you can close the roof with supports down and then fit smaller corewood onto the poles to create a ring. on wich you can continue roofing

https://steamcommunity.com/sharedfiles/filedetails/?id=2645772977
the smaller corewood pieces are freeplaced
(they count as supported by only touching the poles)

freeplaced on the 26° corewood roof support and they clip into the poles which supports them

otherwise leave the ring open, put 2m poles up and then again 26° poles until the tips a touching, put a roof on top (wich is fiddly) to get a nice center chimney

https://steamcommunity.com/sharedfiles/filedetails/?id=2633384562
ignore the outer corewood pieces they are just for the looks