INTUMESCENT SEALANT

The Role of Intumescent Sealants in Passive Fire Protection

 Fire safety is one of the essential legal and ethical pillars of modern building design. In buildings with high human traffic—such as residential complexes, offices, hospitals, and public facilities—active suppression systems (sprinklers, detectors, alarms) alone are not sufficient to prevent the spread of fire. In addition to these, passive fire protection systems that physically block fire propagation are also necessary. At the forefront of these passive measures are intumescent sealants, also known as expanding fire-resistant mastics.

 

What is Intumescent Sealant?

 An intumescent sealant is a special type of firestop material that chemically reacts and expands when exposed to high temperatures. As a result, it seals joints, expansion gaps, and cavities in structural elements, preventing the passage of flames and smoke. Unlike ordinary silicone or acrylic sealants, intumescent mastics begin to swell at around 150–250 °C, expanding up to 30 to 40 times their original volume, and form a low-density char layer. This insulating layer not only blocks heat transmission but also delays the physical spread of fire. These characteristics make intumescent sealants one of the most effective product groups in passive fire protection.

 

How Does It Work?

 As temperature increases during a fire, expansion agents in the sealant are activated. These chemicals cause the material to swell and form a carbon-based char layer, ensuring airtightness. This char layer is non-flammable, does not transmit flame, and significantly reduces smoke leakage. It slows down the fire’s progress, preventing it from spreading into adjacent spaces and providing precious time for firefighting interventions. Furthermore, it helps keep evacuation routes safe for longer durations.

 

Areas of Application

 Intumescent sealants are mainly applied in structural joints and penetrations, particularly in the following areas:

• Around fire doors to seal peripheral gaps

• At window junctions to prevent fire spread to the outside

• Around wall penetrations of plastic pipes (sometimes as an alternative to fire collars)

• Around cable penetrations and trays

• At floor-to-wall joints, expansion and movement gaps

• In compartment walls to prevent fire propagation between levels or zones

 When properly applied, they can provide fire resistance ranging from 60 to 240 minutes.

 

International Standards

Products that provide fire resistance are subject to rigorous international testing and certification. The most widely accepted standards include:

• EN 13501-2 (Europe): Classifies fire reaction levels from A (non-combustible) to F. Also includes smoke production (s1–s3) and flaming droplets (d0–d2).

• ASTM E814 / UL 1479 (USA): Tests fire propagation, integrity, and insulation performance.

• ISO 834: Uses standardized time-temperature curves to measure fire resistance.

 These standards ensure that products are evaluated scientifically and are compliant with legal fire safety regulations.

 

 Leading Manufacturers

 Many companies produce intumescent sealants in both Turkey and international markets. Notable names include Hilti, Promat, Rockwool, 3M Fire Protection, Bostik, Tremco Illbruck, and Sika. Their products typically offer various fire resistance ratings (e.g., EI60, EI90, EI120) customized for different application surfaces.

 

Conclusion

 Intumescent sealants are a cornerstone of passive fire protection. They serve a critical function in halting fire spread at often-overlooked but vital points such as cable penetrations, joints, pipe sleeves, and door/window perimeters. With proper material selection, application, and compliance with international standards, these products contribute not only to structural protection but also to saving lives. Always remember—passive fire protection is invisible until it saves lives when it matters most.