For the most cost-effective installation, place LAMBDABOARD® above the purlins and beneath the roof sheeting when considering over purlin insulation. With a 25 mm board, LAMBDABOARD® can span up to 1800 mm without the need for support on the longitudinal joints.
IsoBoard Insulation installed over purlin under roof sheet. — In South Africa, the bulk of retail and industrial buildings are steel-sheet clad frames, where 70% of the heat gain is through the roof. IsoBoard over purlin insulation is the most cost effective method of achieving thermal efficiency in these buildings.