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The wood-frame conundrum


February 14, 2012
By en Garis Joseph Clare and Karin Mark

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Sprinkler systems appear to mitigate the risks associated with constructing taller wood-frame buildings, according to a new study.

Sprinkler systems appear to mitigate the risks associated with constructing taller wood-frame buildings, according to a new study.

FFIC-woodframe 
This six-storey wood-frame building in Prince George, B.C., burned in May 2011. Photo by Stephanie Tracey, Photography West


 

The report, Sprinkler Systems and Fire Outcomes in Multi-Level Residential Buildings, was released in early January by the University of the Fraser Valley (UFV) school of criminology and criminal justice’s Centre for Public Safety and Criminal Justice Research in Abbotsford, B.C. It was authored by Len Garis, fire chief for the City of Surrey, B.C., UFV adjunct professor and president of the Fire Chiefs’ Association of B.C., along with Dr. Joseph Clare, Strategic Planning Analyst for the Surrey Fire Service.

The intent of the study, which evaluated the historical fire-protection performance of sprinkler systems in multi-level residential buildings in B.C., was to anticipate how these fire safety systems would perform in six-storey wood-frame buildings.

Six-storey wood-frame buildings have been permitted in B.C. since 2009, following changes to the provincial building code (from four storeys previously) that included requirements for enhanced fire-protection systems, including sprinklers. Ontario is also considering changes to its building code to allow for six-storey wood-frame buildings for residential, business and other uses.

The building code changes raised a number of concerns among some members of British Columbia’s fire industry, including:

  • Greater fire risk than existing wood-frame buildings,
  • Strain on resources, particularly in areas served by volunteer departments, and
  • Risks related to infrequent fire safety inspections in some communities.

However, the UFV study did not find evidence to support these concerns. In fact, the study suggests that new six-storey wood-frame buildings should be safer than older, shorter wood-frame buildings, given that the amended building code requires them to be fully sprinklered to a higher standard (NFPA 13) than previously required, and to be constructed with a range of other built-in fire protection systems, such as non-combustible exterior cladding and the use of electromagnetic hold-open door devices that release in the event of a fire.

Study results
The study analyzed 1,942 fire incidents in multi-level apartment and townhouses that occurred in British Columbia between Oct. 5, 2006 and Oct. 5, 2011. Overall, 565 (or 29.1 per cent) of the incidents occurred in completely sprinklered buildings. The incidents occurred in 101 different locations, including urban, rural and First Nations communities.

In general, the fires started in similar locations in the buildings, regardless of whether they were sprinklered or unsprinklered – approximately 40 per cent originated in kitchens or cooking areas.

Analysis of the data showed that sprinklered buildings offered significant improvements in fire-safety protection – there were far fewer deaths and injuries, reduced spread of fire, and less need for fire department intervention.

The odds of a death in a fire in an unsprinklered building were 11.9 times greater than the odds for fires in sprinklered buildings. The death rate was 1.8 deaths per 1,000 fires in sprinklered buildings compared to 21.1 per 1,000 fires in unsprinklered buildings.

The odds of injury in a fire in an unsprinklered building were 2.9 times greater than for fires for sprinklered buildings. The injury rate was 44.2 injuries per 1,000 fires in sprinklered buildings, compared to 127.1 per 1,000 fires in unsprinklered buildings.

More than 21 per cent of fires in sprinklered buildings were extinguished by sprinkler systems. These fires never extended beyond the floor of origin and were contained to the room of origin 96.2 per cent of the time. By comparison, 12.7 per cent of the fires in unsprinklered buildings extended beyond the floor of origin, and 18.8 per cent extended beyond the room of origin.

Nearly 20 per cent of sprinklered building fires required fire department involvement, compared to 39 per cent in unsprinklered building fires.

Sprinkler systems performed the same in both urban and rural areas. Fires in sprinklered buildings served by volunteer, paid on-call or unclassified fire services were contained to the room of origin 100 per cent of the time.

The study also noted that previous UFV research did not identify a relationship between the timing of the most recent fire safety inspection prior to a fire (more or less than one year) and the severity of fires, injury or death. These findings were based on an examination of incidents of fire and injury or death that occurred in 265 inspectable residential properties between 1998 and 2003.

Moving forward
In light of this data, the UFV study recommends continued movement towards a “systems approach” to managing risk, with an emphasis on re-evaluating the risk posed by existing unsprinklered wood-frame buildings, and addressing problems with the system comprised of fire suppression, building codes, enforcement and public education/human factors.

The study now adds to the body of research around fire risk and suppression in wood-frame buildings that can be referenced by fire-service agencies across the country in making evidence-based decisions.

“Based on the evidence in this report, fire-protection systems will more than mitigate the risks associated with the extra two storeys,” noted Vancouver Fire Chief John McKearney. “The improvements to fire-protection systems we’ve seen in the building code are the key to making these changes work.”

The Province of Ontario has also indicated it would introduce strengthened fire-safety measures in conjunction with building code changes to accommodate six-storey wood-frame buildings.

According to the Ontario Ministry of Municipal Affairs and Housing website, “The potential changes include fire-safety measures which would help ensure that the building code requirements for six-storey wood frame buildings will perform at least as well as or better than buildings currently permitted under the building code, such as four-storey wood frame buildings and six-storey non-combustible buildings.”

The full report is available for review at www.ufv.ca (Centre for Public Safety and Criminal Justice > Reports and Publications) and at www.surrey.ca .


Len Garis is the fire chief for the City of Surrey,B.C., and is an adjunct professor in the School of Criminology and Criminal Justice at the University of the Fraser Valley and a member of the Institute of Canadian Urban Research Studies , Simon Fraser University. Contact him at lwgaris@surrey.ca
Dr. Joseph Clare, Strategic Planning Analyst for the Surrey Fire Service in British Columbia, is an associate professor in the Crime Research Centre, University of Western Australia, and a member of the Institute of Canadian Urban Research Studies at Simon Fraser University in British Columbia. Contact him at jclare@surrey.ca
Karin Mark is a former newspaper reporter who writes for publications and corporate clients in Greater Vancouver, B.C.


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