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What is the difference between a roof window and a dormer window?

A roof window (or skylight) is fitted flush within the slope of a roof, while a dormer projects outward, creating additional headroom and floor space.  

Both can be installed under permitted development but must meet specific size and position limits to qualify.  

Also consider building regulations for a new dormer, find out more on Planning Portal  

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Common Questions

Do I need planning permission to put a bin store in the front garden?

A bin store is classed as an outbuilding, these fall under permitted development rules meaning they are allowed as long as they adhere to a set list of rules. However, one of these rules is that outbuildings cannot be placed in front of the principal elevation*. As such, you will be required to apply for planning permission to build a bin store or any permanent structure in your front garden.

Read more about the rules for outbuildings.

‍Principal elevation - The most visible or prominent side of a structure, typically facing a street or public area. While often considered the 'front' of the building, it may not always contain the main entrance.
Do summerhouses or garden offices need building regulations approval?

If you plan to put up a small, detached building like a garden shed, garden room, garden office, annexe or summerhouse (all classed as outbuildings), building regulations generally won’t apply if the building has a floor area under 15 square metres and does not include any sleeping accommodation.

For buildings with a floor area between 15 and 30 square metres, building regulations approval is usually not needed - as long as the building does not include sleeping accommodation and either:

  • it is at least one metre away from any boundary, or
  • it is built mainly from non-combustible materials.

Read more about the building regulations that apply to outbuildings.

Don't forget to check the permitted development rights for outbuildings.

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Do I need planning permission to add a first-floor extension onto an existing ground floor extension?

Adding a storey on top of an extension will always require an application for planning permission.

If you want to add a storey on top of your house under permitted development rights, it must be on the principal part of the house.

If you want to add an additional storey on top of your house, it can be permitted development. It is only permitted development if it follows certain rules:

The current house

  • Is not a building containing one or more flats, or a flat contained within such a building
  • Was constructed between 1 July 1948 and 28 October 2018
  • Has not already had additional storeys added to it
  • Is not on Article 2(3) land or a site of special scientific interest
  • Was not changed to be used as a house (from a previous non-residential use) under permitted development rights.

How many storeys can you add?

  • If the house is one storey then one storey can be added
  • If the house is two or more storeys then two storeys can be added

Where can the storeys be added?

  • The additional storeys must be added to the principal part of the house. The principal part of the house is the main part of the house excluding any front, side or rear extension of a lower height (regardless of these being part of the original house or subsequent additions).
  • Engineering operations must only include works within the existing curtilage of the house to strengthen existing walls and foundations

How high can it be?

  • The house cannot exceed 18 metres in total height
  • Each storey cannot add more than 3.5 metres to the total height
  • If the house is not detached the total height cannot be more than 3.5 metres higher than the next highest building that the house is attached to, adjoins, or is in the same row as.
  • The additional storeys must have an internal floor-to-ceiling height of no more than 3 metres, and no greater than the internal height of any existing storey within the principal part of the house.

What materials can be used?

The materials used must be of a similar appearance to those used in the construction of the exterior of the current house

Where can windows be placed?

Windows must not be placed in any wall or roof slope forming a side elevation of the house.

Following completion of development:

  • The house must remain in use as a domestic residential property
  • No visible support structures must remain on or attached to the exterior of the house
  • The roof pitch of the principal part of the house must be the same as it was prior to the development.

 If any of the limits set out above are exceeded then an application for planning permission will be required. If you are unsure, you should contact your local planning authority.

Find contact details for your local planning authority.

Is planning permission needed for a shed in a conservation area?

A shed is classed as an outbuilding which falls under permitted development rights, meaning that it does not require an application for planning permission. They can be built in conservation areas provided they meet the limits set out in legislation.

Specifically on protected land, including conservation areas, no part of the outbuilding can be on the side or front elevation of the house.

A full list of limits and conditions can be read on our outbuildings common project.

Read the outbuildings common project guidance.

Do I need planning permission to add a small wooden canopy over my front door?

Adding a porch canopy is classed as permitted development provided it meets the limits and conditions set out in legislation. Where this is the case, no application for planning permission is required.

Porches must meet the following limits:

  • the ground floor area (measured externally) would not exceed three square metres.
  • no part would be more than three metres aboveground level (height needs to be measured in the same way as for a house extension).
  • no part of the porch would be within two metres of any boundary of the dwellinghouse and the highway.

Read our mini guide for additional information on installing a porch.

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