Join/cut geometry

[vanderloo5]

I can't seem to get the hang of join/cut geometry. It seems like almost every time I attempt either, nothing happens.
Maybe I'm misunderstanding the use? Please advise.
But, for example, I always try to project roofs beyond where the should end, (into other roofs), and then TRY to cut them back to all of the edges of the other roof by joining or cutting geometry.
Now I realize that part of the problem in my attached file might be that they are slightly offset from each other, (elevations), but even when I make them absolutely even, this never seems to work.
Roof_blend.JPG

[taylor.odell676489]

One question I have is why are you projecting the smaller roof to intersect with the larger roof. You could adjust the sketch line and align and lock the relationship between the small roof and the large roof and then you won't have to worry about the join geometry. Just a thought but maybe you have a reason for intersecting the roofs that I'm not aware of.

[vanderloo5]

Taylor,
You are right and I did correct that here. But there are often times when it seems easier to project a roof beyond another roof plane and cut back the geometry as needed. Like a round top dormer roof projecting onto another roof.
But whenever I try to do this with join/cut geometry it never seems to work,
Also, I thought if I joined geometry it would get rid of the unnecessary lines shown between the roofs as in this attachment.
Roof_blend2.JPG

[bimGirl]

This joining geometry is so time consuming, so I use Multi Join tool (from plugins CGS Revit Tools). Maybe it would resolve your problem also.