Planning - extensions
Many small-scale extensions to single family dwelling houses do not need planning permission. There is a separate booklet “Planning Permission a guide for Householders” which explains what you can and cannot do. See Planning - Do I Need Planning Permission? to find out more.
Whether or not you need to make a planning application, there are some general principles that should generally be followed to make sure the extension looks appropriate and does not unreasonably impact on neighbouring properties:
- Materials should generally match those of the existing dwelling.
- The extension should not dominate the original dwelling. It is a good idea to set it back from the front wall so that it appears subservient.
- Where possible it is generally best to integrate the roof of the extension into the main roof. Flat roofed extensions can look “tacked on” and flat roofs can sometimes need more maintenance.
- The design of porches should reflect the design of the main house in terms of the materials used and the roof detailing.
- The spaces between buildings can be an important part of the character of the area. Side extensions should not result in a terracing effect by closing the gap between properties.
- As a rule of thumb it is good practice for a side extension to be less than two thirds of the width of the main property.
- Where possible dormer windows should have a roof to match the main roof.
- Dormer windows should generally be set into the main roof, rather than replacing it. Overly large flat roofed extensions can dominate a building and look unsightly.
- Care needs to be taken over the siting of new garages so that they do not dominate a property when viewed from the street.
Impact on Neighbours
- Glazing to side walls should generally be avoided because it could result in a loss of privacy to neighbours. Where it is unavoidable obscure glass should be used.
- Balconies on flat roofed extensions are rarely acceptable because they result in a loss of privacy not only to properties to the rear, but to adjacent properties where you can look back into first floor windows at close proximity.
- Two storey extensions are rarely acceptable close to the boundary because of the loss of daylight and sunlight that would affect the neighbouring property. It is good practice to set two storey extensions as far off the boundary as possible.
- It is good practice to restrict the depth of rear extensions to approximately 3m, because in most cases the impact on the neighbouring property would not be unreasonable.
- It is important to take account of windows on neighbouring properties to make sure any extension does not result in unreasonable loss of daylight or sunlight.
- It is important to pay special regard to the ground levels when considering the impact of an extension on a neighbour. Where the ground drops away an extension may appear very much bigger when viewed from an adjacent property.
- Take care to ensure that windows in side dormers do not look directly into the side windows of neighbouring properties (or into neighbouring dormers).
Do Building Regulations Apply?
Even if planning permission is not required to build an extension, Building Regulations probably will apply. You are advised to contact the Building Control for advice.