For Terrassotec; diameter 5 and 5,5 mm,
Hapatec; diameter 5 mm,
Hapatec Heli; diameter 5 mm
Pilot drilling is strongly recommended for fastening tropical woods/hardwoods. This is advisable even with the relatively easily splittable Douglas fir, and when screwing close to wood cut against the grain.
• Boring and countersinking in a single pass
• Screwing torque for inserting Terrassotec and Hapatec screws is greatly reduced ie no more shearing of the screws, above all with the combination hardwood/stainless steel A2 or A4.
• Perfect seat of the screw head