Fixings and Accessories
Self drilling Tec Screws (Tek) are the preferred fixings for cladding and roofing.
Sizes available from 25mm to 150mm with gash point for ease of drilling. When selecting screws, allow for 30mm of thread to go into the timber purlin. For fixing fibre cement sheets, Tec's will be supplied with a BAZ washer. See the image for Z Tecs and which can also be ordered with a moulded colour cap.
Z Purlin Tecs
Z or galv purlins are also known as 'light' or 'cold rolled' sections and have widely replaced timber for providing structural framework. The tecs for fixing into them have a standard drill point and a coarse thread designed for drilling into 1.25mm to 3mm steel.
Fixing into steel or heavy or rolled section requires a heavier duty fixing with a finer thread to bit into the steel. Use them for fixing into materials of 4mm to 12mm in thickness. Be aware that not all steel is of the same quality and very occasionally, impurities in steel may cause the fixing to shear off, making pre-drilling necessary.
Stitchers are used joining sheet to sheet. That's where sheets join end to end, side laps or for fixing flashings.