This Park Slope house plus garage had a layout so awkward the basement stair severed the small kitchen from the rest of the house. Moreover, it suffered from no storage and years of shoddy renovations. By reorienting the stair, the architect gave the kitchen room for multiple cooks and an eat-in island. She also added ample closets to a reorganized entry. A mod walnut wall frames a huge soapstone fireplace. With acoustical tiles removed at the kids’ rooms, cathedral ceilings now soar under the steep slate roof. Built-ins create cozy window seats and clever storage. The new master suite has large steel windows and a private roof deck. She wove traditional materials through the house in modern insertions.