Composite Systems Composistion

There are three main types.

• Bespoke systems that incorporate layers of material and insulation above the purlin.
• Proprietary systems that are built up by layer above the purlin, such systems can be sandwich-type or post and rail.
• Overlay systems that are used for re-roofs over existing roofing.

Composite systems typically incorporate a sealed vapour control layer under the insulating layer, and an absorbent roofing underlay under the top skin. They may be designed as closed systems, or ventilation may be introduced between the insulation and the top surface. The insulation material may be expanded foam, mineral wool, or fibreglass blanket. Top surfaces may be profiled metal or membrane.

Post and rail systems allow thicker insulation to be used, increasing thermal and fire performance.