If you are looking to re-roof your home or insert skylights/roof lights, you do not normally need to apply for planning permission. This is because the permitted development rules allow for roof alterations subject to limits and conditions as follows:

• Any alteration cannot project more than 150 millimetres from the existing roof plane.
• No alteration made can be higher than the highest part of the roof.
• Side facing windows must be ‘obscure-glazed’ and any opening needs to be 1.7m above the floor.

Skylights are a great option to lighten up your home; these are standardly available in 16 or 24 inch frames. You can opt for a larger skylight, but this will mean that the installer will need to cut one or more of the rafters. This is fine for conventionally framed roofs as rafters are doubled up on both sides of the rough opening and headers are added to the top and bottom. HOWEVER, a truss style rood is a different matter. Because these roofs are engineered to carry load, making alterations by cutting the roof members could affect the structural integrity of the roof. Therefore, make sure that the installer installs the skylights between the roof members. If you really wanted a large window, you could have several smaller skylights next to one another to give a similar effect.