An interesting read by Harry de Quetteville for the Telegraph.

There’s nothing so divisive as a caravan. Judging by the way they clog our roads in the summer, hordes of people see them as glorious adornments to their lives. But if the reactions of other road-users are any guide, just as many drivers consider them a nuisance or an unstylish affectation.

If parading a caravan on the road is bad enough, though, what about putting one on the roof of your home? In effect, that is what thousands of us are doing with our loft conversions.

“It can be the lightest, airiest room in the house,” says Tom Howard, an architect with Millar Howard Workshop. “It’s your chance to drink in the London skyline. But so many of them are just sweaty great boxes.”

In a way, one can understand the caravan fans – plain boxes are extremely functional. Loft conversions have been in the London home expander’s armoury for decades, long before kitchen extensions became de rigueur or basements were all the rage.

“The loft conversion was the very first home improvement that one saw, going back 30 years,” says Lindsay Cuthill, the head of residential sales in south-west London for Savills. “Loft companies have designed thousands and thousands of them. They are in their second or third generation. There is no problem that they haven’t encountered.”

Which should give prospective loft converters considerable peace of mind. When the builders say that the job is going to take six weeks, for example, their long experience means it probably will.

In addition, the men in overalls attack the conversion from the outside, via scaffolding, so you can continue to live at home during the process. Try that during the grind of a basement extension.

Provided it is quick and relatively hassle-free, a loft conversion is a good investment, too. Spending up to £50,000 on a standard job is, according to Cuthill, “a bargain”, considering the extra space you get and London property prices.

It could add up to to 20 per cent to the value of your home.

The space is the thing, of course. Two-bedroom Victorian terraces can suddenly become four-bedroom family homes.

“I have worked on some properties where we’ve added two extra rooms and a bathroom for the children – that makes a huge difference,” says Kevin Murray, the senior project manager for Affleck Property Services.

Yet despite the many boons, there is something, well, a little too practical about many conversions. Frankly, they have all the pizzazz of lukewarm porridge, all the romance of a snail farm. No wonder the colour palette of choice for so many converters is beige.

But things are changing. Roaring up in the outside lane in the caravan’s wake is a distinctly groovier convertible that, for only a little bit of extra outlay, ensures a considerably more bespoke space than the standard housetop box.

Seven years ago, Louise Harris converted the loft in her Battersea home. It was an off-the-shelf design and, while she has no complaints, she now sees that it could have been done so much better.

Last year she moved into a near-identical house in the next street. This time, however, she was determined to do something a bit special. So she turned to Howard, and the result could not have been more different.

Instead of standard Velux windows, the design called for a folding glass panel that opens up an entire side of the house to the heavens.

It produced the kind of space and light that makes one want to lie and stare up at the blue skies. So Harris installed a roll-top bath underneath.

“With my friends, I am now evangelical about having lofts done really well,” says Harris, 34. “This time I feel like every inch of the space has been maximised.”

She even had soundproofing added to keep out aircraft noise.

But changes can also be made to keep noise in, rather than out. A loft that Howard created recently in Clapham was transformed into a recording studio. A drawer in a corner turns out to be a pull-out single bed “for whichever musician fails to leave after the session”.

All over the capital, imaginative use of glazing is transforming lofts into the lightest, largest room in the house. No wonder spaces that used to be children’s enclaves are now being reclaimed by parents as master bedrooms.

“It used to be mostly turned into the kids’ bedroom,” adds Murray. “Not any more.”

Of course, any plans for steel supports allowing big windows must be passed by planners. Even if the Government presses ahead with controversial plans to relax planning rules, the change will not apply to many parts of London, protected as they are in conservation areas.

But build something you are not allowed, and you will be asked to take it down.

A good guide is to look at your neighbours’ homes. Unless your house is listed, it is likely that you will be able to elevate both at the front and back of the house, or just at the back. That will create an area of flat roof, but these are not the worry they used to be, and come with long guarantees should the rain find a way in.

They also provide another canvas for your imagination. Instead of asphalt, some converters add sedum rooftops. These provide a habitat for bees and butterflies, and are loved by planners because they act as a sponge in cloudbursts, preventing sewer overloads and flash floods.

Whether the caravan or coupé type, all loft converters enjoy some common benefits. Among them is the fact that new space must meet modern insulation requirements, often improving energy efficiency. Renovated attic spaces keep things warm in winter and cool in summer: you are effectively putting a hat on top of the house.

With so many benefits to be gained from ultra-modern loft conversions, there is no reason not to raise the roof.

Tips for the top

Decide whether you are caravan or coupé – functional or flash. Opting for the latter will be up to £20,000 more expensive, but could be well worth it. Consult an architect for design and structural advice – see Architecture.com.

Most domestic loft conversions do not usually require planning permission, provided certain strict conditions on the size are met. However, building regulations approval will be needed – check with your local authority.

Planning permission is needed if you are in a conservation area.

To comply with building regulations, the space must be at least 7ft 6in high at its highest point.

You will probably have to move your water tank, and the layout will be dictated by the position of the staircase and plumbing.

Consider using a specialist company to handle everything from planning to ordering the skip, and checking you have enough headroom.

If there are bats in your loft, you might have to think again: they are a protected species.