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.
Revit joining exting and new roof.
To create a dormer model required walls and additional roof.
Align one edge of the roof to the reference plane 4 copy the roof paste it in the same place.
Click modify tab geometry panel join unjoin roof.
This tool is located in the modify tab.
Use it to extend the dormer roof to the main roof.
Then follow these 2 steps.
When we create the new entrance area roof we will need to join the two roofs together via the join unjoin roof command found in the modify tab geometry panel join unjoin roof command.
9 join roofs add opening to create dormer.
Summary 1 unjoin the roof 2 create a reference plane 1 away from the edge of the second roof 3 edit the footprint of the unjoined roof.