Our guide to planning and permitted development.


An Essential Resource for Anyone Engaging in the Planning and Permitted Development Process.

A comprehensive guide to Planning and Permitted Development Rights as a homeowner. Check out our Guide to Permitted Development Rights for all the information you need to know. Including comprehensive tips and helpful advice for adding new windows and doors to your home, extension or garden office. 

Permitted development rights have changed a lot over recent years and made it much easier to build extensions and add garden rooms without having to apply for planning permission.

As long as your house isn’t listed and you’re not in a conservation area or an area of outstanding natural beauty for instance, you can now build a single-storey rear extension, conservatory or orangery up to 4m out from a detached house and up to 3m out from a semi-detached or terraced without permission. And, while you can’t go forward from the building line of your original house without planning permission (apart from a porch that’s less than 3m tall,  3m2 max, and not within 2m of the road boundary), permitted development rules do allow you to build a single storey side extension that’s up to half the width of your house. 

Bigger rear extensions (8m for detached houses and 6m for semi-detached and terraced) are still possible under permitted development as long as they are less than 7m from your rear boundary, but you need to notify your local authority before work starts so that they can consult with your neighbours on things like ‘right to light’ and decide if prior approval is required.

Garden rooms
You can also build a garden room up to 2.5m high without planning permission too as long as it’s not being used for living or sleeping in. If it’s got an internal floor area of less than 15m2, it can even be sited right next to the rear boundary.  (Anything between 15m2 and 30m2 needs to be at least 1m away.)

Windows and doors
When it comes to fitting new windows and doors then the rules outside of houses in restricted areas (such as conservation areas) are almost as generous. The good news is you don’t usually need permission for replacing, adding or moving windows and doors if they are in a similar style and size as the rest of the house (even in a garage conversion).  So, for replacements, you could choose windows in our 58BW HI system, a residential door in the 58BD HI or a new sliding door or bi-fold in our SC156BSF70 systems without any restriction - as long as they are in keeping. And, for new builds, you could also consider windows in our C70S or 77 Series, as well as bi-folds or sliders in AluK F82, or SC156.

The only exceptions are new windows on the side elevation of a house which do need planning permission unless they are fitted with level 4 or 5 obscured glass and the only opening parts are at least 1.7m from the floor. And newly built bay windows on the front of a house almost always need planning permission too, even though at the side and the rear they can be counted as part of a permitted development extension. 

The rules for flats are very different though. Not only are there no permitted development rights for flats, flat owners who want to change their windows need planning permission to do so whether the building is in a conservation area or not. And, even to apply for planning permission to change your windows, you need written permission from both your freeholder and the building management company. In our experience, planning departments generally like replacement windows to be similar in style to the original, or at least in keeping with the age and style of the building, and management companies like something low maintenance so it’s wise to choose something at the outset like our 58BW HI windows or 58BD HI, SC156, and BSF70 HI doors, which all parties can agree on.

Remember, planning and permitted development rules are different in England, Scotland and Wales and there are occasions where new houses don’t have full permitted development rights or where the council has made an Article 4 Direction withdrawing the rights in order to preserve the character of a particular area. Before you start any building work, it’s essential to double check the rules that apply in your area.