Hilary Cootes and Crispin Robertson knew they wanted this home the minute they stepped inside. Tucked up a gravel driveway on a vast, bush-ringed section on Tāmaki Makaurau's North Shore, it sat alongside a sleepout on an elevated, sunny spot, "Like an oasis in the city," according to Robertson. Boasting eight-metre high ceilings, sharp lines and an irrefutable "great feeling", they put in an offer on the spot. Hours later, it was accepted, and the place was theirs.

Although the high-pitched ceiling gave the home a decent sense of volume, its footprint was relatively small. With growing kids, the whānau needed more room so they turned to architect Marc Lithgow of Space Division. Working together, the trio forged a plan to absorb the sleepout into the main home by connecting the two forms with a double-height box. "I always think it never looks as good if you try and copy what's there because it will still look 'new'," says Robertson of the design. "And a giant box was the most practical shape."

The connecting form introduces a new [red] language to the home, giving a fun take on a formal entrance. "The old home didn't have a front door," says Cootes. "No one knew how to get in, which was fun in a way because we had people coming in on both sides of the house, but neither of them was that welcoming." The glazed Vantage entrance now welcomes visitors and acts as a pivot point in the house, feeding off to all the different zones. The 'old home' houses the kitchen, living and sleeping quarters, while the sleepout — redubbed the West Wing — accommodates a second living space, home office, utilities and storage. Although the big red box was undoubtedly the standout feature of the project, you only get a peek of it from the street. "It was just for us, not for anyone else," justifies Robertson.

"It was always going to have primary colours," adds Cootes. "I'm absolutely obsessed with primary colours; how good do they look with wood?" Friend and designer Alex Mcleod of at.space helped them introduce reds, blues, yellows and greens strategically, using block colours in different zones and consistent themes — like green doors with yellow handles. To keep costs down, the design forgoes fancy finishes in favour of more rudimentary, textured materials, like Strandboard on the walls and floors. In the same vein, Robertson shouldered much of the painting. "We're not overly sophisticated; we're not about glamour or gold," says Cootes of the overall impact. "We're about colour, function and fun."

The renovation emphasises the home's connection to the view and sprawling surroundings. Generous glazing in the red box is accompanied by a two-metre louvred window that dissipates the summer heat. In the living area, draughty, eighties-era French doors were replaced with a large Vantage window and glass slider that flows straight out to the rolling garden. True to form, the windows were finished with a fire-engine-red powder coating which gives a beautiful contrast against the dark timber cladding, perfectly suited to the whare and its whānau. This fresh glazing has significantly impacted the home's thermal performance, too. "I remember the first ones they replaced were the old, crusty, French door-style windows in the sleepout," says Cootes. "The minute they put in the new Vantage double doors, it transformed the whole space. It instantly felt modern, warm and dry."