My advice would be don’t do it, any of it, we had it done by weathershield on my last house, we got damp patches on the rear wall which I put down to them doing a crap job, I replaced some of the inside window cills later and the insulation was extremely patchy to say the least
and the b******s wrecked my lean too conservatory, I was promised they’d put scaffolding up, as i was at work all day I had no idea they’d put boards on it I was horrified when a neighbour told me and it took my ages to sort the leak
Of course I complained, had various people down and got nothing more than annoyed