Yes, under permitted development, a new dormer must not be higher than the existing highest part of the roof. It should also have materials that are in similar appearance to the existing roof. Additional limits apply in conservation areas and on listed buildings. Read about planning permission for loft conversions on Planning Portal

Whether you need planning permission to install an extractor fan depends on the size and placement of the fan.

For domestic installations, such as a bathroom or kitchen in your house, planning permission is not generally required. If the change significantly alters the external appearance of your home then permission may be required.

If you live in a listed building, you will need listed building consent for any significant changes.

Larger extractor fans for businesses are likely to require an application for planning permission to be made to the local planning authority. These extractors can impact the local area due to their noise, visibility and odour, as such the planning authority will need to assess the change.

Building regulations relating to ventilation and electrical works will have to be complied with, these are covered by Approved Document F and P respectively.

Read more about building regulations and the requirement for ventilation on our common projects.

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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Building a porch at ground level and under 30 square metres in floor area is normally exempt from the need for building regulations approval.

This is provided that glazing and any fixed electrical installations comply with the appropriate sections of building regulations.

To find out more about the building regulations for porches, visit Planning Portal.

Find out more about glazing and electrical installations

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If you do not seek planning permission, build without it when it applies, or do not meet specified conditions of a planning permission, this is known as a planning breach.

Your local planning authority can serve an enforcement notice on you when they consider you have broken planning rules. You may be given the opportunity to apply retrospectively, or be required to remove a building or structure, or alter it to make it acceptable.

Read about your responsibilities.