How long does BSR approval take?

For work to an existing higher-risk building, the Building Safety Regulator (BSR) takes up to 8 weeks to assess an application, unless an extension is agreed. For a new higher-risk building the figure is 12 weeks. The time depends on the quality of the application and the complexity of the work (GOV.UK). That is the assessment period only, so your total timeline is longer.

A realistic timeline

1. Prepare the application. You complete surveys or inspections to evidence how the work affects the building, then prepare drawings, a description of the work, a building regulations compliance statement and the other documents BSR requires. This stage is yours, and its length depends on how quickly your professionals can work.
2. Validation. BSR checks that the required information is there. If something is missing it may ask for it or reject the application. A valid application is not an approved one.
3. Assessment. Up to 8 weeks unless extended. You do not need to chase BSR, which will contact you if it needs more information.
4. Decision. Approved, approved with requirements, or rejected.
5. Before you start. You must send a notice of intention to start work at least 5 working days beforehand.

What slows an application down

GOV.UK is clear that quality matters. Missing information can get an application rejected, and so can applying under the wrong work category. BSR also expects evidence rather than assumptions about the existing building. If assumptions are unavoidable because information is missing, you must back them with surveys or inspections and explain how you will test them during construction.

If the answer is no, or not yet

If an application is rejected, you must not start work. If you disagree with a decision you can request a review, and if you still disagree you can appeal to a First-tier Tribunal. If BSR approves with requirements, you can start only on the approved parts.

Things people forget

• You may also need planning permission, and GOV.UK says to check with the local authority if you are unsure.
• Approval lapses if the work has not reached "commencement" within 3 years.
• There is a fee, set out in the BSR charging scheme.

Planning around it

Do not book contractors or set a start date until you have the decision. Build in time for preparation, up to 8 weeks of assessment and the 5-working-day notice. Our BSR screener can tell you early whether you are likely to need approval at all.

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