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Design - -> 2-4 Weeks

Pre-planning - -> 2+ Weeks

Application - -> 6-8 Weeks

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Design - -> 2-4 Weeks

Notices - -> 48H

Full Planning - -> 3-5 Weeks

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Design - -> 2-4 Weeks

Concept - -> 1-2 Weeks

FF&E - -> 2-4 Weeks

Permitted Development 

Your Limits

Don`t exceed 50% of the total area of the curtilage.

Don`t exceed the height of the roof and eaves.

Don`t extend beyond a wall which forms the principal elevation or fronts a highway.

Single storey limits: 4 metres in the case of a detached dwellinghouse, or 3 metres in the case of any other dwellinghouse, and no more than 4 metres in height.

Above 1 storey limits: 3 metres or be within 7 metres of any boundary of the curtilage of the dwellinghouse opposite the rear wall of the dwellinghouse, or be within 2 meters from the boundaries.

Don`t include balcony, verandah, raised platform or microwave antenna.


Except conservatories, all materials used on the extension must be similar to materials already existing.

Any upper-floor window located in a wall or roof slope forming a side elevation of the dwellinghouse must be obscure-glazed.

The roof pitch of the enlarged part must, so far as practicable, be the same as the roof pitch of the original dwellinghouse.

Wrap-around extension does NOT fall under permitted development, although you can extend through the side and rear, but to build the corner itself you`ll need to make a householder application.


The Pros And Cons

Building a rear single-storey extension to your property is a great way to add value and room to your existing floor space. A well-planned rear single-storey extension can allow easy access to your garden and provide a modern family, open planned living area. It is no secret that as your family grows, your need for space grows too. As a result, the property you started your family in suddenly becomes too cramped and unsuitable.

If you think adding a rear single-storey extension to your property is a possibility instead of moving to a larger property, then consider these pros and cons:


  • One of the cheapest extension options available

  • Ideally used for an open planned kitchen, dining area or a utility room

  • Additional space without moving or relocating to a new, more affordable area

  • More cost-effective than moving to a more extensive property

  • Substantially increase your property's value

  • Depending on the extension, your plans may fall under permitted development

  • Life will stay the same; unlike moving, there will be no need to change jobs, schools, increase commuting times. Plus, friendship groups and family links would not be affected.

  • Use your flat roof to make a nice terrace from the first floor.



  • Outdoor space will be less

  • Possibly need planning permission

  • Costly structural engineers, quantity surveyors and designers

  • Living with a construction site whilst the work is taking place

  • Additional costs for decorating and furnishing the new space

  • The garden may need relandscaping to fit in with the new structure

  • The added property value may be less than you expect

  • Neighbours may object to your plans which can cause delays and a negative relationship

  • It is easy to incur unseen costs that can push you to go over budget

  • Risk of contracting rogue traders that produce substandard work

Once you have agreed you need more space in your home, the next part is to decide how you are going to achieve that. Most families in London these days opt for an open plan house extension. There are, of course, various types of home extensions you can choose from. We have listed here some of the more popular, but happy to discuss other forms of home extensions too.


Single storey house extension

A single storey extension, due to the fact it’s only on one floor, tends to be one of the least expensive home add-ons you can find. It can go on most sides of your house, apart from the front.


The most popular type is the rear extension which tends to encompass a kitchen, dining and seating area with large glass floor to ceiling doors which can be opened at will onto the garden. The latter has the added plus of extending the space.


But what if you only wanted one side of your house extended? Well, yes, just as it is possible to build outwards at the back if you have the space, the same applies to the side of your home. A side extension is another type of extension which has a lower price tag. A perfect choice for decent sized alleyways at the side of the house, it is a case of extending your home outwards using this. You can add glass panels to the roof and fix bi-fold floor-to-ceiling glass doors to open-up and add light to your existing kitchen, as well as gaining more physical space.


An L-shaped extension, as its name suggests, encompasses the length of the back of the property with a smaller extension protruding into the garden. With plenty of glass sliding doors and windows you will feel as if you are actually eating your lunch etc out in the garden. This means you will not have to miss the scenery or visiting wildlife even if it is pouring with rain or freezing outside.


A wrap around extension is an L-shaped extension that goes the other way. In other words, the smaller side does not protrude into the garden but turns inwards towards the house and is built along the side. The plus side with this type of extension is that you do not have to cut into the garden to get the additional space. It is also a great way of using up redundant space at the side of the house.


Double storey house extension


Naturally, due to its size, a double storey extension costs more than a single storey home extension. However, in the long run it actually works out far more financially viable. How so? Well, you are only paying once for the scaffolding, designer drawings, foundations and overall construction etc. You will also get a better deal on materials since you are buying more of them.


How much does it cost to build an Extension?

There are not fixed prices!

In London the general quote per square meter it`s about £1500-2200, but it cannot just be used as it is, you can have a 10sqm extension quoted at £30K as there are several things that can change the final quote of your contractor. 

- Foundations: you might be lucky enough to have your house built on a perfectly vertical ground without any soil problem, but you can also have slopes or ground problems that can raise your quotes. Also, the existing sub-structure might need some adjustment to suit the new design.

- Windows: the difference in cost between a uPVC single pane window and a 6 panes bifold aluminium door it`s massive! Same for skylights, those can be fixed or openable and have special glass to protect you in sunny days.

- Use: if your extension includes a kitchen the cost would be lot higher than an extension with a bedroom. Drainage, gas, boilers can raise your quote.

The only way to know the exact quote for your project is to provide Technical and Structural Drawings to your contractor, or, even, a full tender package. You can get an idea with Planning drawings but this will not be your final figure!