Grand Designs - Season 17

A new run of shows starts with an overgrown, neglected half-acre site in the heart of a Gloucestershire town. It could be the perfect plot to build a house - if you were allowed to cut down its 27 protected trees and clear the site. But local plumber Jon Martin and ceramicist Noreen Jaafar have a much better solution. They love trees and they love their home town, so they're going to build a big modern tree house. The house will be way up in the trees, with stilts screwed into the earth and featuring balconies that see for miles. The only problem is building it, especially on a tight budget. It takes almost two years to crack the engineering as the project becomes an epic self-build, 40 feet up, as an exhausted Jon and Noreen battle towards the finish.

Why are our homes so often designed to be so serious and purely practical? Surely there's space for a bit more fun? That's what Matt and Sophie White from Sussex believe. They want to build a giant family house of fun for themselves and their children. It will be a mysterious black home kitted out with a revolving bookcase door, secret dens, hiding places behind one-way mirrors and a fireman's pole. Matt wants the house to evolve, so he uses a steel frame system which means they can change the layout whenever they want. There are other changes too - like amending the window shapes and sizes and adding a new half floor to create a James Bond room. Just what will this house look like in the end?

Tom and Danielle Raffield's lifelong passion is steam-bending wood into extraordinary curvy shapes. They've spent much of their working lives using the technique to make furniture and lighting. Desperate to escape their tiny gamekeeper's lodge, they've decided to build a spectacular wavy wooden house in South Cornwall, with curvy cladding, twisty furniture, and interior walls covered with naturally-weathered timber. With only a £100k budget to play with, they decide to do a lot of the building themselves. But have they taken on too much?

After artist and teacher Michelle Parsons recovered from serious illness, she and her architect husband David decided it was time to seize the day and build the private hideaway they'd always yearned for. David devised a sleek, black-clad, three bedroom house for a beautiful plot in an Essex woodland, with a separate studio for Michelle. The couple project manage the build, which gets off to a sticky start, including a dangerous gas leak and torrential rain. As the building finally starts to take shape, the big question remains - by choosing to eliminate windows on two sides of the property, could their new home turn out to be just a gloomy bunker?

Paul Rimmer has worked with bricks for 40 years renovating Victorian houses in Bolton. But now he plans to hand-build a state-of-the-art wooden home. If his funding holds up that is.

Can you really build a Grand Design when you've only got £500 to start with? That's what Simon and Jasmine Dale had in the bank when they started to build their unique three bedroom family house high up in the hills of rural Pembrokeshire. This is their take on 21st century low-impact self-building, featuring foraged and recycled materials. Despite the budget, their house will be open plan, have underfloor heating, an inside flushing loo, and a set of greenhouses that wouldn't disgrace Kew Gardens. They are part of a pioneering, government-backed, sustainable village called Lammas, which has a fierce planning condition attached: in return for the right to build on open farmland, they must become self-sufficient on their seven acre plot in five years, or lose everything. It's a huge double challenge.

Kevin McCloud meets Mark and Candida Diacono, who have set about building a home in the shape of a plough on their 17-acre smallholding in Devon. With its complex curved roof, timber-clad exterior and steel-framed working barn, the ambitious project presents a unique technical challenge.

How do you turn your small bungalow from a 1960s dormer into a generous 21st-century piece of slick architecture, all for £175k? Stuart and Rosie Treasurer from the Wirral plan to decapitate their bungalow - cutting the roof off to leave just the walls - then balance a big new floating timber box on top, containing five bedrooms. To keep costs down, they take on the plumbing and electrics themselves, spend as little as they can on insulation, and leave elements of the building unfinished. The hope is to get a stylish industrial look in the process. But the stress levels spiral when their neighbours grumble about the ultra-modern wooden box going up in the middle of their traditional suburb.

Kevin McCloud returns one year later to see the progress of private chef Ed Versluys and Pilates instructor Vicky Anderson, who wanted to convert a concrete cowshed in the Somerset countryside into a three bedroom home. With the help of one young builder and the knowledge they can learn from the Internet, the couple planed to project manage the conversion themselves. However, they had only seven months and a budget of just over £200,000 to make a warm and comfortable home with straw bale walls and wide expanses of glass.