For attaching metal roof sheets to wooden battens or other types of timber substrates, use a type 17 hex head top grip with an EPDM sealing washer. The type 17 screw's point is fluted and sharp, making it ideal for use in steel roof construction where it can easily drive into substrates made of wood. High pull-out strength is a benefit of the flanged hex head, and the class 4 galvanised coating provides excellent corrosion protection. Top grip thread reduces dimpling and guarantees a tight grip on sheeting.