Meir Roofing

Composite boards consist of insulation products which individually are suitable for roofing. The long term bond strength between the materials should be at least as strong as the de-lamination strength of the weakest individual component.   The composite board should be free from warping, bowing and be dimensionally stable both during application and in service. Rigid urethane and phenolic foams are to some extent heat sensitive.   They can be formulated to withstand the heat of mastic asphalt, but are much more heat resistant in composite form with a facing of cork, Perlite or fibreboard.   The facing is also suitable to receive a full bond of the first layer of built-up roofing, and this eliminates the need for BS 747 type vented base layer to provide a partial bond.   The cost saving from omitting this type of material can be set off against the extra cost of forming a composite and can lead to an economic overall specification with useful technical advantages.

CORK/URETHANE COMPOSITE BOARDS

A cork insulation layer can be added to rigid urethane as a facing to form a composite board. This has the advantage of offering a cork surface for the application of the waterproofing. Built up roofing can be bonded direct without the use of a vented base layer, and the cork is an ideal heat resistant surface to receive mastic asphalt.   Cork/urethane composites are frequently used cut to falls to provide a tapered insulation system.

PERLITE/URETHANE COMPOSITE BOARDS

The Perlite surface allows a full bond for built-up roofing. But Perlite has a relatively low laminar strength and the specification may need mechanical fixing through the first layer of roofing when a roof is exposed to high winds, in just the same way as for normal Perlite boards.

PERLITE/PHENOLIC COMPOSITE BOARDS

This composite brings together two materials with improved fire characteristics, and resistance to high temperatures. Due to the low laminar strength of Perlite, mechanical fixings may be required on exposed sites.   Perlite/phenolic composite is suitable for fully bonded built-up roofing, and for mastic asphalt

FIBREBOARD/POLYSTYRENE COMPOSITE BOARDS

Expanded bead polystyrene is extremely heat sensitive and must always be overlaid with a heat resistant insulation before application of built-up roofing or mastic asphalt. The composite board combines the overlay into a single board and forms a low cost insulation suitable for full bonded built-up roofing and asphalt.   Particular care is necessary to install the composite with tight joints between boards and at abutments to prevent damage from hot bitumen penetrating the joints or radiant heat from mastic asphalt when it is applied.   Fibreboard/polystyrene composite is frequently used cut to falls in a tapered insulation roof drainage system.