Concrete Firewalls Still the Standard
The 1995 National Building Code of Canada (NBCC-95) and the 1997 Ontario Building Code (OBC-97) required that all firewalls be constructed of masonry or concrete. Fire performance and structural integrity were thereby assured.
Despite strong objections by the concrete/ masonry industries and others during development of the objectivebased 2005 NBCC, a new provision in the NBCC05 permits a firewall having a fireresistance rating not more than 2Hr. to be constructed of materials other than concrete or masonry.
The Ontario Building and Development Branch, however, found arguments against this change by the Canadian Concrete Masonry Producers Association (CCMPA) to be very compelling. Despite the commitment by all provinces to integrate the national and provincial code development systems and harmoniously adopt NBCC requirements in the provincial building codes, the Ontario Building Development Branch chose to move unilaterally and to amend the NBCC05 on this very important issue.
The 2006 Ontario Building Code will not permit a 2Hr. firewall (and "less") to be constructed of other thin masonry or concrete where they separate buildings or buildings with floor areas having care or detention occupancies, or where they are used in "high buildings". And for all other uses, the level of performance of such alternative firewalls must be not less than of masonry or concrete in areas of performance during fire conditions, mechanical damage during the normal use of the building, and resistance to damage from moisture.
The amended requirements are intended to provide assurances to the Ontario public that the purveyors and proponents of systems alternative to masonry or concrete firewalls must clearly demonstrate byway of standardized tests that such firewalls offer equivalency to masonry/concrete firewalls in all areas of fire performance and related structural performance.
Areas for consideration must include all of the essential properties, characteristics and attributes needed by firewalls to perform satisfactorily (including those not stated or unidentified by the NBCC05 and OBC06, and inherent in masonry/concrete construction prescribed by the NBCC95 and OBC97). Such areas would include, but are not necessarily limited to: resistance to renovation and abuse; duplicity of construction in the field; durability and ongoing performance (resistance to mechanisms of deterioration without maintenance throughout the design service life of the building, in readiness to satisfactorily perform their intended functions during a fire); determination of fireresistance rating (requiring resistance to hosestream after full duration of fire test rather than half duration); structural and fire resistance to direct/localized impact during fire from collapsing members and falling construction debris or other objects; and overall and local structural integrity and serviceability at elevated temperatures.
B.Eng., MSc., P.Eng.
Technical Services Engineer for the National Concrete Masonry Association