Rooflights and Planning Permission

We often get asked about the issue of rooflights and planning, so have compiled the following information to help clarify the situation. Please note that this information is intended as a guide and is not a definitive source of legal information. This guidance relates to the planning regime for England. Policy in other parts of the UK may vary. If in doubt please contact your Local Planning Authority.

Building Regulations

If you are looking to install a rooflight in either a pitched or flat roof, then this can potentially impact how a roof works, resulting in unplanned movement. When making any aesthetic improvements to your roof it is essential that care is taken to ensure the roof continues to perform as it should and without any movement.

Even if planning permission for a new rooflight is not required, building regulations must still be adhered to, as any building or structural modification work must comply with building controls which stipulate minimum standards for design and safety.

There are two sets of building regulations for roofs; work on an existing roof and the construction of a new roof e.g. for an extension.

Be sure to pay particular attention to Parts J and L of Building Regulations; these deal with energy efficiency, thermal insulation and the protection of buildings against the threat of fire.

Approval under the Building Regulations will generally be needed for the installation of a new rooflight for the following reasons:
·     To install a new rooflight, the roof structure will often need to be altered to create the opening.
·     The roof will have to be able to carry the weight of the new rooflight. If the roof is not able to do so it will need to be strengthened prior to installation.
·     Any rooflight installed must prove it has sufficient insulation against heat loss with effective energy performance.
·     In the event a rooflight is in close proximity to a boundary, its fire performance must also be taken into consideration.

Roof structure

To install a rooflight in a roof you will often need to cut part of one or more of the roof’s rafters or joists away. You will need to fit a new support for the cut ends of the rafter or joist in question. Adjacent rafters or joists may also need strengthening as they will be supporting the load transferred from the cut rafters or joists.

Ventilation and energy performance

Any room that a rooflight is designed to serve will also need to be well ventilated. This can be achieved using the rooflight itself for both rapid and background venting.

In terms of energy performance, any window or door must comply with the minimum requirements of the Building Regulations in relation to the amount of heat that can pass through a window or door, including the frame.

This is known and measured as a U-Value. This U-Value should not be exceeded. For more information, read our blog on U-values and rooflights.

For more information on the regulations surrounding U-Values, it is recommended that you refer to Approved Document L-1B, Table 1.

Rooflights in Listed buildings and conservation areas
If the property in which you wish to install your rooflight is a listed building or situated in a designated conservation area, you should check first with your local planning authority before carrying out any work as there will most likely be additional requirements surrounding rooflights and compliance.

Additionally, there may also be an article 4 direction, which is made by the local planning authority. It restricts the scope of permitted development rights either in relation to a particular area or site, or a particular type of development anywhere in the authority’s area.

The laws are slightly different in Scotland and Ireland than to that of the rest of the UK, so if you live in either of these areas and require a rooflight of any kind, it is important to contact your local authority for advice as you should make absolutely certain that you don’t need planning permission for your rooflights before you begin your project.

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