This is the work of the young architect David Mikhail, who was given the task of redesigning the big but compartmentalised late-19th- century house by his clients Mary and David Wright and their three children. The Wrights had seen Mikhail’s alchemical touch at a house in Stockwell, published in this very paper, and signed him up.
In their street, on the cusp of Hammersmith and Shepherd’s Bush, houses routinely change hands for more than £1m. There wasn’t a lot wrong with the house in estate agents’ terms: it was double-fronted, in reasonable nick and had a huge garden and lots of rooms. But the Wrights wanted big living spaces, not just lots of boxes. And given the enormous garden, why not make the house relate to it a bit better? At the time of the move, the Wrights’ eldest child, Tom, now 5, was diagnosed with leukaemia. “It was just about the time we completed on the house and commissioned David,” says Mary. “We thought of forsaking the deposit and walking away.” But they didn’t. Tom overcame the disease, but is also autistic: another hurdle successfully faced up to. So, as Mary relates, the project was “almost a pleasure” as an escape from stress elsewhere.
Mikhail got on with researching the permitted- development business and found that, if you do your calculations with care and apply the rules exactly, you can do a surprising amount.
The idea was to open up a big living space at the rear of the house, and put a bedroom over it. Mikhail rejected the conventional solution of a glass box slammed across the back and instead composed what is effectively a miniature new house sitting back-to- back with the old one. Unlike the original two-bay house, the new part is asymmetrical, placed to one side to allow a clear view to the garden.
It is a judicious mix of dark- stained timber, recycled brick and glass. The upper level sits back to allow a balcony with a freestanding glass balustrade, and the whole arrangement is finished off with its own tall chimney, serving a fireplace in the sitting room below.
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It is a lot of extra space, and Mikhail calculated it to the last cubic centimetre to just fall within the permitted- development rules. “Because it is in a conservation area, it had to be no more than a 10% increase in volume of the original house,” he says. “But that includes the roofs, cellar, chimneys — even an outside lavatory that existed in 1947 but had long vanished.”
So far as local authorities are concerned, the Town and Country Planning Act of 1947 marks Year Zero when it comes to making the sometimes abstruse calculations for “permitted development”. Whatever the house was like then, that’s the starting point. Then there are other rules that apply: for instance, everything becomes much easier if what you build is at least two metres away from your neighbours’ boundaries. Hence the way that Mikhail’s extension stands proud.
In general, you are not allowed to do much at all on the front of the house facing the street, but on the back you can get away with a lot, so long as nothing pokes above the roofline. You can increase the volume of detached or semi-detached houses by 15%, and add 10% to a terraced house, subject to special rules in conservation areas (so the Wrights were held to 10% despite not being in a terrace). However, no permitted- development extension is allowed to be larger than 115 cubic metres, no matter how big the original house.
If you meet all the rules, the local planners have no further say, and give you a “certificate of lawfulness”. Anything outside those rules has to be submitted as a full- blown planning application, which costs more and may or may not be rejected.
The Wrights started house-hunting, says Mary, the moment she became pregnant with Tom five years ago. “We looked all over London. Our budgets went up, down and around. We spent years looking at houses that were all the same — sitting room at the front, kitchen/diner and conservatory at the back,” she says. “In the end we decided we would find a house with a huge garden and make it the way we wanted it.”
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The house they eventually found was satisfyingly unconventional by London standards. It is double-fronted, but has its entrance at the side so it isn’t split by a central hall. In common with all the houses in the street, it has a huge garden, the remnant of market gardens and orchards that existed when this was the edge of London.
The garden was full of sheds and the back part of the house was a warren of tiny low-ceilinged rooms, scarred with much-altered windows that didn’t make the most of the garden anyway. The house itself was in reasonably good condition but had hung around on the market for a while, possibly because it was not an obvious target for developers. The Wrights, however, were poised. After several previous disappointments, they had sold their previous home and were renting, so the purchase and building work could go right ahead. Construction began a year ago.
In the main house, the biggest change is the creation of a large living/dining/kitchen space running from front to back, with folding glass walls that open onto a sunken limestone-paved terrace. The new section of house is on the same level as the terrace (Mikhail dug down, to provide a higher ceiling while keeping the upstairs levels the same). Again, the garden room has glass walls that concertina open to bring the inside and outside spaces together, and the same trick is played in the bedroom above, which opens out onto a balcony. There is also a shower room behind.
The cost of a “permitted development” extension is the same as any other building job and depends on the amount of work and type of materials involved, and whether you are doing up the main house at the same time as building out the back. Building two storeys high is always proportionally more expensive than one.
Across most of England, a house extension of this kind would cost between £100,000 and £250,000. As Mikhail puts it: “You can still find good old-fashioned builders operating on relatively small profit margins.” In London, however, the costs rise to about £500,000. The cost of the Wrights’ extension is confidential, but probably at the higher end of that range.
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Given that this is an expensive area, it’s likely that the market value of the house will rise to reflect the work that has been done.
It is a sizeable chunk of building but, because the garden is so vast, the site can take it. It looks entirely natural, not overdeveloped. The fact that it was all done outside of planning permission suggests that the civil servants who drafted the 1947 planning act were clever and far-sighted people.
However, the rules of permitted development say nothing about aesthetic quality. A hideous breeze-block carbuncle could be just as big and just as legal. The difference here is having a good architect. And it shows.
Riba find an architect service, 020 7307 3700, www.ribafind.org; David Mikhail Architects, 020 7377 8424, www.davidmikhail.com
It's legit
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You can extend a semi-detached or detached house by up to 15% of the size it was in 1947 without a planning application
If it’s a terraced house or in a conservation area you can enlarge it by 10%
You can include the size of additions that may no longer exist if they formed part of your home in 1947
The maximum permitted extension is 115 cubic metres