SPAX window construction screw FEX-H BR WIROX - partially threaded, countersunk head, cross recess, 4CUT

What this means for you: Screw heads that always match the fitting exactly, efficient to work with.

Spax window construction screw FEX-H BR WIROX - Features

The cross power drive Z is a further development of the simple cross power drive from the Philips Screw Company. The difference is that the four flanks of the screwdriver blade do not taper towards the tip. This increases the lateral support for the bit and reduces the cam‑out effect. This effect occurs with conventional cross power drives because the taper causes the torque of the cordless screwdriver to push the driver bit upwards.

The countersunk head (or flat countersunk head) mills a recess into the wood with its polygonal underside (“pockets”) and can therefore be countersunk without additionally countersinking the screw hole. The countersunk head sits flush with the surface.

Partially threaded screws are excellent for attaching thin components such as wood‑based panels, boards or floorboards to thicker components such as timber members or beams. The short thread screws into the thicker component while the unthreaded shank remains in the attached component. This produces maximum clamping pressure between the two. The unthreaded part should be at least the thickness of the attached component.

The term 4CUT refers to the square‑shaped formation of the screw tip. These edges displace the wood fibres during insertion and create space for the core diameter of the screw. The radial spreading pressure exerted by the core in the wood is thus reduced and splitting of the wood near the edge is prevented. The required torque of the cordless screwdriver is also reduced because the screw core does not have to be “squeezed” into the wood.

With WIROX, SPAX has developed a coating that is far superior to galvanisation in terms of corrosion protection. WIROX does not use chromium(VI); the screws remain just as load‑bearing after years in outdoor areas not directly exposed to the elements, and are environmentally friendly. WIROX screws are the first choice for all open structures without direct exposure such as carports or pergolas; for direct exposure to the weather, as with terraces, we recommend our screws in the rust‑free stainless steel variant.