Decking screw for installation of pressure-treated timber. C4 outdoor The screw is CE marked and C4 classified. The screw is waxed which reduces the tightening torque while the wax provides extra corrosion protection. Area of use Decking screw C4 pro is intended for mounting decking timber, etc. against wooden frames outdoors. For very exposed environments or structures with a lot of movement such as marine environments, pool areas, fences, stairs, railings, etc. it is always recommended to use decking screws made of stainless steel or acid-proof material. NOTE! When installing teak-like decking such as Cumaru, Kirai, etc. and Siberian larch, we always recommend stainless steel decking screws and pre-drilling. Calculation of quantities To calculate how many screws you need for your project, you need to know the width of the timber and your intended joist spacing. Below you can see the quantities for the most common dimensions and distances. Width of timber / Rule distance / Number of screws/m2 95 mm / 600 mm / 34 pcs 120 mm / 600 mm / 28 pcs 140 mm / 600 mm / 24 pcs