Stage 4 Fire Strategy - Technical Design

Introduction

A Stage 4 fire strategy is the technical-design version of the fire strategy.

RIBA Stage 4 is Technical Design. The outcome should be completion of the design information required to manufacture and construct the building.

The Stage 4 strategy should therefore move beyond broad principles and coordinated intent. It should be supported by complete specifications, calculations, schedules, drawings and specialist designs.

Purpose

The Stage 4 strategy should:

Complete the fire safety technical design
Embed the strategy into construction and manufacturing information
Close the design risks identified at Stage 3
Coordinate design-team and specialist-subcontractor information
Define testable requirements
Support the Building Regulations application
Establish how changes and substitutions will be controlled
Define the evidence required to demonstrate compliant construction
Provide a clear basis for commissioning and handover

A Stage 4 strategy should not rely on site teams to resolve fundamental design decisions.

Required Inputs

The Stage 4 design should use:

Approved Stage 3 fire strategy
Coordinated architectural and engineering design
Fire strategy plans and compartmentation drawings
Confirmed occupancy and evacuation assumptions
Final structural design
Final façade design
Specialist smoke-control design
Specialist fire alarm design
Specialist sprinkler or suppression design
Lift and vertical transportation design
Emergency lighting design
Door and hardware schedules
Firestopping and penetration strategy
Procurement and contractor proposals
Insurer and warranty requirements
Building control or BSR comments
Change-control requirements
Stage 4 responsibility matrix

Technical Design Requirements

Means of Escape

The Stage 4 package should complete:

Final escape route dimensions
Final exit and stair capacities
Door swings and clear widths
Escape hardware
Security release arrangements
Stair and lobby construction
Refuge details
Evacuation lift design
Final exit arrangements
External escape route construction
Escape signage
Emergency lighting design
Wayfinding requirements where applicable
Final management limitations affecting use or occupancy

Compartmentation and Passive Fire Protection

The technical design should define:

Wall and floor types
Fire-resistance classifications
Junction details
Head-of-wall details
Movement-joint details
Service penetration details
Linear gap seals
Firestopping systems
Cavity barriers
Façade perimeter fire barriers
Roof void barriers
Fire and smoke dampers
Access panels
Fire-resistant glazing
Fire curtain and shutter details
Installation tolerances and substrate requirements
Inspection and evidence requirements

Generic notes such as “firestop all penetrations” are not sufficient technical design.

Fire Doors

The Stage 4 design should coordinate:

Door identification
Required fire and smoke rating
Door construction and certification route
Frame and seal requirements
Self-closing requirements
Hold-open or swing-free devices
Access-control hardware
Escape hardware
Automatic release arrangements
Thresholds and undercuts
Glazing
Signage
Ironmongery compatibility
Installation and inspection requirements

Structural Fire Safety

The package should complete:

Fire-resistance specifications
Protection thicknesses or systems
Connection and junction requirements
Structural fire engineering calculations
Fire-protection interfaces with services and façades
Inspection and quality-assurance requirements
Design assumptions that must be preserved during construction

External Walls and Roofs

The technical design should define:

Complete wall build-ups
Product classifications
Insulation and sheathing
Cavity barriers
Slab-edge fire barriers
Window and curtain-wall interfaces
Balconies and attachments
Fixings and support systems
Fire performance evidence
Roof coverings
Roof and wall junctions
Interfaces with compartment walls and floors
Installation inspection requirements

Active Fire Protection Technical Design

Fire Detection and Alarm

The Stage 4 fire alarm design should normally include:

Confirmed system category and objectives
Device and system performance specifications
Detection coverage
Detector types and modes
Fire detection zones
Alarm zones
Control and indicating equipment
Network architecture
Loop and circuit design
Short-circuit isolation
Sound pressure design
Visual alarm coverage
Voice alarm design where applicable
Alarm transmission
Power-supply and standby calculations
Cable type and routing requirements
Survivability and segregation
Interface design
Monitoring requirements
Device schedules
Layout drawings
Zone plan requirements
Commissioning and witness-test requirements
Final cause-and-effect matrix

BS 5839-1:2025 requires the system design to support the evacuation strategy, identifies the need for defined responsibilities, and requires completed documentation including as-fitted drawings, certificates and a cause-and-effect matrix or text description.

Smoke Control

The Stage 4 smoke-control design should include:

Final design basis
Design fire assumptions
Calculations and modelling
Fan and vent duties
Shaft, duct and damper details
Replacement-air design
Pressure differential calculations
Environmental ratings
Power supplies and controls
Detection and initiation
Firefighter controls
Monitoring and feedback
Cause-and-effect logic
Control panel and interface details
Maintenance access
Commissioning procedures
Performance test and acceptance criteria

Sprinklers and Suppression

The Stage 4 design should include, as applicable:

Final design standard
Hazard classification
Hydraulic calculations
Water supply
Tank and pump design
Valve and zoning arrangement
Pipework design
Head or nozzle layout
Monitoring
Fire alarm interfaces
Release logic
Abort and manual controls
Warning devices
Room integrity requirements
Venting and pressure relief
Commissioning and acceptance tests
Maintenance access and isolation strategy

Detailed Cause-and-Effect Matrix

The Stage 4 cause-and-effect matrix should be detailed enough to:

Configure and program the systems
Coordinate all interfaces
Commission each function
Witness the integrated system test
Train the building operator
Form part of the handover information

The Matrix Should Identify

Input reference, address or clearly defined functional group
Input type
Input location or zone
Operating condition
Alarm stage
Output reference or group
Required action
Delay
Coincidence or dependency
Latching and reset behaviour
Manual override
Disablement behaviour
Fault response
Required confirmation or feedback
Interface owner
Drawing or specification reference
Test and acceptance requirement

Typical Input Conditions

Manual call point
Smoke detector
Heat detector
Multi-sensor detector
Aspirating system alarm levels
Beam detector
Sprinkler flow
Sprinkler valve tamper
Suppression first-stage and confirmed alarm
Smoke-control detector or switch
Firefighter control
Evacuation control
Plant or process fire signal
Common fire, common fault or system-specific signal

Typical Output Actions

Evacuate
Alert
Staff alarm
Voice message
Visual alarm
Alarm receiving centre transmission
Smoke-control fan or vent operation
Damper operation
Door release or closure
Access-control release
Lift recall or grounding
Evacuation lift operation
HVAC shutdown or mode change
Gas or fuel isolation
Fire curtain or shutter operation
Suppression release
Wayfinding or signage change
Fire-service indication
BMS indication

Avoid Ambiguous Entries

Entries such as the following are not sufficiently testable:

“Operate as required”
“All associated doors”
“Smoke control to run”
“Lifts to respond”
“Signal to BMS”
“General alarm where necessary”

Each action should identify the exact intended state, scope, timing and responsible interface.

Interface Schedule

Complex projects should use an interface schedule alongside the cause-and-effect matrix.

The schedule should identify:

System providing the signal
System receiving the signal
Interface location
Signal type
Normal and alarm state
Fail-safe state
Cable and monitoring responsibility
Power-supply responsibility
Terminal or protocol requirements
Required feedback
Testing responsibility
Witnessing responsibility
Final documentation owner

This prevents a gap where both contractors assume the other is providing the interface.

What Should Develop Alongside the Stage 4 Strategy?

Document or activity	Stage 4 purpose
Final architectural details	Provide construction details for escape routes, compartments, doors and shafts.
Final specifications	Define performance, materials, installation and acceptance requirements.
Fire door schedule	Coordinates every fire door and its hardware, controls and certification.
Passive fire protection details	Define firestopping, cavity barriers, dampers and junctions.
Façade technical fire information	Defines final build-ups, barriers, fixings and evidence.
Fire alarm design package	Provides layouts, calculations, schedules, specifications and cause and effect.
Smoke-control design package	Provides calculations, schematics, controls and commissioning requirements.
Sprinkler or suppression design	Provides calculations, layouts, water supplies and interfaces.
Emergency lighting design	Provides layouts, calculations, supplies and test requirements.
Lift fire strategy design	Defines recall, firefighting and evacuation lift functions.
Detailed cause-and-effect matrix	Provides the testable integrated operating sequence.
Interface schedule	Allocates every cross-system signal and responsibility.
Commissioning plan	Defines individual and integrated testing.
Inspection and test plan	Defines construction inspections and evidence capture.
Building Regulations application	Demonstrates the completed design route to compliance.
Change control plan	Controls changes to the approved or agreed design.
Construction control plan	Defines how compliant work and as-built evidence will be achieved and recorded.
Regulation 38 information plan	Defines the content, format and ownership of handover information.

Higher-Risk Buildings

For higher-risk building work in England, Stage 4 may need to support submission of:

Drawings and plans
Building Regulations compliance statement
Change control plan
Construction control plan
Competence declaration
Fire and emergency file
Mandatory occurrence reporting plan
Partial completion strategy where relevant

The fire and emergency file is often known as a fire strategy and must explain how the design provides:

Means of escape and warning
Internal fire-spread control
External fire-spread control
Fire-service access and facilities
Management and maintenance arrangements relevant to emergency evacuation

The design should be sufficiently complete for approval and should not depend on unresolved construction-stage design.

Change Control

Any proposed change that may affect the fire strategy should be reviewed before implementation.

Examples include changes to:

Occupancy or use
Stairs and escape routes
Compartmentation
Fire-resistance periods
Fire doors
Façade materials or build-ups
Cavity barriers
Fire alarm category or coverage
Cause and effect
Smoke-control systems
Sprinkler or suppression systems
Firefighting shafts or lifts
Evacuation lifts
Product specifications
Service routes and penetrations
Management assumptions

The review should identify:

Which strategy assumptions are affected
Which drawings and specifications require revision
Whether regulatory approval is required
Whether calculations must be repeated
Whether the cause-and-effect matrix must change
Whether commissioning and test plans must change
How the change is recorded in the golden thread or project information system

Inspection, Testing and Evidence

The Stage 4 design should specify the evidence required during construction.

This may include:

Product and system certification
Installation records
Photographic evidence
Location-tagged inspection records
Firestopping records
Door inspection records
Damper inspection records
Façade cavity-barrier records
Pressure and flow test results
Electrical test results
Fire alarm design, installation and commissioning certificates
Cause-and-effect test records
Integrated systems testing
Smoke-control performance tests
Sprinkler and suppression test records
Witnessing and sign-off requirements
Red-line and as-built drawing requirements

Evidence should be captured while work remains visible and accessible.

Stage 4 Deliverables

A typical Stage 4 fire safety package may include:

Stage 4 technical fire strategy
Final fire strategy drawings
Final compartmentation drawings
Final fire-resistance and fire door schedules
Passive fire protection details
Structural fire design and specifications
Façade fire technical package
Fire alarm technical design
Detailed cause-and-effect matrix
Interface schedule
Smoke-control technical design
Sprinkler or suppression technical design
Emergency lighting design
EVC and evacuation lift design
Firefighting facilities details
Final specifications
Commissioning and integrated testing plan
Inspection and test plan
Building Regulations application information
Change-control requirements
Regulation 38 and as-built information requirements

Stage 4 Completion Criteria

Stage 4 should not be considered complete until:

All design information required for manufacture and construction is complete
Specialist designs are coordinated
Fundamental assumptions have been closed or formally controlled
Means of escape is fully detailed
Passive fire protection is buildable and specified
Active system designs are complete
The cause-and-effect matrix is testable
Interfaces and responsibilities are defined
The Building Regulations submission is supported by coordinated information
Design alternatives and substitutions have an approval process
Inspection, commissioning and evidence requirements are defined
Regulation 38 and as-built requirements are planned
Residual operational restrictions are clearly recorded

Common Failures

Reissuing the Stage 3 report and calling it Stage 4
Leaving specialist design until Stage 5
Missing penetration, junction and cavity-barrier details
Allowing contractor design without performance requirements
Incomplete fire alarm coverage or sound pressure design
A cause-and-effect matrix that cannot be commissioned
Interfaces with no identified owner
Smoke-control calculations that do not match the final architecture
Product substitutions accepted without fire strategy review
No integrated testing plan
No plan for as-built evidence
Treating Building Regulations approval as a substitute for design coordination

After Stage 4

During construction and handover, the Stage 4 strategy should be maintained as a controlled document.

It should be updated to reflect:

Approved design changes
Accepted contractor proposals
Final installed systems
Final cause-and-effect programming
Commissioning results
As-built drawings
Variations and residual risks
Management and maintenance requirements

The final as-built fire strategy and supporting information should be handed to the person responsible for operating the building.

BS 5839-1:2025 requires completed fire alarm documentation to include relevant certificates, operation and maintenance information, as-fitted drawings, cause-and-effect information, a logbook and records of agreed variations.

Return to Fire Strategies.

Important: A Stage 4 strategy should be supported by complete and coordinated technical design. Any unresolved item should be clearly identified, allocated and controlled rather than silently transferred to construction.