Fire safety is a critical aspect of building design and construction. Passive fire protection systems play a particularly important role, as their function is to restrict the spread of fire and smoke between fire compartments.
Firestop sealants are among the most commonly used materials in such systems. They are primarily used for sealing service penetrations and linear gaps in building elements, such as walls and floors.
Due to their performance characteristics, firestop sealants help maintain the required fire resistance class of the building element, thereby enhancing occupant safety and providing additional time for evacuation and firefighting operations.
Firestop sealants are specialised sealing materials used in passive fire protection systems in buildings. Their primary function is to reinstate the fire resistance performance of building elements where they have been penetrated by services such as pipe, cable, or duct penetrations through walls and floors or where linear gaps are present.
In the event of fire, a properly specified firestop sealant prevents the passage of flames, hot gases to adjacent spaces or fire compartments. Depending on the product type, the material may exhibit intumescent properties, expanding when exposed to elevated temperatures to close openings and maintain the integrity of the penetration seal.
Modern firestop sealants also demonstrate good adhesion to a wide range of construction substrates, including concrete, masonry, steel, and plasterboard. This allows their application across various types of construction, including residential, commercial, industrial, and public buildings.
The effectiveness of firestop sealants is primarily based on the sealing of service penetrations and the material’s reaction to elevated temperatures. This enables the fire resistance performance of the building element—wall or floor—to be maintained, even when penetrated by pipes, cables, or other services.
The primary function of a firestop sealant is to completely fill annular gaps and openings around services passing through building elements. Once installed, the material forms a durable, airtight seal that restricts the passage of air and hot gases between fire compartments.
An example of such a solution is the graphite-based intumescent firestop sealant INTU FR GRAPHITE, which enables reinstatement of the required fire resistance of walls and floors at service penetrations. The product effectively seals annular gaps around cables or pipes, ensuring airtightness and fire resistance performance of up to EI 120, subject to the relevant system configuration and supporting construction.
A key characteristic of many firestop sealants is their intumescent behaviour when exposed to elevated temperatures. In the case of graphite-based products, the reaction typically initiates at approximately 140 °C.
During this process, the material expands and forms a multicellular char structure, which seals gaps around services resulting from thermal deformation during fire exposure or voids created following the burn-through of combustible services.
The resulting insulating layer acts as an effective thermal barrier, limiting the transmission of heat, flames, and hot gases to adjacent compartments. In practice, this ensures that the penetration seal maintains the required fire resistance classification for a specified period, which is critical for overall building fire safety.
Acrylic-based intumescent firestop sealants, such as INTU FR MASTIC, are widely used in passive fire protection systems. Once installed, the sealant forms a flexible and airtight seal with excellent adhesion to common construction substrates, including concrete, masonry, and plasterboard.
In the event of fire exposure, the material exhibits intumescent behaviour, expanding to form a porous char layer that effectively restricts the passage of heat and flames. As a result, such products are commonly used for sealing cable penetrations, cable bundles, and small annular gaps, where maintaining the fire integrity (E) and, where applicable, insulation (I) of the building element for a specified fire resistance period is required.
In the case of non-intumescent fire protection coatings, the mechanism of action is primarily based on physical and thermochemical processes within the material. Under fire exposure, elevated temperatures lead to gradual degradation of the polymer matrix and evaporation of bound moisture, which absorbs heat and delays temperature rise in the protected element.
At the same time, mineral fillers within the formulation form a stable, non-combustible residue that contributes to maintaining the integrity of the protective layer and limits the passage of flames and hot gases.
The effectiveness of passive fire protection systems depends largely on the performance characteristics of the materials used. A properly specified firestop sealant should not only provide the required fire resistance classification but also ensure durability, integrity, and compatibility with the relevant firestop system and supporting construction.
In practice, this involves a combination of critical properties, as demonstrated by firestop sealants such as INTU FR MASTIC, INTU FR GRAPHITE, as well as fire protection coatings including INTU FR COAT A, INTU FR COAT I and INTU FR UNICOAT P.
Fire resistance and effective compartmentation
The fundamental performance characteristic of firestop sealants is their ability to maintain integrity (E) and insulation (I) for a specified fire resistance period. Depending on the tested system configuration, solutions based on INTU FR MASTIC or INTU FR GRAPHITE can achieve fire resistance classifications of up to EI 240. This ensures that, in the event of fire, the penetration seal effectively restricts the spread of flames, hot gases, and heat to adjacent fire compartments.
Suitability for use in firestop systems
Modern fire protection materials are designed as components of complete, tested firestop systems. In addition to sealants, specialist fire protection coatings such as INTU FR COAT A and INTU FR COAT I are used for the protection of cable management systems and for application on mineral wool boards or steel pipes.
The INTU FR UNICOAT P coating is intended for use in mixed penetration systems, where cable installations and metallic or combustible pipes pass through a single opening.
Adhesion to construction substrates
Firestop sealants must demonstrate reliable adhesion to common construction substrates, including concrete, masonry, steel, and plasterboard. This enables their use in a wide range of building elements – both walls and floors – and across various service penetration configurations.
Flexibility and durability in service
An important characteristic of firestop sealants is the retention of flexibility after curing. This allows the material to accommodate minor service movements and structural deflections without cracking or loss of seal integrity.
As a result, the firestop system remains airtight and effective throughout the service life of the building.
Ease of installation on site
A practical advantage of many modern firestop sealants is their ease of installation. Products such as INTU FR MASTIC and INTU FR GRAPHITE are designed for application using standard sealant guns and installation tools, enabling efficient and precise sealing, including in areas with limited accessibility.
Due to this combination of properties, firestop sealants and fire protection coatings constitute essential components of passive fire protection systems, enabling effective sealing of service penetrations, linear joints, and installation interfaces across a wide range of building types.
The correct selection of a firestop sealant is critical to the performance of a passive fire protection system. Not all products are suitable for every application; selection must consider the type of building element, the nature of the services, and the required fire resistance classification.
The key selection criteria are outlined below.
Type of building element
The type of building element (wall or floor), including its thickness and construction, determines the appropriate firestop solution. This parameter is critical, as it defines the achievable fire resistance classification, installation method, and overall system performance.
Therefore, the product used to secure the installation passage must always be selected in accordance with the type and parameters of the partition for which it was tested.
Type of services and penetrating materials
The selection of the firestop solution also depends on the type of services passing through the building element:
Required fire resistance classification
Each building element is assigned a specific fire resistance classification (e.g. EI 30, EI 60, EI 120). The firestop solution must be selected to meet these requirements.
Products offered by Alfaseal Group are supported by technical documentation specifying the fire resistance classifications achieved under defined test conditions. As a rule, products should be selected to meet or exceed the project-specific requirements, ensuring full system performance and compliance.
Installation and service conditions
When selecting a firestop sealant, site conditions and in-service requirements must also be considered, including ambient temperature, humidity, accessibility of the installation area, and potential movement of services after installation.
Products such as INTU FR MASTIC are characterised by ease of installation and reliable adhesion under a range of site conditions, while INTU FR GRAPHITE is particularly suited for applications requiring high-temperature resistance and intumescent expansion in fire conditions.
Certification and technical documentation
All firestop products should be supported by appropriate certifications and technical assessments confirming their performance and compliance with applicable standards.
These may include test reports, classification reports, and approvals (e.g. ETA), which define the scope of application and the fire resistance performance of the system.
