Grand Designs - Season 11

Kevin McCloud looks at the transformation of a derelict mill cottage in Northumberland into a contemporary family home, the longest-running project ever featured on the programme. Stefan Lepkowski and Annia Shabowska began work in 2006, and their ambitious plans involved restoring the Georgian building, reconstructing a watermill and adding a steel-and-glass atrium, but their budget of £250,000 was completely inadequate.

Kevin McCloud meets Paul and Penny Denby, who are demolishing their mock-Georgian home on an exclusive south London estate to replace it with a contemporary mansion. The couple have no building experience and they struggle with many design decisions, finding themselves £250,000 short of the amount needed to finish the property.

Kevin McCloud meets Tim and Philomena O'Donovan, who are trying to convert a lifeboat station in Tenby, Pembrokeshire, into a contemporary home and preserve the historic building for posterity. A weather-worn, rusting and rotting hulk that was never designed for habitation, it is perched on a steel pier 40ft above the sea and can only be reached by crossing the sandy beach at low tide.

Kevin McCloud follows the conversion of a large, Grade II-listed timber-framed barn in Essex into a family home and work-space by artists Freddie Robbins and Ben Coode-Adams. Their plans involve few interior walls to display their collection of toys, but at seven times the size of an average three-bedroom house, the transformation of the 500-year-old building proves extremely challenging.

Kevin McCloud meets estate manager Ed Waghorn and his wife Rowena, a couple living an almost self-sufficient life with their four children on a smallholding in Herefordshire. They have been constructing a timber-framed house using recycled materials, wood from nearby forests and stone from around the site, but as construction becomes a way of life for Ed they seem to have lost sight of their goal.

Stonemason Adam Purchase and his partner Nicola Brennan try to restore a dilapidated Grade II-listed engine house in Cornwall, which was formerly part of a silver mine. With a budget of £100,000, Adam takes a year off work to transform the property into a new home, but has to rely on favours to complete the project before he runs out of time.

Kevin McCloud meets Claire Farrow and Ian Hogarth, who are trying to construct a home containing a sauna, spa, dance floor and DJ booth on a small patch of land in London. They have applied for planning permission to include a basement and started work on the construction, but setbacks including their digger smashing into a neighbour's wall and the re-emergence of the old river under the project threaten to prevent them completing the build.

Kevin McCloud revisits Robert and Milla Gaukroger, who were in danger of their bank foreclosing on their unfinished timber house with views of Lake Windermere when he last saw them. They had begun construction with only a quarter of the £400,000 budget needed, and the physical effort of turning the 1980s property into an eco-home that mirrored the surrounding mountains had begun to put Robert's health at risk.

Kevin McCloud revisits an arch-shaped home made of clay tiles in the Weald of Kent, built by Richard Hawkes, who designed the property, and his wife Sophie. It was intended to be self-sufficient in energy and supply some to the national grid but serious problems occurred when the arch collapsed during construction, so the presenter returns to see if their innovative home has lived up to its promise.

Kevin McCloud revisits Denise and Bruno Del Tufo, who hoped to transform a concrete water tower designed by Edwin Lutyens into a contemporary home. Kevin was originally far from enthusiastic about their project, believing the original building to be ugly and brutal in its design – but the couple soon had other problems to worry about, as rising steel prices forced them to make drastic changes to their budget.

Kevin McCloud revisits Alan and Judith Dawson in west Cumbria, where they began constructing a prefabricated home in 2009. They employed a method of building that should have allowed them to assemble the home in just 15 days on a budget of £300,000, and the presenter returns to find out whether they were successful.

Kevin McCloud revisits a couple who took on the task of constructing a sustainable two-storey timber house heated by glass panels in the Kent countryside. Mimi da Costa managed the project despite a lack of experience, while her husband worked, and intended to have it completed in 16 weeks. But as the complex build threatened to drag on for months it became unclear whether their home would succeed in blending into the landscape and providing them with a greener, healthier lifestyle.