The Importance and Benefits of Tested Fire-Resistant Hybrid Sealants: Spotlight on Nullifire FS704

In today’s construction industry, fire safety isn’t just a regulatory box to tick, it’s a core responsibility. Every component, from the structure to the smallest joint seal, contributes to how effectively a building can resist and contain fire. Among the most crucial yet often overlooked elements are fire-resistant sealants, which help prevent the spread of flames, smoke, and toxic gases through joints and gaps.

As sustainability and performance demands continue to rise, hybrid sealant technologies like Nullifire FS704 are redefining what’s possible in fire protection, combining proven fire performance with excellent durability, versatility, and environmental credentials.

The Science Behind FS704:

Nullifire FS704 is a non-sagging fire resistant sealant with excellent processing properties developed by Tremco CPG UK. Based on hybrid polymers, FS704 is a paintable elastic sealant free of phthalates, isocyanates and silicone. In a reaction with humidity from the air, it forms an elastic sealant that shows good resistance to light, ageing and weathering. The result is a high performance, solvent free sealant that not only provides fire resistance but also exceptional movement capability, adhesion, and weather durability.

Proven, Tested, Fire Resistance:
Fire protection is only as good as its testing and FS704 has undergone extensive, independent testing to the latest standards, EN 1366-4 (Fire resistance tests for service installation - linear joint seals) achieving up to 2 hours of fire resistance. FS704 has also been tested for smoke leakage and has achieved an acoustic rating of 66dB.

By choosing tested and approved systems like FS704, project teams can be sure that both product and application meet the strict requirements of relevant building regulations.

Benefits Beyond Fire Protection:
While FS704 is designed for passive fire protection, its formulation delivers a range of additional advantages:

1. Multi-Functional Performance

FS704 doesn’t just resist fire, it provides excellent weather sealing, acoustic insulation, and joint flexibility; one product can fulfil several functions.

2. Excellent Adhesion & Compatibility

The sealant adheres strongly to a variety of substrates including concrete, masonry, steel and wood, therefore could potentially be suitable for both new-build and refurbishment projects.

3. Sustainable & User-Friendly

Free from phthalates, isocyanates and silicones, FS704 offers low odour, low VOC, and excellent indoor air quality performance, achieving EC1 plus with Emicode and M1 with Eurofins - indoor air quality /emission tests. These characteristics can make it safer for installers. .

4. Long-Term Durability

FS704 maintains elasticity, UV resistance, and weatherproofing over time. It can also be painted over.

FS704 is suitable to fire seal joints in compartment walls and floors, and reinstate s the fire performance of the below substrates :

Concrete - Timber
Concrete - Concrete
Steel - Steel
Steel - Concrete
Drywall - Drywall
Drywall - Concrete
Drywall - Steel
Timber - Timber

Why Tested Products Matter:
Not all sealants are created equal. Using products that lack full scale fire testing or certification can leave unseen vulnerabilities in a building’s passive fire strategy. By selecting Nullifire FS704, specifiers and contractors can be confident they’re using a product backed by independent fire test data, third-party certification and Tremco CPG UK’s decades of expertise in fire protection.

Conclusion:
Nullifire FS704 Fire Resistant Hybrid Sealant represents the next generation of passive fire protection bringing together tested safety, hybrid innovation, and sustainable performance. In an environment where safety, reliability, and compliance are non-negotiable, FS704 gives construction professionals the confidence that every joint is properly protected - today and for the future. Because when it comes to fire safety, only tested, trusted, and proven performance will do.

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