Every Englishman's home is his castle but for Francis Shaw this is quite literally true. He and his wife, Karen, and their two young daughters, bought the ruins of a 14th Century castle in Yorkshire and took on the remarkable challenge of turning a pile of stones into a beautiful home. Surrounded by rolling green fields, the location is idyllic; however, the castle itself was little more than four crumbling walls.

Eight years ago Alex and Cheryl Reay left London for a new life in the New Forest. They bought a run down medieval thatched cottage and lovingly brought it back to life. Then just before Christmas, with Cheryl pregnant, disaster struck. A fault in the chimney caused a massive fire which destroyed the entire building. Overnight Alex and Cheryl had lost almost £400,000.

Whilst most people would have walked away from this, Alex and Cheryl couldn't let go of their dream. Nine months after the fire, they decided to start all over again and rebuild the cottage, bigger and better than before.

Chris Miller and his wife Sze Liu Lai lived in a tiny flat in East London with their two children Alexion and Tayszea. It was very tight for space and as the kids grew they really felt in need of more room. Chris and Sze are both social workers on low incomes and they have very little in the way of savings.

James and Katrin Gray live in Bournemouth on the south coast. James runs his own book distribution business and Katrin works for an investment bank. They used to live in an apartment on the second floor of a former Victorian hotel. But three years ago, James bought the top floor flat. It was originally built as a solarium for the hotel in the 1920's where holiday-makers could soak up the sun. Now James and Katrin plan to convert it into a modern, luxury penthouse

Kevin revisits Andrew and Lowri Davies who embarked on a project to build an environmentally friendly farmhouse in rural Wales. Encouraged by their architect, they opt for some state-of-the-art experimental building materials; but do their builders know how to use them?

As the budget spirals out of control, they find it increasingly difficult to balance the budget with their desire for a sustainable home.

Dean Marks has dreamt of living in a church for as long as he can remember. After searching for the right building for years, he came across St Martin's near Birmingham, a huge 18th century grade II listed church which looks more like a mausoleum. The church wanted £25,000 for it but Dean knocked them down to £12,500. Now, after fighting for planning permission for four years, Dean and his wife, Hilary, are about to transform this derelict monstrosity into a family home.

When Pilots Andrew Berry and his wife Helen bought their cottage near Guildford in Surrey 7 years ago they always planned to add a small extension. But over the last few years the modest extension has evolved so much that retaining any of the original cottage simply wasn't practical. Now it's being completely demolished to make way for a new five bedroom Art Deco style house.

Monty Ravenscroft and Clare Loewe bought a plot of land in Peckham to build their own home - only to be told it was too small for a traditional house. Engineering expert Monty designed a space-age property with a sliding glass roof and mezzanine bedroom pods, and as they grapple with unexpected obstacles, Kevin McCloud visits them to discover how the ambitious project has progressed.

Kevin revisits Tony and Jo, musicians with Scottish Opera, who had long dreamed of a home in the countryside. They found a perfect site on the Clyde estuary in Argyll and Bute. Located in a small village on a hillside, it had glorious views as far as the isle of Arran and was less than an hour's drive from Glasgow. Inspired by local oak-framed barns, they gave architect Andy McAvoy an open brief. In return, he gave them a design that fused medieval and modern and promised a beautifully simple interior. However, the construction was anything but simple...

Kelly and Masoko Neville set about building not just a spectacular oak frame and straw bale house, but a whole new way of life in the Cambridgeshire Fens. Kelly is a carpenter by trade and has always dreamed of building an eco friendly home with his own hands. This highly sustainable house, sitting in harmony with nature and its surroundings, will become the base for Kelly and Masoko's new self-sufficient life where they will produce their own food and energy from the land.

Kevin McCloud meets a couple who bought a ruin and moved to Italy in 1999, hoping to start work building their dream home in Tuscany. Since then they've spent all their time trying to get planning permission, but finally, after four years, they are about to start work. And it's an epic project: they have bought a derelict 1,000-year-old castle in the Tuscan hills. Now, the couple face their biggest battle of all: rebuilding this massive ruin into a comfortable and luxurious five-bedroom home.

In this episode Kevin meets master carpenter Bill Bradley and his wife Sarah, whose plan is to build two identical timber houses in south London, selling one to finance the building of the other.