What Is Anticon And Do I Need It?

"I tell you, it's terrible," said a recent customer. "Every time it rains it sounds like we're being bombed!"

We were only there to replace the gutters, but what the elderly gentleman was describing was the deafening sound of a downpour on uninsulated roof sheets.

Unfortunately, the people who had originally installed his roof had failed to lay an insulation blanket underneath, commonly known as "anticon".

What is Anticon?

Anticon is a glass wool blanket which is laid between the roof battens and the roof sheets during the roof installation, providing a vital layer of thermal and acoustic insulation.

The word anticon is short for "anti-condensation" because it helps to absorb and mitigate the effects of condensation which can form on steel during changes in temperature.

The anticon blanket consists of a layer of silver paper foil, attached to a layer of fibreglass wool. This wool sits against the roof sheets, absorbing the moisture until it dries out again.

What Does Anticon Do?

Anticon helps counteract three main elements: condensation, temperature and noise.


If you've ever walked out to your car in the morning to find it covered in beads of glistening dew, you'll know how condensation can form on steel when cold.

Condensation can also form on the underside of the roof sheets, trickling down on to the ceiling above your head.

This is also why experienced roofers will never step straight on to a steel roof first thing in the morning. When even slightly wet, roof sheets are as slippery as ice. Anyone attempting to walk on it will quickly wish they hadn't.

Morning Dew Condensation on Roof Sheets

Temperature Insulation

"Ok," I hear you say. "It stops the dew. But I live in Perth. I'm more worried about three months of weather hot enough to thaw the heart of Bronwyn Bishop."

Well, you'll be glad to know that anticon can help with that too. Our formaldehyde-free anticon comes in four thicknesses from 55mm to 100mm, providing an R-value (the rating used to determine the degree of insulation) of up to 2.5.

This can save you money in heating and cooling costs as soon as it's installed, and is effective in reducing temperature variation even if you have existing insulation such as ceiling batts.

How much will it reduce the temperature in your home in summer? It is impossible to give an exact number due to the influence other variables such as roof pitch, ceiling type, and building design. But if you'd like to dive deep in to R-values, the Insulation Handbook from the Insulation Council of Australia and New Zealand (ICANZ) is a good place to start.

Anticon comes in varying thicknesses and R Values

Acoustic Insulation

As our lively customer so eloquently expressed, the noise of rain or hail on a bare tin roof can be distracting, annoying, or even overwhelming.

Have you ever tried to have a conversation in a warehouse while it's raining? That can be the result in your home if you skimp on anticon.

If the rain is going to be drumming on your roof, at least let it drum piano instead of forte. A thick layer of anticon can reduce roof noise significantly.

Other Considerations of Installing Anticon

Loft/Attic Conversions

If you're thinking about converting your roof cavity in to a usable space, such as an attic or loft, then anticon is especially recommended. Anyone who has stuck their head inside an uninsulated roof space during the day knows that it is like opening an oven door. Without sufficient insulation the roof cavity is completely uninhabitable.

Choose Formaldehyde-Free

Some insulation can be made with nasty chemicals, but not ours! We only ever use a formaldehyde-free anticon roofing blanket to help keep our workers and your family safe.

It's Cheap

Although, strictly speaking, anticon is optional, given all the reasons outlined above and at only about 5-10% of the cost of a roof replacement it's hard to see why you would skimp and go without it.


In the hotter months an anticon insulation blanket will reduce the heat in your home, and in winter it will help keep it warm. For a relatively small outlay, anticon will make your house quieter when it rains, and keep your roof space dry when it gets cold.

Remember, the only opportunity you have to install anticon insulation is when the roof is being installed. It cannot be retrofitted. So if you're installing a new roof, or considering re-roofing, why not take the opportunity to help ensure your roof is warm, dry and quiet.

And on a completely separate note - does anyone else think it's ironic that the word anticon is itself a condensation?

#anticon #insulation #roofsheeting #reroofing

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