M6 x 80 Mushroom Head Roofing Bolt 4.8 & Nut BZP

Roofing bolts have a slotted musshroom shaped head and come with a square nut.. These roofing bolts are fully threaded up to a certain length and there-after there is a smooth shaft between the under-head hex and the thread.  The tensile strength on these are 4.8 which serves a purpose for specific applications. The tightening strength and torque is worth checking for critical applications to prevent movement of the material under certain stress conditions.  They are supplied with class 4 tensile strength nuts.

These are bright zinc plated fasteners which is a preventative measure from corrosion.  Avoid breaking into the bright zinc plating usually abbreviated as Bzp as this will cause faster corrosion if not covered with a corrosive protected material as in time this will weaken the fastener.  Also bear in mind using different materials can cause fusing through corrosion especially in damp conditions when mixed with aluminium or stainless steel materials.

More information is available from Central Fasteners regarding fastener details, but it's always worth checking with a manufacturer's specifications or drawings if an alternative size, tensile strength or types of fasteners are used.