Building Fire Retardant Coatings: A Solid Barrier for Steel and Wood Structures

Fire retardant coatings create a passive barrier that slows heat transfer and flame spread, safeguarding steel and wood structures from collapse and combustion. Intumescent coatings, which expand into an insulating char when exposed to heat, are the prevailing technology for steel protection, available in ultra-thin (<3 mm), thin (3–7 mm), and thick (7–45 mm) formulations tailored to indoor or outdoor use. For wood, water-based intumescent paints rapidly swell at high temperatures, forming a protective layer that affords 30–90 minutes of fire integrity while remaining decorative and non-toxic. Selecting the right coating depends on substrate type, required fire-resistance rating, and environmental conditions, ensuring both structural safety and aesthetic requirements are met.

Steel Structural Fire Protection

Steel beams, columns, and frames lose strength rapidly when heated, risking structural failure in as little as 5–10 minutes of fire exposure. Applying an intumescent coating forms a carbonaceous char that insulates the steel, delaying temperature rise and maintaining load-bearing capacity under fire conditions. Intumescent formulations based on epoxy or acrylic binders expand up to 50 times their original thickness, providing 30 to 120 minutes of protection depending on film thickness and coating system.

Intumescent Coatings for Steel

• Ultra-Thin Coatings (≤3 mm): Often used indoors for minimal architectural impact, these coatings expand to provide up to 2 hours of fire resistance while maintaining a smooth finish.

• Thin Coatings (3–7 mm): Balance decorative appearance with robust protection; suitable for both interior and sheltered exterior steel elements.

• Thick Coatings (7–45 mm): Economical for concealed structural members; their granular surface is less aesthetic but offers extended fire resistance beyond 2 hours.

• Water- vs. Solvent-Based: Water-based intumescent systems reduce VOC emissions and odor for indoor use, while solvent-based variants offer faster drying and broader temperature tolerance for exterior applications.

Wood Structural Fire Protection

Wood components such as beams, columns, and flooring are inherently combustible and require specialized coatings to meet building code fire ratings. Decorative, water-soluble intumescent paints rapidly swell under heat to form a thick, insulating layer of char, providing 30–60 minutes of protection without altering wood’s natural appearance. These coatings are non-toxic, solvent-free, and easy to apply by brushing or spraying.

Decorative Intumescent Coatings for Wood

• FireGuard E-84: A water-based, non-toxic intumescent coating that achieves fire-rated assemblies on interior wood, drywall, and metals with as few as two coats, minimizing smoke and flame spread.

• FlameOFF® Fire Barrier Paint: Eco-friendly, ASTM E119/UL 263-compliant, providing 1–2 hour fire protection for wood, steel, and gypsum and certified for Class A flame spread on wood surfaces.

• DC360: A water-based acrylic emulsion that delivers a Class “A” interior finish under ASTM E84, and a 30-minute fire rating on wood and OSB, enabling seamless top-coating with decorative latex paints.

Selecting Appropriate Fire Retardant Coatings

Choosing the right coating involves:

1. Fire-Resistance Rating: Match film thickness to the required endurance (e.g., 30, 60, 120 minutes per ASTM E119 or UL 263).

2. Substrate Compatibility: Ensure adhesion and performance on steel, wood, or mixed assemblies.

3. Environmental Conditions: Select water-based for low-VOC indoor use and solvent-based or specialized exterior grades for exposure to humidity, UV, and freeze-thaw cycles.

4. Aesthetic Requirements: Opt for ultra-thin or decorative intumescent paints where visual impact is critical; choose thicker, concealed systems for hidden structural elements.

Conclusion

Building fire retardant coatings—particularly intumescent systems—provide essential passive protection for steel and wood structures, extending evacuation times and preserving structural integrity under fire conditions. By selecting the appropriate coating grade, thickness, and formulation, architects and engineers can meet stringent safety standards while maintaining design aesthetics and environmental responsibility.

Lior Lee

Email:lilin@hzruico.com