Insulating prefabricated houses with PU sandwich elements

Scotframe Limited, a Scottish timber frame house company, has opted for polyurethane sandwich elements. The company manufactures its panels with Hennecke technology and then puts them in its houses, considerably reducing costs. Licensee for these specially insulated houses is the British company SupaWall Limited, which provides its know-how for a smooth technology transfer. This also includes an analysis of the building structure and technical calculations for SupaWall license holders.

So that the polyurethane sandwich elements can be made, Hennecke delivers mixing solutions to AutoRIM, Hennecke's agent for the British Isles. These include HK series metering machines from 650 onwards, metering technology for the blowing agent pentane as well as the hand-held MXL mixhead with deviation and air cleaning system. MXL mixheads are particularly appropriate for areas that are difficult to access and discontinuous manufacture because they are operated by hand.

AutoRIM is a systems integration specialist, manufacturing the presses for discontinuous production of polyurethane sandwich panels, and a year ago it put the line that included the Hennecke wet end into operation at Scotframe in Aberdeenshire.

The advantages of insulating prefabricated houses with polyurethane sandwich elements are obvious: On the one hand, requirements to reduce CO₂ emissions (higher insulation demands) as well as rising energy costs (demands for more effective solutions). On the other, the rising costs in the construction sector (simple and fast installation of polyurethane sandwich panels) and increasingly high transport costs (a growing number of sandwich panel production centres on the ground). Moreover, polyurethane is superior to mineral wool as an insulating material because it coalesces and sticks more completely between facings and the cells are closed, which means that no air can circulate.

Because the cells are closed in polyurethane sandwich elements only a limited amount of moisture can get through. Condensation only forms, if at all, on the outer surfaces. Whereas when mineral wool is used water gets in and the insulation is limited allowing bacteria and fungi to form, says Hennecke. Polyurethane sandwich elements are also better than panels that are filled with mineral wool in terms of fatigue and physical decomposition. Furthermore, as opposed to in mineral wool in polyurethane there is no movement of air because the insulating gas is bound.