Most people who embark on a self-build project believe the one great advantage of doing it themselves will be having the complete freedom to spend their budget exactly as they want - and that's their first mistake.
When Sophie and Jean-Jacques Lorraine set out to create their own little piece of heaven in a conservation area on the fringes of Hampstead Heath, the council first made them agree to spend tens of thousands of pounds creating a new public garden for the local community - and that was just in order to win planning consent to clear the site they had bought.
Thankfully, memories are short and the couple can even laugh now as they tell the tale of the four-year campaign they waged to get a derelict caretaker's house (and former potting shed), knocked down. And had they not agreed to pay the huge sum to improve the local area as part of the planning deal, they might have been spending the rest of their lives living in the hovel they had acquired.
The story begins back in 2005 when Jean-Jacques and Sophie were living in a small "one up, one down" cottage in Dartmouth Park, north London. It was too small for them, let alone the family they hoped to start.
Then Sophie spotted an advertisement for a funny little detached property up the road from them. "We went up in the evening to see what was there and it looked like a little haunted house," she says.
But as they stood staring at it, they could see the potential. The proximity of the heath was a major selling point, as was the idea of tearing down the old house and starting from scratch. The house had started life as a potting shed and equipment store at the heart of an Edwardian development of red-brick mansion blocks. Over time it was converted into the caretaker's house, and the caretaker had bought it from Camden council using right-to-buy legislation.
The couple stumped up £395,000 for the property and moved in while they drew up plans. Jean-Jacques is a director of Morrow Lorraine Architects (morrowlorraine.com), but had zero experience of building private houses from scratch, and spent months creating drawings that were not quite right, while living in tumbledown chaos.
It was "an awful experience," and one that was to last for two and a half years. Like all self-builders the couple needed planning permission, always more difficult in a conservation area. To add to their problems there was a restrictive covenant prohibiting the demolition of the building, and to make matters worse, the place was locally listed.
In order to deal with the issue of the local listing they had to hire a consultant to demonstrate that the existing building was of only limited benefit to the area, and that the appearance of a new house would make a greater contribution to the locality.
Their first proposal - for a larger "white box" of a house - was turned down but after judicious tweaking they were granted consent for a slightly smaller house which looked more in keeping with the traditional red-brick mansion blocks surrounding it.
To overturn the covenant, they had to agree to enhance the look of the local area, and so they paved and planted a former shabby communal space beside the house. They also had to build a new garage for civic use and hand over a cash sum to the council. The whole operation cost well over £100,000.
"We knew about the covenant when we bought the house, but we had no idea how much it would cost to get it overturned, or even if Camden would agree to doing so," said Jean-Jacques, 38.
After all the paperwork was complete, the year-long build was plain sailing by comparison. The couple had already moved out and into a rented home, having been thoroughly ground down by life in the grim cottage, and they were expecting their eldest son Jacques, now aged three. They now also have a second son, Leo, aged one.
Work started in late 2009, right in the teeth of the economic downturn. In fact, with immaculate timing, they secured financing for the £500,000 project just two weeks before Lehman Brothers collapsed and the mortgage famine began in earnest. "A couple of months later and we would never have got the money," said Jean-Jacques. They would have found it hard to get a builder, too. Out of the four contractors they shortlisted to carry out the work, three went to the wall in the recession - fortunately the firm they selected was the sole survivor.
By Christmas last year the family had moved in, having expanded the 1,000sq ft hovel to a 2,600sq ft four-bedroom house with three balconies, a wraparound garden and a dramatic open-plan ground floor.
The centrepiece is the free-standing fireplace that divides living room from kitchen. The piece was designed by the couple themselves.
"I must have a real fire, and we wanted something sculptural in the building. The fireplace seemed to be the perfect way to do it - it is like a piece of art," says 40-year-old Sophie, who runs Spin (studiospin.com), a production company specialising in commercials for the music industry.
The fireplace sits upon a rectangular slate base flanked by two floor-to-ceiling tactile towers of Welsh slate tiles. The side openings create space for logs to be stored.
The floors throughout the ground floor are polished concrete, but the couple have allowed themselves a more attention-grabbing material in the kitchen. The surfaces are Italian piebald Arabescato marble, offset with limewashed oak cabinets - the same wood is used upstairs for the floors and doors.
The walls are white ("with accents of raspberry jam and crayon" thanks to the boys), and huge windows are a feature throughout. One of the family's favourite spaces is the "snug" just off the kitchen, which also doubles as an office, TV room and playroom.
Upstairs are four bedrooms, each one leading to its own balcony, and the top of the house is lit by a large modern lantern that directs light down into the heart of the house.
The master suite's balcony overlooks the paved garden that the couple had to fund in order to build their house - which means that at least they get a good view of where their money went.
And since the house is now conservatively valued at £1.8 million, the last laugh is most definitely theirs.
Little black book
* Complex planning situations may require the services of a planning consultant. City Designer (citydesigner.com) - helped Jean-Jacques and Sophie negotiate the legal hurdles.
* The couple's bespoke kitchen is by Tin Tab, based in Newhaven (tintab.com).
* Much of the furniture was bought new to fit the house. A favourite hunting ground for mid-century modern pieces is EDC London (edclondon.com).
* The blinds and curtains for the endless windows are by Karasel Design (07904 387 931) and the lighting is from Modular Lighting Instruments (modular-lighting.co.uk).
* The garden was designed by Dilip Lakhani (diliplakhani.com)