Insulationheat, noise and condensation

Roof first, always

Most of the heat load in a steel building arrives through the roof as radiant heat from the sun. That is why a shed with insulated walls and a bare roof still cooks. If the budget only stretches to one thing, insulate the roof.

Roof insulation is installed as the sheeting goes on — the blanket is laid over the purlins and the roof sheets fix through it. That means it is genuinely difficult and expensive to add later, because retro-fitting means lifting the roof or working underneath it.

The condensation problem

On a clear night, a steel roof radiates heat to the sky and drops below the dew point of the air inside the shed. Moisture condenses on the underside of the sheeting and drips. People blame a leaking roof; it is almost never a leak.

An insulation blanket with a foil facing keeps the underside of the sheeting warmer and gives the moisture somewhere to go, which is why we recommend it even on open structures like carports where nobody cares about heat but everybody cares about drips landing on a car.

• Reduces radiant heat gain through the roof
• Deadens rain noise on steel sheeting
• Controls condensation dripping onto vehicles and stored goods
• Works alongside roof ventilation rather than instead of it

Insulation and ventilation are a pair

Insulation slows heat getting in. Ventilation moves out the heat that is already there. Do one without the other and the result is disappointing — an insulated shed with no ventilation still builds up hot, still air through the day.

The combination we recommend most often for a Bundaberg workshop is roof insulation plus ridge or roof ventilators, with windows or wall vents low down to let cooler air in as the hot air leaves.