Floor specifications are typically set in the Envelope area. But for those looking for more control at the Zone level, you can determine Zone specific Floors.
Add a Zone specific Roof by selecting the Zone and navigating to the 'Zone Floor' button. Next, select 'Select Bottom Floor', and you can either select 'As Concept', 'From Design' or 'From Template'. Select 'As Concept', cho0se a fabric concept and nominate your performance values. Click 'Save'.