Triple-wall or multi-wall polycarbonate sheet is manufactured by an extrusion process, with integral webs between the walls. It is light in weight (3.2kg/m2), weather and impact resistant and light-transmitting. It is also an insulant; triple-wall 16mm thick sheet has a U-value of 1.7 W/m2K; the thicker 25mm sheet has a U-value of 2.4 W/m2K. Makrolon polycarbonate surfaces for external use have an integral coat which improves durability; surfaces for internal use are coated with a water-dispersant which disperses condensation to a film.
Polycarbonate is available in the traditional transparent sheet or in a white or bronze coloured translucent sheet which allows light through while giving privacy. Makrolon is available from Amari Plastics, tel 01932 835000.
The 16mm polycarbonate sheets were fixed to 32 x 32mm horizontal softwood battens using 3m clear vhb (very high bond) foamed acrylic adhesive. The adhesive is flexible enough to allow for the high levels of thermal movement (3mm per metre horizontally and vertically) of the sheeting.
Foamed acrylic adhesive has been in use on buildings for the last 15 years. It is suitable for situations in construction where the parts to be joined are relatively lightweight or only require restraint. Adhesives can be used to bond material to a framework and to bond stiffeners to material to prevent the deflection caused by wind.