The Carroll Gardens Townhouse, located a block away from the Gowanus Canal, was the family of four's home for a decade before they decided they needed more space.
Working around a magnolia tree in the back yard, Barker Associates Architecture Office (BAAO) designed an extension to all three storeys that provides additional living areas both inside and out.
At parlour level, the floor plan was opened up and storage was created through built-ins.
In the lounge area, colourful decor includes a custom Bower Studios mirror that hangs above the existing marble wood-burning fireplace.
"The finishes feature lots of vibrant colour, pattern, texture, and cozy nooks," said the architecture studio.
The kitchen has white lacquer and fir cabinetry to complement the pine floors, which run through the majority of the home.
The dining table is placed in the extension, where it enjoys views of the back yard through a large window that also accommodates a built-in bench.
Linking the multiple levels, the staircase was restored and modified to fit widened openings that make the most of the skylight above the hallway on the upper floor.
Reorganised bedrooms upstairs are now more spacious, with bright colours and patterned wallpaper used to personalise each room.
The parents' suite is at the front of the building, while the daughters' twin rooms occupy the extended volume at the back.
At garden level, a small kitchen for entertaining joins a sunken blue-tiled living space, a home office and a pegboard wall that allows the family to organise their outdoor gear.
A grey felt curtain can be drawn across to separate an area for guests.
Outdoors, a new steel staircase with wooden treads leads down from the parlor-level deck to the garden.
A bluestone terrace curves around the magnolia tree and is sheltered by the deck above.
Pavers lead past planting to another seating nook, built into the cedar fencing at the back of the property.
"An arborist was consulted to determine the sizing and placement of the extension, deck, and garden terrace, and a plant consultant was employed to help choose appropriate native species for the garden," the team said.
BAAO was founded by Alexandra Barker in 2006, and the Brooklyn studio has worked extensively in the New York borough and beyond.
Last year, the team's completed projects included two daycare centres: one featuring curved apertures and blue tones, and another with house-shaped openings and cheerful hues.
The photography is by Francis Dzikowski/OTTO.
Flooring: Hudson Flooring
Lighting: Allied Maker, Cedar and Moss, Dutton Brown, Hand and Eye Studio, Hollis and Morris, Apparatus
Wallpaper: Farrow and Ball, Hygge and West, Spoonflower
Tile: Cle, Complete Tile
Plumbing fixtures and fittings: Vola, Watermark, California Faucets, Kast
Rugs: Aelfie, Studio Proba