The National Fire Protection Association's Canadian regional manager told Public Eye yesterday he still has "very serious concerns" with the provincial government's decision to allow the construction of six storey wood-frame buildings. Writing on his own behalf, Sean Tracey stated in an email that, even under ideal conditions, those buildings would have just one hour of fire resistance. By comparison, the current expectation in the National Building Code of Canada is "for continuous structures above three storeys to require 2 hour fire resistive construction." This, according to a report prepared by Mr. Tracey and submitted to the government on August 7, 2008.
Moreover, because "fires of today burn hotter and quicker than in the past due to the flammability and toxicity of contents," that resistance could be even less, continued Mr. Tracey in his email. And, "if the fire was to get into void spaces not protected by sprinklers" - such as between the walls - "we could see the entire structure compromised in a matter of minutes."
Mr. Tracey was also worried six storey wood-frame structures could be used to house assisted living facilities, where seniors "may have little chance to self-evacuate." And he expressed concern the government's hasn't evaluated if every fire department in the province would be capable of responding to blazes in six-storey buildings. "This could have tragic consequences," he warned.
As for the government's claim that six storey wood-frame buildings have "performed well" in Seattle and Portland - this, despite the fact no such structures exist - Mr. Tracey responded, "It is not correct to state that the absence of a significant failure is indication that the design is correct. Remember that the Titanic had a perfect sailing record up until it hit the iceberg."
Mr. Tracey is just the latest in a series of engineering, fire and earthquake experts to raise safety concerns about the the Campbell administration's decision to allow six storey wood-frame buildings - which takes effect on April 6, 2009. Government didn't respond to a request for comment by deadline. The following is a complete copy of the aforementioned report.
COMMMENTS REGARDING BC PROPOSAL TO INCREASE LIGHTWEIGHT FRAME CONSTRUCTION TO 6 STOREYS
Prepared by Sean Tracey
Canadian Regional Manager NFPA
7 August, 2008
The BC government has identified that it is considering comments regarding a proposal to permit six storey combustible construction in the province. Currently the BC Building Code (BCBC) is based upon the National Building Code of Canada (NBCC) which in 2005 became an objective-based code document. This limits combustible construction to three storeys.
This report intends to review this issue and provide comments on the proposal. They reflect the views of this author alone and not that of the National Fire Protection Association.
The current NBCC and therefore the BCBC permits alternative design solutions to be submitted to the authority having jurisdiction for approval so long as they demonstrate that they can meet an equivalent level of performance as in the current codes. The intent of going to an objective-based code in Canada was increase potential for innovation. It rests in the hands of the local AHJ whether to approve these or not with the onus on the submittor to prove that an equivalent alternative solution is presented. It is therefore currently possible to submit a design proposal for six storey combustible construction; however, it must be proven to the AHJ that the resulting design is equivalent to the current code.
The intent of the BC government is study whether the current BCBC can be amended to permit six storey combustible construction as an accepted solution. It is believed to only be considering applying this change to Group C Residential Occupancies although this has not been not clearly stated. Nor has it been stated that the intent is to reduce the fire performance requirements for six storey structures to the same as three story structures?
In 2005 the national Building Code of Canada went to an objective-base design. The intent was to link previous prescriptive code requirements to objectives. This would further make it easier for jurisdictions to introduce alternative solutions. Alternative solutions can be considered provided there is acceptable substantiation provided to the AHJ to accept this. The problem is that no clear administrative procedures have been developed and these are left to each AHJ to develop themselves. The general understanding is that a code submission must be able to prove that it is equivalent or better to the current requirements in the code. Under the current code a submission can be made for an engineered design and that could include a six storey combustible construction. A full detailed design submission must be made and this would be approved at the local level.
Currently there is no established procedure for how such a performance based design would be prepared. This was not included in the national model code and was left to the individual provinces to determine. British Columbia has not defined these procedures. NFPA in Chapter 5 of it NFPA 5000 Building Construction and Safety Code establishes procedures for this. It essentially states that a submission shall identify the expected performance criteria to be met, quantify these, then test the design to number of scenarios including fire performance. To date no one has identified that the same performance criteria are to be meet nor has proposed design be presented or verified for its equivalency. If the intent is to reduce the fire performance expectations for these structures then no one has prepared a cost-benefit analysis to quantify what the cost savings shall be against the expected increase in loss of life and property for these changes. (Note: the fire service in Canada has proposed numerous changes to building regulations such as mandatory sprinklers but have been rejected because of the lack of recognition of their cost benefit studies.) - as discussed later there are specific tests that have been conducted on fire performance that should be considered.
The concern is that expected building performance criteria must be established. Currently in the codes the expectations for continuous structures above three storeys to require 2 hour fire resistive construction. (Note: In BC there are examples of four storey construction where the first storey is concrete box and the three subsequent storeys are combustible. These are separated by 2 hour rated construction.) This is intended to prevent the structure from collapse and to provide adequate time for occupants to safely evacuate and the fire service to conduct interior search and rescue and fire attack. If a combustible structure is to be permitted it should not go below the requirements of:
* Provide structural sufficiency for occupant evacuation and fire fighter operations
* Minimize damage to the structure
* Limit or prevent damage to adjacent structures
An area of further concern should be for the value of property at risk and the need to preserve or reduce property losses. This is not a current requirement of the building code. It is a simplification but this is a matter between the insurance companies and the property owners. Increasing the height of combustible construction has the potential to increase property losses due to fire. This would likely increase insurance premiums for these properties - a cost borne not by the builder who may reap savings but the unwitting property owner. The property insurers in the province should be approached to see if the change would impact the premiums they charge for these properties. The province might therefore look at enhancing protection requirements or alerting potential owners to the impact this may or may not have on insurance premiums.
In North America the current relevant building codes, International Building Code, NFPA 5000 Building Construction and Safety Code, and the NBCC have generally used a system of tables to define maximum building heights and areas based on the type of occupancy and the method of construction. These tables have been developed through consensus by the fire and building communities and form the accepted requirements for building construction for fire safety and structural sufficiency since the 1950s. The buildings we are considering here are typically Type V combustible construction under NFPA 220. This would limit any of these occupancies to a maximum of four storeys provided it was protected throughout by a sprinkler system and has minimum protection of one hour fire resistive construction for its exterior walls, columns and floors. Where one hour fire performance is not provided the maximum height in most cases is restricted to three storeys. The same generally holds true in the NBCC and the IBC where the limitation is usually to three storeys when using combustible construction and a requirement for one hour fire resistive construction. The increase to beyond 3 or 4 storeys usually is limited to non-combustible construction with a two (2) hour fire resistance performance.
Fire Resistance in Construction
Fire resistance in construction is assigned to assemblies of light construction. These have been based on full scale performance testing of structures in recognized test centres. In the case of light frame construction it is important that the interior linings of the structure either stop or delay the spread of fire. As stated above the current code requirement could be amended to permit combustible construction but that the hourly fire performance must continue to be proven to meet the required two (2) hour fire resistance ratings for the exterior, the floors, and the bearing columns. This would be very difficult for wood to be able to meet this fire performance requirement as a quick review of the supporting materials in the NBC did not reveal any floor or load-bearing wall components with fire performance beyond one (1) hour.
It appears the only way that this can therefore be accommodated is to accept an increased risk within the code by reducing the fire resistance rating to one (1) hour in these structures. Will concrete and steel be accorded the same benefits? This raises serious concerns on structural sufficiency. Can occupants be expected to safely evacuate from such structures in the required time? Will additional fire protection measures be required to mitigate the increased risk? What impact will the reduced fire performance have on loss of life? Loss of property? What is the impact on insurance premiums to home owners of these properties? It is interesting to note that when added protection features are proposed to the NBC a requirement is a detailed cost-benefit analysis. Will a detailed cost-benefit analysis be required for what may be a reduction in the performance requirements of the BCBC? It would also be naÃ¯ve to believe that such a change could be limited to only BC as a similar proposal would likely be presented to the NBC.
There are currently at least one firm in BC that has product lines of intumescent paints that can be applied to wood that may increase its fire performance to the required two hour fire performance. No tests have been performed on floor and wall assemblies to determine of intumescent paints applied to these assemblies could result in increased fire performance. The BC government should consider approaching ARA Safety with funds to assess the ability of their intumescent products to increase the fire performance ratings of floor and wall assemblies.
NRC has done some tests to determine fire performance of certain wall and floor assemblies to increase their fire performance. It must be stressed that these assemblies require unique design and construction practices that may not be practiced in the province at present. Similarly, as reported in UK TF2000 study to assess increasing combustible construction heights, these design considerations are essential to ensure a fire in a compartment does not spread into the wall cavities.
Current Fire Tests and Research
Very little live fire testing has been undertaken on full scale structures up to six storeys. The approval of this code change is therefore going to rely upon scientific modeling and other means.
No scientific data or tests showing the ability of the combustible construction to adequate perform to the code requirements beyond 3 storeys has been presented for review. A review of international studies did reveal a 1999 study out of the UK entitled TF2000 Project.
In 1991 building regulation in the UK changed to become a performance-based approach. This increased opportunities for new designs if supported by proper engineering design. At least one key project was undertaken to consider the opportunities in increasing the allowable limits for combustible construction. This was the TF2000 Project.
Regulation changes in England and Wales in recent years mean that timber frame buildings can reach seven storeys without loss of economy from excessive fire protection requirements.
With the exciting opportunities this presents, comes the need to 'benchmark' the performance of timber frame construction and the need for more comprehensive design guidance for medium-rise timber frame buildings, particularly with regard to fire and disproportionate collapse. It was for this that the TF2000 project was created.
In this project a test was in 1999 to look at the fire effects on undertaken on a full scale fire involving a six storey wood frame building. A detailed report can be found on the web. A summary of the fire test was:
The fire was ignited in the living area of the flat and progressed to flashover after approximately 24 minutes. Initial burning was concentrated in the front of the living area closest to the ventilation opening. To accelerate the time to flashover the Fire Brigade was asked to intervene by breaking a single windowpane in the kitchen area. This took place 21 minutes and 30 seconds from ignition. Following flashover the Fireline boards over the windows to the floor above were subject to a heat flux of approximately 30kW/mÂ² (peak plume temperature in excess of 500Â°C). The timber frame of the window would, if exposed, have ignited. Peak temperatures in the living area of the fire flat reached approximately 1000Â°C and remained at this level until the test was stopped at 64 minutes having reached one of the planned termination criteria.
NOTE: In the author's opinion, a problem with using this particular test for substantiation is that the fuel load was a timber crib fuel load only. This does not reflect current fuel loads such as those found in Canadian homes and as supported by NRC research in studies such as the National research Council of Canada test such as the Fire Scenario Tests in Fire Performance of Houses Test Facility - Data Compilation Research Report: IRC-RR-208. The fuel load in this case was determined based on survey of Canadian homes and was designed to be a mixed load of lumber and plastics. This is believed to be more reflective of Canadian homes and the fires currently faced by the fire service. The result in the NRC case is a fire that flashes over in less then four minutes (24 minutes in the UK example) and temperatures of 813Â°C in 130 seconds in one scenario. This is a more challenging fire scenario than that presented in the UK study.
Conclusions from the TF2000 report included:
The compartment fire test met the stated objectives of the programme. The following conclusions may be drawn from an analysis of the data and from observations during and after the test.
* Derived values of time equivalence have demonstrated that the performance of a complete timber frame building subject to a real fire is at least equivalent to that obtained from standard fire tests on individual elements.
* Results indicate that fire conditions in the living room of the flat represented an exposure approximately 10% more severe than a standard 60 minute fire resistance test.
* The test has demonstrated that timber frame construction can meet the functional requirements of the Building Regulations for England and Wales and the Building Standards for Scotland in terms of limiting internal fire spread and maintaining structural integrity.
In meeting the requirements of the regulations and the objectives of the research programme a number of issues have arisen.
* The standard of workmanship is of crucial importance in providing the necessary fire resistance performance especially nailing of plasterboards.
* Correct location of cavity barriers and fire stopping is important in maintaining the integrity of the structure.
* This type of construction is one that, in the United Kingdom, has a relatively low market share generally and in medium rise terms is very recent. For this reason fire brigades are unlikely to be familiar with the type of construction details used. Clearly education on timber frame for these bodies is necessary.
* The issue of vertical flame spread from floor to floor via the windows needs to be addressed.
NOTE: The project was comparing the fire performance to only a one (1) hour fire performance requirement. It further identified the problem for vertical flame spread from floor to floor via the windows needs to be addressed. This should be a major concern as NRC testing performed for the City of Calgary and province of Ontario have both identified that flames would exit the window in the room of fire origin after around four minutes in design fire scenarios. This would ignite exposed materials on the outside of the window. In combustible construction this would wick up the outside of the structure thus putting more of the structure than the room or unit of fire origin at risk.
The comments also identified that concerns on the impact on fire fighting operations for the fire service. This shall be discussed in more detail below.
Fire Modelling - FireCam and Others
No fire modeling studies to coincide with this submission have been presented. These can easily be commissioned and should be considered. One model that can be applied is the National Research Council of Canada's FiRECAMâ„¢ model.
FiRECAMâ„¢ is a computer model for evaluating fire protection systems in residential and office buildings that can be used to compare the expected safety and cost of candidate fire protection options. More detailed information on the NRC model can be found at http://irc.nrc-cnrc.gc.ca/fulltext/nrcc43092/nrcc43092.pdf
The FiRECAM model produces two decision making parameters for the property. These are the Expected Risk to Life (ERL) and the Fire Cost Expectation (FCE). The ERL determines the number of expected fatalities per year for the structure and the FCE represents the total cost for a fire for the structure including all capital costs, maintenance costs, and expected fire losses. As all other jurisdictions have apparently accepted the sprinklering of these occupancies as the norm for fire and life safety the FCE factors were not studied in this report.
FiRECAM runs through a number of scenarios, using statistical data and established mathematical models. It then calculates the life hazard to the occupants for each scenario and multiplies this by the probability of that scenario occurring. The overall expected risk to life is sum of all probable fire scenarios in the structure.
A detailed review of a number of design scenarios using the FiRECAM model could quantify the increased risk factors in changing the fire performance requirements for buildings.
Sprinkler Systems NFPA 13 vs. NFPA 13R systems
Sprinkler systems if properly designed and installed can be very effective at suppressing or containing a fire. NFPA has compiled statistics over the years on the effectiveness of sprinklers. Automatic sprinklers are highly effective elements of total system designs for fire protection in buildings. Based on 2002-2004 fires reported to U.S. fire departments, when sprinklers cover the area of fire origin, they operate in 93% of all reported structure fires large enough to activate sprinklers. When they operate, they are effective 97% of the time, resulting in a combined effectiveness reliability of 90%. More detailed figures on the performance of sprinkler systems is attached as Annex A.
NFPA 13R systems are intended to cover residential occupancies up to 4 storeys. These new propose structures would no longer be acceptable under NFPA 13R and therefore would be required to be designed to NFPA 13 throughout the structure. This shall mean that all rooms and spaces shall now be sprinklered this would include attic spaces, all rooms, all closets, exterior balconies, etc. These would be areas that would have been excluded in residential construction up to and including four storeys.
NFPA 13 systems must be kept as the requirement. NFPA 13R systems are considered life safety systems and are not installed for property protection. They involve the use of residential sprinkler heads that are designed and listed to facilitate the early evacuation by occupants. They are not considered to be property protection sprinklers. Additionally masonry, concrete, and steel structures if built to this same height would also require to be designed to NFPA 13 requirements. There is no added protection over these other types of construction and therefore additional safety provisions must be found elsewhere.
A look at the Canadian demographics reveals that Canadian population is aging. Health Canada reports that Canada faces significant aging of its population as the proportion of seniors increases more rapidly than all other age groups. In 2001, one Canadian in eight was aged 65 years or over. By 2026, one Canadian in five will have reached age 65. Currently this age bracket is at high risk to injuries or fatalities from fire.
The BC government in 2005 introduced changes to address Assisted Living Centres in the province. Comments were submitted by this office for consideration on the inadequacy of the proposed changes to protect these at risk individuals. The changes did not address the fire safety when one considers the already higher loss of life in these properties. Of great concern is that many of these facilities will remain Group C occupancies or residential construction. Occupants will have a greater than average inability for self-preservation. This places a greater reliance on fire service to assist staff in evacuation of these facilities. With any reduction in fire performance and no guarantee of the fire departments response capabilities these at risk occupancies must not be permitted under the code.
Similarly, the design requirements for Assembly occupancies (Group A) and Care and Detention Occupancies require special safeguards. Group A occupancies usually represent the general public in large unfamiliar surroundings. Escape is contingent upon having adequate time to safely evacuate the personnel in a required time. No changes should be considered for this type of occupancy. Similarly, Group B occupancies rely on a defend in place concept. Occupants are either moved within the occupancy or enhance protection is provided to keep them in place during a fire. No reduction in fire performance should be considered for these occupancies.
Other types of occupancies should not be permitted to be of combustible construction these should include:
* Any Group C occupancy used as an Assisted Living Centre
* Any Group A Occupancy
* Any Group B Occupancy
Fire Department Concerns
In BC there is a wide variety of fire department response capabilities. The proposed structures could be built in any community in BC. Concern should be that just because the structures are permissible under the code - should not mean they can be built. Approvals of such structures must consider the fire department response capability. The codes in BC make certain assumptions already on the "adequacy of the fire department response" in regards to limiting distances but does not define these.
Concern should be raised that should such a structure be built does it effect or require a different fire department response? This was a concern raised in the TF2000 summary as stated above. As an example there is heightened concerns about fire entering into wall cavities and thus spreading beyond the room of origin to other floors. How many BC fire departments have infrared cameras to detect hotspots in wall cavities?
Does this now require aerial response? What happens if there is a delay? Fire department tools and resources to properly address such fires need to be confirmed before a council permits such construction in their area. Already we have seen White Rock as an example - high rise structures being imposed on a volunteer fire department and other communities without an aerial device having high rise. The fire service concerns are not met.
The trend in BC and across Canada is to the uniform application of the NBC. The problem is the NBC does not define what an adequate fire department response capability is and therefore structures that pose a significant challenge to even a career department with an excellent response time are being built in areas with a volunteer response capabilities. Of similar concern is that the core requirements of the NBC do not consider property preservation. If you can prove that all occupants can safely evacuate in the required time then the fire service should not be entering and it is a matter between the property owner and their insurance company. This runs counter to the raison d'etre of many fire departments who serve a valuable service to their communities in reducing property losses due to fire. It also increases the risk to the fire service who would attempt to reduce some of the property losses in these structures. If they do not perform interior fire attack are they exposing their communities to increased civil litigation? There is a serious potential disconnect between the minimums in the building code and community expectations.
A worst case scenario in analyzing the fire scenarios must be used. The proposal must assume that the building will be constructed in a community with a volunteer response and no aerial device.
The proposal to increased height limitation of combustible construction to six storeys under the code is of interest to the BC government and BC economy. It however has not been presented with any detailed scientific studies, performance based design submission, or fire modeling to show how it can be accomplished under the current codes despite the ability to submit such a proposal under the current codes.
It is believed that the only way this can be accommodated is to reduce the fire performance ratings of all buildings to one hour or less. This has significant impact on the fire performance and is expected to increase the loss of life and property. No detailed cost-benefit analysis has been performed on the submission.
Further detailed information needs to be provided including detailed testing to see if the minimum fire performance can be achieved without reducing the codes. As well the proposal should be restricted in its scope to only consider application in Group C, D, and E occupancies.
ANNEX A - FIRE PERFORMANECE OF SPRINKLERS
The following material has been taken from the NFPA Report U.S. EXPERIENCE WITH SPRINKLERS AND OTHER AUTOMATIC FIRE EXTINGUISHING EQUIPMENT dated June 2007. It is available for free public download at: http://www.nfpa.org/assets/files//PDF/OSsprinklers.pdf
Sprinklers in the area of fire fail to operate in 7% of reported structure fires large enough to
The other estimated failure rates shown in Table 3 are:
* 7% for wet pipe sprinklers,
* 13% for dry pipe sprinklers,
* 23% for dry chemical systems, and
* 5% for carbon dioxide systems
For major property classes and sprinklers, the estimated failure rates range from a low of 4% for residential properties to a high of 20% for storage properties. For storage properties, the estimated failure rates are 17% for wet pipe sprinklers and 26% for dry pipe sprinklers.
The majority of sprinkler failures occurred because the system was shut off.
Table 4 provides the percentages of reasons for failure, after recoding, by type of automatic extinguishing system and property use. For all sprinklers:
* 66% of failures to operate were attributed to the system being shut off,
* 16% were because manual intervention defeated the system,
* 10% were because of lack of maintenance,
* 6% were because the system was inappropriate for the type of fire, and
* 2% were because a component was damaged.