Walk down the streets of any of north London’s conservation zones and you could be forgiven for thinking that all building in the city stopped at some point circa 1898, such is the quaint uniformity of these Victorian suburban streets.

Ham & High: Extension of a modernist 1930s building on the Highgate edge of the Crouch End Conservation Area, N6 by 2PM ArchitectsExtension of a modernist 1930s building on the Highgate edge of the Crouch End Conservation Area, N6 by 2PM Architects (Image: Archant)

Glimpse almost any of these rows of houses from behind however, and the buildings start to tell a different story, of small-scale, individual projects undertaken since London’s expansion as an industrial, suburban city began.

Swelling families have been adding rear extensions to their homes for decades, even centuries, in order to steal additional snatches of that most precious of London commodities: space.

But should a buyer moving into that rare thing – a rear extension-free property in London – add their own extension? Is it the best way to add space and value to a property, or have twenty-first century renovations like the multi-storey basement excavation overtaken the humble side return extension?

First steps

For the novice homeowner in particular, the process of undertaking any kind of renovation can be daunting and can present a minefield of potential frustrations, disappointments and wasted expenditure.

Ham & High: Extension of a modernist 1930s building on the Highgate edge of the Crouch End Conservation Area, N6 by 2PM ArchitectsExtension of a modernist 1930s building on the Highgate edge of the Crouch End Conservation Area, N6 by 2PM Architects (Image: Archant)

According to Peter Wraight and Mathew Byron, principals at 2PM Architects in St John’s Wood, it’s important to get professional advice early in the process.

“There are a lot of things to consider, ranging from the use and style of the extension, to the budget for the building work. We would suggest discussing your project with an architect who can offer detailed professional advice.”

If you’re concerned about the potential expense of a consultation about a project that you might not even follow through on, some architects may not charge for initial consultations or certain smaller jobs.

Belsize Park-based architect Luigi Montefusco, of LBMV Architects says: “If it’s just something straightforward – a small drawing that I can see how it will look on Google maps, for example, or if the house is near the office – sometimes I do it without even charging.”

Of course this is entirely at individual architects’ discretion, but it’s worth finding out if you are at the very start of the process.

Ham & High: Extension of a modernist 1930s building on the Highgate edge of the Crouch End Conservation Area, N6 by 2PM ArchitectsExtension of a modernist 1930s building on the Highgate edge of the Crouch End Conservation Area, N6 by 2PM Architects (Image: Archant)

Planning

Another potential minefield is the planning process. Many homeowners worry that they could pay a significant sum to obtain architects’ drawings and make the application to the council, only to have planning permission denied.

Planning permission is not always necessary for a rear extension as some projects can be completed under permitted development rules but it could be worth getting drawings approved by the council anyway, for peace of mind.

An experienced architect should have a good understanding of the criteria for assessment and can provide invaluable assistance to planning applicants.

Wraight and Byron say: “A good architect will be able to liaise with the council, will understand their criteria and can produce Design & Access Statements to support the application and maximise chances of approval.”

Ham & High: Side and rear extension in Queen's Park, NW6, by LBMV ArchitectsSide and rear extension in Queen's Park, NW6, by LBMV Architects (Image: Archant)

“Conservation Areas will have additional rules and restrictions.”

Councils should make the decision to grant or deny planning permission within eight weeks.

Value

Any permanent work carried out on your house, which is almost certainly your biggest investment, feels fraught with pitfalls.

You may be desperate for more light and space, but will you also be helping to sell the property on when you’re ready to move? Could a misjudged rear extension even decrease the value of your property when it comes to sell?

Ham & High: Side and rear extension in Queen's Park, NW6, by LBMV ArchitectsSide and rear extension in Queen's Park, NW6, by LBMV Architects (Image: Archant)

Nigel Ellis, managing director of Prickett and Ellis in Crouch End says that this is a possibility.

“One thing I’d advise is not to make a big extension and do away with the garden because a garden is a real asset.

“The biggest mistake people make is to assume that the more square foot you can get, the more valuable a house will be, but if you’re losing 35 to 40 per cent of your garden, the extension’s probably too big.”

Style

Ellis also stresses the importance of getting the best quality you can afford and making sensible decisions regarding look and practicality.

Ham & High: Side and rear extension in Queen's Park, NW6, by LBMV ArchitectsSide and rear extension in Queen's Park, NW6, by LBMV Architects (Image: Archant)

“It has to be good quality if you’re going to have a good feel with a garden extension but also the style has to be right,” he says.

“Too much glass can be difficult to live with as you get a lot of extra light heat in summer, and then you’re cold in the winter.”

Anyone who’s seen their fair share of 1980s conservatory disasters will also worry that their fashionable glass box may not stand the test of time.

Montefusco says there is not too much danger of this, however. “The more simple the design, the better it is because it can stay in fashion longer. Technology changes but if it’s designed with basic and simple principles, it can’t really get old.”

What’s next

Wraight and Byron predict that our growing awareness of environmental issues is having the biggest impact on our choices around extensions.

“Green eco architecture is becoming more and more popular and features such as highly insulated grass or wildflower roofs, triple glazing, solar controlled glazing and other energy efficient features are being used more and more in extension and refurbishment projects.”

Meanwhile Montefusco is finding that people are using extensions as a way of dealing with property prices that are spiralling out of reach for even the highest earners.

“Garden flats have a lot of potential. I have quite a few people that are looking for ground floor flats in Belsize Park, on roads like Lyndhurst Gardens and Parkland Crescent, where the gardens are very large.

“With a ground floor flat you can sometimes dig a basement, doubling the size of the flat, and still have the ground floor facing the garden.”

2pm-architects.co.uk

lbmvarchitects.com

prickettandellis.com