Spray Foam loft insulation scammers on the rise

[johnny2007]

But with the foam stuck to three sides of every rafter there is in-adequate ventilation of the timber. Worst case the foam traps moisture in the rafters.

Yes, that's why you shouldn't get that foam sprayed.
I was talking about the roofs traditionally insulated.
I thought you asked how those don't cause rot.
Edit: just seen it wasn't you asking.