8mm (5/16") standard hexagon washer head fastener.
Topfix is not generally recommended. If unavoidable or specified for a particular application a saddle/storm washer should be used and particular care taken in installation.
A 6.3mm diameter coarse thread just under the head stitches the top outer sheet of the composite panel to the head keeping the sheet and washer clamped together giving a typical ultimate resistance force of 1.4kN in normal applications.
See fastener specifications link below.
A minimum 45mm embedment is recommended for HT into timber.
See Composite panel selection chart below.
These fasteners have a minimum 500hr SST coating. Link below.
Use a purpose made screwgun for installation. Cordless drivers and drill drivers are ideal with torque set fairly high on a high speed and in driver mode. Please note: Impact drivers should not be used under any circumstance and automatically voids any warranties.
Figures throughout will be ultimate test results with no safety factors.