What is the best insulation for a steel shed in Queensland?

For most sheds, 55mm Anticon blanket to the roof is the best value — it cuts radiant heat, drops rain noise significantly and controls condensation. Step up to 75mm or 100mm for workshops, gyms or studios where you spend real time in the building.

Do whirlybirds actually work on a shed?

Yes, provided there is a low-level intake for replacement air. A whirlybird with sealed walls and no vents has very little to draw on. Pair roof ventilators or whirlybirds with wall vents or louvres low on the opposite side.

Does a light coloured roof keep a shed cooler?

Noticeably, yes. Lighter COLORBOND® colours reflect more solar radiation, and Thermatech® solar reflectance technology reduces roof surface temperature across nearly the whole range. Insulation still does more than colour, but colour is free to choose.

Can insulation be added to an existing shed?

Blanket insulation sits under the roof sheeting, so retro-fitting properly means lifting sheets. There are retro-fit alternatives such as internal linings and sprayed products, but they cost more and perform less well than specifying it at build. Ventilation, by contrast, can be added at any time.

Does insulation stop condensation in a shed?

Foil-faced blanket is the standard fix for condensation dripping off the underside of the roof sheets on cold mornings. Bare sheeting with no sarking or blanket will drip in the right conditions, which is a problem over machinery, tools or stored goods.

Buyer's guide

Keeping a shedcool up here

A Bundaberg summer will find every weakness in a steel building. Get the insulation and ventilation right at design stage and the shed stays usable through February. Retro-fit it later and you pay twice. Here is what actually works, in the order it matters.

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Where the heat actually comes from

Almost all of the heat load in a steel shed arrives through the roof as radiant heat from the sun, not through the walls. That is why a shed with insulated walls and a bare roof still cooks, and why the cheapest effective upgrade is always roof insulation plus a way for hot air to escape at the ridge.

The second source is trapped air. Hot air stratifies under the roof sheets and stays there unless you give it an exit at the high point and a low intake to replace it. Insulation slows heat getting in; ventilation removes the heat that is already there. You need both.

Insulation options compared

All of these sit under the roof sheeting and are installed as the roof goes on. Choosing at quote stage costs a fraction of adding it later, because the roof has to come off to do it properly.

Shed insulation options compared
Option	What it is	Best for	Notes
Single-sided foil (sarking)	A reflective foil laminate laid over the purlins	Budget storage sheds and carport-style buildings	Blocks radiant heat and controls condensation drips. Minimal effect on noise.
Anticon blanket 55mm	Glass wool blanket bonded to a foil facing	The standard upgrade for most Bundaberg sheds	Good heat reduction, big drop in rain noise, controls condensation. The usual sweet spot for value.
Anticon blanket 75–100mm	Thicker blanket, same construction	Workshops, gyms, studios, anything with a bench you stand at	Noticeably cooler and quieter than 55mm. Small extra cost while the roof is off.
Wall insulation	Blanket or batts to the wall sheeting	Habitable-feel spaces and west-facing walls	Worth it on the western wall even when the rest are left bare.
Insulated panel	Factory-bonded sandwich panel	Cold rooms, clean spaces, high-end workshops	The best performance available, at a significant price step. Quoted case by case.

Anticon thicknesses are nominal. Actual R-value depends on the product and the air gap achieved over the purlins.

Ventilation — the half people skip

Insulation without ventilation still leaves you with a hot box, because the heat that does get in has nowhere to go. Ventilation is cheap at build stage and makes a bigger difference to how a shed feels than most people expect.

Ridge or roof ventilators — the most effective option, exhausting hot air at the highest point of the building
Whirlybirds — wind-driven turbine vents, low cost and effective in a breeze, less so on a still day
Powered ventilators — for workshops, welding bays and anywhere with fumes or heavy machinery
Wall vents or louvres low on the walls — the intake air that makes any roof vent actually work
Roller doors and PA doors positioned to give cross-flow when they are open

COLORBOND® colour and heat

Roof colour genuinely matters here. Lighter COLORBOND® roof colours reflect substantially more solar heat than dark ones, and every COLORBOND® colour except Night Sky® is available with Thermatech® solar reflectance technology, which lowers roof surface temperature without changing the colour you chose.

If the shed is going to be a workshop and you have freedom on colour, a lighter roof in Surfmist®, Shale Grey™, Dune® or Classic Cream™ will run cooler than Monument® or Basalt®. If the roof has to match a dark house roof, put the money into insulation and ventilation instead.

What we would specify for a Bundaberg workshop

55mm Anticon minimum to the roof — 75mm if you work in there regularly
Two roof ventilators or whirlybirds, sized to the roof area
Wall vents low on the two long walls for intake
Insulation to the western wall
A lighter roof colour where the look allows it
Wall height 3.0m or more so hot air sits above head height

Common questions

Keeping a shed cool in Bundaberg — insulation and ventilation

What is the best insulation for a steel shed in Queensland?: For most sheds, 55mm Anticon blanket to the roof is the best value — it cuts radiant heat, drops rain noise significantly and controls condensation. Step up to 75mm or 100mm for workshops, gyms or studios where you spend real time in the building.
Do whirlybirds actually work on a shed?: Yes, provided there is a low-level intake for replacement air. A whirlybird with sealed walls and no vents has very little to draw on. Pair roof ventilators or whirlybirds with wall vents or louvres low on the opposite side.
Does a light coloured roof keep a shed cooler?: Noticeably, yes. Lighter COLORBOND® colours reflect more solar radiation, and Thermatech® solar reflectance technology reduces roof surface temperature across nearly the whole range. Insulation still does more than colour, but colour is free to choose.
Can insulation be added to an existing shed?: Blanket insulation sits under the roof sheeting, so retro-fitting properly means lifting sheets. There are retro-fit alternatives such as internal linings and sprayed products, but they cost more and perform less well than specifying it at build. Ventilation, by contrast, can be added at any time.
Does insulation stop condensation in a shed?: Foil-faced blanket is the standard fix for condensation dripping off the underside of the roof sheets on cold mornings. Bare sheeting with no sarking or blanket will drip in the right conditions, which is a problem over machinery, tools or stored goods.

Genuine Australian steel

Every Spartan Shed is built from 100% Australian BlueScope® steel with genuine COLORBOND® and ZINCALUME® finishes - backed by BlueScope® steel warranties and our own workmanship guarantee. Ask us for full warranty details on your specific building.

Get insulation and ventilation priced properly

Tell us how you will use the shed and we will quote the insulation and ventilation as clear line items, so you can see what each upgrade actually costs.

Request a quote Open the 3D Designer View the COLORBOND® colour chart

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