Why do roofs cut walls when joined?

[kgatzke]

The brick layer on the left extends 5" above the deck the roof sits on, yet when the roof and wall are joined the roof takes priority and cuts the wall!  It doesn't matter if all the layers of the wall are structure or in the core.  The result is the same.  How do I cut away the part of the roof where the brick is supposed to be?

[ToanDN · Accepted solution]

Switch Join order.

By the way, did you use Join Geometry or Attach the Wall Top to the Roof?

And when you draw the footprint, you can choose as below:

[SteveKStafford]

When you edit the sketch of the roof, where is the boundary line? If it is located at the face of core (structural portion of the wall) then it should stop there, assuming you just sketched the boundary. If you use Pick Walls to define the boundary then it should be at the inside face with the option Extend into wall (to core) selected.

[barthbradley]

You want the brick to stop at underside of deck? Why not just change the extents of the deck.

Is the brick a wall layer? Don't use Attach. Or, if part of the wall does Attach, Edit the Wall Assembly and unlock Layers to enable Base Extension Distance on them under the Wall Instance Properties.

If I'm way off base, it's because it's hard to tell what I'm looking at in your Picture.

[barthbradley]

Hey Steve!

..just a shout out 

[Corsten.Au]

This might help you

Unlocking layers

[kgatzke]

@ToanDN Switch Join Order does the trick.  Did not know about that.  The wall was joined by geometry and not attachment.

@SteveKStafford The boundary line is at the outside face so the membrane wraps the top of the brick.  It should turn down the face of the brick for a course and a half but what I really needed was for the edge of the roof to match the perimeter of the building because that's the line for attaching the fascia.

@barthbradley  I don't understand what you mean by changing the extents of the deck.  I generally model flat roofs in two parts using a floor family for the structure and a roof family the insulation, boards and membrane.  I do this because often the membrane and deck portions of a roof do not always share the same perimeter sketch and eventually the structural deck gets moved to the structural engineer's model.  In this case the deck which is a 16" concrete waffle slab stops 6" from the outside face of brick.  The wall and the structural slab are not joined because of the eventual structural model transfer.

Thanks everybody.