How do I show Foot Print instead of 'living area'

[SENWI]

Hi There,

I need to calculate the actual footprint of my design measured to the outside face of all exterior walls (as this is how allowable floor space is measured by my Municipality). My HD Pro 10 is instead showing me the 'living area' of my design which does not include internal wall cavities and the like. I have set each room to be included in teh living area and have also set all my exterior wall types to dimension to the last outside layer, but my living area is still way short (about 123 ft2 short).

Is there not a way to get the actual footprint?

I appreciate and help that you can provide. I did a search and came up with no hits.

Cheers
Sean