Blocks of flats working guide

Fire risk assessment for blocks of flats: a practical working guide.

Blocks of flats are the most common residential building type a UK housing fire risk assessor will work on. This guide is the working reference: building type categorisation, BS 9792:2025 methodology applied to blocks specifically, escape strategy evaluation, compartmentation evidence, periodic review patterns, and the operational realities that distinguish residential FRA from other building types.

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Building types

The variety of blocks you will assess.

A "block of flats" in UK FRA terms covers a wide range of building types. Purpose-built blocks designed and constructed specifically as residential apartment buildings. Converted blocks where an existing building (typically Victorian or Edwardian terraced housing, occasionally former office or industrial buildings) has been converted into self-contained flats. Mixed-tenure blocks where some flats are leasehold and others are social-rented or council-owned. Mixed-use blocks where commercial premises sit at ground floor with residential above. Older purpose-built stock predating modern fire safety design standards. Newer stock built under post-Approved Document B Volume 2 design intent.

Each variation carries different fire safety considerations. Purpose-built blocks are typically designed with stay-put strategies relying on intact compartmentation; converted blocks often have lath-and-plaster compartmentation that performs less reliably than purpose-built construction. Mixed-tenure complicates the dutyholder structure (multiple Responsible Persons, leaseholder service-charge transparency, social housing tenancy-management overlay). Mixed-use brings the Section 156 cooperation duty into play. The competent assessor adapts the methodology to the building rather than the other way around.

Scope of assessment

What a block-of-flats FRA covers and does not cover.

Under the Fire Safety Order 2005, the FRA on a block of flats covers the common parts: escape routes, lobbies, stairwells, plant rooms, refuse stores, cycle stores, roof terraces, and any other shared spaces. The inside of individual flats is generally out of scope unless the dutyholder has reason to enter. The flat entrance doors, however, are within scope as they are critical fire-resisting elements separating the private dwelling from the common parts.

For higher-risk residential buildings (HRBs) of 18m or 7+ storeys, the Building Safety Act 2022 imposes the building safety case regime on top of the FSO duty. The FRA is one input into the safety case; the safety case sits at a higher level. The audit grade the FRA needs to meet on an HRB is correspondingly higher than on a non-HRB block.

For non-HRB blocks (typically below 18m / 7 storeys), the FSO duty applies in standard form. The audit grade is what BS 9792:2025 expects: traceable evidence, named competent assessor, named competent reviewer, content hash and timestamp on the issued report. The trail does not need to be safety case-grade, but it does need to be defensible if a landlord, insurer, leaseholder, or tribunal asks.

Methodology applied to blocks

BS 9792 in practice on a block-of-flats assessment.

Building description

Type, height, construction, occupancy profile, year of construction, design fire strategy (stay-put or simultaneous), compartmentation arrangement, escape route layout, fire detection coverage, and any known limitations to the assessment.

Hazard identification

Sources of ignition (electrical, kitchen, smoking, candles), sources of fuel (storage in common parts, decorative features), behavioural factors (resident profile, vulnerable residents needing PEEPs), and structural factors (compartmentation gaps, external wall systems).

Persons at risk

Residents, visitors, contractors, and emergency responders. Vulnerable resident profiling: mobility, cognitive, sensory, medical, and behavioural factors that affect alarm response or evacuation.

Evaluation

Adequacy of compartmentation, fire alarm coverage, escape route protection, evacuation strategy match to resident profile, and the operational management arrangements.

Significant findings

Each high-priority issue traced to its observation, location, and supporting evidence. Risk rated with reasoning rather than only a colour code.

Action plan

Prioritised actions with owner, target close-out timeframe, and the dutyholder responsible. Significant change triggers noted for next review.

Evacuation strategy

Stay-put vs simultaneous: the most important judgement call.

On a UK block of flats, the design evacuation strategy is typically stay-put. The principle is that a fire in one flat is contained within that flat by adequate compartmentation, while residents in other flats remain safely in their homes. The strategy depends on intact compartmentation between flats and between flats and common parts. Where compartmentation is verifiably intact, stay-put remains the operational strategy.

Where compartmentation is in doubt, the position changes. Post-Grenfell external wall system concerns, partial cladding remediation, internal compartmentation gaps from poorly fire-stopped service penetrations, or unauthorised flat entrance door modifications can all undermine the stay-put assumption. In these situations, an interim simultaneous evacuation strategy may be appropriate, often with a Waking Watch in place during the transitional period until the underlying issues are addressed.

For the FRA, the evaluation of the current evacuation strategy and its continued appropriateness is one of the most important judgement calls the assessor makes. The standard expects the assessor to record what strategy the building was designed for, whether it remains appropriate given current conditions, what compensatory measures are in place if it does not, and what the action plan implications are. Software that surfaces this section explicitly (rather than leaving it buried in generic narrative) operationalises what BS 9792 expects.

Compartmentation

Why compartmentation evaluation is the technical heart of the FRA.

Compartmentation in a block of flats works at multiple levels. Between flats and between flats and common parts: the primary fire-resisting boundary. Within service shafts: vertical compartmentation maintained through floors. Around escape routes: protected stair shafts, lobbies, and access corridors. At the building envelope: the external wall system and its fire performance. Each layer carries its own design and verification questions.

For the working assessor, the practical challenge is what is actually verifiable on a non-intrusive FRA inspection. Visible compartment boundaries can be inspected for obvious gaps and unauthorised penetrations. Fire doors can be inspected for closure, intumescent strip presence, and door specifications where labels are visible. Risers and service shafts can be opened where access is granted. But the full picture often requires more than the FRA itself can deliver: a separate compartmentation survey, an external wall investigation under PAS 9980 or similar, or a fire door inspection programme.

A pragmatic FRA records what was verifiable, what remained unverifiable, and what action plan implications follow. Where the FRA cannot fully evaluate compartmentation through normal inspection, the action plan typically includes a separate survey rather than the FRA itself overstating the position. This is the discipline a competent reviewer should expect to see, and it is the discipline BS 9792 implicitly demands through its evidence model.

Resident profile

How resident considerations shape the assessment.

A block of flats serves a resident population whose profile affects the FRA. General-needs blocks have residents of all ages and mobility profiles; sheltered or supported housing serves older or vulnerable residents whose evacuation needs differ from the general population (see the sheltered housing sector page for the detailed treatment); HMOs have higher occupancy density and a different resident-turnover pattern (see the HMOs sector page); student accommodation has its own profile; build-to-rent often has young professional populations with different alcohol-consumption and lifestyle patterns.

For the FRA, the resident profile shapes the persons-at-risk evaluation, the evacuation strategy adequacy assessment, and any PEEP arrangements that may be needed. Where individual residents have specific evacuation needs (mobility limitations, medical conditions, cognitive impairments), Personal Emergency Evacuation Plans are the standard mechanism. The FRA does not replicate the PEEP itself (which is a separate document and contains personal information that should not duplicate into the FRA dataset), but it does record that the consideration was made and that arrangements are in place.

Evidence capture

How to capture observations on a block-of-flats walkround.

A typical block-of-flats walkround follows a logical route: external approach, lobby, ground floor common areas, escape stair from ground to top, top floor common areas, descent via the same or alternative escape route, basement and plant areas if present, refuse stores, cycle stores, roof access if relevant. The route reflects how a resident would experience the building during evacuation.

For each location, the assessor captures observations against the BS 9792 sections relevant to that location. A flat entrance door observation in a lobby attaches to the fire door section. A storage observation in a stairwell attaches to the escape route section. A risk score and reasoning is assigned per significant finding. Photos attach to the observations they support, and the link survives sync, export, review, and final issue.

In a well-designed FRA workflow (such as the FRA Flow tablet app), this capture is structured but not slow. The assessor walks the building with one tool open. Observations attach to the right BS 9792 section as they are recorded. Photos link to findings at the moment of capture, not three days later from a camera roll. The structured material that becomes the report is on the platform by the time the assessor walks out of the building.

Periodic review

How often a block-of-flats FRA should be reviewed.

BS 9792:2025 expects the periodic review interval to be set against the building risk profile rather than a calendar default. For higher-risk residential buildings (HRBs), the typical interval is annual. For other purpose-built blocks of flats, intervals can be longer where the building risk profile justifies it, though annual remains common in social housing portfolios for operational consistency. For converted blocks with potentially less reliable compartmentation, more frequent review can be appropriate.

Alongside the periodic review, the significant-change trigger applies. Common significant-change triggers on blocks of flats include cladding works, fire door replacement programmes, change of occupancy profile (for example, sheltered to general-needs conversion), new fire safety equipment installation or removal of existing equipment, and post-incident reviews after any actual fire event. Where a separate compartmentation survey or external wall investigation returns adverse findings, that itself can be a significant-change trigger.

Software fit

What good FRA software does for blocks-of-flats work.

A working FRA software product for blocks of flats should do several things. The capture flow should match how the assessor walks the building, with observations attaching to the right BS 9792 section as they are recorded. Photos should link to findings at the moment of capture. The drafting process should produce narrative findings that trace back to source evidence, with the audit trail recording who edited what. The reviewer queue should surface high-risk findings and AI-drafted text for the competent person to verify. The output report should be a BS 9792-shaped PDF with the audit trail attached, branded per landlord client, ready for issue without manual reformatting.

For an in-house compliance team or a contracted consultancy running a portfolio of blocks, the software should also support the programme view: every property visible at once, periodic dates tracked, action plans rolled up, significant change triggers surfaced. The picture stays connected across assessments rather than each FRA being a standalone document.

FRA Flow is built around this pattern specifically. The data model uses BS 9792 sections as primitives. The capture flow is tablet-first and offline-capable. The drafting is AI-assisted with evidence linkage. The reviewer queue is exception-led. The output is a BS 9792-shaped report with per-landlord branding. For the broader product context, see the core software page or the BS 9792 software page.

FAQ

Questions buyers ask before they commit to a new workflow.

FAQ 01

Does a block-of-flats FRA cover the inside of individual flats?

Generally no. The FSO duty and BS 9792 methodology cover the common parts of the building. The flat entrance doors are within scope (as fire-resisting elements separating the flat from the common parts), but the inside of individual flats is generally out of scope unless the dutyholder has reason to enter. The standard exception is where a known issue inside a flat (for example, a hoarding situation, a vulnerable resident with specific evacuation needs) requires consideration in the broader FRA evaluation.

FAQ 02

How does the FRA handle stay-put vs simultaneous evacuation?

The evacuation strategy section in the FRA workbench is one of the most important judgement calls. The assessor records what the building was designed for (typically stay-put on UK blocks), whether it remains appropriate given current conditions (compartmentation evidence, external wall position), what compensatory measures are in place if it does not (Waking Watch, interim simultaneous evacuation), and what action plan implications follow. The position is recorded with reasoning rather than asserted as a default.

FAQ 03

What about HRB stock under the Building Safety Act 2022?

For blocks at 18m or 7+ storeys with two or more residential units, the Building Safety Act 2022 imposes the building safety case regime on top of the FSO duty. The FRA is one input into the safety case; the audit grade expected is correspondingly higher. See the high-rise residential sector page for the detailed treatment.

FAQ 04

How often should I review the FRA on a block of flats?

BS 9792:2025 expects the interval to be set against the building risk profile. HRBs typically annual; other purpose-built blocks can be longer where justified, though annual is common in social housing for operational consistency. Significant change to the building, occupancy, or fire safety arrangements triggers an out-of-cycle review regardless of when the next periodic review would otherwise fall.

FAQ 05

Does FRA Flow handle blocks-of-flats assessments specifically?

Yes. Blocks of flats are the most common building type FRA Flow is used for. The capture flow is shaped around how an assessor walks a block, the workbench surfaces blocks-of-flats-specific elements, and the output report is BS 9792-shaped. See the FRA Flow software page for the workflow detail or the tablet app page for the capture detail.

FAQ 06

How does AI-assisted drafting handle the judgement calls in a block FRA?

AI in FRA Flow drafts narrative findings from the structured observations the assessor captured on site. The model has source material to work from, not a vague prompt. Every drafted line carries a footnote-style link back to the source observation. The competent person edits where judgement requires, regenerates where the AI got the framing wrong, and signs off the final report. The AI never signs off; the Fire Safety Order 2005 duty sits with the named competent person.

Keep exploring

BS 9792 working guide BS 9792:2025 reference High-rise residential Social housing software Tablet app workflow

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