Cutting angles for inner corners can be a bit tricky. There are several ways to do this, but here is how we usually fix it:
1. Start by putting the list upside down in the saw. The part that will be placed at the ceiling should be placed on the saw table, as seen in the first image (the side mounted on the ceiling is marked a; the side mounted on the wall is marked b). The list must be kept in the position it should be mounted.
2. While keeping the list in position, saw it at 45 degrees (image 2). Then do the same in the opposite direction on the connected roof rails.
Thus, when it comes to inner corners, the edge facing the roof will be shorter than the edge facing the wall. And the opposite applies to outer corners - the edge to the ceiling will be longer.