Rob I think you need some lessons too.

volume part 2 =plan floor area*a/2
volume part 1=plan floor area*C
the "B" values are already accounted for in the floor plan area.
and yes easier to use a zone and trim it to the roof. You can even schedule all the volumes in the buidling.
Cheers John
John Hyland : ARINA : www.arina.biz
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