Grand Designs - Season 27

Kevin McCloud follows more of Britain's most ambitious self-building projects, as intrepid individuals attempt to design and construct the home of their dreams. After 40 years living largely in the southeast of England, artist Sarah is returning to her roots in the northeast with towering ambitions for an exposed, three-acre plot that she's bought at auction in the Durham Dales. She wants to create a radical home and creative hub combined, including a studio and gallery for displaying and selling art. With her budget of £330,000, Sarah hopes to build with a super-sustainable yet still relatively unknown and hard-to-predict material - hempcrete. Left exposed throughout the interior, the hempcrete will provide a dramatic earthy look, but this relies on the building process going perfectly. But, just a few months into Sarah's eight-month schedule, her plan to move in before winter is scuppered as her inexperience as a project manager starts to show. With material costs going through the roof, and her budget doing likewise, selling her one-bed holiday cottage looks like the only way to keep building. As the critical hemp process gets going, and proves increasingly tortuous and unpredictable, the success of Sarah's project hangs in the balance.

Pete and Aey order a factory-built house to be constructed in Wales and transported to their rural West Sussex plot, where they plan to demolish an older property to make way for the new one. But there are two big problems - the old house is home to hibernating bats, and moving five gigantic modules down tiny lanes from Wales to Sussex is not going to be easy.

Kevin McCloud meets Marcus and Abi, who are building a luxurious off-grid family home deep in 20-acre woodland in Pembrokeshire on a budget of just £100,000. Granted permission through the One Planet Development planning laws, which are unique to Wales, they are armed with determination and timber from the surrounding forest. With no detailed plans, the project pushes the limits of design and endurance, and proves a raw, physical adventure that defies convention and challenges many of the ideas around what a home should be.

Kevin McCloud follows a couple who face a race against time to realise their dream. Two years ago, corporate accountant Pep was diagnosed with terminal cancer. But rather than rest and avoid stress, Pep and partner Malene focused their attention on a long-held ambition to build a new house on their land in the Surrey Hills. The plan is to construct a modern take on a Viking hall, inspired by their love of all things Scandinavian and Malene's Danish heritage. But they must build quickly so Pep can enjoy what time she has left in the finished home.

Piers and Emma build the first new listed castle in the UK for 100 years, complete with a tower, moat and futuristic tech. It's the biggest ever Grand Design, so is even their £2m budget enough?

Kevin McCloud revisits Stuart and Rosie Treasurer from Wirral, who he first met in 2016 when they set out to transform a small bungalow from a 1960s dormer into a slick piece of 21st-century architecture. The plan saw the couple decapitate the building and balance a new floating timber box on top to create five bedrooms, spending as little as possible on plumbing, electrics and insulation, but stress levels spiralled when neighbours grumbled at the ultra-modern creation. Nine years on, Kevin sees how Stuart and Rosie are getting on.

Kevin McCloud revisits Greg and Georgie, who in 2019 set out to convert a dilapidated 35-year-old barn in Georgie's parents' garden in Sevenoaks into a peaceful safe haven. It was a highly challenging build involving the painstaking conservation of the existing rotten structure, building a new two-storey internal steel frame and recycling everything they could to stretch their £250,000 budget. But how are they getting on six years since the original show went out?