Fire Trends- Ducting and Timber Frame€¦ · 30% of non Residential fires are in small takeaways , restaurants and shops. Difficult to ident\爀倀爀椀洀愀爀礀 䌀愀甀猀攀ⴀ
Primary Cause- Cleaning• 30% of non Residential Fires• Poor cleaning Programs or Shine
and sign• Flare ups or Cooking fires• Grease has insulating properties• Thermal degradation• Hydrolysis
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30% of non Residential fires are in small takeaways , restaurants and shops. Difficult to ident Primary Cause- Cleaning Poor cleaning Programs , if at all – TR19 programs are rarely applied yearly if you are luckly Shine and sign Flare ups or Cooking fires ignite grease deposits in ducting But also some concerns of grease build up requiring only small spark to ignite Grease has insulating properties- heats up during cooking over the day – spark hits Thermal degradation- some Studies show Thermal degradation- EG corn oil Flash point reduces 25 degrees to 227 deg C after 8 heating cycles. Not far off average cooking temperatures 200 . All it needs is a flame. Hydrolysis- Hydrolysis when cooking with wet foods, chips etc. lowers these values also
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Extreme example of build up
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A fire from basement to roof level This fire started in a basement area and spread through the building, causing damage to the basement, the ground floor, the first floor, the stairwell, the roof and the entire course of the ducting. The fire needed 6 fire engines and 30 fire fighters to bring it under control. As the roof was damaged, after the fire, emergency contractors were needed to prevent further significant damage from the weather. This would have resulted in a very large repair bill as well as lost business.
Poor Design
• Cleaning access 3M• Unprotected runs through
compartments and through residential
• Lack of FR to these routes• Lack of access for cleaning In
these routes
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In order to enable a grease extract ductwork system to be fully cleaned, access doors must be installed within the system at minimum intervals Of 3m
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Poor installation, Extract canopy cut into Ceiling plaster board
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Fitting to underside of Flat floor boards
Solid Fuels and Ducting
• Charcoal, wood• Embers entrained• High risk Combination
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High risk combination of Grease , Embers and air flow
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Indian restaurant Westminster. Posh housing block above
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30K Air handling unit – reduce fumes and smells
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Paper filter as spark arrest!!!
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Jamie Oliver's union Jack Covent garden- fire 1 30m duct run under site Introduced drencher system for spark arrest
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Covent garden fire 2 Blowing onto tiles
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Jamie's Barboccea fire 3
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Note wood log at rear of Pizza oven, The group went back to Gas fired only after these
Suppression For solid fuels?• In line suppression water, CO2, dry
powder• Systems well developed in Dust and hot
works extract systems• Poor understanding in Kitchen Fume
extract systems• Some bespoke systems• Spark arrest- centrifugal and drencher
systems
Timber Framed Construction• 1990’s more popular due to speed
and cost• 1 in 4 projects are Timber Framed• Water tight in 5 weeks compared
with 12 weeks for brick and block• Environmentally friendly • CO2 footprint much lower
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Positives
Timber Framed Construction • 1983 World in Action Expose
– Workmanship affected the industry for 20 years
• Different uses Hotels, Sheltered housing, residential under 18m.
• Hi rise CLT – reservations
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18m can be put on top of per existing traditional CLT timber buildings going Higher , Protected shaft out of wood?
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All aware of problems with pre compartmented Essentially they are a big pile of well ventilated wood
Risks After Occupation
• Cavity barriers and compartmentation critical
• Building Movement• Concealed Fire spread• Structural stability
compromised
Passive fire protection -objectives
•Building needs to remain standing..•Fire shouldn’t spread between buildings•Restrict the spread of fire within a building•Restrict unseen spread of fire and smoke
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The degree of sub-division that should be provided by fire compartmentation will be dependent on: The use of the building. The fire load in the building. The height of the building. The availability of a sprinkler system
Focus: Blocks of flats• Sleeping risk• Defend in place
strategy• Reliance on passive
fire protection measures
• Concept of the ‘burn out box’
Cavity Barriers
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Critical to Timber frame compartmentation are the Cavity Barriers Compartment Wall Compartment Floor Roof
Summary: The fire was first discovered on the external right hand side of the column of bay windows at first floor level, which were located on the front left hand side of the property. Initially, two fire engines During the cutting away operations smoke was seen by crews further to the right of the visible area of fire, smoke was also noted within the property, The fire appeared to have originated in the wall void on the left hand side of the entrance lobby at ground level, possibly caused by an electrical fault and spread up through the void into the loft and along inside the left hand side of the front wall where it breached the wood surrounding the bay window
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Fire damage to right of windows from first to third floor.
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Fire damage within wall on left hand side of staircase, ground floor.
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Fire damage within wall on left hand side of the communal staircase, first floor.
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Fire damage within wall on left hand side of staircase, second floor.
Bennett Close –(TF Example)• Built 2006• Timber frame• 15 pump fire• Missing cavity
barriers• Fire spread to roof
within around 40 minutes
• Block demolished
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Built 2006 Timber frame 15 pump fire Missing cavity barriers Fire spread to roof within around 40 minutes Block demolished
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Hounslow Benett Close The fire, two years after the block was built, spread quickly. Eye witness statements indicate that within 40 minutes of first identifying the fire in the flower bed, smoke was seen issuing from the roof structure Upon arrival of the crews, fire was evident within the cavities with fire/smoke visible through light fittings which penetrated into the cavity, as well as fire evident externally from airbricks within the cavity. The result from the disposal of a single cigarette was clearly disproportionate, resulted in the loss of the entire block with structural collapse occurring at around the four hours mark. The fire spread due to inadequate compartmentation. This was due to poor fire stopping/ lack of fire protection in: 1) riser cupboards, 2) services above the ceiling tiles, and 3) walls between flats, and 4) fire doors.
Piper Way
• Fire Started in cupboard Common parts
• Spread up to roof• Multiple rescues
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Fire spread in common parts Trapped all residents on 3rd / 2nd floor
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Fire spread in common parts Trapped all residents on 3rd / 2nd floor
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Piper way Ilford
Solutions?
• Difficult to identify Problems• Watch for movement• Building control• Remedial Solutions?
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Difficult to Identify Cavity barrier problems problems until there is a fire Watch for movement , internal surveys? The industry need to ensure competence of installers of fire stopping (that’s a whole other story) and cavity barriers Building control, Approved inspectors Inspections at this critical stage
Construction Competence
• Fitting (if at all). • Location• Brick layers
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-Sometimes not fitted properly because they are awkward, time consuming and expensive to fit. - SnotsBrick layers remove them as they push out face bricks if cavity is tight loose brick laying mortar falls onto barrier and dislodges allowing smoke and fire spread. A gap of two fingers is enough to allow significant Fire and smoke travel
Competence of Installers
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Most fire Safety professionals have seen this standard of workmanship Its much hard to see in a sealed Cavity
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Just to provide Balance- We Occasionally see this , Labelled and signed by competent installer, this is the way to go.
What should I consider?
• Potential risk to occupants• Any risk to attending crews• Building may no longer support
defend in place strategy• May need to adopt a common
