insulate more effectively and safely.
Note that a 90mm gap applies for around hot flues or exhaust fans. You should also ensure any wiring in the ceiling is appropriately rated (ask an electrician) to avoid a fire risk.
How can I be sure that the company I purchase my insulation from can be trusted?
Not all types of insulation are covered by an Australian Standard, so in many cases the buyer must beware. Ask as many questions as possible - for example:
- Has the product been treated for vermin and insect attack, or with a rot-proofing agent?
- Has the product been treated with a fire retardant? (Always ask for written proof that the products have been treated.)
- Are these treatments likely to settle or leach out of the product and how long are they expected to keep working?
- Does the product come with a guarantee? Remember a guarantee is only as good as the company that provides it - if they go out of business, the guarantee is worthless.
- The NSW Department of Fair Trading can tell you if a company has a legal action against it or if a plumber, builder or electrician has a licence to operate in NSW.
I'm installing insulation in my house, what safety precautions should I take?
Wear protective clothing: facemask (half face disposable respirator), long sleeved loose fitting clothing (pants and shirt) and gloves. Following installation, wash skin with warm soapy water and wash clothing separately.
What insulating products present a fire risk?
- Fibreglass and rockwool insulation do not burn, smoulder or break down over time.
- Reflective foil insulation is available in fire retardant grades.
- Cellulose fibre can be a fire risk if not treated with sufficient fire retardant (or if the retardant settles or leaches).
- Although natural wool is flame resistant, dirt or grease in sheep wool can add to its flammability. Check if the manufacturer can supply independent fire resistance tests. For added safety, wool insulation should be treated with additional fire retardant.
- Wool insulation blended with polyester should not have less than 50% wool. Polyester does not burn, however it will melt if exposed to a flame.
Page last updated: 27 February 2011