What happens if I start work without BSR approval?

Carrying out building work on a higher-risk building without the required approval is a criminal offence, and you must not start any work until the application is approved (GOV.UK). If an application is rejected, you must not start either.

Who is responsible?

The client, not only the contractor. GOV.UK says the client must make sure approval is granted before any building work starts. A client can nominate someone else to apply, but the legal responsibility for the application stays with the client. If you are a leaseholder commissioning work on your own flat, that is you. A builder saying the job is fine is not approval.

Common ways people get caught out

• Starting strip-out or demolition while waiting for the decision.
• Assuming a small layout change does not count. Changing the internal layout is category A building work.
• Treating a project as exempt when only part of it is. Exempt work in a wider project that needs approval must be included in the application.
• Applying under the wrong category, which BSR is likely to reject.

Other consequences

GOV.UK's general building regulations guidance warns that the person doing the work could be prosecuted and fined if they do not comply, and that the relevant building control body, which for higher-risk buildings is the BSR, could make you pay to fix faulty work. It also says that without approval you will not have the certificates of compliance you may need when you sell your home (GOV.UK).

The emergency repair exception

There is one route that does not need approval first: an emergency repair to manage an urgent risk to people's health, safety or welfare. You must tell BSR by the end of the first working day after the repair starts. You need to describe the work, explain why it was urgent and why applying first was not practical, and describe how risks are being reduced until the repair is finished. After the work, you must apply for a regularisation certificate as soon as possible.

This is a narrow exception. GOV.UK says emergency repairs are not for problems caused by a lack of planning or foresight. If BSR decides the work does not meet the criteria, the work counts as unauthorised and BSR will decide whether to take action.

If work has already started

Stop and take advice from a building control professional straight away rather than carrying on. Contact BSR through its contact page if you are unsure how to proceed. GOV.UK sets out the regularisation route only for emergency repairs, so do not assume it applies to other work.

Avoiding the problem

Check before you start. The BSR screener gives an early indication of whether your plans are likely to need approval, and How long does BSR approval take? explains the timeline.

Sources: GOV.UK, Building control approval for higher-risk buildings (updated 1 October 2026); GOV.UK, Building regulations approval.