Try giving your dormer walls a stronger priority strength than the complex profile (roof?) wall.
You might need to turn off the setting to enable skin priorities.
Note this will not cut away the complex profile wall behind your dormer window - you will still need to create an opening for that as suggested by Matthew.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11