This is a general.
Revit roof geometry joining.
You cannot join a roof to more than one top face of another roof.
The joined elements then share the same line weight and fill.
The forgotten options.
You can join roofs to other roofs or walls or unjoin them if they were previously joined.
It will join in the wrong order and you will need to use the drop down menu next to join to switch the join order.
3 adjust wall join display in view properties.
As shown in the following illustrations the tool removes the visible edge between the joined elements.
The wall must be attached to the target roof and the target roof must be a footprint roof.
You can join a roof to the top face of another roof and the wall below that roof if you select the wall as the target.
The third and final technique to control the wall joins is to use wall join display in the instance properties of the view.
I ve zoomed in closely here hoping that you can see.
We are around the back side of the building now select this tool in the geometry tab called join unjoin roof.
Use the join geometry tool to create clean joins between 2 or more host elements that share a common face such as walls and floors.
Then from the modify tab on your ribbon use the join geometry command and select the 7 1 2 roof and the wall.