Stage 3 Fire Strategy - Spatial Coordination

Introduction

A Stage 3 fire strategy develops the concept into a spatially coordinated fire safety design.

RIBA Stage 3 is Spatial Coordination. Architectural and engineering information should be coordinated so that the detailed technical design can proceed without major redesign of the building.

This is commonly the stage at which clients, building control bodies and contractors expect a substantial fire strategy report. However, Stage 3 is still not the completion of every specialist technical design.

Purpose

The Stage 3 strategy should:

Test and validate the Stage 2 concept
Coordinate fire safety measures with architecture, structure and services
Undertake the necessary Building Regulations review
Record key design decisions, risks and deviations
Define the performance requirements for Stage 4 technical design
Identify all specialist design responsibilities and interfaces
Provide a defensible basis for planning, procurement or statutory submissions where applicable

The strategy should be detailed enough that unresolved fire safety matters do not cause major changes to the spatial design during Stage 4.

Required Inputs

The Stage 3 strategy should use:

Approved Stage 2 fire strategy
Coordinated plans, sections and elevations
Confirmed occupancy and use schedules
Structural design information
MEP strategies and plant layouts
Façade build-ups and materials
Vertical transportation strategy
Inclusive design strategy
Specialist smoke-control, sprinkler and alarm input
Fire service and building control feedback where available
Existing-building survey results
Planning conditions and fire statement commitments
Insurer and warranty requirements
Procurement strategy and responsibility matrix

Spatial Coordination

Means of Escape

The Stage 3 strategy should normally confirm and coordinate:

Design occupancy by floor, area or use
Occupancy load factors where applicable
Travel distances
Number and distribution of exits
Exit widths
Stair widths and capacities
Stair protection
Lobbies and protected corridors
Alternative escape
Dead ends
Inner rooms
Escape from basements and roofs
Final exits and external routes
Escape route signage and lighting principles
Security controls on escape routes
Accessible escape arrangements
Evacuation lifts and refuges

The calculations and drawings should use the same occupancy assumptions.

Compartmentation

The Stage 3 package should define:

Compartment floors and walls
Sub-compartment boundaries
Protected shafts
Firefighting shafts
Protected corridors and stairs
Separation of uses
Ancillary and high-risk accommodation
Fire-resistance periods
Fire door requirements
Cavity barrier principles
Service penetration strategy
Junctions with roofs and façades
Interfaces with smoke control and suppression

Compartment lines should be shown consistently on coordinated drawings rather than described only in text.

Structural Fire Safety

The strategy should coordinate:

Required fire-resistance periods
Loadbearing elements
Compartment-supporting structure
Transfer structures
Structural protection systems
Atrium or large-space conditions
Any structural fire engineering
Effects of movement on firestopping and façades
Robustness and disproportionate collapse considerations where relevant

External Fire Spread

The Stage 3 strategy should establish:

Boundary distances and space-separation approach
Unprotected area calculations where required
External wall material requirements
Insulation and sheathing requirements
Cavity barriers
Fire stopping at compartment lines
Spandrels and slab-edge interfaces
Balconies, canopies and attachments
Roof covering and roof junction requirements
Evidence required for non-standard façade systems

Active Systems Coordination

Fire Detection and Alarm

The Stage 3 strategy should identify:

System objective
BS 5839 category or categories
Areas requiring automatic detection
Detector-type constraints
Fire detection zones
Alarm zones
Simultaneous, phased or staged alarm arrangement
Voice alarm requirements
Visual and tactile alarm requirements
Alarm receiving centre transmission
Control and indicating equipment locations
Repeater or fire-control panel requirements
Interfaces with smoke control, lifts, doors, HVAC, access control and suppression
Cable performance assumptions where these affect the strategy
Resilience and network architecture requirements where relevant

For categories such as L2, L5 or P2, the protected areas and objectives should be clearly defined rather than stated by category alone.

Smoke Control

The Stage 3 strategy should coordinate:

Design objectives
Design fire and calculation basis
Smoke-control zones
Shaft and duct routes
Vent and fan locations
Replacement-air paths
Pressure differential zones
Power supplies
Environmental and standby conditions
Detection and control principles
Firefighter controls
Monitoring and fault reporting
Interfaces with doors, dampers, lifts and ventilation
Maintenance access

Sprinklers and Suppression

The Stage 3 strategy should coordinate:

Design standard
Hazard classification
Coverage boundaries
Tank, pump and valve-set locations
Incoming water requirements
Fire-resisting separation
Monitoring and alarm signals
Interfaces with smoke control and evacuation
Fire-service connections
Maintenance and replacement access
Any compensatory role within the fire strategy

Stage 3 Cause-and-Effect Matrix

A Stage 3 cause-and-effect matrix should usually be a coordinated functional matrix.

It should identify, as applicable:

Causes

Manual call points
Automatic detectors
Sprinkler flow switches
Sprinkler valve tamper switches
Suppression system signals
Smoke-control system inputs
Firefighter switches
Evacuation controls
Plant fire signals
Gas detection or process safety signals where relevant
Alarm receiving centre return or fault signals

Effects

Evacuation or alert signals
Voice alarm messages
Visual alarm devices
Alarm receiving centre transmission
Smoke-control operation
Damper operation
Door release or closure
Access-control release
Lift recall, grounding or evacuation lift mode
HVAC shutdown or mode change
Gas, fuel or process isolation
Sprinkler and suppression indications
Fire shutters and curtains
Wayfinding or dynamic signage
Fire-service indications and controls

Logic

The matrix should define:

Immediate versus delayed action
Coincidence or confirmation requirements
Investigation periods
Escalation between alarm stages
Relationships between fire detection zones and alarm zones
Manual escalation controls
Timer cancellation
Reset and latching principles
Dependencies on occupancy mode or time of day
Required feedback and monitoring

The Stage 3 matrix may use functional groups, zone references or system groups rather than final point addresses. It should nevertheless be detailed enough for every discipline to understand what it must design.

What Should Develop Alongside the Stage 3 Strategy?

Document or activity	Stage 3 purpose
Coordinated architectural drawings	Show escape routes, compartments, doors, shafts and firefighting facilities.
Compartmentation plans	Provide a clear graphical record of fire-resisting boundaries and ratings.
Fire door schedule or strategy	Defines ratings, smoke control, self-closing, hold-open and access requirements.
Occupancy and escape calculations	Demonstrate the capacity and arrangement of exits and stairs.
Structural fire engineering report	Develops any non-prescriptive structural fire solution.
Façade fire report	Defines materials, cavity barriers, slab-edge details and evidence requirements.
Smoke-control design basis	Records design objectives, calculations, zones, controls and interfaces.
Sprinkler design criteria	Defines standard, hazard, coverage, water supply and monitoring.
Fire alarm design brief	Defines category, coverage, zoning, warning and interface performance.
Functional cause-and-effect matrix	Coordinates the required actions across all systems.
Emergency lighting strategy	Coordinates coverage, duration, central supplies and controls.
Inclusive evacuation strategy	Develops refuges, EVC, evacuation lifts and assisted escape procedures.
Firefighting facilities drawings	Coordinate shafts, lifts, mains, access and fire-service controls.
Building Regulations review	Tests the coordinated design against all relevant functional requirements.
Stage 4 responsibility matrix	Identifies who completes each specialist technical design.
Procurement information	Defines fire safety requirements that must be preserved through procurement.

Stage 3 Is Not Automatically Stage 4

A detailed Stage 3 report can still be incomplete for construction.

Typical Stage 4 items that may remain outstanding include:

Final product selections
Final wall, floor and door specifications
Penetration and junction details
Firestopping systems
Final façade details
Final smoke-control calculations and equipment schedules
Final sprinkler hydraulic design
Final fire alarm device and circuit design
Final power-supply and battery calculations
Final cause-and-effect implementation matrix
Interface wiring and monitoring details
Installation and commissioning procedures
As-built evidence requirements

A Stage 3 strategy should identify these outstanding items and assign responsibility for them.

Procurement and Employer's Requirements

Where Employer's Requirements or tender information are issued at Stage 3, additional Stage 4-level information may need to be drawn forward.

The fire strategy should make clear:

Which requirements are prescriptive
Which are performance-based
Which specialist designs remain contractor-designed
What standards and acceptance criteria apply
What submissions are required before manufacture or installation
Who reviews contractor proposals
How alternative products or value engineering will be assessed
How fire strategy changes will be controlled

A statement such as “specialist contractor to design” is not sufficient unless the required outcome, interfaces and review process are defined.

Stage 3 Deliverables

A typical Stage 3 fire safety package may include:

Stage 3 coordinated fire strategy
Fire strategy plans
Compartmentation plans
Occupancy and escape calculations
Fire-resistance schedule
Fire door strategy
Firefighting access and facilities drawings
Fire alarm design brief
Functional cause-and-effect matrix
Smoke-control design basis
Sprinkler or suppression design criteria
Façade and external-wall fire strategy
Inclusive evacuation strategy
Emergency lighting strategy
Fire safety design risk and assumptions register
Building Regulations review
Stage 4 design responsibility matrix
Specialist design submission schedule
Record of consultation and key decisions

Stage 3 Completion Criteria

Stage 3 should not be considered complete until:

The architectural and engineering design is spatially coordinated
Means-of-escape calculations agree with the drawings
The evacuation philosophy is confirmed
Compartment lines and fire-resistance periods are coordinated
Firefighting access and facilities are coordinated
Active system objectives and spatial requirements are confirmed
The functional cause-and-effect is coordinated across disciplines
Façade and external-wall requirements are defined
Relevant Building Regulations requirements have been reviewed
Major deviations and fire-engineered solutions are justified
Specialist Stage 4 responsibilities are allocated
Remaining technical design actions are clear
The client has approved the Stage 3 fire strategy basis

Common Failures

Calling a generic narrative a coordinated strategy
Inconsistent occupancy figures between the report and drawings
Compartment lines missing from drawings
Fire doors specified without a coordinated function or schedule
Leaving service penetrations and cavity barriers entirely to site resolution
Alarm category stated without protected areas or system objectives
Cause-and-effect limited to vague statements such as “all associated systems to operate”
Smoke-control systems shown without replacement air or control philosophy
Suppression systems used as compensation without identifying the dependency
Façade details deferred until after procurement
Specialist contractor responsibilities not defined
Issuing tender information that permits alternatives with no fire safety review process

Relationship to Stage 4

Stage 4 should turn the coordinated design into complete information for manufacture, installation, testing and construction.

The Stage 3 package should give the Stage 4 designers:

Fixed fire safety objectives
Coordinated geometry
Defined performance requirements
Agreed system interfaces
A functional cause-and-effect matrix
A clear responsibility matrix
Acceptance and submission requirements
A controlled list of residual actions

Continue to Stage 4 – Technical Design.

Important: A Stage 3 strategy should be detailed enough to coordinate the building and define the Stage 4 requirements. It should not be mistaken for complete construction information unless the technical design has genuinely been completed.