Vertical Opening "Can't cut host for inserted objects"

[Anonymous]

I'm trying to use a vertical opening to cut off the corner of a square roof, but I'm getting this error.  Any ideas what I can do differently?

[bimscape]

Just so I understand, why are you using the Vertical Opening to cut off the corner? Can you just form the shape you want in the Footprint of the square Roof itself. I'm not saying your strategy is off- but I always try to understand the strategy first, then the tech solution second.

[Anonymous]

Good question, the reason is that I'm using the "modify sub-elements" tool to make the roof in question part of a four-way low-slope roof.  Making the footprint the way you're describing will create two sub-elements in the place of one, which in my experience has led to the roof becoming triangulated in an undesirable way.  

[cbcarch · Accepted solution]

Try using an in-place void family to cut the roof.

[barthbradley]

Shaft Opening would do the trick too.