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Cardiff Council

When do I need building regulations approval?

Compliance with the building regulations is a legal requirement and is the responsibility of the person carrying out the work and/or the person that commissions the work.

Following the Council’s building regulation approval process will ensure that you receive a certificate of completion of those works which will provide evidence, but not conclusive evidence, that the completed work/building complies with the relevant statutory requirements. 

Approval is required when you undertake any of the work defined in Regulation 3 of the building regulations​​​​​​​​​​​​​​​​External link opens in a new window this includes, but is not limited to the following work:

  • erect or extend a building,
  • materially alter a building, e.g. carry out structural alterations,
  • extend or alter a controlled service or fitting within a building, e.g. install a WC,
  • change the building's fundamental use/purpose, or
  • install replacement  windows or doors using a person/company that is not FENSA registered.


Please note that the regulations are continually updated and revised by the Welsh Government so it is recommended that you always refer to the legislation for the latest up to date amendments and requirements.  


Banks and building societies may ask for confirmation that proposals will, or completed work does, comply with the regulations before being willing to offer you a loan or mortgage. Keep documents issued during this process safe as they will be required by solicitors conducting any conveyance in the event that you decide to sell the property in the future. 

Carrying out building work without the appropriate permission is a criminal offence and you can receive a fine, upon conviction, of up to £5,000. 

For more details, including building regulations exemptions, visit the planning portal website​​​​​​​​​​​​​​External link opens in a new window or  Local Authority Building Control (LABC)​​​​​​​​​​​​​​​​External link opens in a new window.  

Can I get retrospective approval if the work is already complete? 

If building work was undertaken without the necessary building regulation approval, it will be difficult to sell the property or re-mortgage. You can however obtain approval retrospectively for works done after the 11th November 1985. 

The charge for this type of ‘retrospective’ approval does not attract VAT but is 150% of the normal charge (pre VAT) as indicated in the charge advice tables. 

A surveyor will contact you to visit the premises and evaluate what has been done. You might need to expose certain parts of the construction and carry out some remedial work before we can ascertain compliance with the relevant requirements of the building regulations and issue a regularisation completion certificate.

Download an application form for a retrospective approval (781kb PDF)​​​​​​​​​​​​​​Link opens in a new window​​, known as a regularisation. For further information or advice on the process please contact us.

Contact us

You can contact the team on any of the following numbers:

​​029 2233 0383​​​029 2233 0382​029 2233 0381​

© 2022 Cardiff Council