Approved Document B Is Evolving: What It Means for Existing Buildings

4th June 2026

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For block managers, estate teams and facilities leads, Approved Document B can feel remote and technical. It is often seen as something that applies mainly to new buildings, major developments or design teams working through Building Control approval.

That view no longer reflects how fire safety and building compliance are being approached in practice.

Existing buildings are not automatically made non-compliant when guidance changes. That is not how the Building Regulations work. However, where building work is carried out, dutyholders need to understand how that work affects fire safety and how their decisions will be evidenced.

Fire safety regulation in England has shifted fundamentally in recent years. The Building Safety Act has not simply introduced new roles and gateways. It has changed how responsibility, risk and compliance are understood across the industry.

Against that backdrop, updates to Approved Document B matter more than they used to.

The legal requirements sit within the Building Regulations themselves. Approved Document B provides recognised guidance on one way those requirements may be met. It supports compliance, but it does not replace the need for project-specific judgement.

That distinction matters.

Fire safety is no longer only about following guidance. It is about demonstrating that the approach taken is appropriate, coordinated and effective.

For existing buildings, this distinction is critical. Changes to Approved Document B do not automatically make existing buildings non-compliant. However, where building work is carried out, dutyholders are increasingly expected to show how the work affects fire safety, why the chosen approach is appropriate and how that decision has been recorded.

What is actually changing and when?

Approved Document B is not changing all at once. The amendments are phased and each stage has a different focus.

This matters because the changes do not all have the same purpose or the same commencement date. Understanding the phasing helps avoid confusion about what applies now and what is still to come.

2025 — Regulation 38 and the strengthened fire safety information process

Regulation 38 is not new, but the 2025 amendments have sharpened the process around fire safety information, particularly the requirement for the responsible person to acknowledge receipt and confirm that the information is sufficient.

Where Regulation 38 applies, the person carrying out the work must provide fire safety information to the responsible person no later than completion or occupation, whichever is earlier.

Regulation 38 does not apply to every item of fire safety work in an existing building. It applies where the work consists of or includes the erection or extension of a relevant building, or where the work is carried out in connection with a relevant change of use and Part B applies.

The important change is the handover loop. This is not simply a client sign-off exercise or a late-stage document drop. The responsible person must acknowledge receipt of the fire safety information and confirm that it is sufficient to allow them to understand, operate and maintain the building and its fire safety systems after the work is complete.

That requires usable information, formal acknowledgement and a clear evidence trail.

Even where Regulation 38 is not formally triggered, the same principle is worth applying on existing buildings. If works affect fire doors, compartmentation, smoke control, alarms, escape routes or other fire safety measures, the information should still be recorded clearly and handed over in a form the building manager can actually use.

This is particularly important where new works need to sit alongside older fire strategies, legacy information, previous approvals or incomplete records. If the information cannot be understood or relied upon by the people managing the building, the handover has failed in practical terms even if documents have technically been issued.

2026 — Design expectations are tightening

The next phase introduces changes that will directly influence the design of taller blocks of flats.

The 2026 amendments include a new recommendation for more than one common stair in blocks of flats with a storey 18m or more in height. They also introduce building design provisions to support the use of evacuation lifts in blocks of flats.

These provisions are framed as guidance, but they are likely to become the default expectation for many relevant schemes.

They will affect early layout decisions, core and stair design, vertical circulation, escape strategy, fire strategy, coordination between architecture, structure and services, and approval risk.

The key point is timing.

These are not matters to resolve at the end of technical design. They need to be considered at feasibility stage. If they are left too late, the likely result is redesign, delay or difficult conversations with Building Control.

For existing buildings, the position is more nuanced. The changes do not mean every existing block of flats over 18m must be retrospectively upgraded. However, where significant building work is proposed, those changes are likely to influence how risk, future use and design judgement are assessed.

2029 — Removal of national classes for fire resistance

The later amendments focus on the removal of the remaining national classes for fire resistance from Approved Document B. This continues the move away from the former BS 476 based classification routes and towards European classification standards as the sole route of specification within the guidance.

This is a technical change but it has practical consequences. Product selection, specifications, test evidence and compliance submissions will need to be checked against the applicable classification route.

The direction of travel is clear. Compliance will increasingly depend on current, relevant evidence rather than reliance on historic specification habits or “this is how we have always done it”.

For projects with long design or delivery programmes, this matters. The 2029 amendments are due to take effect on 2 September 2029, with transitional arrangements for projects where the relevant building control notice or application has been made before that date and the work is sufficiently progressed within the permitted period.

Clients and design teams should understand the transition points rather than assume that today’s specification route will remain available throughout a long-running project.

What this means for existing buildings

Changes to Approved Document B do not mean that existing buildings must automatically be upgraded to current standards.

That is not how the Building Regulations work.

The principle remains that where building work is carried out, the work itself must comply with the applicable requirements and the building should not be left more unsatisfactory in relation to those requirements than it was before.

That does not mean every alteration triggers a full upgrade to modern standards. But it does mean that the impact of the work must be properly understood.

This is especially relevant where works involve fire door replacement, compartmentation upgrades, services installations, façade or cladding remediation, structural alterations, roof works, photovoltaic installations, smoke control, alarm or detection systems, and changes to escape routes.

For existing buildings, the legal threshold has not automatically changed simply because Approved Document B has been amended. What has increased is the need to evidence decisions clearly.

Dutyholders need to be able to show how proposed works affect the building as a whole, how existing fire safety measures interact and whether the completed works maintain or improve the building’s fire safety position.

The risk is no longer just doing the wrong thing.

It is being unable to prove that the right thing was done.

How Approved Document B applies in practice

Approved Document B should be considered as a whole. Its guidance on escape, compartmentation, smoke control, alarms, structural fire resistance, external fire spread and firefighting access is interconnected.

This matters because a decision made in one area can affect the assumptions made elsewhere. For example, a change to escape arrangements may affect alarm strategy, smoke control, management procedures or the level of compartmentation relied upon.

Approved Document B also recognises that alternative approaches may be appropriate. However, where a project does not follow the guidance in the usual way, the approach should be considered early, properly justified and coordinated with the wider fire strategy.

Where relevant, it should also be discussed with the Building Control Body before the design becomes fixed.

The point is not that every project must follow a single standard solution. The point is that the chosen approach needs to be coherent, coordinated and capable of being explained.

Key risks for dutyholders

The risks are no longer purely technical. They often arise from the way information, responsibilities and decisions are managed across a project.

Fragmented projects

Uncoordinated work packages can undermine the fire strategy, even where each package appears acceptable when viewed in isolation.

Inconsistent information

Misalignment between drawings, specifications, fire strategies, surveys and Regulation 38 information can create uncertainty about what has actually been designed, approved and handed over.

Weak justification

Decisions that cannot be clearly explained or evidenced are more likely to be challenged, particularly where the project departs from standard guidance or relies on existing building constraints.

Over-reliance on management procedures

Management procedures are important, but they should not be used to compensate for poor design unless that approach has been properly assessed and justified.

Historic assumptions

Existing buildings often rely on assumptions that may no longer be clear. If those assumptions are not understood before work starts, they can easily be disturbed or undermined.

What dutyholders should be doing now

The response does not need to be excessive but it does need to be deliberate.

Engage early

Fire safety advice obtained at feasibility stage is usually more useful and more proportionate than advice obtained after the design has already been fixed. Early advice allows options to be considered before cost, programme and layout decisions become difficult to change.

Take a whole-building view

Even limited works can affect wider fire safety assumptions. The question is not only whether the immediate work complies. It is whether the completed building remains safe and justifiable.

Align the documentation

The fire strategy, FRA, design drawings, specifications, survey information and handover information need to tell the same story. If they contradict each other, that needs to be resolved before the project relies on them.

Coordinate design properly

Fire safety is not owned by one document or one consultant. It sits across architecture, structure, services, products, installation and management. Responsibility for each part of the design should be clear.

Record decisions clearly

Judgement is only useful if it can be explained. Records should show what was considered, who was involved, what information was relied upon and why the final position was considered reasonable.

Approved Document B is not becoming more complex for its own sake.

It is becoming clearer about expectations: better information, stronger accountability, coordinated design and evidence-based decision making.

Those who treat the changes as simple guidance updates may miss the wider point.

Those who recognise them as part of a wider shift in how compliance is demonstrated will be far better placed.

For existing buildings, the message is not “upgrade everything”.

The message is: understand the building, understand the work, understand the risk, record the judgement.

That is where real building safety sits.

If you are planning works to an existing building and need a clear view of the fire safety implications, get in touch.