RG/347 Investigation of a roof via 4 Polekam to determine its construction: the soffit is wood wool situated on concrete purlins, the roof sheeting old big six asbestos secured with relatively new hook bolt to the concrete purlins, form the underside the hook bolts are visible except to the eaves and ridge purlin.
Via the 4Polekam one was able to determine that the fixings at the valley gutter were wood drive screws therefore one can conclude that the construction is Concrete purlins, wood wool slabs, timber purlins mirroring the concrete ones, Big Six Asbestos sheeting in the main secured by hook bolts but to the eaves and valley timber drive screws