Kevin McCloud follows a project to renovate and extend a classic 1920s cinema in Thorne, South Yorkshire. With little knowledge of restoration, Gwyn and Kate boldly set about turning the dilapidated building into a family home using masses of concrete after taking advice from an architect friend. The couple are hoping to create a hydraulic glass wall that opens up one side of the house to form a UV-filtered canopy, and there are also plans for a white roof extension that resembles a diving board.

Jonathan Broom and his wife Deborah have put everything on hold while he pursues his dream of building a mini Hollywood Hills-style mansion right in the gritty heart of north London. For ten years Jonathan Broom has been obsessed with building his own home.They finally stumble across a scrap of land right in the gritty heart of North London, but it's fraught with problems, and the only way they can build their wildly ambitious £1million pound family home, complete with nanny flat and swimming pool, is by sinking half of it six metres below ground. It's a project that pushes the couple and their builder to the very limit. Desperate to make every penny of the budget stretch, Jonathan strikes every deal he can, and even sells his business to raise funds. Originally scheduled to take a year, this giant hole in the ground consumes their money and lives for much longer.

Kevin meets Martin and Kae Walker, who want to build the ultimate family home inspired by a giant farm shed.

When he lost three limbs in Afghanistan, Jon's life changed forever. Now he wants to build a house that allows him to live independently. The design is cutting edge, but the budget spirals. Marine captain Jon's life changed forever when he stepped on a land mine. Before his injuries, home for Jon had meant a crooked chocolate box Devon cottage. After countless viewings of uninspiring specialist dwellings and awkward conversions, they realised that the only way to get a house that would enable Jon to live independently was to build it themselves. The design boasts sleek glass walls, open plan spaces and a dramatic wing-like roof. Crucially the design concept is for there to be no noticeable adaptations due to Jon's disabilities. Despite his lack of experience, Jon decides to project manage and calls on the support of a number of military charities for this hugely ambitious project. The pressure to finish on time increases when Becky discovers she is pregnant.

Kevin meets flying instructor Colin Mackinnon and trapeze artist Marta Briongos and the incredible metal home they're building next to their very own airfield in Strathaven, Scotland. There aren't many people in Britain who can say they own their own airfield. But Colin and Marta Briongos are part of the very select few. The airfield is so important to them, they've decided to live there too. Their ambitious plan is to build an incredible metal sculptural home next to the runway, designed by one of Scotland's most eminent architects and inspired by aircraft hangars. But the difficulties of building their beautiful design soon become apparent. And before the project is barely off the ground they're contending with violent rain, snow, 100-mile-an-hour winds and the worst storms for 100 years. With work slowed down to a snail's pace, what was supposed to be a year-long project heads into its third year.

Tamayo Hussey's missed Japan ever since she moved to the UK with her husband Nigel. To stave off the homesickness they've decided to transform a forester's lodge into a Japanese house complete with roof bath, tatami room and sliding paper walls.

Keen to keep costs under control, Nigel and Tamayo decide to engage only the design skills of an architect and with no previous building experience they bravely go it alone, working without any detailed drawings and fire-fighting problems every step of the way.

The wood they're using for the timber frame - Japanese larch - hasn't been used for building houses before in the UK, so no one can be sure it will be strong enough, the new interior walls don't meet properly and the replacement window design can't cope with the rain.

But Nigel and Tamayo are determined to overcome any obstacle to get the Japanese house they're so desperate for.

A young couple want take on an average 1950s house and turn it into an architectural masterpiece.

After a year of searching London for somewhere exciting to live with their young girls Lola and Sylva, Ben and Rachel Hammond stumbled upon a house on a totally unique plot, buried within the leafy depths of a beautiful south London park. Only problem is the house itself - an ugly, inefficient and uninspiring red brick property.

Their solution is uncompromising. With the help of their architect friend Zac, they decide not to knock it down, but to radically redesign, remodel and transform this unsightly lump it into a sleek, crisp, modernist masterpiece.

This is no easy task however. Their cutting edge new materials struggle to get past the local planning department and building control. Delivery of key elements like the giant glass window panes is massively delayed. The contractors struggle to deliver on an incredibly tight fixed price contract, and Ben and Rachel have to work flat out in their day jobs to pay for everything.

Kevin meets a master craftsman whose dream is to build a castle made entirely of mud.

Kevin McCabe is the leading living exponent of the ancient art of cob building - wrestling houses out of mud using his bare hands. But Kevin doesn't just want to build another cob house, he wants to build a cob castle.

Not only that, Kevin also wants their gigantic new cob house to meet the highest environmental performance targets ever set. It is truly an almighty challenge.

The house will be formed of two vast curved cob roundhouses - the largest of which is inspired by the natural geometry of a snail shell - connected by glazing and topped with undulating wild-flower meadow roofs to mirror the surrounding Devon countryside.

But building it involves mixing and laying a mind boggling 2000 tonnes of cob, all during warm sunny weather. Kevin is determined to have the main cob walls up in a few months. But soon the sheer scale of the task becomes clear.

Confirmed city dwellers Michael and Phil have moved to the country to run a farm, start a micro brewery and create in a vast, dramatic 21st-century farmhouse to live in.

Michael Butcher and Phil Palmer were confirmed Londoners, loft-livers in the heart of Soho. Until they fell in love with Christmas Farm, near Newbury, and took the life changing decision to quit their urban media jobs and move to the country.

They faced two big problems however: first there was an agricultural tie on the land, so Phil and Michael would have to become farmers; the second problem was the uninspiring faux-alpine timber chalet serving as a farmhouse - it had to go.

But Phil and Michael have decided they don't want to build a regular brick farmhouse as a replacement. Determined to bring a bit of urban glamour to their new home, they want a 21st-century farmhouse unlike anything the area has seen before.

Phil and Michael's version cleverly combines a vast, white, dramatic open-plan party pad upstairs, with muddy functional farming spaces below.

As the builders go to work on the extraordinary hand-crafted flint exterior, complete with the largest sliding trapezoid window in Britain, Phil and Michael must juggle construction with farming the land.

And in order to make it all work financially they decide to set up a new micro-brewery in the barn.

Kevin catches up with the story of a daring modernist home in the Andalucian hills in southern Spain..

Ten years ago Gil and Hillary Briffa decided to retire to southern Spain. Rejecting the coastal sprawl around Malaga they found a virgin plot of land up in the Andalucian hills for just £35,000.

But instead of building a home like the traditional old fincas nearby, their architect son's design was a confrontational, modernist glass box, surrounded by boldly coloured connected rooms, hidden behind a giant citadel wall.

Construction proved stressful. The couple put all their trust in a local Spanish builder who had never built a house like this before. The local residents didn't like it and the mayor tried to get it re-painted white. But if they could just finish the build, it promised to be the coolest retirement home Kevin McCloud has ever seen.

Sadly, Gil died a few years ago, but now Kevin returns to meet with Hillary again and to see whether or not their building has settled into its landscape, whether it's still multi-coloured, and to find out just how life is for her as a British widow living up in the Andalucian hills.

Six years ago Lucie Fairweather and Nat McBride began to build an affordable eco home in Woodbridge for themselves and their two young children. However, their journey was to be about more than bricks and mortar. Just before they got started, Nat discovered he had cancer, and after just a few months he passed away.

Lucie decided to carry on with the project Nat had devised.

Kevin McCloud returns to find out just how life has moved on for Lucie and to discover whether her wonderful and striking house has become part of the landscape.