2 roof by extrusion needs to be cut and use multiple pieces as it turns corners this link explains a similar process fear and loathing in a cad vs.
How to join double pitch roof in revit.
Then draw the arrow to define the slope direction.
Http pbl stanford edu how to attach walls to roof objects in revit.
Use it to extend the dormer roof to the main roof.
If necessary use the viewcube to spin the design to facilitate selecting the wall or roof edges.
Revit roof slope can seem complicated at first glance but by learning a few critical features you can create any roof shape you desire.
For creating complex roof it might be easier if you create separate roof then use join roof tool to join them later.
Whether you want a double gable roof with 6 pyramid shaped dormers or a simple gambrel roof the basics remain the same.
Groin vaults for your single groin needs 3 create a flat roof no edges defining slope then use the roof shape editing tools add split line set heights see attached revit file.
Select an edge of the roof that you want to join and then select the wall or roof to which you want to join the roof.
You can use height or slope value specify the method and the constraint values from properties palette.
With the join unjoin roof tool selected you need to click on the line of the roof which is on the face of what you want to join to the other roof.
Use join unjoin roof tool.
Then follow these 2 steps.
1 check define slope to create a sloped roof.
This tool is located in the modify tab.
Click modify tab geometry panel join unjoin roof.
9 join roofs add opening to create dormer.
Then select the face of the roof you want to join in to and then.