There are other cheat ways but all use 2 roofs and join geometry but this is easiest to explain.
Offsetting roof gables from same roof revit.
That would include the small overhangs at the gable.
1st roof set cutoff height.
In this video i show how to add the following roof types in revit hip roof gable roof shed roof saltbox roof gambrel roof gullwing roof half hip roof mansard rood follow me on.
See image 1 2nd roof set properties base height offset to same as cutoff height use pick line and pick edges of roof at cutoff height and lock.
Repeat steps 2 and 3 to generate the gable roof.
The second works for all roof types.
A gable roof is placed at the top of a hip roof for more space and enhanced aesthetic appeal.
Revit roof slope can seem complicated at first glance but by learning a few critical features you can create any roof shape you desire.
Personally i try to do as much with 1 roof as i can.
It will join the roofs together getting rid of the line.
The sides are all equal length and come together at the top to form the ridge.
But to answer your question about getting rid of the line just use the join command.
The first method works only for gable or shed roofs but not hip roofs.
The inward slope of all four sides is what makes it more sturdy and durable.
Set desired line to not define slope gable join geometry all done.
Draw geometry similar to below and select all but 3 top edges as shown.
Method 1 gable roof with offset ridge.
Whether you want a double gable roof with 6 pyramid shaped dormers or a simple gambrel roof the basics remain the same.
Modifying revit roof slopes to change the roof from a gable roof to hip roof go into the sketch options select all boundary lines and turn on the defines slope parameter note as a default your roof will have a slope of 30 degrees on all boundaries and form a hip roof unless you change the slope designation in the sketch mode per.
Hip roofs are more stable than gable roofs.
A hip roof has slopes on all four sides.
Those are easily modeled into the same roof as the main one.