Stage 2 Fire Strategy - Concept Design

Introduction

A Stage 2 fire strategy develops the fire safety concept alongside the architectural concept.

RIBA Stage 2 is Concept Design. The design team should establish a concept that aligns with the Project Brief and clarify the intended route to Building Regulations compliance.

At this stage, the fire strategy should begin recording the key design decisions that shape the building.

Purpose

The Stage 2 strategy should:

Translate the Stage 1 fire safety requirements into a workable building concept
Identify the principal fire safety measures
Test major design options
Establish the intended compliance route
Prevent the architecture from developing around assumptions that later prove unworkable
Record the key decisions that must be carried into Stage 3

The document should be specific enough to influence the concept but should not pretend to be a completed technical design.

Required Inputs

The Stage 2 strategy should be based on:

Approved Project Brief
Stage 1 fire safety requirements
Site information and surveys
Initial architectural plans, sections and elevations
Proposed uses and occupancy
Initial structural and servicing concepts
Planning constraints
Inclusive-design requirements
Insurer and warranty requirements
Existing-building information, where applicable
Stakeholder and client feedback

Any missing information should be recorded as an assumption, risk or action.

Concept Fire Safety Decisions

Occupancy and Evacuation

The Stage 2 strategy should establish the intended:

Occupancy profile
Design occupancy basis
Evacuation or stay-put approach
Simultaneous, phased, progressive horizontal, delayed or staff-led evacuation
Approach to disabled and vulnerable occupants
Need for refuges, evacuation lifts or assisted escape
Staffing and management assumptions
Alarm investigation and escalation philosophy

The strategy should explain why the proposed approach is appropriate to the building and its occupants.

Means of Escape

The concept should address:

Number and broad location of exits
Number and broad location of stairs
Escape route arrangement
Alternative escape
Dead-end conditions
Inner rooms and access rooms
Initial travel-distance checks
Initial exit and stair capacity
Final exits and external escape
Security interfaces affecting escape
Escape from basements, roofs and plant areas

Detailed dimensions may continue to develop, but the concept must be feasible.

Compartmentation and Structure

The concept should identify:

Main compartment floors and walls
Separation of different uses
Protected shafts and stairs
Firefighting shafts
Sub-compartmentation where relevant
Initial structural fire-resistance periods
High-risk or ancillary accommodation requiring separation
Potential compartment interfaces with façades, roofs and services
Any reliance on compartmentation to support evacuation or firefighting

External Fire Spread

The strategy should consider:

Proximity to boundaries
Space separation
External wall performance
Roof coverings
Cavities and concealed spaces
Balconies and attachments
Relationship between compartment floors and façade construction
Fire spread between buildings on the site

The Stage 2 façade concept should not be developed independently from the fire strategy.

Firefighting Access and Facilities

The concept should address:

Fire appliance access
Perimeter access
Hardstanding and turning
Firefighting water supplies
Access to building entrances
Firefighting shafts
Firefighting lifts
Fire mains
Fire-control or information points
Access to roofs, basements and complex areas

These items often affect the site layout and core arrangement and should not be postponed.

Active Fire Protection Concept

Fire Detection and Alarm

The Stage 2 strategy should identify:

The purpose of the system
Likely BS 5839 category or categories
Broad extent of automatic detection
Simultaneous or staged alarm philosophy
Need for voice alarm
Need for visual, tactile or other warning
Broad fire detection zones and alarm zones
Need for alarm receiving centre transmission
Principal interfaces with other systems
Management arrangements supporting any staff alarm or investigation period

The fire alarm concept should derive from the evacuation strategy.

Smoke Control

The strategy should identify:

Whether smoke control is required
The safety objective of each system
Natural or mechanical approach
Areas or shafts to be protected
Broad smoke-control zoning
Relationship to evacuation and firefighting
Likely detection and control philosophy
Space and plant requirements

Sprinklers and Suppression

The strategy should identify:

Whether suppression is required
Life-safety, property-protection or compensatory purpose
Broad extent of coverage
Likely system standard
Initial water-supply approach
Space requirements for tanks, pumps and valve sets
Principal alarm and monitoring interfaces

Preliminary Cause-and-Effect Philosophy

A full device-level matrix is not normally required at Stage 2, but the principal sequences should be understood.

The Stage 2 strategy should describe:

What initiates an alarm
Which areas receive alert or evacuation signals
Whether manual call points cause immediate evacuation
Whether automatic detectors initiate an investigation period
Whether coincidence is used
When signals are sent to an alarm receiving centre
How smoke control is initiated
Which doors release or close
How lifts respond
Which ventilation or process systems shut down
How sprinkler and suppression signals are treated
What manual controls are required

The purpose is to verify that the building concept can support the intended operational strategy.

What Should Develop Alongside the Stage 2 Strategy?

Document or activity	Stage 2 purpose
Architectural concept drawings	Show the building form, cores, escape routes and principal fire safety features.
Outline specification	Records the intended performance of key construction and systems.
Occupancy schedule	Defines design populations, uses and occupant characteristics.
Evacuation strategy note	Develops the evacuation philosophy and management assumptions.
Inclusive design strategy	Coordinates assisted escape, refuges, evacuation lifts and accessible communication.
Structural fire strategy note	Identifies fire-resistance periods and any special structural fire engineering.
Façade fire review	Tests the external-wall concept and boundary conditions.
Smoke-control concept	Defines objectives, system type, zones, space and principal controls.
Suppression concept	Defines the need, extent and major infrastructure requirements.
Fire alarm concept	Defines category, warning approach, zoning philosophy and major interfaces.
Preliminary cause-and-effect narrative	Defines the principal operating sequences.
Planning fire statement	Provides planning-specific fire information where required.
Cost plan	Includes realistic allowances for fire safety measures and specialist systems.
Stage report	Records key fire safety decisions and client approval.

Planning Fire Statements

A planning fire statement may be required for certain developments in England.

It should remain focused on fire safety matters relevant to planning, including matters such as:

Site layout
Fire appliance access
Firefighting water
Principles and concepts applied to the development
Relevant consultation
Local planning policy

It should be consistent with the Stage 2 fire strategy, but it is not a substitute for the more detailed fire strategy needed for Building Regulations design.

Expected Level of Detail

A good Stage 2 strategy should be able to answer:

What is the proposed evacuation approach?
How many stairs and cores are required in principle?
Where are the principal escape routes?
What is the basic compartmentation strategy?
What structural fire-resistance approach is proposed?
What active systems are expected?
How will the fire service access and operate within the building?
What major interfaces or management dependencies exist?
What remains to be tested and coordinated at Stage 3?

It would not normally be expected to contain every construction detail, cable calculation, fan calculation, product classification or specialist drawing.

Stage 2 Deliverables

A typical Stage 2 fire safety package may include:

Stage 2 concept fire strategy
Fire strategy drawings or marked-up architectural drawings
Key fire safety decision schedule
Initial occupancy and evacuation schedule
Initial means-of-escape assessment
Initial compartmentation and structural fire-resistance principles
Firefighting access and facilities concept
External fire spread and façade concept review
Fire alarm and warning concept
Smoke-control concept
Sprinkler or suppression concept
Preliminary cause-and-effect narrative
Updated fire safety risk and assumptions register
Stage 3 information requirements
Planning fire statement where required

Stage 2 Completion Criteria

Stage 2 should not be considered complete until:

The architectural concept can accommodate the fire safety requirements
The compliance route has been clarified
The evacuation philosophy has been agreed in principle
The number and broad position of stairs, cores and exits are viable
Firefighting access and facilities are feasible
The principal passive and active measures have been identified
Major plant and spatial requirements have been allowed for
The external-wall concept has been considered
Key fire safety decisions have been recorded
Outstanding assumptions and risks have defined Stage 3 actions
The client has approved the concept and its fire safety basis

Common Failures

Treating the Stage 2 strategy as generic narrative
Fixing the architecture before the evacuation and firefighting concepts are tested
Failing to account for plant, shafts, tanks or smoke-control space
Assuming that a sprinkler system can compensate for unresolved means-of-escape issues without justification
Failing to coordinate inclusive evacuation
Deferring the façade fire strategy
Selecting a fire alarm category without defining its purpose or extent
Producing a detailed cause-and-effect matrix that is not based on agreed procedures
Omitting management assumptions on which the strategy depends
Failing to record why key decisions were made

Relationship to Stage 3

Stage 3 should test, coordinate and validate the Stage 2 concept.

The Stage 2 strategy should clearly identify:

Decisions that are fixed
Decisions that remain provisional
Required engineering analysis
Required specialist input
Interfaces requiring coordination
Information that must appear in the Stage 3 report

Continue to Stage 3 – Spatial Coordination.

Important: The Stage 2 strategy should establish a robust fire safety concept. It should neither remain generic nor drift into uncoordinated technical design.