Dormers across planes... Can someone help me??

[WendyWelton]

Phillip

You will need to use a manual dormer. The auto dormers will give an error when the hole in the roof exceed the main roof plane itself.

It can be useful to start with an auto dormer that's close, explode and edit. Yours might start shorter or smaller than the final. Or, you could bring your main house roof down far enough to hold the dormer, get an auto dormer the height, width etc that you want, then explode and clean up the roofs.

In your case, you'll find that the roof hole needs to be eliminated and the main house and porch roofs shaped around the dormer. The roof hole often makes a good guide. Trace it with a polyline, then notch and shape the porch and house roofs following that polyline.