What size clout nails should I use?
Clout nails should be 15mm large head clout nails.
I will also need to overlap the felt, how much overlap should I use?
Overlaps will typically be minimum 50mm and will depend upon the slope of the roof. On shallow sloped roof, we would suggest the overlap is increased to 75mm.
Is it necessary to use adhesive?
Lap adhesive also provides extra waterproofing security to the lap so it it recommended to use.