Assessing the potential of a ruin is an exercise in creativity and optimism. Christine and Pete Hope were seized by the possibilities of a derelict black house on the Isle of Harris. But, by their own admission, their positivity bordered on naivety. Armed with a budget of only £50,000 and a fervent desire to escape an urban existence in Sheffield, the couple - whose two grown-up children are now in their twenties - were undeterred by the fact the building they had set their sights on had only three walls, a tin roof and was being used as a sheep shed.

The black house was prevalent throughout the Highlands and islands of Scotland for centuries. It was a low, stone dwelling with a thatched roof and a dark, smoke-filled interior (there was no chimney as such, just a hole in the roof). In the post-second-world-war years the people of Harris left their black houses for modern comforts within concrete walls.

The Hopes are incomers who have brought vision and Herculean effort to their building project, and they have succeeded in turning this relic of an abandoned tradition into a contemporary and comfortable home. It has been a long, hard slog, however.

Pete, 48, says: “If I had assessed that I had even half the amount of hard, physical labour ahead of me that this project demanded, I would have refused to start. But having started we were determined to see it through.”

Black Sheep House, as it is now known, sits at the edge of the sea, and its extensive bay windows offer a cinematic outlook on to the Hebridean landscape. Its turf roof and gently curved stone walls blend effortlessly into the surroundings. In fact, the house cannot be made out in an aerial photograph.

As often happens with self-build projects, costs spiralled. By the time the build was completed last May, the final tally, including the site, labour, architect's fees and materials, came to £130,000. While this undoubtedly represents good value for a bespoke property that incorporates two double bedrooms and a generous living space, it meant the Hopes could not make Black Sheep House their home. Instead, they live in a small rented cottage while the house is let out to guests. The couple reclaim it when business is quiet.

Visitors are charged between £700 and £1,100 a week, and so far there has been no shortage of bookings for the main season between March and October. Luring customers to the island out of season is a challenge the Hopes are now taking on. But how do these former punk rockers cope with the wilder weather of winter and the isolation of their adopted home?

Pete says: “After living in a city for so long the remoteness and lack of people is inspiring. It suits my underlying misanthropy. We wanted to find a place that was small enough to be familiar yet big enough to retain some mystery. I always wanted to be on the outside looking out.”

The Hopes may be outsiders, but the success of their new life has been dependent on their ability to inspire friendship and co-operation from the locals. Obtaining a suitable building plot is in itself no easy matter, but by moving up in 2003 and living in a caravan for a few months the couple gave themselves time to get to know the area and the people whose attachment to the land extends back through generations.

A crofter showed them the black house on his land and named his price. While the exact amount remains secret, it was obviously a bargain offered in the spirit of friendship. Little is known of the house's history, but the Hopes did befriend an elderly local, who has since died, who remembered eating cormorant stew in the place as a child.

Finding an architect who shared the Hopes' sense of vision was also essential. The first one they consulted recommended the ruined house should be utilised as a bike shed. Luckily the second name on their list was Stuart Bagshaw - an English architect who has been based in Stornoway on Lewis for more than 20 years.

Christine, 53, says: “We were very lucky to find someone who understood what we wanted. Stuart has a particular aesthetic which compliments ours. Also, he is extremely practical and was always on hand to discuss the sourcing of materials.”

Building work started at the end of 2005. Christine took responsibility for managing the project and spent hours trawling the internet to find suitable bargains, such as the Brazilian slate flooring, purchased for £25 per square metre including delivery.

She has more than 20 years experience as a social worker and, although no longer in that line of work, she brought patience and perseverance to her new role. Costs were minimised and problems solved with creative solutions. For example, she hit upon the idea of hoisting a Jolly Roger flag on the building site so that delivery drivers could find their way.

Pete is a professional dry-stone waller, so he was able to do all the stone work himself with the occasional help of a labourer. He kept the remaining structures in place and added to them to extend the height of the building and to double its original size.

Building regulations dictated the need for a wooden structure to support the turf roof, so a post-and-beam system that incorporates curved roof struts was designed. Bagshaw provided a paper pattern and a local contractor cut the curved beams from straight blocks of douglas fir. Before the roof went on, the frame had the appearance of a whalebone corset. This was then covered by a double skin of marine ply and a waterproof layer. At one point the waterproof layer was being tugged off by the wind, so a fishing net was put over it to keep it secure. Somewhere, underneath the vegetation, it remains in place.

Cutting the sods for the roof was a gargantuan task. Christine sat at the top of the ladder and Pete climbed up with each piece of hand-cut turf. The total weight of the turf came in at several tons, so this part of the work took three to four months.

Pete says: “Our crowning glory was turfing the roof. By the time we finished my legs were really strong and Christine had overcome her fear of heights, but it's worth the effort.”

The interior of the house is stunning, and far removed from the cramped intimacy of the original black house. Its generous proportions come as a complete surprise and the sense of space echoes the endless shoreline and moorland surrounding the house.

A large double-height, split-level living area incorporates a kitchen and dining room and opens out on to a bell-shaped sitting room. There is a large double bedroom downstairs and another double bedroom occupies a gallery above the sitting area. Viewed from the bed, the ceiling takes on the soft curves of a Bedouin tent and there is a procession of wooden arches that curve towards the bay window. The plastering is the work of yet another local craftsman, who managed to retain the soft, circular lines of the walls as they undulate between posts.

There is evidence of Christine's craft skills throughout. Soft furnishings and occasional panels of painted wooden cladding add splashes of vibrant colour. The bathroom is a tasteful collage of Mediterranean mosaics in blue, green and white. Cheap tiles were broken into component parts and put together over a period of four weeks. Yet another unique effect achieved for a modest outlay.

There may be other bargains to be had in the Hebrides, but not everyone can make it work. Christine says: “You have to have a very fit husband with a strong work ethic who is not going to give up.”

Pete, meanwhile, is gearing up for another challenge. He says: “We have surpassed our expectations and now have a beautiful house and an income. Our challenge now is to build somewhere at least as good as Black Sheep House and once we've done that we can choose which works best for us.”

For further details call 01859 520 306

www.blacksheephouse.co.uk

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