Double Skin Insulated System
Insulated Sheets
How a double skin roof is built
A double skin system is two metal sheets with insulation between them. The outer sheet takes the weather. The inner liner sheet gives a finished ceiling from below. The core between them does the thermal and acoustic work.
Unlike a factory-made sandwich panel, the layers are built up on site over a spacer system, which means the insulation thickness can be set to the job rather than to what a panel is manufactured at.
Where it is specified
Showrooms, food units, clean areas and anywhere the underside of the roof is visible and needs to look finished. The liner sheet is the point: a rockwool blanket laid under a single skin does the insulation job but leaves a soft, dust-catching underside, which is unacceptable in a food or clean environment.
It also suits buildings where the insulation requirement is unusual. If you need more thickness than a standard panel offers, a built-up system gets you there.
Double skin against PUF panel
A PUF panel arrives as one finished unit and goes up faster, which is why it dominates cold storage. A double skin takes longer to erect because it is assembled in layers.
What the double skin gives you in return is flexibility. Insulation type and thickness are chosen separately from the skins, so you can use mineral fibre where fire behaviour is being considered, and you can vary the depth without changing product.
The details that decide performance
Compression is the usual failure. Insulation squashed at the fixings loses most of its value at exactly the points that repeat across the whole roof, so the spacer system matters as much as the insulation specification.
Continuity is the other. Insulation that stops short at the eaves, at the ridge or around a roof light leaves a path for heat straight through, and it will show up as a hot line on the ceiling below.
The liner sheet needs to be sealed at laps if the building is humid or refrigerated, otherwise warm moist air passes into the insulation and condenses in it, which ruins the insulation and corrodes the sheet from the inside.
What to send us for a quote
The covered area, the purlin spacing, what the building is used for, and the insulation thickness if the specification names one. If it is a cold or humid application, say so, because it changes the liner and the sealing detail.
Frequently asked questions
Is a double skin better than a PUF panel?
Different jobs. PUF is faster to erect and better where every millimetre of thickness costs floor area. A double skin gives you free choice of insulation type and thickness, which matters for fire behaviour or unusual depths.
Can I add a double skin to an existing roof?
Often yes, by adding a liner and insulation below the existing sheet. It depends on the structure and the clear height you can afford to lose. Send photographs and we will tell you.
Which insulation goes between the skins?
Rockwool, glasswool or a reflective layer, depending on whether you are prioritising fire behaviour, cost or radiant heat. The category page covers the differences.
Does it help with noise as well as heat?
Yes. A mineral fibre core cuts rain noise and machine noise considerably, which is often why it is specified in workshops and auditoriums.
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