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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  

Common Questions

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.

Can I convert my loft into a liveable space?

You may wish to make loft alterations to enhance the storage facilities available or to increase the living space of the home. Converting the loft of a house is considered to be permitted development (not requiring an application for planning permission) subject to certain limits and conditions.

Remember, building regulations approval is required to convert a loft or attic into a liveable space.

Find out about loft conversions

There are different rules for flats and maisonettes regarding loft conversions. Read guidance for converting the loft of a top floor flat.

Do I need planning permission for a single storey extension?

In many circumstances, rules known as ‘permitted development’ rights allow you to extend a house without needing to apply for planning permission, providing specific limitations and conditions are met. If you want to exceed these limits and conditions, then it is likely that an application for householder planning permission will be required.

The limits and conditions for building an extension under permitted development rules are covered in our guidance on the Planning Portal, and there are other points to take into consideration.

Visit Planning Portal to find out more.

How high can I build a single-storey extension without planning permission?

A single storey rear extension can fall under permitted development, meaning planning permission may not be required providing it meets certain criteria.  

In terms of height, the extension must:

  • Be no taller than four metres at its highest point
  • Have eaves no higher than the eaves of the original house
  • Not exceed the height of the original dwelling  

Read about planning permission for extensions on Planning Portal

Is planning permission or building regulations approval required to change to an electric garage door?

Changing a standard garage door to an electric garage door will not normally require planning permission. Instead, they are covered by permitted development rights.

Permission may be required if your property is listed, you live in a conservation area or there will be a visual impact on the appearance of the house as viewed from the street. If you are unsure, it is advised that you contact your local planning authority.

Work to install an electric garage door must comply with Part P of the building regulations. This can be done by using an electrician who is registered with the competent person scheme.

Visit the website for registered electrical competent persons.

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