[foobazbar]

What size and type of nails should I use to secure battens to the rafters?

The roof is a standard pitched roof on a 1930 house, breathable membrane underlay, 400mm pitch rafters, double roman clay tiles, pitch >35 degrees, 38mm*25mm battens.

Thanks in advance

[Bristol_Bricky]

A good rule to follow for any fixing is, your nail or screw should be two and a half times the thickness of the batten or what you are fixing.

So if you are fixing a 25mm roofing batten you should use 65mm fixings