All standard sized slates come holed as in the diagram below. This is for a standard 3" (75mm) lap.
We can however hole the slates to any lap or specifiction. If you require this special service please contact us. There is no extra charge for special holing but delivery lead time will be a minimum of six weeks from receipt of order.
The horizontal line along which the nails can be fitted has to be at the lowest point where the nail will not penetrate the slate below. If it is higher up the slate it will miss the batten, unless the slates are being nailed directly to rigid sarking boards. The higher the nail fixing is up the slate the less effective to wind uplift forces they will be. The best location for the nail fixings is 3- 5mm above head of the lower slate, making the nail hole position one gauge + one headlap + 4mm from the leading edge of the slate. But as the head lap and gauge dimensions can vary proportionally the headlap needs to be determined to allow the gauge to be calculated.
Take the length of the slate, deduct the headlap and divide the answer in half for the gauge dimension. For a 500mm long slate with a 100mm headlap the gauge is 500-100=400x0.5= 200mm. In this case the nail holes should be 200+100+4=304mm from the leading edge of the slate.
You can download the holing diagram here.
NB. Holing for 300x200mm slates is at 191mm
Last Updated: June 29, 2011