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Second Edition Applicable to the 2024 OBC (O. Reg. 163/24) – In Effect January 1, 2025 Overview The Guide to Mid-Rise Wood Construction in the Ontario Building Code (Second Edition) provides a technical overview of the provisions permitting 5- and 6-storey combustible (wood) construction under the 2024 Ontario Building Code. Developed by WoodWorks Ontario / the Canadian Wood Council, this updated edition reflects O. Reg. 163/24 and recent amendments affecting mid-rise residential (Group C) and office (Group D) buildings. The Guide identifies key requirements, conditions, and limitations associated with mid-rise wood construction and is intended to support architects, engineers, builders, regulators, and code professionals working in Ontario. What’s Included This technical reference outlines: Height and building area limits for 5- and 6-storey wood buildings Fire-resistance requirements for floors, roofs, mezzanines, and loadbearing assemblies Sprinkler system requirements (NFPA 13 vs. 13R) Combustible cladding limitations and compliance pathways Fire blocking and concealed space requirements Fire department access and street-facing provisions Emergency power enhancements Structural and seismic design considerations Mixed-use building permissions and occupancy separation requirements The Guide focuses on new construction and is intended to be used in conjunction with the Ontario Building Code.

Innovative Strategies for Light-Frame Mid-Rise Buildings in High-Seismic Regions presents a detailed design example and practical guidance for engineers and builders responding to rising seismic demands on Canada’s West Coast. With the 2020 National Building Code of Canada significantly increasing seismic forces—particularly in Vancouver and Vancouver Island—conventional light-wood-frame (dimensional lumber) shearwall systems often no longer meet code requirements without costly additions. This guide, prepared by WHM Structural Engineers for WoodWorks BC and the Canadian Wood Council, explores two high-capacity shearwall solutions: Mid+Std walls, a code-compliant adaptation of Midply construction that achieves roughly 50% greater capacity than standard walls without increasing wall length, and Double Nail walls, a research-based approach using double rows of edge nails to match Mid+Std strength. Combined with lightweight floor topping strategies, these systems enable six-storey light-frame buildings to remain viable and cost-competitive even on poor soils and in the highest seismic regions. Cost analysis shows Mid+Std walls incur about a 30% framing cost increase over baseline, while Double Nail walls add about 20%, both more economical than doubling corridor wall lines. The publication includes complete design calculations, construction considerations, and conceptual connection details to help practitioners implement these strategies confidently. This resource equips designers, contractors, and owners with practical, innovative approaches to maintain the competitiveness of light-frame wood construction while meeting the stringent seismic requirements of the latest building codes.

What do the experts have to say about wood-frame mid-rise construction? Graham Finch, Building Science Research Engineer Michael Green, Principal, Michael Green Architecture Mid-rise Wood Construction – a detailed look at a changing landscape (Part 1) Mid-rise Wood Construction – a detailed look at a changing landscape (Part 2) Seven-storey wood-frame earthquake test BC Housing is supporting wood-frame construction for seniors’ rental housing Is mid-rise and tall wood building construction a new phenomenon: Wood-frame and heavy timber construction (up to ten storeys) was the norm in the early 1900’s, and many of these buildings still exist and are in use in many Canadian cities. Check them out here: http://www.flickr.com/photos/bobkh/337920532/. Over the past 10 years, there is a revival in the use of wood for both mid-rise (up to six-storeys) and tall buildings. In British Columbia alone, as of December 2013, there were over 250 five- and six-storey wood product based mid-rise buildings either in the design or construction phase. Why have code change proposals? This 2015 building code change is not about favoring wood over other building materials; it’s about acknowledging, via the highly thorough code process, that science-based innovation in wood products and building systems can and will lead to more choices for builders and occupants. Are these buildings safe? Regardless of the building material in question, nothing gets built unless it meets code. Mid-rise wood-frame buildings reflect a new standard of engineering in that structural, fire and seismic concerns have all been addressed by the expert committees of the Canadian Commission on Building and Fire Codes. As an example, when it comes to concerns from firefighters, there is increased sprinkler protection for concealed spaces and balconies, greater water supply for fire protection, restrictions on types of building claddings used and increased consideration for access by firefighters . In the end,  when occupied, these buildings fully meet the same requirements of the Building Code as any other type of construction from the perspective of health, safety and accessibility. What are some of the new safety provisions being proposed? Fire safety: Increased level of sprinkler / water protection: More  concealed spaces sprinklered Balconies must be sprinklered Greater water supply for fire protection Non-combustible or limited combustible exterior wall cladding on 5th and 6th storey 25% of perimeter must face one street (within 15m of street) for firefighter access Seismic and wind provisions: Similar to BC Building Code Guidance (Appendix) on impact of increased rain and wind loads for 5- and 6-storey Acoustics: Requirements for Apparent Sound Transmission Class (ASTC) Supported by science from FPInnovations, NRC and many others. Doesn’t wood burn? No building material is impervious to the effects of fire. The proposed code changes go above and beyond the minimum requirements outlined in the NBCC. Health, safety, accessibility, fire and structural protection of buildings remain the core objectives of the NBCC and wood industry at large. What about construction site safety? The Canadian Wood Council has developed construction site fire safety guides which outline best practices and safety precautions to take during the construction phase of a building. Are mid-rise wood-frame buildings cost effective? For the most part, yes. Mid-rise wood-frame buildings are often a less expensive construction option for builders. This is good news for main-street Canada where land is so expensive. The recommended changes to the National Building Code of Canada (NBCC) would give the opportunity to erect safe, code compliant buildings that would otherwise not be possible. The net benefit of reduced construction costs is increased affordability for home buyers. In terms of new economic opportunity, the ability to move forward “now” creates new construction jobs in cities and supports employment in forestry communities. This also offers increased export opportunities for current and innovative wood products, where adoption in Canada provides the example for other countries.

In the early 1900s, light-frame wood construction and heavy timber, up to ten-storeys in height, was commonplace in major cities throughout Canada. The longevity and continued appeal of these buildings types is apparent in the fact that many of them are still in use today. Over the past decade, there has been a revival in the use of wood for taller buildings in Canada, including mid-rise light-frame wood construction up to six-storeys in height. Mid-rise light-frame wood construction is more than basic 2×4 framing and wood sheathing panels. Advances in wood science and building technology have resulted in stronger, safer, more sophisticated engineered building products and systems that are expanding the options for wood construction, and providing more choices for builders and designers. Modern mid-rise light-frame wood construction in incorporates well researched and safe solutions. The engineering design and technology that has been developed and brought to market is positioning Canada as a leader in the mid-rise wood-frame construction industry. In 2009, via its provincial building codes, British Columbia became the first province in Canada to allow mid-rise buildings to be made from wood. Since this change to the British Columbia Building Code (BCBC), which increased the permissible height for wood frame residential buildings from four- to six-storeys, more than 300 of these structures have been completed or are underway with BC. In 2013 and 2015, Québec, Ontario, and Alberta, respectively, also moved to permit mid-rise wood-frame construction up to six-storeys in height. These regulatory changes indicate that there is clear market confidence in this type of construction. Scientific evidence and independent research has shown that mid-rise wood-frame buildings can meet performance requirements in regard to structural integrity, fire safety, and life safety. That evidence has now also contributed to the addition of new prescriptive provisions for wood construction, as well as paved the way for future changes that will include more permissible uses and ultimately greater permissible heights for wood buildings. As a result of this research, and the successful implementation of many mid-rise wood-frame residential buildings, primarily in British Columbia and Ontario, the Canadian Commission on Building and Fire Codes (CCBFC) approved similar changes to the National Model Construction Codes. The 2015 edition of the National Building Code of Canada (NBC) permits the construction of six-storey residential, business, and personal services buildings using traditional combustible construction materials. The NBC changes recognize the advancements in wood products and building systems, as well as in fire detection, suppression, and containment systems. In relation to mid-rise wood-frame buildings, several changes to the 2015 NBC are designed to further reduce the risks posed by fire, including: increased use of automatic sprinklers in concealed areas in residential buildings; increased use of sprinklers on balconies; greater water supply for firefighting purposes; and 90 percent noncombustible or limited-combustible exterior cladding on all storeys. Most mid-rise wood-frame buildings are located in the core of smaller municipalities and in the inner suburbs of larger ones, offering economic and sustainability advantages. Mid-rise wood-frame construction supports the goals of many municipalities; densification, affordable housing to accommodate a growing population, sustainability in the built environment and resilient communities. Many of these buildings have employed light-frame wood construction from the ground up, with a five- or six-storey wood-frame structure being constructed on a concrete slab-on-grade, or on top of a concrete basement parking garage; others have been constructed above one- or two-storeys of noncombustible commercial occupancy. Mid-rise wood buildings are inherently more complex and involve the adaptation of structural and architectural details that address considerations related to structural, acoustic, thermal and fire performance design criteria. Several key aspects of design and construction that become more critical in this new generation of mid-rise wood buildings include: increased potential for cumulative shrinkage and differential movement between different types of materials, as a result of the increased building height; increased, dead, live, wind and seismic loads that are a consequence of taller building height; requirements for continuous stacked shearwall layouts; increased fire-resistance ratings for fire separations, as required for buildings of greater height and area; ratings for sound transmission, as required for buildings of multi-family residential occupancy, as well as other uses; potential for longer exposure to the elements during construction; mitigation of risk related to fire during construction; and modified construction sequencing and coordination, resulting from the employment of prefabrication technologies and processes. There are many alternative approaches and solutions to these new design and construction considerations that are associated with mid-rise wood construction systems. Reference publications produced by the Canadian Wood Council provide more detailed discussion, case studies and details for mid-rise design and construction techniques.   For further information, refer to the following resources: Mid-Rise Best Practice Guide (Canadian Wood Council) 2015 Reference Guide: Mid-Rise Wood Construction in the Ontario Building Code (Canadian Wood Council) Mid-Rise 2.0 – Innovative Approaches to Mid-Rise Wood Frame Construction (Canadian Wood Council) Mid-Rise Construction in British Columbia (Canadian Wood Council) National Building Code of Canada Wood Design Manual (Canadian Wood Council) CSA O86 Engineering design in wood Wood for Mid-Rise Construction (Wood WORKS! Atlantic) Fire Safety and Security: A Technical Note on Fire Safety and Security on Construction Sites in British Columbia/Ontario (Canadian Wood Council)

Studies General “The Historical Development of the Building Size Limits in the National Building Code of Canada“, by Sereca for CWC (2015) (17 Mb) Structural & Seismic Vertical Movement in Wood Platform Frame Structures (CWC Fact Sheets) Basics Design and detailing solutions Movement prediction Design of multi-storey wood-based shearwalls: Linear dynamic analysis & mechanics based approach A Mechanics-based Approach for Determining Deflections of Stacked Multi-storey Wood-based Shearwalls Design of Stacked Multi-storey Wood Shearwalls using a Mechanics Based Approach Linear Dynamic Analysis for Wood Based Shear Walls and Podium Structures Design of wood frame and podium structures using linear dynamic analysis, by Newfield, G., Ni, C., and Wang, J., Proceedings of the World Conference on Timber Engineering 2014, Quebec City, Canada (2014) Testing Other Reports Final Report – Full-scale Mass Timber Shaft Demonstration Fire (including the National Research Council test report as an Appendix), by FPInnovations (April 2015) Full Scale Exterior Wall Test on Nordic CLT System, by the National Research Council (January 2015) Report No. 101700231SAT-003_Rev.1 – Report of Testing Cross-Laminated Timber Panels for Compliance with CAN/ULC-S101 Standard Methods of Fire Endurance Tests of Building Construction and Materials: Loadbearing 3-ply CLT Wall with 1 Layer of 5/8″ Type X Gypsum Board – 1 hr FRR, by Intertek for CWC (November 2014) Report No. 100585447SAT-002B – Report of Testing Cross-Laminated Timber Panels for Compliance with CAN/ULC-S101 Standard Methods of Fire Endurance Tests of Building Construction and Materials: Loadbearing 3-ply CLT Wall with 1 Layer of 5/8″ Fire-rated Gypsum Board (60% load) – 1 hr FRR, by Intertek for CWC (December 2013) Report No. 100585447SAT-002A_Rev.1 – Report of Testing Cross-Laminated Timber Panels for Compliance with CAN/ULC-S101 Standard Methods of Fire Endurance Tests of Building Construction and Materials: Loadbearing 3-ply CLT Wall with Attached Wood-frame Partition – 1 hr FRR, by Intertek for CWC (January 2012) Visit Think Wood’s Research Library for additional resources

Modern six-storey light-frame wood construction in British Columbia (BC) incorporates highly-detailed, researched and safe solutions. the engineering technology being adapted in the province is positioning BC at the forefront of the north American wood-frame construction industry. Mid-rise building solutions currently being developed and refined in BC will lead to more sustainable communities and affordable housing solutions that will positively change the face of north American cities.

Since the 2009 change to the British Columbia Building Code (BCBC) that increased the permissible height for wood frame residential buildings from four storeys to six, more than 300 of these structures have been completed or are underway around the province. Most are located in the core of smaller municipalities and in the inner suburbs of larger ones, offering a more sustainable and cost-effective option for densification than concrete or steel equivalents. Most of these buildings have employed wood frame from the ground up, with a five- or six-storey building being constructed on a concrete slab-on-grade, or on top of a concrete basement parking garage; others have been constructed above one or two storeys of commercial accommodation, currently still required to be built in noncombustible construction. This requirement will change when British Columbia adopts the 2015 National Building Code of Canada (NBC), which will allow light wood frame assemblies, mass timber slab elements and wood beams and columns to be used in place of concrete or steel. Over the past eight years, architects, engineers, municipal authorities and local fire departments have become familiar with the basic parameters of this new building type. Over the same period, market conditions have continued to evolve. Beyond the energy conservation standards referenced by LEED and mandated by municipalities, there is an increasing interest in ultra-low energy buildings that comply with the Passive House standard, now formally administered in Canada by Passive House Canada. There is also a growing need to explore new approaches to project delivery, particularly when building on infill lots that have little or no space for vehicles, materials storage and staging, and where the inconvenience to neighbours from the traffic, noise and dust generated by traditional site construction is increasingly disruptive. Further revisions to the 2015 NBC to be introduced in British Columbia in 2017 will expand the permissible use of six-storey wood construction from multi-family residential (Group C) occupancies to business and personal services occupancies in Group D. Prior to “modern” building codes, such buildings were often constructed using heavy timber post-and-beam systems, with solid timber floors. However, with the advent of new mass timber panel products, the opportunity has arisen for developers and design teams to explore new forms of wood construction, including hybrid mass timber/light wood frame construction. In response to these new market conditions, traditional wood frame construction techniques and project delivery methods have been modified or adapted to achieve greater efficiency, economy and performance. This case study looks at three different projects in the Vancouver area, similar in having a predominantly multi-family residential program, but differing considerably in their approach to design, construction details and project delivery

The Mid-Rise project and the ensuing publication were conceived in order to provide a guide for opportunities that have been created by Canadian Code Provisions progressing, allowing 6 storey wood buildings over at least a decade. The foundation for some of the ideas contained within, came from the Wood WORKS! program hosting regional focus groups, made up of key industry stakeholders. They were held at various locations across Canada during 2019. From the focus-group conversations and the research gathered and analyzed, it was evident that each province was at varying degrees of adoption, understanding and application for wood buildings up to 6 storeys. The opportunities that are available for wood use in mid-rise development are varied and many and it is hoped that some of the illustrations and information contained inside this guide will continue to inspire the design and construction industry. The Code Matrix captures the variations of code provisions currently in use in each of the Canadian provinces, and highlights Part 3,4 and 5 requirements for wood buildings up to 6 storeys in height. Permissible building types, heights and areas, permitted mixed major occupancies, required fire resistance ratings and sprinkler provisions are illustrated. The flow of the sections is laid out to mirror basic project planning steps that are generally undertaken by design teams. A keen understanding of what is allowed by code, creates the conversation around ideas for buildings and potential project opportunities. The location of a site, how it fits into local planning and zoning regulations, and a business case that makes it achievable, are all stages a design team navigates early with a client. Many factors drive the business case. Goals set early for greener and environmentally sustainable development, applications of sustainable materials having significantly lower embodied carbon, can be incorporated into design principles. Schedule often drives design and project efficiency, creating consideration into using prefabricated and modular wood structural systems. Part 5 of the guide contains some technical considerations for 5- and 6- storey wood buildings is laid out to help designers better understand some of the practical considerations needed for the construction and design of mid-rise wood buildings. It is written for design professionals in the construction industry, and builders with the necessary skills to consider taller wood buildings. This guide is illustrated to be relevant to all design and building professionals involved in building our future environments, including architects, engineers, the development community, material suppliers, manufacturers, building inspectors, municipal officials and planners, project managers, contractors, innovators, and the general public at large.

When the provincial government changed the British Columbia Building Code (BCBC) in 2009 by increasing the permissible height for wood-frame construction from four storeys to six for residential buildings, it joined many other jurisdictions around the world in recognizing the role that wood construction should play in the creation of a sustainable, built environment. Scientific evidence and independent research had shown that such buildings could meet the performance requirements of the BCBC in regard to structural integrity, fire safety, and life safety. That evidence has now also contributed to the addition of new prescriptive provisions for wood construction, as well as paved the way for future changes that will include more permissible uses and ultimately greater permissible heights. As a result of this research, and the successful implementation of many mid-rise wood-frame residential buildings in BC, the Canadian Commission on Building and Fire Codes approved similar changes to the National Model Construction Codes. The 2015 edition of the National Building Code of Canada (NBC) now permits the construction of six-storey residential, business, and personal services buildings using traditional combustible construction materials. The changes to Part 3 of the NBC, which are being considered for adoption by British Columbia in late 2018, address the objectives of safety, fire, and structural protection of buildings. With more than 100 five- and six-storey woodframe buildings completed in BC since 2009, and many others either designed or under construction, there is clear market confidence in this new type of building. This construction supports the goals of many municipalities: to find affordable and sustainable ways to accommodate their growing populations, as well as create more complete and resilient communities. With each completed building, architects, engineers, builders, and developers have added to their knowledge base and refined their best practices for mid-rise wood-frame construction. The five projects featured in this publication are representative of the diverse and varied application of these techniques to different geographic and market conditions, from small towns to dense urban centres and from affordable rental accommodation to high-end condominiums.

On September 23, 2014, after many years of research, development, stakeholder feedback and discussion, the Ontario Ministry of Municipal Affairs and Housing announced amendments to the 2012 Ontario Building Code (OBC) that permit 5- and 6-storey combustible construction for Group C and D occupancies. e amendments to the OBC increase opportunities for designers and builders to create versatile and affordable new buildings. The changes recognize the advancements in wood products and systems as well as in fire detection, suppression, and containment systems. Densification is mandated in almost all municipal growth plans in the province. Mixed-use mid-rise buildings are seen as an important solution that will help create higher density and attract businesses and families to urban centres. Previous code restrictions on combustible construction made non-combustible solutions the only option for mid-rise development and many potential developments were stalled because they were deemed cost-prohibitive. Developers now have a new, cost effective option to provide mid-rise solutions. Decisions about how and where we build our communities have significant impacts on the natural environment and on human health. Wood is a natural, sustainable material and the processing of raw material into building materials has a lower environmental impact when compared to other major building components. e use of sustainable materials and components reduces the negative impact our buildings have on the environment and assists in mitigating climate change. The amendments to the OBC have created exciting new opportunities but there are also new design and construction challenges to consider. Ontario Wood WORKS! developed this guide to explain the new provisions in the OBC and to discuss the opportunities as well as the challenges.