Download mid-rise combustible construction in ontario building

MID-RISE COMBUSTIBLE
CONSTRUCTION IN ONTARIO
BUILDING CODE ISSUES
Prepared For
RESCON and BILD
13 - 25 North Rivermede Road
VAUGHAN, ONTARIO
March 21, 2013
RBA File No. 13-053
© Copyright 2013 Randal Brown & Associates Engineering Ltd.
Randal Brown & Associates Engineering Ltd. is not responsible for any changes or revisions made to this document.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
March 21, 2013
13-053
Page i
TABLE OF CONTENTS
PAGE
EXECUTIVE SUMMARY ....................................................................................................................................................... 1
1.0
INTRODUCTION ..................................................................................................................................................... 2
2.0
BACKGROUND ........................................................................................................................................................ 3
2.1
2.2
GENERAL ...................................................................................................................................................................... 3
RESCON AND BILD .................................................................................................................................................... 4
3.0
DISCUSSION ............................................................................................................................................................ 5
3.1
DO THE FIRE SERVICES HAVE THE CAPACITY TO RESPOND TO FIRE INCIDENTS RESULTING FROM COMBUSTIBLE
CONSTRUCTION DURING CONSTRUCTION?............................................................................................................................... 5
RBA Commentary ....................................................................................................................................................................... 5
3.2
DOES THE FIRE SERVICES HAVE CAPACITY TO RESPOND TO FIRE INCIDENTS IN MID-RISE COMBUSTIBLE BUILDINGS
AFTER OCCUPANCY? .................................................................................................................................................................. 6
RBA Commentary ....................................................................................................................................................................... 6
3.3
WILL THERE BE AN INCREASE IN THE NUMBER OF FIRE INCIDENTS AS THESE BUILDINGS ARE OF COMBUSTIBLE
CONSTRUCTION? ........................................................................................................................................................................ 8
RBA Commentary ....................................................................................................................................................................... 8
3.4
HOW WILL INSPECTIONS DURING CONSTRUCTION BE AFFECTED? ........................................................................... 9
RBA Commentary ....................................................................................................................................................................... 9
3.5
HAS THE PERCEIVED RAPID COLLAPSE OF STRUCTURAL SYSTEMS BEEN ACCOUNTED FOR? ................................... 9
RBA Commentary ....................................................................................................................................................................... 9
3.6
WILL THE CONTINUITY OF FIRE SEPARATION BE COMPROMISED BY SHRINKAGE OF COMBUSTIBLE ELEMENTS? .. 10
RBA Commentary ..................................................................................................................................................................... 10
3.7
HAS PERFORMANCE DATA BEEN PROVIDED FOR CROSS LAMINATED TIMBER UNDER FIRE LOAD CONDITIONS? 10
RBA Commentary ..................................................................................................................................................................... 10
3.8
DOES THE PROVISION OF A BUILDING FACING ONE STREET IN A TYPICAL URBAN SCENARIO PROVIDE ADEQUATE
FIRE FIGHTING ACCESS WITH RESPECT TO A PERCEIVED INCREASED FIRE LOADING OF THE STRUCTURE? ......................... 11
RBA Commentary ..................................................................................................................................................................... 11
3.9
IS THERE A PERCEIVED GREATER RISK TO OCCUPANTS WITH SPECIAL NEEDS IN THESE PROPOSED BUILDINGS OF
COMBUSTIBLE CONSTRUCTION?............................................................................................................................................... 11
RBA Commentary ..................................................................................................................................................................... 11
3.10
IS THERE A CONCERN WITH ALLOWING EXIT STAIRS TO BE OF COMBUSTIBLE CONSTRUCTION? .......................... 12
RBA Commentary ..................................................................................................................................................................... 12
3.11
IS THERE AN INCREASED RISK TO FIREFIGHTERS AND OCCUPANTS WITH THE USE OF COMBUSTIBLE EXTERIOR
CLADDING? ............................................................................................................................................................................... 12
RBA Commentary ..................................................................................................................................................................... 12
3.12
IS THERE AN INCREASED DANGER TO ADJACENT STRUCTURES? ............................................................................. 13
RBA Commentary ..................................................................................................................................................................... 13
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
March 21, 2013
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TABLE OF CONTENTS (Cont'd)
PAGE
3.13
HAVE THE CHALLENGES OF RURAL FIRE DEPARTMENTS BEEN ADDRESSED FOR THESE LARGER BUILDINGS OF
COMBUSTIBLE CONSTRUCTION?............................................................................................................................................... 13
RBA Commentary ..................................................................................................................................................................... 13
3.14
IS THE FLOOR FIRE RESISTANCE RATING BEING REDUCED TO 1 H RATHER THAN 2 H WHICH WOULD BE REQUIRED
FOR A BUILDING OF NONCOMBUSTIBLE CONSTRUCTION OF THE SAME HEIGHT? ................................................................. 14
RBA Commentary ..................................................................................................................................................................... 14
3.15
WILL OTHER OCCUPANCIES BE PERMITTED IN THESE BUILDINGS? ......................................................................... 14
RBA Commentary ..................................................................................................................................................................... 14
4.0
SUMMARY .............................................................................................................................................................. 15
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
March 21, 2013
13-053
Page 1
EXECUTIVE SUMMARY
As a result of the ongoing evaluation of mid-rise combustible construction by the National Research
Council, RESCON (Residential Construction Council of Ontario) and BILD (Building, Industry, and
Land Development Association) have retained Randal Brown and Associates Engineering Ltd. to
provide commentary on concerns that have been expressed by the Fire Services and other
stakeholders to the proposed mid-rise combustible construction and to provide commentary on
these issues. This report addresses:
x
Safety of first responders,
x
Fires during construction,
x
Inspections during construction,
x
Structural integrity during fire,
x
Integrity of fire separations of combustible construction,
x
Fire department access,
x
Protection of occupants with special needs,
x
Protection of exits of combustible construction for first responders and occupants,
x
Equipment for fire fighting,
x
Adequate water supply,
x
Protection of adjacent structures from exposure fires,
x
Fire spread on the exterior of combustible buildings,
x
Adequacy of fire resistance rating of floors and structures, and
x
Permitted occupancy types.
This document is for use by RESCON and BILD
It is not intended for use by any third party or subsequent owners.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
1.0
March 21, 2013
13-053
Page 2
INTRODUCTION
The potential use of mid-rise combustible construction has been evaluated by the National Research
Council (NRC) since 2010.
As a result of the ongoing evaluation of mid-rise combustible construction by NRC,
RESCON (Residential Construction Council of Ontario) and BILD (Building, Industry, and Land
Development Association) have retained Randal Brown and Associates Engineering Ltd. to provide
commentary on concerns that have been expressed by the Fire Services to the proposed mid-rise
combustible construction and to provide commentary on these issues.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
2.0
BACKGROUND
2.1
General
March 21, 2013
13-053
Page 3
The potential use of mid-rise combustible construction in the National Building Code of Canada has
been under review for several years. The potential for mid-rise combustible construction was
prompted due to the submission of several code change requests to the National Research Council
for increased permitted heights of buildings of specific occupancies to be of combustible
construction. Following the initial presentation of the code change requests to the Standing
Committees, a Joint Task Group was formed in 2011 to review the submitted code changes and to
develop proposed changes for the National Building Code of Canada (NBCC) and the National Fire
Code of Canada (NFCC).
The Joint Task Group at the NRC consisted of many stakeholders concerned with the increased
height of combustible construction. These included representatives of Fire Marshalls, Fire
Departments, architects, engineers, and the original code change proponent, the Canadian Wood
Council. As well, many observers participated in the meetings of the Joint Task Group to ensure
that their opinions and interests were heard.
After preliminary meetings of the Joint Task Group, four (4) sub-task groups were formed to
address specific areas of the proposed changes. These sub-task groups are:
x
STG on Fire Protection and Safety – responsible for Subsection 3.2.2 Building Blocks and the
construction Articles.
x
STG on Structural, Earthquake and Mechanical Systems – responsible for Part 4 and
structural and earthquake design.
x
STG on Building Envelope and Environmental Separation - responsible for Part 5 and
building science requirements, and
x
STG on Fire Code, Construction and Demolition – responsible for protection during
construction and maintenance of fire separations.
Following review by the sub-task groups, the Joint Task Group presented a series of proposed
changes to the Standing Committee on Fire Protection and the Standing Committee on Use and
Egress. As the proposed construction exceeds three storeys in building height, all Standing
Committees responsible for Parts 3, 4, and 5 are responsible for reviewing the proposed changes
including the National Building Code Standing Committees on Structural Design and
Environmental Separation.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
2.2
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RESCON and BILD
Following the development of the proposed changes by the National Research Council Joint Task
Group to permit six storey combustible construction, RESCON and BILD have indicated that the
Fire Services has expressed concerns and have outstanding questions regarding this proposed
change of the National Building Code. As such, RESCON and BILD have retained Randal Brown
and Associates Engineering Ltd. to review the concerns that have been expressed by the fire services
and to provide commentary on these issues.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
3.0
March 21, 2013
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Page 5
DISCUSSION
The following addresses concerns raised by Fire Services with respect to mid-rise combustible
construction currently being proposed under the National Building Code of Canada.
3.1
Do the Fire Services Have the Capacity to Respond to Fire Incidents Resulting from
Combustible Construction During Construction?
RBA Commentary
During construction, measures are being proposed to be implemented into the National Fire Code
to address risks to emergency responders, construction crews and adjacent properties. In general, it
must be remembered that the National Fire Code and in Ontario the OHSA regulations for
construction projects, already contain many provisions to address potential fire hazards and
provides solutions to reduce risk at construction sites.
Recognizing that there is always a potential for fire incidents during construction, from any type of
combustible construction, the National Fire Code is proposing to contain measures to:
x
Improve Fire Department access during construction. It is proposed that a stairway (rather
than a construction ladder) be provided as each new floor is added to allow for first
responder access.
x
Ensure proper fire department access is provided to the construction site for the fire
department vehicles. An appendix note is proposed to be added that the construction fire
safety plan for the site is to take into consideration the elevation of the fire access route to the
first storey of the building under construction to facilitate firefighter access to the roof.
x
Provide water supply to the construction site when combustible materials arrive on-site. It is
proposed that the provision of this water supply would be required when combustible
construction material arrives on the job site.
x
Implement restrictions on smoking on construction sites to have designated smoking areas
be at least 3 m away from combustible construction materials. It is also proposed that no
smoking is permitted in the building(s).
x
Restrict the location of refuse containers to minimize the potential for fire spread from a
refuse container into a building under construction. The proposals are to have the containers
for combustible refuse located 3 m from exits – this will improve exits from buildings under
construction for workers and improve access into the building under construction for first
responders. This same 3 m limit is proposed to be applied between roofing kettles and exits
or means of egress.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
3.1
March 21, 2013
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Page 6
Do the Fire Services Have the Capacity to Respond to Fire Incidents Resulting from
Combustible Construction During Construction? (Cont’d)
RBA Commentary (Cont’d)
x
Ensure proper fencing or a barricade is provided around the construction site to minimize
unwanted / unauthorized access, which reduces the potential for vandalism/arson.
x
Ensure that proper signage be provided to help reduce the response time. It was
recommended that signage giving stair location, street address and floor level be provided
on each floor and that signage indicating the street address be provided at fire department
access route entrance. The proposed changes arose as the fire services identified a concern
that a fire in any building under construction has the potential to get out of control, since
buildings under construction don’t have fire protection or detection systems.
As well, it should be noted that the increased use of plastic tubing for plumbing and plastic piping
for drains reduces the need for soldering and brazing on job sites.
3.2
Does the Fire Services have Capacity to Respond to Fire Incidents in Mid-Rise
Combustible Buildings After Occupancy?
RBA Commentary
Several factors must be considered in evaluating this scenario.
x
These buildings are proposed to be provided with a minimum 1 h fire resistance rating for
the structure, including the roof and for any mezzanine. Note that with the height limits
imposed on these buildings, it is unlikely that more than one mezzanine will be provided in
the building.
x
These buildings are proposed to be provided with electrically supervised automatic sprinkler
protection designed to NFPA 13. As well, proposals have been included to require
automatic sprinkler protection on exterior balconies which are over 610 mm in depth from
the exterior wall. The provision of automatic sprinkler protection serves to both provide
early warning to the occupants, early warning to the Fire Services by way of a listed central
station, and serves to control a fire in the building prior to it spreading beyond the space of
origin.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
3.2
March 21, 2013
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Page 7
Does the Fire Services have Capacity to Respond to Fire Incidents in Mid-Rise
Combustible Buildings After Occupancy? (Cont’d)
RBA Commentary (Cont’d)
x
Measures are being proposed in the National Building Code to ensure that adequate fire
department access is provided to the building for the Fire Services. Currently, the NBC
requires any sprinklered building to face a street or access route that is located within 15 m
of the principal entrance. As the proposed combustible mid-rise buildings are required to be
sprinklered, they will be required to face one street or access route, but to achieve this, the
Code will also be requiring 25% of the building perimeter to be within 15 m of the street or
access route in accordance with Article 3.2.2.10 and Subsection 3.2.5 of the National Building
Code.
x
Limitations have been proposed on the elevation difference between the fire access route and
the first storey. As well, limitations are being proposed in the construction requirements
limiting the distance between the fire access route and the uppermost floor level (currently
proposed at 20 m). It should be noted that this is to the uppermost floor level and not the
uppermost storey. In this manner, it is not possible to use mezzanines in order to increase
the building height. This limitation on the distance from the fire access route to the
uppermost floor level has been included to provide fire fighting streams to the upper floors.
x
The Ontario Building Code requires that an adequate water supply be provided to a building
for Fire Services. Appendix material in the OBC provides direction to the designers on the
quantity of water required in the event that the building is located in an area which is not
serviced by a municipal water supply. For sprinklered buildings, such as these mid-rise
combustible buildings, the OBC recognizes that the sprinkler and hose stream supply
demands required in NFPA 13 are sufficient.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
3.2
March 21, 2013
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Page 8
Does the Fire Services have Capacity to Respond to Fire Incidents in Mid-Rise
Combustible Buildings After Occupancy? (Cont’d)
RBA Commentary (Cont’d)
x
It is foreseen that most mid-rise combustible buildings will be constructed in areas serviced
by a municipal Fire Department. While some of these may be volunteer fire services, it must
be remembered that automatic sprinkler protection is being required within all of these
buildings.
- In remote areas where mid-rise (six storey) combustible buildings may be built where the
Fire Services may not be provided with a ladder truck, the use of a monitor and nozzle will
likely reach the top floor (depending on conditions such as pressures, wind, etc). It must
be remembered that building is provided with automatic sprinkler protection.
- Regarding fire fighting capability, the fire services indicated to the JTG that the safest
means to fight a fire in these buildings would likely be through an exterior fire attack. It is
for this reason that the JTG spent considerable time in addressing street access and
limitations on roof construction. It should be remembered that an internal attack is still
possible and will be at the discretion of the responding fire crews.
3.3
Will There Be An Increase in the Number of Fire Incidents as These Buildings Are of
Combustible Construction?
RBA Commentary
National Fire Incident Reporting System (NFIRS) data does not show that fire incidents are related
to the type of construction, but rather to the use and occupancy of the building. As such, it is
anticipated that the number of fire incidents will not increase just because these buildings are of
combustible construction.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
3.4
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Page 9
How Will Inspections During Construction Be Affected?
RBA Commentary
As these buildings will be constructed under Part 3 of the Building Code, they will be required to
have professionals, such as architects and engineers responsible for the design and inspections.
These professionals will be responsible for general review. As well, a majority of these buildings
are anticipated to be constructed using engineered wood products including pre-manufactured
panelized walls and floor elements, such as cross-laminated timber panels, this will provide for a
high quality of construction and maintain tighter control on structural design tolerances.
It should also be noted that design guidelines can be developed to assist authorities and designers
and are likely to be similar to the guidance document developed and published by the Association
of Professional Engineers and Geoscientists of British Columbia (APEGBC) in response to the
changes in the British Columbia Building Code in 2009 to permit mid-rise 6-storey residential
combustible construction.
3.5
Has the Perceived Rapid Collapse of Structural Systems Been Accounted For?
RBA Commentary
While it may be possible for these buildings to be constructed of traditional wood frame
construction designed in accordance with Part 4, as part of the Code requirement, the structural
elements including the floor assembly and load-bearing elements are required to have a 1 h fire
resistance rating. This requires that the assemblies, when exposed to a standard fire test, exhibit the
ability to carry full design loads during the fire for that time period, without failure. This passive
structural fire resistance will most likely be provided by a provision of fire rated drywall
membranes installed as wall and ceiling finishes.
It is also foreseen that some of these buildings will be constructed of cross-laminated timber
construction, in which case, drywall encapsulation of combustible CLT elements may be used,
unless it has been shown that unprotected CLT elements of greater thickness can provide the
required fire resistance rating without any specific gypsum membrane protection. Such protection
would have to be based either on results of standard fire resistance testing or provision of an
alternate solution that calculates the fire resistance rating based on the structural loading and
charring rates for the CLT elements. It is to be remembered that electrically supervised automatic
sprinkler protection is provided throughout this building in accordance with NFPA 13 to limit the
growth and spread of a fire.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
3.6
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Page 10
Will the Continuity of Fire Separation be Compromised by Shrinkage of Combustible
Elements?
RBA Commentary
The requirement for ongoing maintenance of the continuity of fire separations is addressed by the
Fire Code. This includes whether the damage to the fire separation would be caused by any
building movement, including shrinkage, penetration by a service element, or mechanical damage
to a fire separation. As previously noted, a majority of these buildings are anticipated to be
constructed using engineered wood products including pre-manufactured panelized walls and floor
elements, such as cross laminated timber, and this will provide for an improved quality of
construction and maintain tighter control on structural design tolerances, which will result in much
less shrinkage than would be experienced with traditional wood frame construction.
3.7
Has Performance Data Been Provided for Cross Laminated Timber Under Fire Load
Conditions?
RBA Commentary
Fire research has been conducted at the National Research Council with stakeholders to provide
data on fire resistance ratings on cross laminated timber wall and floor assemblies under fire load
conditions. As well, the building codes allow for the use of alternate solutions or alternate methods
to address the fire resistance rating of cross laminated timber. Char rates for timber have been
established for many years.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
3.8
March 21, 2013
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Page 11
Does the Provision of a Building Facing One Street in a Typical Urban Scenario Provide
Adequate Fire Fighting Access with Respect to a Perceived Increased Fire Loading of the
Structure?
RBA Commentary
As previously noted, the fire loading of a building would come from the contents of the structure,
rather than from the actual structural elements. The structural elements are generally protected by
fire rated drywall in addition to electrically supervised automatic sprinkler protection. As well,
measures have been implemented into the proposed code changes to address firefighting issues of
concern. These measures include:
3.9
x
As the building is required to face one street, defining that this is equal to 25%
of the building perimeter required to be located within 15 m of a street or
access route. (3.2.2.10),
x
Limitations on the use of combustible exterior cladding on the fifth and sixth
storeys of these buildings,
x
Requirement of sprinkler protection on exterior balconies to limit exterior fire
spread.
x
Limitations on the Class (combustibility) of the roof covering when the roof is
above a specific height,
x
Restrictions on the construction (combustibility) of the entire roof assembly
when it is above a specific height, and
x
Provision of a fully sprinklered building designed to NFPA 13.
Is There a Perceived Greater Risk to Occupants with Special Needs in These Proposed
Buildings of Combustible Construction?
RBA Commentary
The Building Code currently addresses occupants with special needs by provisions in Article 3.3.1.7.
One of these provisions is the installation of automatic sprinkler protection throughout the building
to provide protection in place for occupants with special needs.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
3.10
March 21, 2013
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Page 12
Is There a Concern With Allowing Exit Stairs to be of Combustible Construction?
RBA Commentary
The actual stair landings and stair treads (the exit stair) are constructed within a fire rated stair
enclosure. The exit stair enclosure itself is proposed to be constructed using a 1 h fire separation.
With this level of passive fire protection limiting fire spread into the exit stair, and as the building is
provided with automatic sprinkler protection to control the fire growth and fire spread, the JTG
considered discussed that there was no significant risk for the exit stairs to be of combustible
construction. It is understood that a fire department, in staging to fight a fire will use the stairs
below the fire floor in approaching the fire.
It should be noted that the Codes currently permit combustible stairs (the exit stair itself, and the
exit stair enclosure) to be of combustible construction in residential buildings up to four storeys in
building height where the building is provided with an automatic sprinkler protection designed to
NFPA 13R, which requires less firefighting water supply and allows more unsprinklered spaces
than otherwise permitted by NFPA 13.
3.11
Is There an Increased Risk to Firefighters and Occupants with the Use of Combustible
Exterior Cladding?
RBA Commentary
The type of exterior cladding addresses the risk of fire spread on the exterior of the building which
may or may not extend to the interior of the building if uncontrolled. The proposed code changes
have proposed limitations on the type of exterior cladding on the fifth and sixth storeys of these
buildings. The proposed code changes would require that the exterior cladding on the fifth and
sixth storeys be either non-combustible or comply with CAN/ULC-S134 for exterior cladding.
The S134 test is a vertical exterior spread test which simulates an interior fire projecting through an
exterior window and measuring the extent of flame travel on the exterior wall, as well as measuring
the heat-flux from the exterior wall construction. As such, limitations have been placed on the
cladding on the fifth and sixth storeys to recognize the firefighters potential difficulty in reaching
these floors.
As well, the proposed code changes have included for automatic sprinkler protection on any
exterior balconies or decks which exceed 610 mm in depth as the contents on an exterior balcony
may pose a fire ignition source to the exterior cladding.
It should also be remembered that the S134 test is run without automatic sprinkler protection on the
interior of the test furnace while the subject building’s would be provided with automatic sprinkler
protection.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
3.12
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Page 13
Is There an Increased Danger to Adjacent Structures?
RBA Commentary
The spatial separation requirements of the current building code would be required to be met for
these buildings. It should be noted that the current spatial separation requirements in
Subsection 3.2.3 of the Building Code are not driven by the type of construction of the building, but
rather by the occupancy type and whether or not automatic sprinkler protection is provided.
As well, measures have been implemented through the Fire Code such that measures have been
taken to reduce the risk of a fire during construction and the potential exposure to adjacent
properties.
3.13
Have the Challenges of Rural Fire Departments Been Addressed for These Larger Buildings
of Combustible Construction?
RBA Commentary
It may be foreseen that rural fire departments, which may be volunteer or part full-time / part
volunteer fire departments may have less time for search and rescue in buildings which may result
from a longer turnout time and response time.
To assist all fire departments in fires in buildings of these heights, the proposed changes to the
NBCC have required that they be provided with electrically supervised automatic sprinkler
protection. This will assist to control the fire in the suite of origin in conjunction with the
compartmentation requirements already incorporated in the Building Code for residential
occupancy.
In addition, water supplies are still required to be provided. It is understood that the requirements
in the Ontario Building Code for provision of an adequate water supply may provide more
guidance than what is currently in the National Building Code of Canada.
Regarding whether fire departments have the necessary equipment to address the additional two
storeys in building height, this would be an issue whether the buildings are of combustible or
noncombustible construction. It should be remembered that for these buildings, in addition to the
provision of automatic sprinklers, they will be provided with a standpipe and hose system for
interior fire attack.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
3.14
March 21, 2013
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Page 14
Is the Floor Fire Resistance Rating Being Reduced to 1 h Rather than 2 h Which Would Be
Required for a Building of Noncombustible Construction of the Same Height?
RBA Commentary
Currently, the proposals for combustible mid-rise construction are to permit sprinklered
5 and 6 storey combustible Group C and Group D buildings, designed with a 1 h fire resistance
rating on major structural elements.
For similar 5 and 6 storey sprinklered buildings of
noncombustible construction, the Code currently requires only a 1 h fire resistance rating. In
evaluating the proposed change to the National Building Code for Group C and Group D
occupancies, the Joint Task Group looked at the building areas currently permitted for five and six
storey noncombustible buildings and significantly reduced them. In doing so, the Joint Task Group
followed other area / height provisions in the Building Code which were based on being tied to a
total building volume, regardless of building height. The proposed permitted areas for Group C
and Group D combustible mid-rise buildings are, respectively, limited to ¼ and 2/5 the areas
permitted for similar buildings of noncombustible construction.
Other major occupancy uses such as Group A, Division 2, and Group E and Group F, Division 3, are
proposed to be permitted in either the Group C or Group D mid-rise combustible buildings, but
only on lower storeys.
Along with these specific occupancy limitations, and when considered with respect to the other fire
protection measures being implemented for these buildings, the provision of a 1 h fire resistance
rating for these sprinklered five and six storey buildings of combustible construction for residential
and business occupancies, was deemed to provide a level of safety and protection that meets the
objectives of the NBC and is comparable to that which is currently provided in the Code. It should
be noted that in increasing from four storey to six storey Group C residential buildings, the
automatic sprinkler protection has also been increased from that permitted by NFPA 13R for
residential sprinkler protection for 4-storey buildings, to the automatic sprinkler protection required
by NFPA 13 which applies to all occupancy types and building sizes.
3.15
Will Other Occupancies be Permitted in These Buildings?
RBA Commentary
In evaluating the proposed code changes, the Joint Task Group reviewed the provision of other
occupancy types on lower floors, recognizing the need for urban design to incorporate other uses to
complement streetscapes. As noted in Section 3.14 above, while these occupancies on lower floors
are proposed to be permitted to be constructed of combustible construction in accordance with
Articles 3.2.2.50 or 3.2.2.57, these are of significantly reduced building areas than what would be
permitted for a six storey noncombustible building.
Randal Brown & Associates Engineering Ltd.
Mid-Rise Combustible Construction in Ontario - Building Code Issues
4.0
March 21, 2013
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Page 15
SUMMARY
In evaluating the proposed change to permit five and six storey buildings of combustible
construction, the Joint Task Group reviewed the risk factors during construction, as well as the risk
factors during occupancy. Measures were implemented in the proposed code changes to the
National Building Code of Canada and the National Fire Code of Canada to address these issues.
It is my opinion that these proposed changes to the NBCC and the NFCC serve to address the life
safety and fire protection issues with the proposed permission for five and six storey buildings of
combustible construction of Group C residential and Group D business occupancies.
Respectfully Submitted,
Randal G. Brown, P.Eng., P.E., BDS, FSFPE
Consulting Engineer
President
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