How building height is measured

A rough guide can be floor to floor height = 3m although not always accurate.

Number of storeys may not be the best measure of building height.

Storey heights vary

Sloping sites

Double height ground storey

How building height is measured

Evacuation Strategies - Commercial

o Simultaneous – everyone out at the sound of an alarm.

o Phased - Usually the fire floor and one above first, then two at a time until all floors above the fire are empty, then two at a time for all floors below.

o Staged - Shopping malls and complexes of linked buildings will usually be divided into evacuation zones. Only the zone of fire origin evacuates in the first instance. Other zones evacuate if the fire continues to spread.

o Staff Alarms - alert staff to prepare to evacuate before the evacuation alarm sounds.

o Delayed Evacuation - a predetermined investigation period allows staff to confirm fire or false alarm before evacuation.

o Double Knock - The fire alarm system is programmed to identify and only go into full alarm mode when two devices from different zones or the same zone are activated.

Evacuation Strategies - Residential

• Simultaneous - Hotels and traditional University halls of residence

• Progressive Horizontal* - Institutional buildings (Care homes and Hospitals)

• Stay-put - Purpose built flats – stay put (defend in place / safe to stay).

- Double Knock

*This method involves moving the residents facing the greatest fire risk away to a safer part of the building, usually through a compartment wall to a room on the same floor (hence the 'horizontal' part of the name).

Compartmentation

Compartment has a different meaning for Business Fire Safety than for Operational staff.

• Fire resisting construction protects the escape routes.

• Compartmentation protects Fire Fighters and supports the evacuation strategy.

• Office blocks might be one compartment

• Different uses are separated by compartment walls and floors.

• Hospitals Residential care are ‘protected areas’

• In a block of flats, each flat is a compartment.

• High risk areas/ rooms should be separate compartments.

• Stairs and other vertical shafts should be protected shafts.

External Wall Systems

• External walls should not promote fire spread

• Compartmentation should extend to outside walls of the building and around window reveals.

• There should be fire breaks in cavities and voids to limit fire spread.

Why does compartmentation fail?

• Poor design – How easy is it to build?

• Poor installation / build quality – Unskilled workers / lack of oversight.

• Poor co-ordination between trades

• Poor choice of materials / substitution – pink foam / Aluminium

Composite Material

• Installation of new services after occupation – Voice and data cables

• Poor maintenance – particularly fire doors

• DIY and unauthorised alterations – flat entrance doors

• Fire strategy information not passed on to occupier

• Structural movement

• Vandalism – cannabis farms (illegal use)

Number of stairs and travel distance

High Rise Commercial

• >11m – 2 Stairs

• Single direction travel distance 18m*

• More than one direction travel distance 45m*

High Rise Residential

• Often single stair

Common areas flats

• Single direction travel distance 7.5m*

• More one direction travel distance 30m

Hospitals & Residential Care will have multiple stairs to support Progressive Horizontal Evacuation & Travel distances will differ

Corridors linking 2 stairs should be subdivided to avoid both stairs being compromised.

Travel distance within flats

Fire-fighting lifts and stairs – buildings >18m

Number of stairs and travel distance

Smoke control – more than one stair

a. Corridor access without dead ends b. Corridor access with dead ends

The central door may be omitted if Maximum Travel Distance Is not more than 15m

7.5m Max

Smoke Control Ventilation – Blocks of flats

• Can be natural or mechanical Smoke vents

• Various types

• - Permanently open vents (POVs)

• - Openable Vents (OVs)

• - Remotely Openable Vents (ROVs)

Switch or winder at entrance level

• - Automatically Opening Vent (AOVs)

Controlled by smoke detection

• Stair vent will be a vent at head of stair or openable window on each level in the stair.

• Corridor vents will either be on an outside wall or into a smoke shaft

• Stay put strategy requires effective smoke control

• Should be mechanical >30m

Smoke Control Ventilation works – Blocks of flats

• On detection of fire the vent at the head of the stair and the vent on the fire floor should open. All other vents should remain closed.

• If there’s a smoke shaft the vent at the top of the shaft will also open.

• Mechanical ventilation can be either:

– Pressurisation – air is pumped into the stair to keep smoke out.

– Extraction – air / smoke is extracted at the head of a smoke shaft to draw smoke up and vent it to outside.

• Below ground car parks may have a smoke clearance system. Not intended to maintain tenable conditions but to clear smoke post incident.

• With smoke control we always protect the stair and the area immediately before the stair

Fire suppression

• Sprinklers required in all buildings >30 and any new residential buildings >11m.

• Automatic water fire suppression systems (AWFSS)

– Commercial sprinklers (global isolation)

– Residential sprinklers (local isolation, may not cover ancillary areas)

– Water mist – similar to residential sprinklers

– Person protection systems – protect vulnerable people in their home

• AWFSS may be used to compensate for variations from guidance

• CO2 or inert gas suppression may be provided in substations.

• Localised powder, foam or wet chemical systems to protect cooking equipment within flats or communal facilities.

Emergency escape lighting and signage

• Can be Maintained or Non Maintained

• Integrated or stand alone

• Power supply can be self-contained or central battery

• Level of illumination is much lower that normal lighting level.

• Duration 1 – 3 hours.

• Exit signage only a requirement for alternative / unfamiliar routes

• Wayfinding signage is now a requirement for new High Rise Residential Buildings.

• And all High Rise Residential Buildings from 23 January 2023

*Permanently illuminated

**Only illuminates on mains power failure

Premises information

• There is a legal duty for Responsible Persons to establish links with the Fire and Rescue Services and provide information relevant to fire-fighting and rescue.

• No standard format for the provision of information but may include:

• Premises Information Boxes (PIB) and wayfinding signage

• Plans adjacent to the fire alarm panel

• On site concierge

• Security responders

• Residents

• SSRI, 7.2.d visit

Management

• The Responsible Person is required to implement suitable management arrangements for the effective planning, organisation, control, monitoring and review of the preventative and protective measures.

• These arrangements should define roles and responsibilities to:

-Review the Fire Risk Assessment and action findings.

-Formulate and implement the emergency plan.

-Arrange for the maintenance of the fire safety provisions in the building.

-Appoint people to assist if necessary.

-Provide information to occupants.

-Management involves paying people! Can be seen as an easy cost saving.