Specifying Fire Resistive Coatings Presented by: Jayson L. Helsel, P.E. KTA-Tator, Inc. 1

Learning Objectives Comprehension of the webinar will enable the participant to: Describe how intumescent coatings protect underlying steel from heat exposure List two fire rating classification tests that are used to qualify intumescent coatings for use in building construction Identify two primary resin types that are used to formulate intumescent coatings Explain how steel size and structure design affect specified thickness and number of coats

Fire Resistive Coatings Sprayed Fire Resistive Materials (SFRM) are broad group of materials including: –Cementitious and gypsum based materials –Intumescent coatings (Note: There is a separate category for “Fire Retardent” coatings, which are not reviewed here)

Fire Resistive Coatings Intumescent Coatings: –Are categorized as SFRMs –Similar to conventional coatings –Have unique fire resistant properties

Intumescent Coatings How they function: –Intumescent coatings char and swell when exposed to fire/heat –The charred layer acts to insulate the steel from fire

Intumescent Coatings Performance ratings –Coatings rated by how long steel is protected at specified thickness –Ratings from 1 to 3 hours (at 30 minute intervals –Specific to shape/size of steel, e.g. W10 x 49 column

Fire Resistance Classifications Underwriters Laboratories (UL) is recognized authority that evaluates and approves intumescent coatings for a certain classification and fire rating Certifications can be verified online at

Fire Resistance Classifications Certifications are “design” specific by coating manufacturer Numbering system defines an alphanumeric design number

Fire Resistance Classifications Beams –W, M or S shaped steel sections (AISC) –Minimum beam size for fire resistance is expressed as W/D ratio W = weight of beam per lineal foot D = perimeter of protection material –Beams of same configuration with greater W/D ratio may be used in design

Fire Resistance Classifications Columns –Minimum column size and configuration specified in X and Y series designs –Same hourly rating applies when section with equal or greater W/D ratio is substituted for same configuration

Fire Resistance Classifications Beams and Columns –Required coating thickness increases as weight of steel decreases Lighter steel heats up more rapidly and requires more protection

Fire Resistance Classifications ANSI/UL 263 –Used for resistance to cellulosic fire (e.g. combustion of wood or building materials) –Slower rise in temperature 1000 F at 5 min.; 1550 F at 30 min.; 1700 F at 60 min.; 1925 F at 180 min.; 2000 F at 240 min. –Interior and exterior exposures

Fire Resistance Classifications ANSI/UL 263 Classified Coatings –Typical use for structural steel in commercial structures

Fire Resistance Classifications ANSI/UL 1709 –Used for resistance to a hydrocarbon fire –Rapid rise in temperature 2000 F at 5 minutes –Interior and exterior exposures Environmental tests include, accelerated aging, high humidity, salt spray, thermal cycling for exterior exposure

Fire Resistance Classifications ANSI/UL 1709 Classified Coatings –Typical use for steel structures at petrochemical facilities, e.g. Chemical plant Refineries Offshore oil platforms

Other Approvals Intumescent coatings may also need approval by city building codes Coating manufacturers should provide approvals as applicable

Generic Coating Types Intumescent coatings are generally the following generic resin types: –Acrylic/vinyl –Epoxy Intumescents are also generally categorized as “thin-film” or “thick-film” coatings

Generic Coating Types Acrylic/vinyl Thin-film coating Solvent or water-based Single component Typically rated under UL 263

Generic Coating Types Acrylic/vinyl Applied in several coats Time-frame for a complete application may span several days Additional time may be needed before application of any required exterior finish coat.

Generic Coating Types Epoxy Thick-film coating Applied by plural component spray equipment in one or two coats Rapid cure Typically rated under UL 1709

Generic Coating Types Epoxy May require mesh reinforcement (e.g. metal, fiberglass, carbon) Typically requires the use of applicators licensed or approved by the coating manufacturer

Generic Coating Comparison Coating TypeRequired Thickness (mils) Number of Coats Recoat Time (between Time to Finish Solvent based acrylic hours25 days Solvent based vinyl hours20+ days Water based acrylic hours10+ days Epoxy1801n/a24 hours Epoxy w/mesh n/a48 hours 33

Testing for Coating Cure Intumescents may require testing for proper cure Typical test is Durometer Hardness (Shore D) –Resistance of coating film to indentation by Durometer instrument –ASTM D2240, “Standard Test Method for Rubber Property-Durometer Hardness”

Testing for Coating Cure

Coating Appearance Intumescents generally have a rough or orange peel appearance Methods to improve include: Back rolling following spray application Sanding (not recommended) Finish coat application (may be required) Test sections recommended

Coating Systems Intumescent design approvals typically include a primer and/or finish coat –When included in design primer/finish must be applied to meet fire rating Primer/finish must be endorsed by intumescent coating manufacturer –Preference always for same manufacturer

Use of Primers Intumescent coating manufacturer may have approved list of primers –Types include alkyd, acrylic, epoxy and zinc- rich –Application thickness important

Primers Function of primer –Provides adhesion to substrate –Provides suitable surface for intumescent –Provides additional barrier protection Can also provide inhibitive or sacrificial protection

Use of Finish Coat May be required in design approval for exterior exposure Intumescent coating manufacturer must endorse finish material –Types include 100% acrylic and aliphatic urethane coatings May affect/improve appearance

Finish Coats Function of topcoat –Color and gloss –Abrasion resistance –Chemical resistance –Washability –Resistance to the environment

Finish Coats Acrylics –Advantages Single component Ease of application Color & gloss retention Flexibility Low VOC content for waterbased

Finish Coats Acrylics –Limitations Limited alkali and solvent resistance Moderate abrasion resistance Application temperature >50ºF for waterbased

Finish Coats Urethanes –Advantages Color & gloss retention (aliphatic) Adhesion Acid, alkali resistant Chemical resistant Impact/abrasion resistant

Finish Coats Urethanes –Limitations Multi-component Short recoat intervals Limited pot life Moisture sensitive during cure Difficult to recoat

Fire Resistive Coating Inspection Technical Manual 12-B –Published by Association of the Wall and Ceiling Industries (AWCI International) –Individual measurement = average of 3 gauge readings (similar to SSPC-PA 2) –Testing frequency one bay per floor or one test per 10,000 square feet (further defines required shapes)

Fire Resistive Coating Inspection Technical Manual 12-B –Scope –General Information –Substrate Conditions –Site Conditions –Inspection Procedures –Method of Tests –Conditions of Finished Application –Patching

Fire Resistive Coating Inspection Intumescent (and Mastic) Coatings –Coating thickness specification in a design is minimum average thickness measured in accordance with Technical Manual 12-B Average thickness should not exceed maximum thickness published (if listed) in individual designs No individual measurement <80% of specified design thickness

Summary of Key Points When specifying intumescents consider: –Required UL approval –City building code approval –Include required primer and finish coats –Applicator certification if needed (e.g. plural component materials) –Include test sections to evaluate appearance

Specifying Fire Resistive Coatings Questions?