Architect George Clarke and master craftsman Will Hardie travel to Norway, to discover how a country with some of the harshest weather on the planet has become a leader in small space design. Norwegian craftsmanship and determination puts the country at the forefront of global architecture. George travels by husky sled to a tree house in a forest that can withstand nine tonnes of snowfall and gale force winds. There's also a visit to an ice hotel - the mother of all igloos, complete with 30 rooms, a bar, and even a snow chapel. The boys meet members of the local Sami community, to see the moveable home that has kept members of their community safe for hundreds of years. There's a disused oil silo turned into a circular home; a geodesic aluminium dome; and an epic family home in the mountains. And Will meets leading explorer Borge Ousland.

George meets an old friend in Norfolk who sees the potential in the most unpromising of spaces - an old sewage works. With no plans, no budget and just 'brute force and ignorance' - Reuben's audacious idea to create a unique chill out space for his family, including a self-supporting dome roof and a circular carp pond, could be the most incredible Amazing Space ever. George also travels over 5,000 miles exploring Japan. This week features a breathtaking chapel made of intertwining concrete ribbons, where bride and groom tie the knot in the heavens. In the Midlands, a father and daughter work together on salvaging a dilapidated childhood tree house with a budget of just £300. And George and Will continue building a giant toy tree house, and are inspired by a modern tree pavilion. They set about figuring out a way to bring George's impossible childhood fantasy to life using the most unlikely of vegetables.