By now you can probably see how these techniques can be easily applied to a situation where a dormer window is set back from the external wall. Here we have another gable-roofed dormer and roof void situation, but the window is not coplanar with the external wall.
Firstly, create the planes which will define the main pitched roof. Draw null lines marking the middle and side limits of the dormer (on a real project, follow your drawings).
Create the planes which will define the pitched roof over the dormer. Note that it doesn’t matter if the points selected are not within the limits of the dormer’s location according to the plans – as long as the points are on the correct line, the planes will intersect correctly to define the dormer limits.