The secret to transforming your home – without planning permission

Anyone who has ever gone through the rigmarole of applying for planning permission will be well-versed in the process’s drawbacks. The form filling and plan drawing, the long wait for a verdict, the neighbours just itching to kick up a fuss, and the uncertainty of a system in which different councils have their own in-house rules and standards.

The good news is that it is possible to radically remodel your home without going near the occasionally Kafkaesque planning department. The surprisingly generous exemptions which are known collectively as “permitted developments” mean you can extend most houses up, out, and to the side without needing anyone’s permission.

The key is that the project has “no impact on your neighbours or the environment”, according to government advice.

In order to do this, you’ll have to get familiar with the rules and check your plans with your local council. Despite the difficulties, permitted development has helped hundreds of thousands of home improvers cut through the red tape – here are some of their stories.

The stylish kitchen extension, that doesn’t anger the neighbours

Sharon and Ed Stanley bought their Victorian home in Catford, south London, in 2006, and had long put up with its dated downstairs – which came complete with a cold and rickety lean-to extension and a dowdy kitchen.

When they were ready to remodel, they enlisted the help of Sam Cooper, director of e2 architecture (www.e2architecture.com). He drew up plans to extend the space, linking it to the back garden with the help of sliding glass doors at the back and side of the room.

The house is terraced. Under permitted development rules, this means they could extend back into the garden by 3m without needing to apply for planning consent. 

“The garden is quite small and we are close to our neighbours and didn’t want to impose too much on them, so that was enough,” said Sharon, who works for a software company.

Although the family were only able to add a fairly small amount of extra space, Mr Cooper designed it with generous overhanging eaves. “Eaves don’t count in the technical measurements, so they can project quite a bit, giving a nice architectural feature,” he said.

However, they decided against doing a side return to extend the kitchen across the full width of the house.

“We often find that less is more,” explained Mr Cooper. “People do a side return, and end up adding an extra meters’ width, which doesn’t really add much useful space and takes away the window from the middle room of the house. It also costs more, because you have got to build a long party wall, and all you end up with is somewhere to put a sofa that you never use.”

Even if you are confident that your plans fall under permitted development, Mr Cooper recommends applying to your local council for a certificate of lawfulness to confirm that you’re allowed to go ahead with the work. “It is easy to get tripped up on the technicalities,” he said.

Those technicalities include the fact that there are different rules for different homes. You can build a single storey extension up to 3m deep on a semi-detached or terraced house, for example, but you can push out 4m if you have a detached home.

It’s also worth noting that permitted development does not cover flats, listed buildings, or homes in conservation areas. In these cases, extra rules are likely to limit what building work you can do, and you’ll need explicit permission for most projects.

While the work took place Sharon, 48, and Ed, 49, who works for an investment bank, plus their 12-year-old daughter Agnes, moved out of the house for around six months – but they think the upheaval was worth it.

“I love it, every single day,” said Sharon. “Sometimes I still text Sam just to tell him that. It is so light, simple, and spacious. In the summer we can open the doors and spill out on to the garden, which we use far more than we ever did before.”

The outbuilding that became a designer garden gym 

Whether you want a home office or a yoga room, you can build a self-contained structure in your garden using permitted development, although there are many ifs and buts to navigate.

One of the most fundamental decisions, said architect Francesco Pierazzi, director of Francesco Pierazzi Architects, is square footage. “You do have to think about striking a good balance between the outside space, and the gain in additional covered space,” he said. “You don’t want to compromise your actual garden.”

Another decision is whether to hire someone to design your garden room. There are plenty of companies offering off-the-peg options, which tend to be the best value. But if you want something more personal, with specific finishes and scales, you may need the services of an architect.

Under permitted development, you can build a single storey outbuilding in your back garden, so long as you stick to strict rules on height and size. The maximum eaves height is 2.5m, while the highest point of the roof can be up to 4m, depending both on the style of the roof and how close it will be to the boundary of your garden.

You are not allowed to add extras like verandas or balconies, and you can’t cover more than half your garden (less if you live in a National Park, Area of Outstanding Natural Beauty5 or a World Heritage Site).

Finally, while your outbuilding can be used for a myriad of purposes – play room, art studio, home office – it has to be ancillary to your main house. This means using it as self-contained accommodation is out. To make sure you don’t accidentally overstep, it’s worth seeking professional advice so someone can look over your plans and advise you on any changes you might need to make.

Professional advice can also help elevate a simple box-shaped room into a thing of beauty. Hired to build a gym in the back garden of a house in Wimbledon in 2021, Mr Pierazzi created a flat-roofed building sheathed in Siberian larch, which will weather down to silver grey over time. For privacy and security reasons the glass door has been mirrored, and a skylight brings in natural light into the 130ft space.

To make the most of the building’s 2.5m height, Mr Pierazzi had a low trench dug for the foundations of the gym, so that it is entered at garden level, without a step up, and clever planting softens its appearance. He estimated that a similar project would cost around £40,000 today.

The no-nonsense loft extension

Architect Jeremy Foster, director of J Foster Architects, said the crucial advantage of using permitted development is certainty. If your project falls within the Government’s guidelines, then you are guaranteed permission to start work. Neighbours are not consulted, which means there is no risk of them attempting to object.

The downside is that you do have to fit into permitted development’s cookie-cutter style. 

“For example, you have to use materials which complement the existing houses, and for some councils that means that if your house is white render and brick, then that is all you can use,” said Mr Foster. “It is quite rigid and prescriptive.”

He agrees with Mr Cooper that it is wise to apply for a certificate of lawfulness before embarking on a project – a process which can take up to eight weeks. During this time owners (and their architects) have a chance to plead their case to council planners, and in Mr Foster’s experience they can be willing to stretch their interpretation of the rules.

Hired to extend a 2,153 sq ft period terrace in Highbury, North London, with a new loft extension, Mr Cooper was able to persuade Islington Council to allow him to clad the extension in dark-coloured fibre cement, which he successfully argued complemented the property’s mellow red brick. A large roof light was installed, as well as two dormer windows, and the work added 538 sq ft of living space – enough for a spare bedroom, a bathroom and a study.

“You can persuade councils, but you have got to be tenacious and put your case,” said Mr Foster. The problem is that some councils are simply more accommodating than others – just as they are when adjudicating planning applications. 

“It is not consistent,” said Mr Foster.

His six-month Highbury project was completed in 2019, and cost around £220,000 (or just over £400 per square foot). Today, taking rising prices into account, Foster expects it would cost more like £275,000, so it is worth calculating whether you are likely to get your money back when you come to sell the property before acting.

For owners Ishan and Isobel Maini, both 39, the rationale of the loft extension project was to provide extra space for their growing family – they have three children aged two, five, and seven.

“Since the pandemic I have also needed somewhere to work from home,” said Ishan, who is a tax consultant.

He and Isobel, a buyer for Liberty before the children were born, were relieved not to have to work through the planning system, and love the extra room they have created. 

“Do we miss having a loft? Not really,” said Ishan. “We have built-in eaves storage, and we took the opportunity to declutter a lot before the conversion. The utility of the space we have far exceeds the storage that we used to have.”

As with other permitted development projects, loft extensions are subject to a whole load of rules and restrictions.

The size you’re allowed, measured in cubic meters, depends on whether your home is detached, semi-detached, or terraced. You can’t extend beyond the highest point of your roof, and verandas and balconies are prohibited. While you may be able to sidestep a planning application, it’s not free of bureaucracy; you may need to carry out a bat survey to make sure you are not disturbing a protected species.