The holing gauge can be calculated as.
How to felt and batten a slate roof.
This is not required for dry fix systems.
Roof battens and gauge the gauge is the space between the roof battens this will set the overlap of your chosen slate in most cases.
Underlay is generally held in place by the tile battens but where nailing is required nails should be extra large head felt nails of 3 35 mm shank diameter and 20 mm long.
The batten gauge can also be calculated using the formula.
Start at the lower edge of the roof and position the first batten so that the slates tiles give the required overhang over the fascia set the distance at both ends of the roof and run a string line between check along the line to make sure that the distance is fairly consistent and satisfactory fascia boards may sometimes wonder a little bit but this can be checked by eye looking along the front face.
If a batten end is to be set in mortar be sure an appropriate treatment has been applied.
Lay the underlay starting at and parallel to the eaves maintaining a consistent tautness.
Batten gauge length of slate headlap 2.
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.
Holing gauge batten gauge headlap 10mm.
Joints should be directly over rafters with the batten square cut tightly butted and skewed nails.
Roofing felt was introduced primarily to act as a secondary barrier against wind driven snow and rain but its use also causes a reduction in air movement within the roof space particularly if the roofing felt is impervious and this effect is often compounded by the introduction of insulation.