Construction materials and fire safety: How combustibility affects fire risk
Why construction materials matter for fire safety
When a fire starts, building materials play a major role in how quickly flames spread, how severe damage becomes, and how likely a structure is to experience a partial or total loss. Some materials ignite easily and add fuel to a fire. Others resist heat and slow fire growth – buying critical time for evacuation, fire protection systems, and recovery. Construction material selection is not just a design decision. It directly influences employee safety, property damage, and operational continuity during and after a fire.
Risk insight: Structure fires account for the majority of fire related property losses in the U.S., making construction and material choices a business risk decision – not just a design choice.1
How building materials influence fire behavior
Building materials shape how a fire develops inside a structure. Materials that ignite easily can accelerate fire spread and increase damage, while fire resistant materials help slow fire growth and limit loss.
- Slow the spread of fire
- Reduce structural damage
- Improve occupant safety
- Support faster recovery after a loss
Understanding combustibility in buildings
Not all building materials perform the same way in a fire. Understanding the difference between combustible and fire-resistant materials helps explain why some fires grow rapidly while others are contained.
Combustible materials
Combustible materials can ignite, burn, and intensify a fire. Once ignited, they release heat that increases fire size and makes fires more difficult to control.
- Solid wood and engineered wood products, including laminated beams, trusses, and mass timber components
- Plastic tanks, piping, panels, and totes
- Foam or other combustible insulation
- Certain wall and ceiling finishes
- Packaging, pallets, and stored products
Risk insight: Some modern engineered wood systems can lose structural integrity much faster than traditional solid wood during a fire — sometimes within minutes — raising collapse risk in enclosed spaces.2,3
Fire-resistant materials
Fire resistant (or noncombustible) materials resist ignition and slow the movement of heat and flame through a structure. These materials buy time – time for evacuation and for fire protection systems to work.
- Concrete and masonry
- Brick and stone
- Gypsum board (installed correctly)
- Fire rated steel assemblies
- Fire rated roofing systems
Using materials as they’re intended
Fire performance doesn’t just depend on what a product is made of – it also depends on how and where it’s used. Materials that perform well in one setting can become a serious fire hazard if they’re installed outside their intended or listed use. Examples include residential-grade doors in repair shops, decorative wall panels in washdown areas, or metal skin installed over exposed foam insulation. When selecting or replacing materials, verify that products are rated and approved for the way they’ll actually be used in your facility.
How construction type affects fire behavior and potential loss
While individual materials matter, how those materials are assembled into a building matters just as much. That’s where construction type comes in. Construction type is a fire protection classification used by insurers and fire professionals to understand how a structure is likely to react in a fire. These classifications help anticipate how a building may perform during a fire and how likely it is to experience severe damage or total loss. In simple terms: The more combustible the structure, the faster a fire can spread and the higher the likelihood of severe damage or total loss.
Common construction types and fire performance
Construction type influences how quickly fire spreads, how much damage occurs, and how likely a total loss may be. The following categories describe typical fire performance characteristics and are provided for general understanding rather than formal code classification.6,7
| Construction type | Typical structure | Fire behavior | Plain-language impact |
|---|---|---|---|
| Type 1: Frame | Wood or wood framed structures | Structural elements are combustible. Fire spreads rapidly with higher collapse and total loss potential. | Burns easily and fuels the fire. |
| Type 2: Joisted Masonry | Masonry walls with combustible roof or floors | Walls resist fire, but roof and floors can burn intensely once involved. | Walls don’t burn; roofs and floors do. |
| Type 3: Noncombustible | Steel or noncombustible framing | Structure won’t ignite, but heat can cause damage or deformation. | Doesn’t burn but can still be damaged. |
| Type 4: Masonry Noncombustible | Masonry walls with noncombustible framing | Walls limit fire spread; roofs and floors may still be damaged by heat. | Walls don’t burn; upper systems can be damaged. |
| Type 5: Modified Fire-Resistive | Fire-resistant assemblies added | Structural elements are protected to slow fire impact and buy time. | Modified to resist fire longer; have at least a 1-hour fire resistance rating but also less than 2-hour resistance rating. |
| Type 6: Fire-Resistive | Reinforced concrete or fire rated assemblies | Structure resists ignition and major fire damage for extended periods. | Highly resistant to fire damage; typically ≥ 2 hour resistance rating |
Risk insight: Fire resistive assemblies can be designed to maintain structural integrity for one to four hours, depending on material and assembly design – helping limit damage and support safer response and recovery.4,5
What if you can’t change your construction type?
- Improved housekeeping practices
- Effective fire protection systems
- Isolate high hazard areas
- Clear operational controls and employee training
- Avoiding “off-label” substitutions: Use building materials and assemblies only in ways that match their fire rating and manufacturer’s intended use.
- Separate or limit storage to daily use amounts in key areas
These measures help existing buildings behave more like fire-resistant structures, even when the original construction type cannot be changed.
Why construction materials and building type matter to operations
- How fast a fire can grow
- How likely structural collapse is
- How severe damage may be
- How quickly operations can recover
Facilities built with more fire resistant materials and construction often experience slower fire development, less structural damage, and reduced business interruption.
Key takeaway: Reducing fire risk through material and construction choices
Fire safety goes beyond minimum code requirements. Construction material and building type decisions directly affect employee safety, property damage, and recovery after a loss. Considering fire resistance during construction or renovation strengthens long term operational resilience.
Quick summary for facility and operations leaders
Construction materials and building type influence how fires grow, how much damage occurs, and how quickly operations recover. Fire resistant materials and assemblies slow fire development, reduce total loss potential, and support safer outcomes during fire events.