What Is Roof Sarking

We all need shelter from the elements, especially in a country regularly lashed with ferocious storms, with piercing sunshine in between them. Our homes need a sturdy, well-built roof that will protect us from the rain and heat, and go the distance.

A key element to a protective roof is sarking, and in this article, we’ll explain its purpose, how it works, the benefits, types, and costs, and more.

What is roof sarking?

Roof sarking is a thin pliable sheet with an aluminium foil lining that sits underneath the tiles of a roof. It’s hardy and waterproof, and creates an additional protective layer of insulation for the roof, by reflecting up to 97% of radiant heat from the sun.4 If rain gets the tiles and reaches the sarking, the water is safely channeled into the roof gutters to protect the roof from becoming damaged.

Aluminium is a material that naturally protects against the hot and cold, helping to regulate the temperature in the roof cavity.

What are the benefits?

The main purpose of sarking is to provide additional insulation for your home, but it has a number of other benefits, including:

  • It helps to regulate the temperature in the roof cavity, improving thermal performance
  • It protects your home against thunderstorms and rain
  • With moisture reduced in the roof cavity, mould is unable to grow. This also reduces the risk of ravenous termites.
  • It prevents dust from entering the roof cavity
  • It protects the roof cavity from high winds
  • Some types of sarking allow a little vapour to get through, which reduces the buildup of condensation and moisture within the roof cavity.4
  • It protects a home from flyer embers, providing fire protection

Is roof sarking mandatory?

Under the Building Code of Australia (BCA) it is mandatory that all modern tiled residential roofs with a rafter length greater than six metres are sarked, however, it is considered good building practice to sark all tiled roofs to protect homes from the entry of external moisture. This goes for both tiled, and metal roofs.

What are the different types?

The main purpose of sarking is to protect the property from rain, but different types of sarking are available that provide other specific benefits such as hail protection, or extra thermal insulation. These are also usually split between the property’s roof type—tiled, or metal.1

Do you need sarking under a COLORBOND roof?

COLORBOND steel is designed to be thermally efficient, but because roof sarking has a high reflective quality, it will improve the thermal performance of the roof even more, helping to keep your house cooler in summer.2

How to repair roof sarking

If you find a tear in your sarking, the insulation that it provides will be less efficient. Thankfully, tears are easily fixed with special tape, such as Enviroseal’s ProctorWrap tape.

How much does it cost?

The cost of reflective roof sarking varies, depending on its thermal efficiency. Cheaper sarking costs around $100 for a 60m x 1350ml roll, with expensive “air cell” barrier sarking that offers a BCA 6-star energy efficiency costing around $350 for a 22.5m x 1350ml roll.3

How to install sarking?

Essentially, the sarking is rolled out in sections away from the eaves of the roof, with a slight overlap between each layer. But the process is much more complex than this. You’ll need to consider a range of issues such as thermal bridging, vapour barriers, ventilation, and air gaps. Because proper insulation is critical for a home, it’s highly recommended to hire roofing experts for the job, as they’ll have the experience needed to complete the job effectively.

If you’re set on installing the insulation yourself, check out this comprehensive article from the government.

When should sarking be installed?

The easiest time for installation is when a house is being built, or when a roof is being replaced. By installing the sarking early in the build process, the house will be protected from the weather until the roof is completed.

Roof sarking is not only necessary for improving the thermal efficiency of your home, it’s mandatory under the Building Code of Australia, in an effort to tackle wasted energy and the effect that it has on climate change. Our homes must protect us from the elements and be properly insulated to regulate the temperature, and sarking helps us to achieve these goals.


  1. Select the right sarking product for your roof type, Bradford Insulation
  2. 2017, The Long-Term Value of Metal Roof Sarking, Pantex Roofing
  3. Rob Schneider, 2020, 2020 How Much Does Roof Insulation Cost?, Hipages
  4. Roof sarking – what is it, why do you need it, what should you get? – Benefits of Roof Sarking, Bradford Insulation