To clarify, you cannot do this directly in the Floor and Roof System Family!!!
You would need to create 2 separate instances of each, one with the main build up and then place another on top with the thickness of the extension part and draw this with a larger area.
So basically 2 Floors or Roofs on top of each other each with their own thickness and area requirements.
Again go directly to the manufacturer’s website for specification guidance as one of the link above is for a ceiling system that fixes to a CLT panel for fire protection.
Jay Colcombe
Autodesk Certified Instructor
Revit Architecture & Structure Certified Professional
AutoCAD Certified Professional
B.Sc. Hons Civil & Structural Engineering
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