In architecture tab select roof roof by footprint tool and choose desired roof type.
How to make different kinds of roofs revit.
Choose a relevant level for a bottom face of the roof.
Then follow these 2 steps.
There are a lot of different combinations that could hold the membrane in place like glue or nails gravel or rubber.
9 join roofs add opening to create dormer.
One of the most important elements of any flat roof is the membrane.
Define roof parameters like overhangs slopes offset from level rafter cut.
Use it to extend the dormer roof to the main roof.
See hd version of video tutorial here.
To create a dormer model required walls and additional roof.
To embed this screencast choose a size.
Use join unjoin roof tool.
There may be other components added to make sure that the functionality of the membrane remains protected.
This tool is located in the modify tab.
Use pick walls tools and hover over a wall press tab to select all joined perimeter walls.