“The one thing we agree on is to question everything,” says Kim Colin of her work with husband Sam Hecht. The duo are known for their rational approach and radical imagination in designing products for clients from Epson to Panasonic, as well as for the Japanese retailer Muji, for whom they are creative advisors for Europe. There is nothing flashy or superfluous in Colin and Hecht’s work—and it’s no surprise that their compact home shares the same low-key beauty.

An architecture-trained academic, Colin moved to the U.K. from Los Angeles in 1999 to commission architecture and design books for Phaidon Press. She met Hecht, a Londoner who had studied industrial design at the Royal College of Art, and they quickly discovered that their mutual interests made for a successful commercial as well as personal partnership. They went on to found a design business, Industrial Facility, in 2002—the same year they stumbled upon a derelict and crumbling 1924 mechanic’s garage and decided to make it their home.

Situated on a desirable lot of London’s Primrose Hill, a stone’s throw from Regent’s Park, the building sat unnoticed behind an old brick wall. Tempted by its prime location and undisturbed state, the couple began by working with design-build team Turner Castle Associates to transform the three-story property into a habitable form. This involved repairing a major water leak, renovating the original guts of the building, and adding central heating.

The small size of the house (around 1,000 square feet) was a challenge that Colin and Hecht relished with the same precision they apply to their product design. “Spatial and material constraints mean that we have to think differently,” says Colin. This means there isn’t an entrance hall or space wasted on corridors. “Every inch is designed as a room, apart from the small staircase,” Colin adds. The front door leads directly into the sparely furnished kitchen and living area—the sum total of the ground floor.

Upon entering, it’s impossible not to notice how spare the space looks for a pair of product designers. “Stuff can take over,” says Hecht. “I like the idea that less is better.” He continues, “I grew up in the ‘have everything’ Thatcher era, which left me feeling disappointed with grab-it-all, short-term thinking when we left college and nobody could get a job. Now I see people thinking harder about what they are going to have around them.”

Stage two of the renovation involved acquiring planning permits, ripping the roof off, and creating a top floor for the children’s bedroom and bathroom. A wall of windows maximizes the light, while the L-shaped layout creates separate areas for both Josh (four) and Noah (two). Colin and Hecht’s characteristic attention to detail is evident throughout the room: An overhead light pipe provides natural light to the internal bathroom, the light switches and door handles are fixed at child height, and there’s even a brick-sized window by Josh’s bed to allow him to peep into the gardens behind the house.

Colin’s preoccupation with light ensures that there are no heavy drapes at the windows (“In contrast to so much of Britain,” she says, “which is still closed off behind lace curtains”). This contributes to a strong relationship between the indoor and outdoor spaces—and reflects the California modernist ideals with which Colin grew up. Open doors from the living area ensure that the family makes full use of the small courtyard garden, which serves as another room, complete with a decked area for outdoor meals and space for the children to play.

In a home that’s predominantly white, it’s tempting to think that the couple lives in a monochromatic world, although Hecht claims to love color. “It has to be integral to the object,” he explains, describing a digital projector they designed for Epson and deliberately colored gray, so that it would fade into the background. “It’s the screen, not the projector, that should catch your eye.” For Hecht, it’s the essential characteristic of their pared-down, peaceful home, where, he says, “people themselves provide the color.”