The consortium of Nordic Wood Structures, EBC and Yvan Blouin Architect are designing a 13- storey residential building using a mass timber structure. The project, named "Origine" is proposed to be located in the eco-neighbourhood of Pointe-aux- Lièvres in Quebec City and to start construction in spring 2015. The mass timber structure would be composed primarily of glue-laminated timber and crosslaminated timber (CLT). The cross-laminated timber consists of at least three orthogonally bonded layers of solid-sawn lumber that are laminated by gluing of longitudinal and transverse layers with structural adhesives to form a solid rectangular-shaped, straight and plane timber intended for floor, roof or wall applications. The National Research Council Canada (NRC) was requested to assist in the demonstration of an alternative solution to noncombustible construction as prescribed in the Québec Construction Code  and the National Building Code of Canada (NBCC) . Three series of fire tests were conducted at NRC to investigate: the fire endurance (fire resistance) of CLT floor and wall assemblies , the fire performance of a CLT exterior wall assembly , and the fire demonstration of a CLT stair/elevator shaft for the proposed building. This report provides the description and results of the fire demonstration for the CLT stair/elevator shaft. This fire demonstration was funded by the Government of Quebec’s Ministère des Forêts, de la Faune et des Parcs through FPInnovations.
Standard fire endurance tests were performed on a full-scale floor assembly and a full-scale wall assembly constructed with cross-laminated timber (CLT) as the main structural element. The full-scale floor assembly consisted of CLT panels encapsulated with fiberglass wool and a single layer of 15.9 mm thick Type X gypsum board on the exposed side and with two layers of 12.7 mm thick cement board on the unexposed side. The full-scale wall assembly was constructed from CLT panels encapsulated with two layers of 15.9 mm thick Type X gypsum board on both faces. Nine thermocouples were installed on the unexposed face of both assemblies to monitor the temperature rise throughout the test and nine deflection gauges were installed on each assembly to monitor deformations. The superimposed load applied on the floor assembly was 9.4 kN/m² and the load imposed on the wall assembly was 449 kN/m. The fire endurance period of the full-scale floor assembly was 128 minutes and that of the full-scale wall assembly 219 minutes. Both the full-scale floor assembly and the full-scale wall assembly failed structurally afterwards under the applied loading. No hose stream tests were carried out on the fullscale floor and wall assemblies.
Recent architectural trends include the design and construction of increasingly tall buildings with structural components comprised of engineered wood referred to by names including; cross laminated timber (CLT), laminated veneer lumber (LVL), or glued laminated timber (Glulam). These buildings are cited for their advantages in sustainability resulting from the use of wood as a renewable construction material. Previous research has shown that timber elements contribute to the fuel load in buildings and can increase the initial fire growth rate – potentially overwhelming fire protection system and creating more severe conditions for occupants, emergency responders, and nearby properties.
The overarching goal of this project Fire Safety Challenges of Tall Wood Buildings Phase 2 (involving five tasks) is to quantify the contribution of CLT building elements (wall and/or floor-ceiling assemblies) in compartment fires and provide data to allow comparison of the performance of CLT systems against other building systems commonly used in tall buildings.
This article provides an overview of the code requirements pertinent to large cross-laminated timber (CLT) buildings and the methods for meeting the requirements in Canada. Canadian building codes are objective-based. Compliance with the code is achieved by directly applying the acceptable solutions up to certain prescriptive building sizes (height and area) or by developing alternative solutions beyond the height and area limits. The fire safety design for a CLT building larger than the prescriptive limit must demonstrate that the building will achieve at least the minimum level of performance afforded by noncombustible construction in limiting the structural involvement in fire and contribution to the growth and spread of fire during the time required for occupant evacuation and emergency responses.
Working in collaboration with the Canadian Wood Council and FPInnovations and in partnership
with Natural Resources Canada and the governments of Ontario, Quebec and British Columbia,
the National Research Council conducted a comprehensive research project, Research
Consortium for Wood and Wood-Hybrid Mid-rise Buildings. This consortium project aimed to
develop technical information that could be used to support acceptable solutions that meet the
NBC’s objectives for fire safety, acoustics, and building envelope performance, in order to
facilitate the use of wood-based structural materials in mid-rise buildings.
The objectives of the Wood and Wood-Hybrid Midrise Buildings research project were to
develop performance data and technical solutions in the areas of fire safety, acoustics and
building envelope pertinent to the use of wood-based structural materials in mid-rise buildings,
i.e. to develop an alternative solution to meet the 2010 NBC requirements for non-combustible
construction for 5-6 storey (and taller) buildings.
This project was intended to address the immediate needs for technical
solutions for mid-rise wood buildings that do not compromise the minimum levels of safety and
performance required by the 2010 NBC in the areas of fire safety and fire protection, acoustics,
and building envelope performance.
Client Report (National Research Council Canada. Construction)
In early 2018, with funding support from Natural Resources Canada and the Province of Ontario, the National Research Council of Canada conducted a series of room scale fire tests of Encapsulated Mass Timber Construction (EMTC). The goal of this test series is to further quantify the contribution of mass timber elements to fires and provide additional data for forming the technical basis for exposed mass timber elements in EMTC buildings without significantly increasing fire risks to life and property. The goal includes studying the fire performance of the 2nd generation cross-laminated timber (CLT) in resisting char layer fall-off, which could cause fire regrowth in the cooling phase of fully developed fires. The issues of char layer fall-off for the 1st generation CLT panels resulting in fire regrowth during the cooling phase of the fire were clearly revealed in the previous large scale CLT compartment fire tests under the auspices of the Fire Protection Research Foundation.
This report describes a full-scale exterior wall fire test conducted on December 16, 2014 on a Nordic cross-laminated timber (CLT) wall system. The test was conducted in accordance with CAN/ULC-S134-13, Standard Method of Fire Test of Exterior Wall Assemblies. The test was conducted using the exterior wall fire test facility located in the Burn Hall of the NRC Fire Laboratory, Mississippi Mills, Ontario. The CLT wall system was assembled to represent a continuous solid wood wall covered by a water barrier membrane and insulation. The pilot burners were lit prior to the commencement of the test. Gas flow to the burners was manually adjusted to follow the prescribed heat input required by the standard.
A full-scale demonstration fire was conducted at National Research Council Canada (NRCC) to show that a 2-hr non-standard severe design fire in an apartment would have little or no effect on an adjacent elevator or stair shaft. The test was performed to support the approval of an alternative solution for a deemed-to-satisfy 2-hr noncombustible construction assembly, intended for the construction of a tall wood building in Quebec City (Canada). Throughout the duration of the fire no impact was observed in the CLT shaft: there was no evidence of temperature rise and no apparent smoke leakage. This suggests there was little to no effect of the design fire on the structure of the CLT shaft itself.
A full-scale demonstration dire was conducted at National Research Council Canada to show how a mass timber vertical shaft could withstand a severe fire exposure lasting at least two hours. The fire resistance tests and the demonstration fire were performed to support the approval and construction of a tall wood building in Quebec city; the building is planned to be 13 storeys which includes a 12-storey wood structure above a 1-storey concrete podium. An updated calculation methologody to determine the fire resistance of CLT is provided in Capter 8 (Fire) of the CLT Handbook.