Design - -> 2-4 Weeks

Pre-planning - -> 2+ Weeks

Application - -> 6-8 Weeks

Design - -> 2-4 Weeks

Notices - -> 48H

Full Planning - -> 3-5 Weeks

Design - -> 2-4 Weeks

Concept - -> 1-2 Weeks

FF&E - -> 2-4 Weeks

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Wish to Build within your Permitted Development Rights?


  • 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.

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


How much does it cost to build an Extension?

What a difficult question! 

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 suits 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 skilights, those can be fixed or openable and have special glass to protect you in sunny days.

-Windows: the difference in cost between a uPVC single pane window and a 6 panes bifold aluminium door it`s massive!

-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. you can get an idea with Planning drawings but this will not be your final figure!

For a first approach you can budget in this way:

15% Professionals

15% Substructure and Structure

15% Floor and Walls

9% window and doors

9% Mechanical and electrical

9% Finishes

9% Kitchen and Applicances

5% Roof

4% Drainage

An important point that we like to highlight is that if you would like to build your extension using sustainable construction methods instead of traditional, your costs will not increase as you might think!

What are the benefit of an extension?

The first thing that come in mind is LIGHT! Of course the space it`s an important factor, but don`t forget the features you can add to your extension to make your space looks faboulus! You can use skylights as well as bifold doors, which will make your house communicating directly with your garden, it sounds extremely enjoiable expecially in summer!

Another benefit is to use your flat roof to make a nice terrace from the first floor.

You can take advantage of the costs you are already paying to renovate your house completely, or in the other way round you can design your garden after the extension and have your corner of paradise.