Grand Designs — Season 19

Kevin McCloud returns for a new series of the show that follows intrepid individuals trying to design and build their dream home. In Buckinghamshire he meets young Spanish architect Jaime and his wife Mimi as they embark on an epic mission to convert a Grade II* listed folly into a family home. Originally designed to exhibit a fossil collection, but gutted by fire and left in ruins for the last 200 years, the crumbling mini castle beguiles Jaime and Mimi. Giving themselves a wildly optimistic six month deadline to finish before the birth of their second child, it's not long before the couple hit trouble. The Saxon burial ground the folly is built on throws up some macabre surprises. Their stonemasons from Madrid let them down and local builders with no restoration experience have to take on the crumbling stonework. Jaime puts all his energies and creativity into the project, using innovative 3D mapping to squeeze living spaces into the tower, but it's an exhausting struggle.

Harry and Briony Anscombe have made a radical change to their lives, moving with their three young children from London to Cornwall - and setting up an outpost of their media business at the same time. It's a bold attempt to emulate the positive work-life balance and lifestyle they experienced in California. But even bolder is the giant five-bedroom house they want to build, heavily inspired by an American modernist house Harry saw in the 80s teen comedy Ferris Bueller's Day Off. All floating steel and glass, Harry by his own admission has become 'obsessed' with living somewhere just like it. But creating such an architecturally ambitious home would typically cost over a million pounds, and Harry and Briony have just £400,000 to play with.

In the first 'healthy' home project ever seen on Grand Designs, gallery owner Elinor and fitness entrepreneur Born set themselves the near impossible task of creating Britain's first hypoallergenic house in a leafy back garden plot in south west London. Driven by the need to alleviate their two young sons' life-threatening allergies, their new part-submerged, shed-inspired home, will be constructed using low toxin materials and deploy cutting-edge filtration systems to clean the air they breathe. Right from the start, Born and Elinor are up against it, with access issues to their plot and the need to be super strict concerning suitable materials. It's an immense burden and with the children still suffering weekly allergy attacks, a race against time to get moved in. But will their innovative new house deliver the benefits Elinor and Born are hoping for?

Chiropractor Steph Wilson has spent 20 years dreaming of living on her grandfather's farmland in Leominster, Herefordshire, which was sold when she was 16. Steph and her husband Alex have re-mortgaged their current house to buy back 27 acres of the farm. Steph has secured planning permission for a sleek contemporary cantilevered farmhouse in the old gravel pit where she played as a child. She is determined to give her two young children a version of the blissful childhood she had. Steph and Alex are told their ambitious design will cost £500k - twice what they can borrow. Regardless, the family take a leap of faith and move into a draughty old caravan on site. It's supposed to be a temporary solution. But after six months, caravan life is starting to look like it could become permanent. The family are in desperate need of a saviour, or their dream could turn into a nightmare. Then along comes Steph's oldest friend.

Identical twins Nik and Jon Daughtry run a graphic design company together. They drive the same car and even own identical dogs. Now these two brothers are building two near identical houses next door to each other in Sheffield. Raised up on steel stilts on the site of an old corn mill, the houses pay tribute to Sheffield's industrial past. Huge steel frames with exposed blockwork and black steel cladding should create two sleek and modern family homes. But Nik and Jon's plan is incredibly ambitious. Not only do they want to build the two houses for the price of one, but the materials and finish have to be absolutely perfect. With a tight budget, it's an almighty stretch from the start. As delays, overages and imperfections hit, it's clear the twins' intuitive and incredibly close relationship will be tested like never before.

Professional deep-sea diver Adrian Corrigall is obsessed with concrete. He fell in love with this cold uncompromising material in the skateparks of Scotland. Now he's convinced his wife Megan to agree to build their new family home in rural East Sussex almost entirely out of the stuff - both inside and out. No cladding, no carpets, no plaster or wallpaper - this will be as pure a concrete building as possible. Construction involves cutting-edge technologies conceived in Switzerland and never used to build a house before. The hope is these new mix recipes will overcome the historic negatives of concrete and keep costs down. However, the perils of being a pioneer soon become evident. With both schedule and budget under strain, Adrian is forced to resume work as a diver, servicing North Sea oil installations and taking him away for a month at a time. With Megan now left juggling the build, all the while looking after three young children, the concrete dream seems a long way off.

Kevin McCloud returns to Devon to meet Kevin McCabe, a man who wanted to build one of the biggest houses the programme has ever seen. Finally, seven years after it began, the herculean task of building this giant cob castle is complete. Has it proven to be the great home he originally intended, and does it prove as he hoped that cob is a viable material for contemporary architecture?