Fire in block of

flats which

spread

through the

smoke

ventilation

shaft

James GallSenior Fire Protection Inspector

Fire Engineering & Planning

Introduction

This presentation follows a serious fire in a residential block of

flats with a single staircase where significant fire spread

occurred from the floor of origin to other floors through the

natural smoke ventilation shaft system

The Building• The building is a seven storey purpose built block of flats

and part of a development of seven blocks of flats all of

similar designs.

• Development is located above a communal basement car

park.

• Natural smoke ventilation shaft system to achieve ventilation

of smoke from the common corridor/lobby areas on each

floor.

The Building- basement car park

The basement car park has natural cross ventilation

Single protected staircaseThe protected staircase has a lobby on each floor. At the head of the

stair there is a vent which opens on actuation of the smoke detector

at the head of the staircase or from a manual override switch.

Smoke vent shaft doors on flats corridors

operated by AFD

Smoke Shaft

Top

Bottom

(Permanent

opening into

car park for

all seven

blocks)

The fire

• 5 November 2016 approx 12:56 hours

• Flat 17 second floor

• Ignition source: Candle

• Bedding caught fire from candle

• Fire could not be extinguished by occupant

• Occupant evacuated the flat

• Fire spread into communal corridor- no self closer

located on flat entrance door!

• Smoke vent shaft doors opened on second floor and fire

spread on this floor

• Significant fire gases/heat spread up the smoke shaft

• Vent shaft doors opened on 6th, 4th and 3rd floors

• Heat/smoke damage to 6th & 4th floors, fire on 3rd floor

General floor layoutBed of origin

Common corridor

Smoke shaft

Lounge

Flat entrance door

This building design versus ADB

ADB 2007 design diagram

7 (current)

ADB 2000 design

diagram 12 note the

similarity to this

building in terms of

floor layout

Operational response

• Time Of Call 12:57

• 13:03 Enhanced PDA (4) sent due to multiple calls

• 13:20 Priority Assistance make pumps 5

• 13:28 Assistance make pumps 8

• 13:32 Incident confirmed as persons reported

• 14:06 INF- Fire now out 3 floors heavily smoke logged 8

BA’s in use, Offensive mode, Incident still persons

reported

• 14:35 INF – Incident now sectorised, Fire Search. Still

persons reported

• 15:18 INF- All persons accounted for

• 16:24 Incident reducing to 4 pumps

This building- second floor

Flat involvedKitchen 2nd bedroom

2nd Floor CorridorExit route smoke shaft to left Toward flat, smoke shaft to right

Fire Doors did their job!

Could have been worse!

3rd Floor Corridor

4th floor

5th Floor Corridor

Injuries to residents on sixth floor corridor

Two occupants from a sixth floor flat attempted to escape along the corridor

to the staircase by crawling on their hands and knees and holding a wet

towel over their faces.

Both burnt their hands and hair and inhaled smoke. They could not reach

the doors to the staircase at the end of the corridor and had to turn back.

Contributing Fire Growth Factors

• Bedroom fire door left open

• Flat entrance fire door left open

• Balcony door in lounge of flat open throughout the fire

(adjacent room to bedroom of origin)

• Smoke shaft opened by corridor smoke detector (AOV)

• Shaft functioned at most efficient immediately (open at bottom

and top)

• Bedroom window in flat failed (maximum ventilation to

compartment)

• Additional smoke shaft doors opened on other floors

• Windy conditions

Why did the smoke vent shaft doors

open on other floors?

• Testing carried out with artificial smoke on AFD devices.

• Without resetting the system multiple floor vents opened.

• Manual override devices also allowed multiple floors to be

opened.

• It is possible smoke leaked from the shaft onto upper

corridors and was picked up by AFD resulting in the shaft

doors opening.

Operation of these systems

Current guidance

These systems should ‘lock out’ or be programmed such that

only the vent on the fire floor opens all other vent doors should

remain closed even if smoke is subsequently detected on

other floors:

Paragraph 2.26 (b) (iv) of Approved Document B states that

only the vent on the fire affected floor should open and all

other storeys should remain closed;

Clause 14.2.2.4 of BS 9991 2015:

Clause 6.2.6.1 of the Guidance on Smoke Control to

Common Escape Routes in Apartment Buildings (Flats

and Maisonettes) produced by the Smoke Control

Association:

WYFRS programme of testing

• WYFRS Inspectors sampled eight blocks of flats with

smoke vent shafts to ascertain the cause and effect of

the systems;

• 80% of the blocks tested operated in a similar manner to

this building and therefore enforcement action is being

taken to rectify these deficiencies;

• From discussion with smoke vent & fire alarm engineers

there is some confusion in the industry as to how these

systems should operate;

• Where smoke vent shafts are present and have inlet

provision at the base, the inlet location is being checked

to confirm they are not open to a car park.

Maintenance and Testing

The main purpose of the visit is to have a test carried out of

any shaft smoke control system. For a shaft system:

• Actuate a lobby or corridor detector:

Check that the shaft vent opens only on that floor

and at the head and foot of the shaft if required.

• Without resetting the system proceed to another floor

and repeat the test, nothing should happen.

• Repeat as you feel necessary, to have a good sample.

• Again without resetting the system, find an override

switch and activate, nothing should happen.

• Have the system reset, any vents that opened should

close now.

• Check all smoke vent doors are close fitting and have

intumescent strips and smoke seals fitted.

National implications

• Some confusion in the industry in how these systems

should be programmed with inadequate cause and effect

testing.

Action so far

• BRE report (due to FOSI) sent to DCLG.

• Information brief sent through the National Operational

Learning Process.

• Addition into BS 7273-6 Code of practice for the

operation of fire protection measures – Interface

Systems.

• PAS 79 form to include cause and effect testing of these

systems.

Questions