By default when calculating material takeoff area totals in Revit, you may notice the faces for all sides of the object are scheduled for the total area.
Using a door panel for this example, take a 3’-0” x 7’-0” panel extrusion. The overall size of the door panel has an area of 21 SF.
If you schedule the door panel however, it will show a default “Material: Area” of 45 SF [or 45.3 SF without any rounding].
What is happening is that each face of the door panel extrusion [front, back, left, right, top & bottom] is being included in the surface area since the material appears on each face.
This takes 21 SF x 2 for the front & back + 1.16 SF X 2 for the left & right + .5 SF X 2 for the top & bottom for a total of 45.3 SF rounded down to 45 SF by default.
To achieve a more specific number for scheduling, we can create a new parameter for “Material: Thickness” and use it in a calculated value column with the approach below:
1. Since “Volume” is calculated, first create a project parameter for materials called "Thickness". Set type to “Length”.
2. Next add a “Calculated Value” column in the schedule to divide the “Material: Volume” parameter by the “Material: Thickness” parameter [which would be entered manually for each material in the project] once you add that parameter to the schedule. Calculated value column should be set to “Area”.
3. The “Calculated Value” column will display a more specific number for scheduling.
The Calculated Value formula would be: Material: Volume / Material: Thickness