A slight sag between rafters is ideal as it will allow any water to drain down the felt.
How to felt and batten a roof uk.
These battens were developed in conjunction with the bre and meet nhbc requirements for fully graded roofing battens.
Set the first batten at eaves so that the first course of tiles overhangs the gutter by 45 to 55mm or into the centre of the gutter whichever is the lesser distance.
When the first length is complete lay the next layer of felt on top of the first so that it overlaps by at least 100mm 4 inches horizontal overlaps where one roll ends and the next one is started should be at least 150mm 6 inches.
Work along the roof taking out any excess slack in the felt but do not pull it tight.
Jb red battens from marley is a high quality roofing batten that is pre graded and meets the performance requirements of bs 5534.
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