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Planning Permission or Permitted Development for Loft Conversions?

Updated: Apr 11, 2023

Take a good look around most suburban areas in the southeast and you can find at least one example of an ugly loft conversion or extension spoiling the appearance of the street. As you might expect a planning system has developed over the years that aims to prevent the proliferation of such eyesores whilst at the same time continuing to encourage homeowners to spend money developing their homes. The key thing to understand about the planning system is that all development work where the external appearance of a building is changed requires planning consent. However, there is usually more than one way in which that consent can be provided. This is where the subject gets complicated!


For the purposes of developing loft conversions there are potentially two types of planning consent that homeowners might consider; Permitted Development Rights or Planning Permission. Most projects make use of Permitted Development Rights but a significant minority of projects cannot use those rights and so those projects need to secure Planning Permission. Here is a bit more detail about the two types of consent:


Permitted Development Rights


Most loft conversion development work is covered by Permitted Development Rights. Think of these rights as a general blanket planning permission that has already been granted. The consent comes from Parliament rather than the local planning authority. The basic idea is that Permitted Development Rights allow homeowners to extend their houses without specifically seeking the planning consent of the local authority, providing the development work falls within certain limits. It is important to say here that although most homeowners can develop a loft conversion using Permitted Development Rights not everybody can. Houses within Conservation Areas, Areas of Outstanding Natural Beauty or in National Parks are all likely to have restricted rights. Many new build houses will also have restricted rights and flats and maisonettes do not benefit from Permitted Development Rights at all. You must be satisfied that any development work you want to carry out as Permitted Development is in fact covered or else the consequences could be really quite severe.


The general parameters of Permitted Development Rights when it comes to loft conversions are that they allow you to:

  • Extend the roof space by adding rear or side dormers and by building up the gable ends of the roof. Permitted Development Rights do not allow you to build dormers on the "Principle Elevation" of the roof (which is usually the front elevation) nor do they allow you to extend the height of the roof beyond the existing highest part. There is also a limit as to how much cubic volume you can add to the original roof using Permitted Development Rights (the limit is 40 cubic metres for terraced houses and 50 cubic metres for detached and semi detached houses). Any materials used will have to be are similar in appearance to those already in use on the building.

  • Install roof windows although any which face to the side will have to be non opening and obscure glazed.

  • Install windows and French doors although any which face to the side will have to be non opening and obscure glazed.

There are many other specific technical points relating to Permitted Development Rights which must be complied with in order for a development to be considered lawful so it is a very good idea to ask the local planning authority to confirm their view about the proposed development before any building work takes place. The way to do this is to make an application to the local authority for a Lawful Development Certificate. The application should include planning drawings. If the local authority agrees that the drawings submitted show a lawful use of Permitted Development Rights then they will issue a Lawful Development Certificate. If they don't agree then they will refuse and planning permission should be sought instead.


Planning Permission


Applying for Planning Permission is essentially the process of asking the planning department of your local authority for permission to carry out the development. The local authority will usually have in place a development plan which they will use to decide whether or not to grant Planning Permission. A planning officer will look over the loft conversion plans and assess the likely effect or impact of the development on neighbouring properties and the neighbourhood in general. They will consider the outside appearance of the development, how big it is, how it sits within its surroundings, what effect it might have on access, landscaping etc. Unfortunately they will not tell you in advance what you can and cannot build but will instead insist upon seeing a written proposal including planning drawings which they will then assess. Since you need to spend money having these planning drawings drawn up and submitted, without knowing for sure what the outcome will be, this route is one which homeowners tend to avoid where they can.


In summary I think it is fair to say that, although the planning system can be very complex, for most people looking to convert their lofts it is fairly straight forward to navigate. However, don't forget that the planning system is aiming to balance the competing interests of homeowners who want develop and extend their property, neighbours who don't want to be adversely affected by such developments and local people who want to preserve the appearance of the area, so there is always potential for someone to be unhappy with it. That's just how it is.

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