Roof Insulation Cost

Depending on the size of your roof and the scale of the job, a decent estimate would be around $1800 for a 150 sqm house house to supply and install r 3.5 fiberglass batts. 

I just recently had my 225 square meter house done with fiberglass batts from a supplier in the local newspaper and I was charged $2500.

What is Roof Insulation and Do I Need It?

Insulation, as the name implies, is meant to act as an obstruction to the transfer of heat. It keeps heat from entering or exiting. You see it all the time, applied in many different ways. It’s what keeps the water in your bottle cold and what your clothes use to keep you warm.

For homes, insulation is used in your walls and in your roof to keep you feeling warm when the weather is chilly, and cool when the weather is toasty. In particular, insulating your roof is a great way to moderate the temperature of your house, since a significant amount of heat comes in and leaves through ceilings. 

Actually, roof insulation is mandated by Australian law, so you will most definitely have to do it. But don’t worry, because no matter how you look at it, you’ll be at an advantage insulating your roof.

roof insulation prices


Not only does it help to keep your home at a comfortable temperature, but it also does a lot in terms of becoming efficient with energy by reducing the need to use heaters or air conditioners. In the long run, this could also save you a lot of money on your electric bill. Insulation is also meant to prevent damage from moisture.

How Much Does Roof Insulation Cost?

How much to allot for the materials and installation your roof insulation depends on a few different things, like the location of your home, the kind of insulation you choose, and the laborers you decide to hire.

For fiberglass batts in the roof space it will cost $2500 for an average sized home. Most builders will include the minimum required R-rating batts to your roof to keep your house cost low.

Of course, this is just an approximation. The cost of your job also depends heavily on what kind of insulation you choose. There are a few materials you can choose from. According to hipages, here are some of the most commonly used types of insulation:

  • Reflective Foil: the most typically used insulation, installed under the roof
    • Cost: around $11.66 per sqm
  • Glass Wool / Fibreglass: a very popular insulating material installed in the ceiling cavity
    • Cost: around $6.66 per sqm
  • Sheep’s Wool: the oldest method of insulation, which is still used today
    • Cost: around $10 per sqm
  • Polyester: a more modern option, usually made largely of recycled polyester
    • Cost: around $10 per sqm
  • Reflective Sarking: a pliable material, one of the cheapest kinds of insulation
    • Cost: around 1.25$ per sqm

Keep in mind that these prices are merely estimates, and that you may not always be able to purchase them per sqm. Depending on your supplier, they may come in rolls with specific dimensions. 

roof insulation cost

Reflective foil comes with a kind of air pocket system that prevents heat from crossing. This is required in reflective foil insulation to comply with Australian energy efficiency law, and makes it very efficient in maintaining temperature.

R-Value Of insulation

You may also want to consider the R-value of the material you choose. This may come up in your research, but the most basic definition of R-value is a value indicating the thermal ability of a material. The best R-value depends on your specific circumstances. If you live in a warm area, you might want to go for a material with a lower R-value, while colder areas might need something with a higher R-value.


While roof insulation may require you to spend a bit, it is a great way to achieve a comfortable temperature for your home, while saving both money and energy in the long run. For anyone that may be experiencing difficult temperatures, it’s a great option to look into.

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