After a slow start, the Backyard Cottage project at Northgate is proceeding apace. This 499 s.f. structure is intended for an au pair for the homeowners’ new baby. It includes a living room, kitchen, bedroom and bath. Its shed roof slopes up to the south, to draw more natural light into the spaces, and has an upturned butterfly roof over the living room, with a deeper overhang there to allow use of the patio on drizzly days.