It’s very unlikely that you’ll need planning permission to build a mezzanine floor. That said, you may need to get building regulations approval from your local council (if required). Reasons for this could include…

• If the mezzanine is being used for office space or work purposes
• If the mezzanine covers any areas that require planning permission
• If the mezzanine will involve external alterations to your building
• If it’s going to be used for office or retail usage of over 200 sqm