You have two ways of drawing dormers with overhang:
Activate Roof Covering in one of the following ways
General: Roofs, Planes, Sections
Activate Slab in one of the following ways
Basic: Walls, Openings, Components
What do you want to do?
Draw a dormer with overhang using the Roof Covering tool
Draw a dormer with overhang using the Slab tool