The holing gauge can be calculated as.
Roof tile batten gauge.
This gives 32 14cms which is the tile gauge you should use for the remaining battens to ensure correct spacing between them.
So using the previous example divide your roof height of 450cms by the batten number of 14.
Set the last batten at the ridge so that the ridge tiles will overlap the top course of tiles by at least 75mm.
Setting out up the roof gauge set the first batten at eaves to allow the tails of the eaves course tiles to overhang the fascia by 40 to 45mm ie.
Battens should be fixed to rafters set at centres not more than 600 mm apart and should span at least 3 rafters.
For example if the distance between the tops of the lower and upper battens is 204 inches and the maximum gauge of the tiles is 13 inches then the number of courses and strips of batten is 16 because 204 13 15 6.
It also allows you to determine the holing gauge distance from hole to tail of slate and the number of linear metres of batten per m 2 of roof.
Recalculate your tile gauge based on the number of battens specified in step 7.
Batten gauge length of slate headlap 2.
The batten gauge can also be calculated using the formula.
Not more than one in four battens should be joined over one truss for gauges over 200mm.
Holing gauge batten gauge headlap 10mm.
Just short of the centre of the gutter.
The result is the number of courses of tile on the roof rounded to a whole number.