Approved Document B 2026: second stairs, evacuation shafts and MEP interfaces
What the 30th September Approved Document B changes mean for taller residential projects, lift strategy and building services coordination.
Approved Document B 2026: second stairs, evacuation shafts and MEP interfaces
Approved Document B has been updated ahead of the 30th September 2026 fire safety changes.
For building services teams, the headline is not only the architectural requirement for additional stairs in taller residential buildings. The more useful question is what this now means for lifts, life safety systems, smoke control, risers and project information.
What has changed?
The updated guidance introduces provision for more than one common stair in blocks of flats with a storey 18 metres or more above ground level.
The consolidated Approved Document B guidance was updated by government on 16th September 2026, with the relevant amendments taking effect on 30th September 2026, subject to transitional arrangements.
The guidance also introduces evacuation shaft arrangements.
One point worth being precise about: the wording does not create a blanket requirement for evacuation lifts in every affected building. Where evacuation lifts are provided, the guidance sets out how the evacuation shaft, protected stairway and evacuation lift lobby should be arranged.
Why this matters to MEP and lift design
It would be easy to treat this as a stair-core issue for architects and fire engineers. That would miss a fair bit of the engineering risk.
The changes can affect:
lift strategy and evacuation lift provision, where applicable
life safety electrical supplies and containment routes
fire alarm interfaces and evacuation controls
smoke control interfaces and shaft coordination
services passing through protected stairs, lobbies and risers
plantroom, switchroom and riser locations relative to the protected core
Gateway information and design change control for HRB projects
A residential scheme near the 18 metre threshold can quickly drift into redesign if the applicable guidance and transition position are not agreed before tender or Gateway submission.
What live projects should check now
For projects currently in design, the key checks are practical rather than theoretical.
Design teams should confirm:
building height and whether the 18 metre threshold is triggered
the relevant building control submission date and transitional position
whether the current core arrangement remains valid
the evacuation lift strategy with the fire engineer and client, where relevant
life safety power, fire alarm, smoke control and lift interfaces
riser and containment routes through protected areas
the agreed design basis in the employer’s requirements and technical schedules
Commercial implication
The commercial risk is not that every project suddenly needs to be redesigned.
The risk is finding out too late that the design team, contractor and building control body are working from different assumptions.
On taller residential and higher-risk building work, this can affect programme, tender qualifications, Gateway submissions and change control. The best time to resolve the position is before the project relies on it.
How J-WEBS can help
J-WEBS can support clients, architects, project managers and fire engineers by reviewing the building services and vertical transportation interfaces arising from the updated Approved Document B guidance.
This can include:
MEP and lift interface reviews for taller residential projects
life safety systems coordination checks
employer’s requirements and performance specification reviews
Gateway 2 and Gateway 3 MEP evidence reviews
technical due diligence commentary on fire safety and vertical transportation interfaces
The fire strategy remains the responsibility of the appointed fire engineer.
The J-WEBS role is to make sure the mechanical, electrical, public health and lift interfaces are properly understood, coordinated and recorded.
Useful source
Government guidance: Fire safety: Approved Document B, GOV.UK. The page was updated on 16th September 2026 and includes the 2026 amendments and transitional information.
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