Increasing the size of a window will often fall under permitted development rights, meaning an application for planning permission is not required to make the change, provided limits and conditions are met.

Any new window must be of similar appearance to the original which you are replacing.

Permitted development rights do not apply to flats. To increase the size of a window in a flat or maisonette you will require planning permission.

 If you live in a listed building, you will require listed building consent for any major changes.

Where the work has as significant impact on the external appearance of the house, especially on the principal elevation, planning permission may be required.

Building control approval will likely be required where the change impacts the structure of a building, this primarily occurs when an opening Is widened. When altering walls you may want to consult a structural engineer.

Building control will also consider energy efficiency, glazing, ventilation and fire safety.

For houses, replacing windows with double glazing usually doesn’t require planning permission, provided the style and appearance are similar to the original. However, if you live in a flat/maisonette, listed building, or a conservation area, planning permission or listed building consent may be required, especially if the changes affect the external appearance.

Read more about planning permission for windows and doors for houses

Read about planning permission for windows and doors for flats and maisonettes

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A pergola is classed as permitted development, meaning an application for planning permission is not required provided it meets specified conditions and limits.

Outbuildings cannot be installed on the principal elevation of the property, additionally any platform must not exceed 0.3 metres in height.

If the building is listed, then you will need to apply for listed building consent and planning permission for the change.

For more details read our outbuildings common project.

Merging two flats into one, commonly known as amalgamation is likely to require planning permission as it will impact the local planning authorities housing supply. The council’s views on this will vary from council to council. It is recommended that you contact your local planning authority to understand their position.

If you do not need to apply for planning permission then you can apply for a lawful development certificate to prove that the change is lawful.

Building regulations will be required if there are physical works taking place as part of the amalgamation, this may include removing walls or changing electrics. Visit the relevant common projects on our site for more information.

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Installing a new septic tank in your garden will often require both planning permission, building regulations approval and a septic tank permit.

The planning permission will ensure that the tank is installed in an appropriate location with information being provided to understand any potential implications for the surrounding environment and water.

Building regulations is required for the installation of a septic tank to ensure it meets the drainage and waste disposal standards set out in Approved Document H.

Where possible it is recommended that you connect to an existing public sewer instead of installing a septic tank, this reduces waste entering the waterways.

For more information visit our drains common project or contact your local planning authority.

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