Applying Fire Rated Intumescent Paint on Steel

Passive Protection for Non-Combustible Materials

Steel is a popular construction material, being appreciated by constructors for its resistance and versatility. Steel is also a noncombustible material and, as such, properly constructed steel structures can preserve their integrity during prolonged elevated temperatures. Some steel-based structures such as low-rise buildings do not require fire protection or only require sprinkler systems.

Despite being the strongest metal used in construction, there are circumstances where steel can lose its capacity to handle heavy loads only a few minutes after being exposed to severe heat if it is left unprotected. Building codes take into consideration several cases where this can be the case and some steel-based construction structures require passive fire protection.

Flame Retardant vs. Intumescent Paint for Steel Structures
Steel beam in fire

When passive fire protection is required and flexibility and aesthetics are important, constructors can consider reducing the risks of a structural collapse in the eventuality of fire by applying intumescent coatings on the steel structures in question. Intumescent products can also be used to upgrade the fire rating of a steel structure that is already protected, for example from 1 hour- to 2 hour- fire rating.

There are two different types of fire resistant paint that can be used for steel: fire-retardant and intumescent. Fire retardant paint responds to heat with flame-damping gas that limits the spread of flames across a surface. Flame retardant paint is not used on steel structure as often as intumescent paint because it has limited insulating properties.

Intumescent Paint in Action
Steel beam covered by fire intumescent paint

Fire rated intumescent paint is the most commonly used coating to protect steel against fire and acts as an insulator, forming a solid char in response to heat. Intumescent paint can be applied on steel as a thin or a thick film coating. Thin film fireproof paint materials that can be used for steel are water or solved based and are typically applied to prevent fires in regular buildings. While thick films were originally used in hydrocarbon and off-shore industries, a modified version of them is currently used for fire prevention in buildings. As their name suggests, thick films have a higher thickness and are useful in places where thin films may not work, with a good example being the external steel structures from skyscrapers.

Fire barrier paint

Our intumescent paint can be applied on steel with a brush or spray with an application rate per coat of 1138.8 sq ft/gallon at 1 mil and 37 sq ft/gallon at 30 mils

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Technical Data

FlameOFF® intumescent coatings provide the installer an easier application of the intumescent coating and offer design professionals many benefits.


The performance criteria as set out in a building code are clear and unambiguous, and need to be tested by an independent third party. Our tests are completed by national accredited testing laboratories. Their unbiased results are the basis for our certification listings.

FlameOFF® Fire Barrier Paint has been tested to ASTM E-119 and ASTM E-84 Fire Endurance standards to meet the requirements set forth by IBC/NFPA Building Codes. Our ICC listings are available here, via the ICC-ES listing directory. Please contact FlameOFF Coatings® Technical Team to receive individual test reports conducted to ASTM E-119/UL 263 and ASTM E-84/UL 723 test standards for all substrates.

Report number Details Codes
ESL-1117 Structural Steel
ESL-1157 Structural Steel
ESL-1162 Structural Steel
ESL-1190 Structural Steel
ESL-1191 5/8" Type X Gypsum
ESL-1192 E-84 Class A
ESR-3874 Structural Steel

Applying FlameOff® Fire Barrier paint on exposed structural steel elements can provide additional fire-resistance, increasing the hour fire rating of an element while also improving the aesthetics of the structure in question.

The product must be applied to the steel in layers to achieve the required DFT for the appropriate rating as specified by building codes.

The intumescent paint can be topcoated with latex or acrylic paints in order to obtain a specific color.

When applied on steel, our intumescent fire barrier product produces a thick surround which protects the steel elements.



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For most applications, yes! For Structural Steel Applications, an Alkyd Metal Primer is required. For Galvanized Steel Applications, an all purpose acrylic primer is required.
Intumescent paint is typically thicker than a standard latex paint. Our product, FlameOFF® Fire Barrier Paint, is 71% volume solids; almost twice the thickness of a standard latex paint! Required Dry Film Thicknesses vary depending upon substrate. For more details, please contact a FlameOFF® Representative to figure DFT and coverage rates for your particular project.
Wet Film Thickness, or WFT, is the measured thickness of any applied wet paint/coating. Dry Film Thickness (DFT) is the thickness of the coating once it has cured, and is calculated based on the volume solids content of the material. Both variables are measured in mils. Our product is 71% volume solids. Therefore, DFT can be calculated as WFT x 0.71.

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