But three years might be too long to wait because a government amnesty allowing many home owners to extend their property substantially without the aggro of gaining planning permission comes to an end next spring.
With a general election looming there is no way of predicting whether the amnesty will be extended.
“We have consulted on this and we are examining the responses. We will announce something in due course,” was all that a spokesman for the Department for Communities and Local Government had to say on the matter.
Right now you can add a good-size rear extension, carry out a loft conversion or put up a conservatory without needing planning permission — though the system isn’t a total free-for-all.
People living in listed buildings or conservation areas are not able to take advantage of this temporary relaxation of the rules, but the rest of us can make changes under a system known as Permitted Development (PD), so long as we stick to strict size limits and a style guide.
“If you go down the planning application route then your neighbours — and all and sundry — can comment and they can thwart your plans,” says Andrew Mulroy, director of Andrew Mulroy Architects in Highgate Road.
“If everyone gangs up on you, you can be derailed. PD is like a forcefield. You do still have to make an application to the council for what is called a Certificate of Lawfulness, but it is all relatively easy.”
Mulroy used PD rights when he extended a Thirties end-of-terrace house in Muswell Hill for a family who wanted a larger, more open-plan ground floor.
By keeping the extension to within PD size limits — still a substantial 16ft 4in high and 12ft 1in wide — he was able to create a bright, modern dining room overlooking the garden and Alexandra Park beyond.
This project proves that the aesthetic restrictions of PD — which state that your building materials must match the rest of the property — are not immoveable.
Mulroy was able to successfully argue that, although the house was red brick, since two entire walls of the extension are glazed, the contemporary dark grey aluminium that surrounds them constituted nothing more than a window frame.
Tom Vincent of Granit Architects used PD when remodelling a run-down Thirties house in Twickenham. He was able, without planning permission, to build a home office at the end of the garden.
The flat-roofed building measures 21ft 3in by 11ft 5in and is clad in a mixture of white render and cedar slats, which are used to provide a useful shaded canopy area since the garden room is south facing.
The theme is continued through the garden where low, white rendered walls enclose the flower beds. And, at the back of the house, the garden room is mirrored by a cedar and render extension measuring 21ft 3in by 13 ft 1in. The extension houses a modern kitchen while walls have been removed to give an open-plan downstairs living area.
Executing a similar project would cost about £80,000 to £90,000 for the garden room and between £375,000 and £450,000 for the whole house renovation, including the extension.
Vincent says that a typical London house may well not have a garden large enough to merit an extension exceeding the PD limits, and recommends this approach for its speed and relative simplicity. “You are able to start work before you get your Certificate of Lawfulness,” he says.
Adding floor space is the universally accepted route to increasing the value of a property. A recent study by Savills, based on a four-bedroom property in London worth £1.5 million, found that a loft conversion — another project which can be done under PD — would typically add 10 to 15 per cent to its value. A side return extension would add five to 10 per cent.
“Adding space definitely adds value,” says Robin Chatwin, head of Savills’ south-west London division.
“You have got to do it properly,” adds Chatwin. “Lowering the floor to give you higher ceilings will make the whole space feel much bigger and airier.”
KNOW THE RULES OF ENGAGEMENT
The golden rule is always to consult with your local council or an architect about your plans before starting work.
Permitted Development rules are detailed, and issues such as proximity to your neighbours’ boundary and previous extension work can come into play.
If an extension is even just a few millimetres too large, or the materials you use are not quite right, you could face legal action and have to tear it down.
- Rear extensions are allowed under PD so long as they are no more than six metres (19ft 8in) deep on a semi-detached or terrace home, or eight metres (26ft 2in) on a detached property.
- Roof height is restricted to four metres (13ft 1in).
- You can add an extra 40 cubic metres (1,412.6 cubic ft) of space to the loft of a terrace house or 50 (1,765.7 cubic ft) to semi-detached and detached properties.
- You can insert roof lights at the front of a property, and can also create dormer windows to the rear, although building a balcony will still need planning permission.
- Windows are allowed on a side wall, but you must use obscure glass to protect the privacy of neighbours.