Whether you need planning permission for your loft conversion depends entirely upon which type of loft conversion you require: roof line or dormer.
As the loft is converted within the existing shape of the roof there would be no extension or alteration to the existing shape of the roof/building.
The only time when planning permission is required is if your property is in a conservation area where there may be restrictions on the size and shape of the VELUX windows you wish to install.
Because the size, shape and general design of Dormers can vary greatly, not all dormer conversions require planning permission. Householders have what is known as a permitted development allowance. This permitted development allowance is usually measured in cubic metres. The amount allowed (cubic metres) varies from property to property. Generally, the allowance would be between 50 and 70 cubic metres or 20% of the overall volume of the property.
We will easily calculate the required volume for any dormer and whether or not this would fall within permitted development rights. Please note, there are further guidelines whilst trying to identify if your project would be allowed under permitted development rights. These are;