The Second Staircase Rule: What Changes on 30 September 2026

From 30 September 2026, every new residential building in England taller than 18 metres must be designed with two separate protected staircases. It is one of the most concrete building safety changes to come out of the post-Grenfell reforms, and the deadline is now close.

What the rule covers

The requirement, set out through Approved Document B, applies to new residential buildings where the floor level of the highest occupied storey is more than 18 metres above ground, which typically means six storeys or more. That captures blocks of flats, build-to-rent schemes and student accommodation. The 18-metre line deliberately matches the higher-risk building threshold under the Building Safety Act, bringing fire safety and building safety into alignment.

Why two staircases

A single staircase becomes a single point of failure in a serious fire. A second protected staircase gives occupants an independent escape route and gives firefighters a separate route in to work. It reflects a wider shift across fire safety design towards always having more than one way out. Existing buildings are not automatically required to retrofit a second staircase.

What it means for fire safety trades

A second staircase is an architectural decision, but it ripples straight into the work fire and electrical trades do. Two protected stairwells mean more emergency lighting, more detection coverage and more carefully designed escape routes to certify. The systems that protect those routes have to be designed, installed and commissioned to standard, then evidenced with the right emergency lighting and fire alarm certificates. Our guide to emergency lighting testing and certification covers the BS 5266 requirements that apply to escape routes.

For the technical detail, the changes flow through the higher-risk building definition and Approved Document B.

Published 2026-06-24. This article is for general guidance only and does not constitute legal or professional advice. Always refer to the relevant standards and consult qualified professionals for definitive requirements.