UNECE Regulation No. 118 establishes requirements for the burning behaviour and fuel or lubricant repellency of materials used in certain buses and coaches, covering multiple aspects of material and component fire performance.
Resonate provides UNECE R118 flammability testing for materials and components used in buses and coaches. Our testing capability supports manufacturers and suppliers assessing horizontal and vertical burning behaviour, melting behaviour, fuel and lubricant repellency, and electrical cable flame propagation against applicable UNECE R118 requirements.
When discussing automotive flammability testing, FMVSS 302 and ISO 3795 often dominate the conversation. Both focus on the horizontal burning behaviour of interior materials and provide a consistent way to compare materials under controlled laboratory conditions.
UNECE Regulation No. 118 takes a broader approach.
Rather than concentrating solely on horizontal flame spread, UNECE R118 evaluates multiple aspects of fire behaviour, including vertical burning, melting behaviour, cable flame propagation and fuel or lubricant repellency. This wider scope reflects the increased complexity and passenger risk associated with large public-service vehicles, particularly buses and coaches.
For organisations supplying materials into European and UNECE markets, understanding UNECE R118 is essential.
UNECE Regulation No. 118 is a United Nations vehicle regulation establishing requirements for the burning behaviour and fuel or lubricant repellency of materials used in certain categories of motor vehicles.
The regulation applies primarily to M3 Class II and Class III vehicles, which include many buses and coaches used in passenger transport.
Unlike FMVSS 302 or ISO 3795, UNECE R118 is not simply a laboratory test method. It forms part of a vehicle approval framework that includes requirements for both components and complete vehicles.
Ready to plan UNECE R118 testing? Send your material details, vehicle application, installation direction and required test annexes for engineer review.
UNECE R118 test programmes require early consideration of the material or component, its location within the vehicle, installation direction and the applicable requirements of the regulation.
Share your material or component description, intended vehicle application, construction details and installation orientation. Resonate Testing can review the required assessment and help identify the relevant UNECE R118 test methods before testing.
Public-service vehicles present unique fire-safety challenges.
Compared with passenger cars, buses and coaches often:
For these reasons, regulators adopted a broader assessment philosophy. The objective is not just to evaluate burning rate, but to understand how materials behave in multiple realistic fire-related situations.
The regulation contains several annexes that address different fire-performance characteristics.
Each annex focuses on a specific question relating to material behaviour.
This structure allows approval requirements to be matched to the material’s intended location and function within the vehicle.
| Specification | Capability |
|---|---|
| Annex 6 – Horizontal Burning Rate | Annex 6 is the section most closely related to ISO 3795 and FMVSS 302. A specimen is mounted horizontally and exposed to a controlled ignition source. Flame propagation is then assessed using distance and time measurements. The objective is to determine how rapidly fire spreads across a material surface under defined conditions. For many suppliers, Annex 6 is the point of entry into UNECE R118 because it employs equipment very similar to that used for other automotive interior flammability methods. |
| Annex 7 – Melting Behaviour | Horizontal burn rate alone does not reveal everything about a material's behaviour during a fire. Some materials melt and drip when heated. In certain environments, these droplets may ignite other materials below them. To address this hazard, Annex 7 evaluates melting behaviour. The test examines whether molten droplets are capable of igniting cotton wool positioned beneath the specimen. This provides an additional safeguard against secondary ignition hazards that may not be apparent in a standard horizontal burn test. |
| Annex 8 – Vertical Burning Behaviour | Annex 8 evaluates materials installed in vertical orientations. Vertical burning behaviour can differ significantly from horizontal burning behaviour because buoyancy effects promote upward flame spread. The test assesses: • Flame propagation. • Burning rate. • Self-extinguishment characteristics. Marker threads are used to monitor flame progression, and the resulting performance is evaluated against defined acceptance requirements. Materials that perform adequately in a horizontal orientation cannot automatically be assumed to satisfy vertical burning requirements. |
| Annex 9 – Fuel and Lubricant Repellency | Insulation materials located in engine compartments and heating compartments may be exposed to fuel or lubricant contamination. Annex 9 evaluates the extent to which materials absorb these liquids. The purpose is to ensure that contamination does not significantly increase fire hazards. The regulation uses mass-gain measurements to determine fuel or lubricant uptake. This requirement demonstrates how UNECE R118 extends beyond traditional flammability assessment into broader fire-risk management. |
| Annex 10 – Electrical Cables | Modern buses and coaches contain extensive electrical systems. Cables can become pathways for flame propagation if insulation systems perform poorly during fire exposure. Annex 10 introduces dedicated assessments for cable flame propagation. The objective is to ensure that cable insulation does not support unacceptable fire spread. The regulation also addresses cable sleeves and conduits through associated requirements. |
One of the most important aspects of UNECE R118 is that it supports both:
This means compliance is not limited to individual materials.
Manufacturers must demonstrate that components, installations and complete vehicle systems satisfy applicable requirements.
Vehicle approval therefore becomes a broader systems exercise rather than simply a collection of isolated material tests.
A key concept within UNECE R118 is installation direction.
The regulation recognises that materials may behave differently depending on how they are installed within a vehicle.
A material approved for one orientation cannot automatically be assumed suitable for another.
This principle is particularly important when evaluating:
Successful compliance therefore requires an understanding of both the material and its intended application.
As with other automotive flammability methods, UNECE R118 recognises that vehicle materials are rarely simple single-layer constructions.
Adhesives, substrates, foams and reinforcement layers can all influence performance.
The regulation therefore considers complete constructions where required rather than relying solely on individual material layers.
For suppliers, this highlights the importance of testing representative assemblies rather than isolated material samples whenever necessary.
The rate at which a flame travels across a material specimen positioned horizontally.
The rate at which burning progresses along a material specimen positioned vertically.
The spread of flame across or along the surface of a material or component.
The behaviour of a material when burning stops after the ignition source or flame exposure is removed.
A prepared sample of a material or component used during a flammability test.
The orientation in which a material or component is installed within the vehicle, such as horizontally or vertically.
A construction consisting of more than one material or layer, such as combinations of coverings, foams, adhesives or substrates.
Ignition that can occur when burning or molten material causes another material to ignite.
Threads used during vertical burning assessment to indicate the progression of the flame along the specimen.
The ability of a material to resist the uptake of fuel or lubricants.
Formal approval demonstrating that a defined vehicle or component type satisfies the applicable regulatory requirements.
The behaviour of a material when molten portions separate and fall from the specimen during fire exposure.
A common misconception is that UNECE R118 is simply a European version of FMVSS 302.
While both standards address fire behaviour, their scope is fundamentally different.
FMVSS 302 focuses primarily on horizontal burning behaviour within a vehicle occupant compartment.
UNECE R118 incorporates:
It therefore represents a more comprehensive regulatory framework.
Organisations seeking compliance with UNECE R118 should begin with a structured review of:
Testing should then be planned against the relevant sections of the regulation.
Assuming a single burn-rate test provides complete coverage is one of the most common mistakes made during programme planning.
As vehicle systems become more complex and passenger-transport expectations continue to rise, comprehensive fire-safety frameworks are becoming increasingly important.
Electrification, advanced materials, lightweight construction and expanding electronic systems all create new design challenges.
UNECE R118 provides a framework capable of addressing multiple fire-performance considerations within a single regulatory structure.
For suppliers serving the bus and coach market, familiarity with UNECE R118 will remain a critical aspect of product qualification and market access.
Book UN R118 fire and flammability testing for materials and components used in buses and coaches. Use the contact route to share the material, application, installation orientation or approval requirements for review.
Whether you’re looking to contact us for the first time or have another testing requirement, we’d love to hear from you.
