CMHI National Codes Task Report. Spatial Separation THE ISSUES. Current Status

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1 CMHI National Codes Task Report Spatial Separation April 2009 Current Status The SCs has made final recommendations on proposed changes. These will be forwarded to the CCBFC for final decision in the fall Some issues are ongoing. THE ISSUES Abbreviations CCBFC Canadian Commission on Building and Fire Codes NBC National Building Code SC Standing Committee TG Task Group Edgemont Fire, Calgary, 2006 (photo courtesy of Calgary Fire Dept.) Spatial separation addresses potential fire hazards presented by a building to buildings on adjacent properties as a result of: limiting distance - the proximity of the building to the property line (see sidebar for full definition) materials used in the construction of the exposing building face, unprotected opening area or glazed opening area, projections from the exposing building face. A number of issues have been addressed in the context of this task. 1

2 Limiting Distance and Response Time Many requirements related to protection against spread of fire to adjacent buildings depend on limiting distance. Where limiting distance is shorter, other requirements become more stringent. Part 3 has a quantitative limit for fire service response time which, if exceeded, results in half of the actual limiting distance being used to determine application of other requirements. The intended interpretation of the current requirement is not clear. Further, Part 9 does not have a quantitative limit, resulting in the potential for over- or under-enforcement of the requirement. Concentration of Unprotected or Glazed Openings A larger area of unprotected or glazed openings in an exposing building face will increase the level of hazard for adjacent buildings. The relationships between limiting distance and maximum area of these openings in the existing requirements were developed based on an assumption that the openings would be relatively small and spread over the exposing building face. Current building designs often concentrate areas of unprotected or glazed openings, increasing the level of hazard presented by these openings. In light of fire incidents, particularly in Alberta, existing provisions that allow combustible construction and cladding are no longer considered to provide a minimum acceptable level of safety, especially where buildings are constructed close together. Construction of Projections from Exposing Building Faces Different interpretations of existing provisions related to projections from exposing building faces have exacerbated the problem. Soffits above exposing building faces that are close to property lines, and consequently may be close to adjacent buildings, can facilitate fire spread between buildings at the roof level, especially where the soffits are vented. Protection of the Subject Building from Spread of Fire from Adjacent Buildings There is no objective in the NBC to address the protection of the subject building from adjacent buildings. Recommendations have been made that the addition of this objective be considered. Important Terms from NBC 2005: Limiting Distance Limiting distance means the distance from an exposing building face to a property line, the centre line of a street, lane or public thoroughfare, or to an imaginary line between 2 buildings or fire compartments on the same property, measured at right angles to the exposing building face. Exposing building face Exposing building face means that part of the exterior wall of a building that faces one direction and is located between ground level and the ceiling of its top storey or, where a building is divided into fire compartments, the exterior wall of a fire compartment that faces one direction. Unprotected opening Unprotected opening (as applying to exposing building face) means a doorway, window or opening other than one equipped with a closure having the required fire-protection rating, or any part of a wall forming part of the exposing building face that has a fireresistance rating less than that required for the exposing building face. 2

3 HOW DOES THIS APPLY TO MANUFACTURED HOUSING? Manufactured Housing on Urban and Suburban Sites The changes MAY affect the design and construction of manufactured housing and/or its installation if: your homes are installed where the fire service cannot reach the building within 10 minutes 90% of the time. The changes WILL affect the design and construction of manufactured housing and/or its installation if: your homes have stacked suites (stacked townhouses or apartment buildings) and - the maximum permitted unprotected area of the exposing building face is >25% and <=50% (affects buildings with an exposing building face 4.0 to 6.0 m from a property line depending on the area of the exposing building face), or - the soffits extend to less than 1.2 m from a property line your homes do not have stacked suites (single-family, semi-detached or row units), and - these are installed less than 1.2 m from a property line, or - the soffits extend to less than 1.2 m from a property line. THE APPROACH A joint Task Group (TG) of the Standing Committees on Fire Protection, and Housing and Small Buildings was charged with reviewing the code change requests from the City of Calgary, related reference material and to develop code changes as needed. NBC Div. B Parts Part 3 Fire Protection, Occupant Safety and Accessibility Part 9 Housing and Small Buildings THE CHANGES PART 9 HOUSES As many CMHI members products would fall within the application of Part 9, and many are single-family homes, information on these changes is provided first. Note The descriptions of the Code changes are summaries only and should not be assumed to provide all of the detail of the Code requirements. 3

4 CHANGE IMPLICATIONS Limiting Distance and Response Time The current requirement states that where there is no fire department or the fire department is not organized, trained and equipped to meet the needs of the community, and where the building is not sprinklered, the actual limiting distance must be halved and the application of subsequent requirements applied as if the building was closer to the property line than it actually is. The provision has been changed to require the actual limiting distance of unsprinklered buildings to be halved for determining the application of subsequent requirements where the fire service cannot reach the building within 10 minutes 90% of the time. There may or may not be any implications depending on how individual municipalities have been interpreting the current qualitative requirement. Concentration of Glazed Openings The change applies to exposing building faces with a limiting distance of 2 m or less, unless the building is sprinklered. The change: limits the maximum concentrated area of glazed openings to 50% of the total permitted glazed opening area. The 50% limit does not apply to egress windows required for bedrooms. specifies a minimum 2 m distance between these openings where they serve the same room or space Where unsprinklered houses are close to the property line, this change may affect window sizes or the location of windows or glazed doors depending on the design of the home. The Code places limits on construction of the exposing building face where the limiting distance is less than 1.2 m. In all cases, the assembly must have a minimum fire resistance rating of 45 min. Where the limiting distance is not less than 0.6 m: the current requirements allow - any non-combustible cladding - any combustible cladding the new requirements allow - any non-combustible cladding, - metal cladding - wood-based cladding with a flame spread rating not more than 25 after weathering and installed over gypsum board or masonry - vinyl cladding installed over gypsum board or masonry - any assembly that passes a specified fire test. Aside from metal cladding, flamespread rated woodbased cladding, and certain vinyl-clad assemblies, combustible cladding is not permitted unless it is tested. 4

5 Where the limiting distance is less than 0.6 m: the current requirements allow - any non-combustible cladding - vinyl cladding installed over gypsum board or masonry the new requirements allow - any non-combustible cladding, - metal cladding - vinyl cladding installed over gypsum board or masonry - any assembly that complies with Sentences (2) and (3) when tested in conformance with CAN/ULC-S134, Fire Test of Exterior Wall Assemblies. Metal cladding will be permitted where it was not currently. Combustible claddings other than vinyl will be permitted if the assembly is tested. Construction of Projections from Exposing Building Faces Projections from walls, such as for fireplaces or chimney chases, are enclosed with walls themselves. By definition, the faces of these projections would define the location of the exposing building face. Some authorities have been allowing construction of these projections within 1.2 m of property lines without additional protection. The changes to the Code would allow these kinds of projections to be constructed without their faces defining the location of the exposing building face provided: the projections do not enclose habitable space (they could, for example, enclose fireplaces or chimneys), and the construction of the face and sides of the projection comply with the corresponding requirements for exposing building faces with limiting distances less than 1.2, and the underside of the projection is protected where it is more than 0.6 m above the ground. The change may result in more or less stringency depending on how individual municipalities have been interpreting the definition of exposing building face. Current requirements related to soffit protection relate to protection of the subject building from the spread of fire through openings below the soffit. There are no requirements related to protection from spread of fire between buildings. The change would: not allow soffits closer than 0.45 m from the property line require protection of soffits that are more than 0.45 m but less than 1.2 m from the property line The change may require elimination of overhangs or protection of soffits above exposing building faces 5

6 THE CHANGES PART 9 RESIDENTIAL BUILDINGS Limiting Distance and Response Time Change The change is the same as for Part 9 houses described above. Implications See above for Part 9 Houses. Concentration of Unprotected Openings and Glazed Areas The change would limit the maximum area of individual unprotected openings and specify minimum separation between openings that serve the same space such that heat radiation would not exceed that assumed in the development of the existing requirements. The result is that, except for buildings that are sprinklered and for bedroom egress windows required by Article : the maximum area depends on limiting distance and can be taken from a table or calculated from an equation provided in the Code a minimum 2 m separation is required between openings that serve the same space. Where unsprinklered buildings are close to the property line, this change may affect window sizes or the location of windows or glazed doors depending on the design of the home. For Part 9 residential buildings, the Code places limits on construction of the exposing building face depending on the maximum permitted area of unprotected openings in the exposing building face. The change places more stringent requirements on cladding and construction of the exposing building face, and exterior walls above that enclose and attic or roof space, where the maximum permitted area of unprotected opening is greater than 25% and not more than 50%. This can affect buildings with limiting distances of 4.0 to 6.0 m depending on the area of the exposing building face. For residential buildings, the change would require the cladding to be non-combustible except where: the limiting distance greater than 2.5 m the building is sprinklered the cladding is wood-based with a flame spread rating not more than 25 after weathering and installed over gypsum board or masonry the cladding is vinyl installed over gypsum board or masonry the cladding-sheathing assembly passes a specified fire test Construction of Projections from Exposing Building Faces The change is the same as for Part 9 houses described above. The change is the same as for Part 9 houses described above. Aside from flamespread rated woodbased cladding, and certain vinyl-clad assemblies, combustible cladding is not permitted unless it is tested. See above for Part 9 Houses. See above for Part 9 Houses. 6

7 THE CHANGES PART 3 Change Implications Limiting Distance and Response Time The requirement has been clarified to make the intent clearer and to also allow 10% lenience in meeting the 10 minute response time before actual limiting distance must be halved for determining the application of other requirements No implications are expected. Concentration of Unprotected Openings and Glazed Areas The change is the same as for Part 9 buildings. See Part 9 buildings above. The change for Part 3 buildings and Part 9 non-residential buildings is the same as for Part 9 residential buildings as described above except that the exception to allow combustible cladding based on limiting distance does not apply until the limiting distance is greater than 5 m. The change is the same as for Part 9 buildings and houses See Part 9 houses above 7