Rather than clear their building plot of plant life, tree-lovers Jon and Noreen decide to build an enormous treehouse up in the canopy. But undertaking such an unusual project requires some cutting-edge engineering, which takes years to work out. Then the build itself proves to be an epic undertaking, as they wrestle their ambitious design into life, 40 feet up, using only a meagre budget.

Matt and Sophie want to build a giant house of fun for themselves and their three children. Their plans feature secret stairs, revolving bookcases, hiding places and a fireman's pole. But Matt keeps changing the design radically as he goes along, bewildering his builders and threatening the project. With all the alterations, what will the building look like when completed?

Tom and Danielle are craftspeople who have dedicated their lives to creating furniture and lighting by steam bending wood. But now they want to scale-up their skills and construct an entire house in this way. They have just 100k to hand-build this spectacular family home with curvy wood cladding and twisty handmade furniture. But soon business commitments and family life start to overwhelm them.

After recovering from illness, artist Michelle and her architect husband David, want to build a refuge from the world on a beautiful plot in remote woodland. But the radical design’s quest for privacy involves a lack of windows throughout the structure. Soon, issues such as a dangerous gas leaks and torrential rain threatens the project. But even if they do finish, will it just be a gloomy bunker?

Builder Paul has spent his whole career constructing homes from brick. But for his own ultra-modern home, he decides on an ambitious project involving wood. He soon finds working with this new material rather tricky. With a small crew, and roping in his family to help, he soon runs behind schedule. Then he’s hammered by extreme weather, his funding dries up and the entire project is put at risk.

Simon and Jasmine have decided to start building their family home on a remote hill in Wales. They have virtually no money and plan to use volunteer labor and foraged materials to create their vision. But planning constraints dictate that they must be completely self-sufficient to live there. If they fail to achieve this, they might not be able to live in the house they’ve sweated over for years.

Mark and Candida have decided to build a sweeping, curvy new home in Devon, featuring a complicated roof design. They’re also planning to construct a working barn, from completely different materials, at exactly the same time. And they’ve set themselves just seven months to do it. It proves to be a unique, technical challenge, complicated by a builder with very strong ideas of his own.

Stuart and Rosie plan to transform their drab, single-story home into a radical, ultra-stylish dwelling. The plan is to drop a new, floating timber box on the old structure. But an attempt to save costs by doing much of the work themselves, actually stretches their meagre budget. Then when the ultra-modern wooden box appears in their traditional suburban area, the neighbors start to grumble.