The choice of steel for screws and bolts is crucial. What kind of wood will you be attaching? Is it coniferous or exotic wood? Is it rich in tannins? What is the hardness and density of the wood? What dimensional changes does it exhibit as it dries? All this matters when choosing steel.
The attachment to the supporting structure has several requirements. The screw heads must be flush with the profile face. Both the screw hole and the countersink must be pre-drilled. The fastening means must be permanently corrosion-resistant. The length of the fasteners shall be chosen to ensure sufficient strength of the joints but shall not overhang to damage the tightness of the foil if any. The minimum distance for screws from the ends of the boards is 3 cm minimum and 5 cm maximum. This will prevent cracks from forming at the ends later on as the wood is worked. Use HOBOTEC or HAPATEC screws for spruce facade timber and HAPATEC HELI screws for Siberian and Silesian larch facade timber. HAPATEC HELI screws are suitable for facade wood made of Red Cedar, Thermo Pine, and Dark Red Meranti.