Insulation is any material that reduces the amount of hot or cold air lost through your home’s walls, ceilings or windows.
Installing insulation in your home will help to:
- keep the warmth inside your home in winter
- prevent heat from entering your home in summer
- reduce your need for heating and cooling appliances
- reduce your heating and cooling related costs and greenhouse gas emissions.
On this page:
Types of insulation
Insulation R-values
Advice for having insulation installed in your home
Types of insulation
There are two main types of insulation:
- bulk insulation
- reflective insulation.
Some insulation products use a combination of both bulk and reflective foil to achieve their insulating effect.
Bulk insulation
Bulk insulation is the most common type of insulation used to insulate walls and ceilings. It is usually made from:
- fibreglass mineral wool or rockwool
- synthetic fibre
- sheep's wool.
These products come in two forms:
- blankets - long rolls of insulation that must be cut to fit into place
- batts - pre-cut lengths of insulation.
Blankets usually come with a moisture barrier, foil or plain paper backing while batts can come with or without backing.
Batts are a common choice when there is easy access to the space needing insulation.
Loose fill insulation
Loose fill insulation is another form of bulk insulation. It has no backing and is pumped into a wall cavity or roof space.
Loose fill insulation is one of the fastest and easiest forms of insulation to install. It can easily fit into areas where blankets or batts may be difficult to install.
Loose fill material includes:
- mineral wool
- cellulose fibre.
Cellulose fibre is made from recycled paper that has been chemically treated to resist fire, rot and vermin.
Use a water resistant grade of loose fill to insulate external cavity walls.
Rigid insulation
Rigid insulation comes in pre-cut boards that are primarily used in new home construction. They are ideal for insulating:
- raked or cathedral ceilings
- solid brick external walls
- under wooden floors
- around concrete slabs.
To be effective, rigid insulation needs to be installed with a tight seal between boards.
Reflective foil insulation
Reflective foil insulation reflects radiant heat reducing the amount that enters the home.
Reflective foil only affects heat transfer in one direction. To prevent heat from escaping, the home reflective foil insulation is often bonded with batts or plasterboard to provide insulation benefits in both directions.
Reflective foil insulation can act as a water proofing membrane under a roof and as a moisture barrier for roofs and walls.
Reflective foil is available in:
- single layered form
- multi-layered form - an air pocket between layers provides extra insulating benefit.
If installing single layered reflective foil insulation under a tiled or metal roof, bulk insulation may still be needed at ceiling level to achieve a good level of insulation through all seasons.
Reflective insulation requires an air layer of at least 25 mm next to the shiny surface in order for it to insulate effectively.
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Insulation R-values
What is an insulation R-value?
The insulation R-value is a measure of a material's resistance to heat transfer. The higher the R-value the higher the level of insulation.
Bulk insulation will show one material R-value which refers to the insulating value of the product alone.
Reflective insulation R-values can differ depending on the direction of heat flow through the product:
- up R-value - resistance to heat flow upwards (sometimes known as winter R-values)
- down R-value - resistance to heat flow downwards (sometimes known as summer R-values).
Both R-values should be quoted when installing reflective insulation.
What is the recommended R-value?
In Adelaide the recommended insulation R-value is 3.2 for the ceiling or roof and 1.9 for walls. In colder climates - eg Mt Gambier - a higher insulation R-value is recommended, 3.7 in ceiling or roof and 2.2 in walls.
New homes must comply with building energy efficiency requirements which include insulation levels for walls, floor and roofs.
Comparing insulation performance
Use the R-value to compare the performance of insulation material. If two different types of material have the same R-value they will perform equally.
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Advice for having insulation installed in your home
- Always get multiple quotes and ensure they show the correct R-value and the insulation is certified to Australian Standard AS3999.
- Use a builder who is licensed to install insulation in South Australia. Check the licensing public register from the Office of Consumer and Business Affairs.
- Beware of the hot box syndrome - when insulation is installed without adequate window shading heat can build up inside the home until temperatures inside are higher than outside. The insulation will keep this heat inside. Provide adequate window shading to prevent the hot box syndrome.
- Make sure your insulation has been properly treated for fire or is a non-combustible product. Insulation products have a fire rating under Australian Standards AS1530.3.
- Batts should be cut so they fit snugly between ceiling joists and allowance made for them to expand to their natural thickness.
- Insulation should be kept clear of electrical equipment - eg downlights, exhaust fans - and electrical wiring. Barriers and covers should be installed.
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More information
Other websites
Insulation - Your Home Technical Manual, Australian Government
Insulation installation - Your Home Technical Manual, Australian Government