Home » Sarking vs insulation: which does your metal roofing installation need?

Sarking vs insulation: which does your metal roofing installation need?

Your roof protects your house from heat, cold, and Melbourne’s famously unpredictable weather conditions.

However, for your roof to provide optimal protection and comfort, it needs the support of additional components like insulation or sarking. 

But what exactly are these materials, and which one is more crucial for your metal roofing installation? Let’s explore.

While we all know insulation’s job of forming a barrier against heat from outdoors and maintaining indoor temperature, fewer people understand the role sarking plays in your roof.

So, what is the difference? And which one matters more for your upcoming metal roofing installation?

metal roofing installation

 The difference between insulation and sarking

While both sarking and insulation contribute to a building’s efficiency and comfort, they serve different purposes. Here’s a quick comparison:


Feature Sarking Insulation
Primary Function Weatherproofing and radiant heat reflection Thermal regulation
Installation Location Directly under the metal roofing Within the roof cavity or ceiling space
Condensation Control Yes Yes (through temperature regulation)
Acoustic Benefits Minimal Significant
Fire Protection Yes, in bushfire-prone areas No

What is roofing insulation?

We all know how insulation works – it stops heat from getting in, and warmth from getting out. Be it summer or winter, it works hard to passively keep your house cool or warm.

If your roof is insulated, you and your family will be protected in both summer and winter.

Here are some of the common problems without proper insulation:

  • Roof joists, beams, rafters, and flashing may expand due to hot temperatures
  • With increased heat build-up inside the home, cooling costs will also increase
  • Condensation and mould growth can damage structures and affect health
  • Second storey rooms or attics may feel hotter
  • Temperature inconsistency throughout your house

Insulation comes in a variety of forms. You may get foilboard, rigid foam, rockwool, blankets and loose-fill to name a few, in a range of different materials.

To ensure your house is left with an ideal insulation solution, be sure to talk to an expert prior to metal roofing installation – the last thing you want is to have to rip up your newly installed roof and do everything all over again.

And while you’re there, don’t be afraid to ask your metal roofing team about roof sarking, either!

What does sarking do?

Despite playing a role that’s equally important, sarking is often completely overlooked. Many even assume that sarking and insulation are the exact same thing, just with a different coat of paint!

While it does have some insulating properties, sarking’s primary function concerns condensation, moisture, and water vapour.

Furthermore, while insulation can take several forms, sarking almost always uses reflective foil instead.

Sarking protects your home during roof installation

During metal roof insulation, sarking is installed first, providing some protection against the rain during the installation process.

Combined with a protective waterproof cover, sarking ensures that your property is kept dry while your roof installer executes your metal roofing installation.

Sarking provides a vapour barrier

Once your roof is in place, sarking forms a vapour barrier.

As we’ve mentioned several times before on this website, moisture build up in your roof cavity is a major problem.

Once moisture gets in, you’ve got all the ingredients needed for rapid mould growth:

  • Moisture
  • Darkness
  • Food (wood and insulation)

Basically, sarking adds a waterproof layer to your roof, preventing moisture from getting in and thereby stopping mould and other moisture-related damage.

By forming a non-permeable barrier, sarking stops outside moisture from getting in. Combined with good ventilation, and you won’t have to worry about water damage to your roof or insulation.

metal roofing

Condensation prevention

We all know that water evaporates and turns into steam and vapour when it’s warmed up. 

The opposite is also true – when steam or vapour cools down, it transforms back into droplets.

This point is what’s known as the dew point.

In many cases, when vapour comes into contact with a cold surface, its temperature drops below the dew point, turning into droplets and condensation (this is why your car windows start fogging up in winter).

When air moisture and vapour come into contact with the cold metal of your roof, it passes the dew point and turns into condensation and droplets. This leads to water and moisture building up in your roof – not a good outcome!

By providing an extra layer, sarking stops moisture from coming into contact with the cold metal of your roof. And that in turn protects your roof from condensation and moisture damage.

Bushfire protection

With the current bushfire season breaking records, it’s little wonder that many Melburnians are starting to put more thought into fire protection – especially those living in outlying suburbs that are at risk of fire.

Here’s something you may not have known: in addition to moisture protection, sarking also helps protect your home from bushfires.

Many insulation materials are flammable – as such, you’ll need to take great care to ensure that your insulation is thoroughly protected from embers and sparks that may be blown around if you live near a fire zone.

In addition to forming a physical barrier against outside humidity, sarking can also provide protection against embers and sparks.

The vast majority of roof sarking products on the market are made using fire-resistant materials, so you needn’t worry about your sarking catching fire.

Want a beautiful, strong roof that keeps moisture and heat out?

Call Watermaster Roofing today!

When we call ourselves the Masters, we do it for good reasons: with 20 years of experience performing all manner of metal roofing installation, repairs and upgrades, we’ve earned the title!

Our Masterful roofing team will look after your roof. In addition to ensuring the metal panels are strong and durable, we’ll also ensure that your roof is combined with sarking installation and ventilation design for maximum comfort.

Want a stronger, more attractive and longer-lasting roof? All you need to do is pick up the phone and dial 1300 576 075 or click here to organise an inspection.

2024-06-06T04:10:08+00:00 May 29th, 2024|Metal roofing|

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