What you get
The feasibility read answers the questions a second story turns on, from the public record and your photos: the zone and the height limit above your roof; the setbacks an upper floor must hold; whether the City maps the lot as Hillside Area, which brings the slope-band floor area rules; whether it sits in a Historic Preservation Overlay Zone, which adds a preservation review; and what the house's age and type usually mean for the structure under a new floor.
With it comes the massing sketch: the new floor drawn as a simple volume on a photo of your house, so you see the shape and the height, where the stair would land, and what a partial second story looks like next to a full one.