Rock fibres

Press, 12 June 1984, Page 24

Rock fibres

There is a new thermal and acoustic insulation product on the New Zealand market. Roewool offers both the quality of batts and the benefits of blown insulation. Although new to New Zealand, it has been available in many countries overseas since late last century. Roewool is manufactured by melting basalt rock (road metal) and selected fluxing agents in a three-phase electric furnace, where an electric current flows through the molten rock at temperatures of more than 1400 degrees. The molten rock is poured on to a three-wheel spinner, from which thin strings of molten rock are thrown off and stretched into fine fibres as they move through the air. These fibres are then collected together to form a thick, fibrous mat which is granulated and conveyed to a bagger for automatic packing into bags, ready for despatch. This product is specific-

ally designed as insulation for walls and roofs. It is claimed to have a higher insulation value than previously available products and is completely incombustible, non-corrosive and non-hygroscopic. Because of its cohesive nature, it will not move or blow around in the ceiling. It is not dusty, and unlike previously-available loose fill, it can be installed prior to the gib stopping on a new house. Roewool is available only through licensed professionals. The installation machine is pre-set to ensure that Roewool is installed in ceilings at a minimum density of 32 kilograms per square metre, which ensures there are no settling problems. For new-house walls, the product is applied at the same stage as batts would be, by spraying glue into it through a “wet head.” This gives a total, monolithic coating which ensures no gaps are left, and no sagging or shrinkage occurs in the walls at a later date.