Combustible vs. Non-combustible Construction | Key Rules in Toronto

When laying the first stone—or perhaps, raising the first beam—for your Toronto project, a pivotal question arises: will your structure be built from materials that bravely resist the flames, or those that might yield to them?

This essential consideration in Combustible vs. Non-combustible Construction in Toronto profoundly shapes not just a building’s immediate safety and cost, but its lasting legacy and resilience. As Ontario’s Building Code (OBC) continues to adapt, with key changes on the 2025 horizon, understanding these material choices isn’t just advisable—it’s fundamental for every insightful homeowner, developer, and builder. Let this guide be your clear map through these important decisions.

Core Material Attributes Defined

At the heart of building science lies a crucial classification: how materials behave in the presence of fire. The Ontario Building Code (OBC) provides clear distinctions between “combustible” and “non-combustible” materials, which directly impacts their application in construction projects across Toronto.

A non-combustible material is formally defined by the OBC as one that, when tested per CAN/ULC-S114, “Test for Determination of Non-Combustibility in Building Materials,” meets the specified acceptance criteria. Essentially, these materials do not significantly contribute to the spread of a fire. Think of them as the silent guardians against flame spread.

Conversely, a combustible material fails to meet these stringent non-combustibility test criteria. These materials can ignite and burn, potentially contributing to the intensity and propagation of a fire if not appropriately managed or protected within a building assembly. To put this into practical terms, here are common examples:

Non-Combustible Materials Typically Include:

• Steel (structural beams, studs)
• Concrete (foundations, slabs, walls)
• Masonry (bricks, blocks)
• Gypsum board (drywall, a key component in fire-rated assemblies)
• Glass and most ceramics

Combustible Materials Often Encompass:

• Wood and wood-based products (framing lumber, plywood, OSB)
• Many plastics and foams (insulation, vapour barriers, some claddings, decorative elements)
• Paper and paper-based products
• Certain types of asphalt shingles

Toronto Building Code Parameters

In Toronto, selecting between combustible or non-combustible materials is closely managed by the Ontario Building Code (OBC). This code outlines precisely where and how different materials can be utilized, focusing on building size, height, its designated use (occupancy type), and overall fire safety targets. Securing the necessary home building permits Toronto hinges on strict adherence to these OBC stipulations.

Generally, larger, taller structures, and buildings designated for higher-risk uses (like hospitals) are mandated to use non-combustible construction for their primary structural elements. This approach ensures a higher degree of passive fire protection.

In housing construction (less than 2 units in a building, Garden units or laneway units) when the sides setbacks are less than 2 feet then non-combustible cladding like brick will be required, they also need to use absorptive materials between studs (ruxul) and use Fire rated drywall 5/8 type-X for interior

But in construction of small buildings (houses with more than 2 units inside like Triplex or fourplex) side wall with setbacks less than 7to 10 feet from property line need to be from non combustible construction like Concrete cement walls or steel stud walls.

Key 2025 OBC Updates Affecting Material Choice

Staying informed about regulatory shifts is vital. The Ontario Building Code is regularly updated to incorporate new research and safety protocols. Ontario’s 2024 Building Code, which largely takes effect on January 1, 2025, introduces notable changes regarding fire protection and occupant safety.

These revisions can influence project designs, particularly for Combustible vs. Non-combustible Construction. For example, evolving rules around taller wood-frame buildings and Encapsulated Mass Timber Construction (EMTC) reflect new understandings. Land Signal stays current with these details, helping align your plans with the latest legal requirements.

Fire Performance and Safety

When discussing Combustible vs. Non-combustible Construction in Toronto, the paramount consideration is undoubtedly fire performance and the safety of occupants. The behaviour of materials during a fire can be the difference between a contained incident and a catastrophic event.

Non-combustible materials, by their very definition, do not contribute fuel to a fire. Steel and concrete, for example, will not ignite or burn. This inherent characteristic means they help to:

• Limit Fire Spread: By not providing additional fuel, they slow the progression of a fire within a building.
• Maintain Structural Integrity: Many non-combustible materials, like protected steel and concrete, can maintain their load-bearing capacity for longer periods under fire exposure, allowing more time for evacuation and firefighting.
• Reduce Smoke and Toxic Gases: While any fire produces smoke, non-combustible materials themselves do not add significantly to the volume or toxicity of combustion byproducts in the same way some combustible materials can when they burn.

Combustible materials, on the other hand, will burn and contribute to the fire’s load. However, this doesn’t mean they are inherently unsafe or unusable. The OBC permits their use extensively, especially in residential and smaller-scale construction, provided specific fire safety measures are in place. These can include:

• Fire-Resistance Ratings: Assemblies using combustible materials (like wood-frame walls) can be designed to achieve specific fire-resistance ratings by incorporating materials like gypsum board and insulation, delaying fire spread.
• Sprinkler Systems: Automatic sprinkler systems are often mandated in conjunction with combustible construction, especially as building size or height increases, to control or extinguish fires in their early stages.
• Fire-Retardant Treatments: Some combustible materials can be treated to reduce their flammability and flame-spread characteristics.

Cladding Considerations for Fire Safety

A building’s exterior cladding is significant for fire performance. The OBC sets standards (like CAN/ULC S-134) for exterior walls. Choosing between combustible or non-combustible cladding is key for safety and compliance. Experts at Land Signal can help you evaluate these options to ensure your building envelope meets all safety and code requisites.

Construction Budgets

The financial implications of choosing between combustible and non-combustible materials are a significant factor for any Toronto construction project. While upfront material costs are one piece of the puzzle, the decision impacts a broader range of budgetary items.

Initially, non-combustible materials like steel and concrete can sometimes have a higher per-unit purchase price compared to traditional wood framing. However, factors like speed of erection for certain non-combustible systems, or reduced labour for others, can offset some of these initial differences. Conversely, wood remains a popular and often cost-effective choice, particularly for low-rise residential projects.

To get a preliminary idea of these costs, many find a construction cost calculator Ontario to be a helpful starting point. These online tools can provide rough estimates based on project type, size, and general material choices.

However, they rarely capture the full nuance of a specific project’s design, site conditions, or the fluctuating market prices. For detailed and tailored financial planning, especially for unique projects or when assessing something specific, a more in-depth analysis with professionals is key. Beyond raw material and installation costs, consider these budget-related factors:

• Insurance Premiums: Buildings constructed with non-combustible materials may benefit from lower insurance premiums due to their inherent fire resistance.
• Long-Term Maintenance & Durability: Non-combustible materials often offer superior resistance to rot, pests, and, of course, fire, potentially leading to lower long-term maintenance costs. Concerns over the long-term durability and potential fire-related costs of newer mass timber high-rises compared to traditional concrete structures are part of ongoing industry discussions.
• Construction Timelines: Depending on the system, some non-combustible methods can expedite construction, potentially saving on financing costs and labour.
• Skilled Labour Availability: The cost and availability of skilled labour for specific construction types (e.g., specialized steel erection vs. wood framing) can also influence the budget.

Zoning, Expansion, and Material Choices

Toronto’s zoning by-laws add another layer of complexity to your construction material decisions. These regulations dictate what can be built where, influencing density, building height, setbacks, and even sometimes, indirectly, the types of materials that are feasible or permissible for specific projects.

This is especially relevant when considering newer housing initiatives like ehon Toronto (Expanding Housing Options in Neighbourhoods) or the development of additional dwelling units such as Garden Suites or Garage Suites.

For example, certain zones might have height restrictions that make taller wood-frame constructions (now permissible under specific OBC conditions) an attractive option, while other areas might prioritize different aesthetic or performance characteristics influenced by the surrounding built form. When planning these accessory dwelling units, even the decision between Two-Storey vs. Single-Storey Garden House Toronto can have zoning implications that intertwine with material choices for efficiency and compliance. Ambitious plans around home Stratification in Toronto also hinge on understanding how existing structures can be modified or expanded, with material choice playing a key role in feasibility and code adherence.

Navigating these intricate zoning requirements and understanding how they affect your material selection is where expert guidance becomes invaluable. Need help understanding how zoning bylaws impact your material choices for your Garden Suite or EHON project in Toronto?

The specialists at Land Signal offer comprehensive zoning by-law interpretation, helping you select the optimal materials that align with both your vision and municipal regulations, ensuring your project starts on solid legal ground.

Permit Pathways and Specialized Approvals

The building permit process in Toronto is a critical phase, significantly influenced by your material choices. Whether you need a Deck Permit Toronto or are embarking on a more intricate structure, full compliance with the Ontario Building Code, including its rules on combustible and non-combustible materials, is essential.

Permit applications require detailed plans specifying materials and fire-resistance ratings. This detail becomes even more pertinent with potential shifts like the New Toronto Mortgage Rules in 2025, which could influence project financing and material decisions based on budget and timelines. The entire field of Combustible vs. Non-combustible Construction in Toronto is complex.

Why face this intricate process alone? Land Signal excels at simplifying the permit journey, from initial zoning reviews to final approvals. Let our knowledge ease the path for your project.

Conclusion

Choosing between combustible and non-combustible construction in Toronto is a decision with far-reaching implications. It touches everything from occupant safety and regulatory compliance with the evolving Ontario Building Code, to project costs and timelines. A clear understanding of these material differences and a commitment to meticulous planning, supported by expert consultation, are the cornerstones of any successful and responsible building venture in this vibrant city.