Thank for the quick reply. The boarding doesn't go all the way to the side. I can see some insulation for the last 300mm. There are plenty of vents in the roof already.
I have a loftspace that is boarded out and I now want to insulate between the rafters to make it a better environment for storage. The rafters are 100mm and I will be leaving a 50mm gap for airflow.
What do I do when I get down to the eaves? Do I need to cut the insulation sheets with a chamfer...