Grand Designs Season 21

Justin plans to restore a neo-Gothic cemetery keeper's lodge and convert its toilet block into a luxury extension complete with a moat and swimming pool. But can he keep his budget under control?

Kevin McCloud meets Greg and Georgie who are taking on the highly ambitious task of converting a dilapidated, 35-year-old barn in Kent. The build will be a huge challenge involving the painstaking conservation of the existing rotten structure, building a new two-storey internal steel frame and recycling everything they can to stretch their £250,000 budget.

Nathan and Amye are building a cathedral-like home modelled on local Dutch barn houses with a sleek twist and a 5000-tile armadillo roof. But the pressure mounts for project manager Nathan.

Energy conservationist Andrew plans to build a radical, self-heating home by storing the warmth of the summer sun into insulated earth banks. But will this gigantic thermal experiment work?

Leigh and Richard plan to transform a derelict 17th-century flour mill, full of rotten timbers and riddled with structural cracks, into a warm, contemporary, four-floor, three-bed home.

Kevin McCloud revisits Adrian and Megan, whose dream home in East Sussex became a nightmare. With the house now fully complete, what is living in a cutting-edge concrete bunker really like?