Kevin McCloud meets Tamayo Hussey, who has missed Japan ever since she moved to the UK 14 years ago with her husband, quantum physics professor Nigel. The couple want to transform a 1960s forester's lodge into a unique Japanese house, complete with a tatami room - decorated in her homeland's traditional style - sliding paper walls and a bath on the roof. Keen to keep costs down, they have decided to engage only the design skills - rather than the full services - of an architect, so with no previous building experience they tackle the project alone.

Kevin meets Kevin McCabe who wants to build what may be the largest Cob structure in the world. With 6 metre-tall walls, McCabe fights a battle with the weather and his implausibly small £350,000 budget. He plans to form the huge property out of two vast curved roundhouses - the largest of which is inspired by the natural geometry of a snail shell - connected by glazing and topped with wildflower meadow roofs to mirror the surrounding countryside. However, the project involves mixing and laying a mind-boggling 2,000 tons of cob, all during warm, sunny weather - and the sheer scale of the task soon becomes clear.