How passive fire protection, EI classifications and Firebreather® technology help protect modern timber buildings.
Wooden constructions can be both sustainable and fire-safe when fire protection is designed as a complete system. This includes documented fire resistance, tested passive fire protection, correct installation, and active measures such as alarms and sprinklers.
Critical areas include ventilated façade cavities, eaves and fire-rated walls, where flames, smoke and hot gases can spread if the building assembly is not properly protected.
Wooden constructions are highly valued in Europe for their sustainability, reduced carbon footprint, natural aesthetics, and positive impact on occupants [1, 2, 4].
Thanks to advancements in technology, wood can be used for tall and complex buildings. Yet, compared to non-combustible materials, wood is more susceptible to moisture, pests, and fire. Combining appropriate passive and active fire protection is essential. This article explores how understanding each product as part of an integrated system and using solutions like Flamro’s Firebreather® products, helps wooden buildings achieve the required classifications.
Wood is an excellent choice for sustainable building. Trees sequester carbon during growth, and wooden homes often show about 12(±3)% lower carbon footprints than non-wooden dwellings under similar conditions [1].
Wood’s natural insulation significantly reduces energy needs [2, 3].
With proper design and maintenance, wooden structures can be long-lasting, promote healthier indoor air, and provide psychological benefits linked to the warmth of wood surfaces [4].
Mjøstårnet in Norway is one of the world’s tallest timber buildings [5].
Post-completion studies found this 85.4-meter structure to have an impressively low overall carbon footprint of around 83.1 tons of CO₂ [9].
Timber elements emitted up to four times less CO₂ than comparable concrete components. Although Mjøstårnet is high, it adopts a carefully planned fire-safety design, including Firebreather® Cavity Barriers for ventilation and compartmentation [6].
This demonstrates that, with the right system approach, wooden high-rises can meet stringent requirements.
Wood begins losing moisture at around 100 ºC, softens around 180 ºC, and typically ignites between 250–300 ºC [10].
A char layer forms at about 0.8 mm/min in solid wood (0.7 mm/min for glued laminated timber), delaying deeper combustion and aiding in structural prediction. Though combustible, wood’s known burn rate can be factored into fire design.
Fire safety rules for timber buildings vary across Europe, but many countries now allow tall wooden construction. Insurance companies and local authorities demand rigorous proof of fire safety. Regardless of location, ensuring proper documentation and using tested, certified products is crucial.
An effective fire-safety strategy must address both reaction to fire and resistance to fire.
Reaction to fire focuses on how quickly a material ignites or contributes to flame spread, while resistance to fire measures how long an assembly maintains integrity and insulation during a fully developed fire.
If either aspect is overlooked, the entire system could fail to perform when a fire occurs. Consistently applying the correct classification to each component in a wooden structure, while confirming their interaction through system tests, helps ensure genuine fire-safety compliance.
European standards EN 13501-1 for Reaction to fire.
European standards EN 13501-2 for Resistance to fire.
The most common system tests for EU are:
SP105 (Scandinavia), Lepir 2 (France) and BS8414 (UK).
Wooden buildings must integrate both active (e.g., sprinklers, alarms) and passive (e.g., cavity barriers, intumescent seals) measures.
Although individual product ratings matter, real-world performance is best verified through large-scale tests like SP105, Lepir2, or BS8414.
When an assembly must meet, for example, EI30, each element, from claddings and insulation to cavity barriers, must be verified to achieve that rating in combination.
Water damage happens more frequently than fire, so many projects allocate sufficient resources to waterproofing. Yet fires, though less common, can be far more devastating. Investing in high-quality fire protection for timber structures is a sustainable choice—protecting people, property, and the building’s carbon benefits.
A common passive fire protection challenge in wood construction lies in the hidden cavities behind claddings and inside walls. Fire and hot gases can spread rapidly through such gaps if not sealed promptly. Traditional intumescent-only barriers might require minutes to close. By contrast, Flamro’s Firebreather® Cavity Barrier employ immediate flame blocking, activated at the very first exposure [11].
The Firebreather® technology preserves normal airflow in everyday conditions but halts embers, sparks, and flames from traveling through the facade or partition at the earliest stage of a fire.
Firebreather® Cavity Barrier strategically installed at floor level to ensure optimal compartmentation of the facade, enhancing fire safety by preventing the spread of fire between floors.
No bypassing fire compartments via air gaps and breaking windows (A).
Fire spread is limited on the facade (B).
100% passive. Our products are passive, meaning there are no moving parts, detectors, activation, or cabling.
Application areas. The Firebreather® technology can be applied in different configurations, and application areas. Our ventilated fire stopping solutions can be implemented and customized in construction, offshore installations, shipping, batteries, industry, and more.
Instant flame arrest. The Firebreather® technology and products have key advantages including stopping flames instantly, from the first second.
Multiple fire ratings. The minimum fire rating (EI) requirement for cavity barriers is 30 minutes. Firebreather® Cavity Barrier is available in EI30, 60, and 90.
Many buildings require mechanical or natural ventilation in fire-rated walls. Flamro’s Firebreather® Air Transfer Grille offer the same instantaneous flame-blocking principle [12, 13], enabling both normal airflow and immediate, code-compliant fire compartmentation.
Timber structures often need proper ventilation at roof eaves to manage moisture and airflow. Flamro’s Firebreather® Eaves Vent provides an instant flame-blocking solution while maintaining normal ventilation under eaves, preventing fire spread into attic or roof cavities from the building’s exterior [14].
Like other Firebreather® solutions, it works from the very first second of exposure.
When a project calls for a certain EI rating, say EI30, each component of the assembly (cavity barrier, insulation, cladding, etc.) must be tested and shown to achieve or exceed that threshold together.
Selecting products like Firebreather® Cavity Barrier and Air Transfer Grille can help ensure the entire system is consistent with an EI requirement, rather than mixing unknown or untested elements that could compromise the overall rating.
Ventilated cavities, crucial for moisture control, present “chimney” pathways for undetected fires, underscoring the need for robust passive compartmentation [8].
Connections such as beam-to-column joints must be sealed adequately to limit smoke and flame travel.
Clear documentation and adherence to manufacturers’ guidelines are just as important, any gaps in records or faulty installation risk invalidating safety certifications.
Modern timber buildings can be both environmentally sound and highly fire-safe. Achieving the required EI classifications demands an integrated approach: specifying materials and products, like Flamro’s Firebreather® range, that provide immediate flame blocking while allowing normal ventilation. Coupled with active suppression and alarms, these passive solutions create a safer, more sustainable future for wooden constructions across Europe.
Wooden constructions offer strong sustainability benefits, but timber is still a combustible material. Fire protection is therefore essential to reduce the risk of flame spread, smoke movement and fire development in hidden cavities, facades, eaves and fire-rated walls.
Yes. Tall timber buildings can be designed to meet strict fire safety requirements when the complete building system is properly planned, tested and documented. Mjøstårnet in Norway is an example of a tall timber building where fire safety was addressed through a system-based approach.
Reaction to fire describes how a material behaves when exposed to fire, including how easily it ignites or contributes to flame spread. Fire resistance describes how long a building element or assembly can maintain its integrity and insulation during a fire, often expressed through EI classifications.
EI classification refers to fire resistance performance. “E” stands for integrity, meaning that flames must not pass to the unexposed side during the certified period. “I” stands for insulation, meaning that the temperature rise on the unexposed side must remain within defined limits during the same period.
Ventilated cavities are important for moisture control and airflow, but they can also create hidden pathways for fire, smoke and hot gases. If these spaces are not properly protected, fire can spread rapidly behind cladding or inside wall and roof structures.
Active fire protection includes systems such as sprinklers and alarms, which detect or suppress fire. Passive fire protection includes built-in solutions such as cavity barriers, fire-rated grilles and intumescent seals. In wooden constructions, both active and passive measures should be part of the overall fire safety strategy.
Firebreather® products from Flamro Norway are designed to maintain normal ventilation in everyday conditions while blocking flames, sparks and embers immediately when exposed to fire. This helps reduce the risk of fire spread through ventilated cavities, facades, eaves and fire-rated walls.
Firebreather® products can be used in several critical areas of wooden buildings, including façade cavities, fire-rated walls, air transfer openings and roof eaves. Relevant solutions include Firebreather® Cavity Barriers, Firebreather® Air Transfer Grilles and Firebreather® Eaves Vents.
A single product rating is not always enough to confirm real-world fire performance. In timber buildings, cladding, insulation, cavity barriers and other components must work together as a complete assembly. System-level testing helps verify that the full construction achieves the required fire performance.
Wooden buildings can reduce carbon emissions and support more sustainable construction, but those benefits must be protected through robust fire safety design. By using tested and documented passive fire protection products alongside active systems, timber buildings can be both sustainable and fire-safe.
Do you have questions about passive fire protection for wooden constructions? Please contact us.
