New residential buildings of 18 metres or more in England must have a second staircase. Your project is only outside the requirement if a building control application, initial notice or building notice was made before 30 September 2026 and the work is started and sufficiently progressed, either before that date or within 18 months of it.
The requirement
Amendments to Approved Document B introduced a requirement for a second staircase in new residential buildings of 18 metres or more. A transitional period was set so that projects already well advanced were not forced to redesign.
Are you inside the transitional arrangements?
Your project keeps its single-staircase design only if both of the following apply:
- A building control application with full plans, an initial notice or a building notice was made before 30 September 2026, and
- the work is started and sufficiently progressed, either before 30 September 2026 or within 18 months of that date.
For a new building, "sufficiently progressed" broadly means that concrete has been poured for the permanent foundations, or permanent piling has started. For work to an existing building, the work must have started.
If your project does not meet these tests, the design will need a second staircase.
Higher-risk buildings
Most new residential buildings of 18 metres or more are also higher-risk buildings. For those, building work cannot start until the Building Safety Regulator has approved the Gateway 2 application, so the design must clearly show how it meets the current requirements before you can get on site.
Our advice
If you are close to the deadlines, get a clear view early on whether your project qualifies, because a late redesign can affect viability, layout and planning. A fire strategy that addresses the staircase question directly will make the building control conversation much easier.
This answer is general guidance on the law in England and is not a substitute for advice on your specific premises.