Yes, in most cases you can use an outbuilding as a home office without needing planning permission. As long as the use remains incidental to the main dwelling it is still considered part of your domestic residential use.

Read more about outbuildings

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Building above an attached garage is treated the same as adding a storey to the rest of your home. This is considered to be permitted development, not requiring an application for planning permission provided you meet the set rules and requirements.

You will still need to submit an application for prior approval to your local planning authority.

Read the list of rules and requirements for extending upwards.

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You do not need planning permission to move internal walls.

Removing a load bearing wall will require building control approval as it is altering the structure of the property. You will be required to provide a report from a structural engineer who will provide structural calculations.

Work on internal walls may also affect fire escape routes, ventilation, drainage or electrics. These should be considered during the design process and work should be carried out by a member of the competent person scheme where possible.

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In most cases, yes - planning permission is required to operate a business from your garage. This is because the use would no longer be purely domestic, and the garage would be considered to have changed use from residential (Class C3) to a business-related use, which requires planning consent.

Once submitted, your planning application first goes through a validation process. After its validated, the formal decision period is 8 weeks. However, in some cases, especially for more complex proposals or if further information is needed, your local authority may request an extension of time.

Understand more about the decision-making process on Planning Portal