New roof lights or skylights will not normally require an application for planning permission providing:

• they do not protrude more than 150mm beyond the plane of the roof slope

• they are no higher than the highest part of the roof

• if they are in side elevation roof slope, they must be obscure-glazed and either non opening or more than 1.7 metres above the floor level

However, if additional volume is created it may be treated as an extension and separate rules will apply.

If you live in a listed building or designated area (conservation area, national park, area of outstanding natural beauty, etc...) you should check with your local planning authority before carrying out any work.

Flats and maisonettes

The planning regime for flats and maisonettes differs in many important ways to that which covers houses. Local policy and interpretation of the rules covering changing windows in flats varies from council to council and you are advised to contact your local planning authority for advice before starting work. If you are a leaseholder, you may first need to get permission from your landlord, freeholder or management company.

If you would like to install a roof light or roof window, then building regulations are likely to apply for the following reasons:

• to install a roof light the roof structure will generally need to be altered to create the opening

• the roof will have to be able to carry the load (weight) of the new roof light, if the roof cannot do this, then it will need to be strengthened

• any window that is installed will need to prove that it has sufficient insulation against heat loss (i.e. it is energy efficient).

Where a roof light is replaced, building regulations approval will be required.

Flats and maisonettes

Building regulations apply to all replacement glazing. The regulations apply to thermal performance and other areas such as safety, air supply, means of escape and ventilation.