Chapter Five

Fire-Resistive Construction Elements

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Learning Objectives

• Describe the difference between specification codes and performance codes

• Explain why a rated assembly must be maintained as a unit

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Learning Objectives

• Describe origin of STTC and its significance

• List three nationally recognized testing labs

• Explain why labeling is mandated

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Specification Code

• A code provision that specifies a type of construction or materials to be used

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Specification Code

• “The protection on all floor and roof beams shall be at least one inch thick of concrete or porous terra-cotta or brick set in cement.”– 1916 Boston Building Code

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Performance Codes

• Identify a performance feature rather than specific construction elements

• Fire resistance in hours

• Load bearing ability in pounds per ft²

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Performance Code

• “Vertical exit enclosures four stories or more shall be 2-hour fire-resistance rated.”– 2006 International Building Code

• Performance Code Performance Based Design

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“Fire Resistance Rating of One Hour”

• One hour of what?

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Tests for Fire Endurance of Building Materials

• Based on tests developed in early 1900s

• Standard Time-Temperature Curve

• ASTM E119

• UL 263

• NFPA 251

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Standard Time-Temperature Curve

• Reproducible test fire• Under laboratory

conditions• By ASTM in 1918• Based on fire tests in

“Ordinary construction”• 8,000 BTUs/lb

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Tests of a Rated Assembly

• Specified in specific standards and include

• Ability to support a specified load

• Limit heat transfer

• Prevent passage of heat

• Withstand hose stream test

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Fire Walls versus Fire Barriers

• Fire walls

• Separate buildings

• Designed to withstand collapse of structures on either side during fire conditions

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Fire Walls versus Fire Barriers

• Fire barriers or fire separation walls

• Separate fire areas

• Rated assemblies constructed within the building

• Extend from floor to floor above or to the roof

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Opening Protectives

• Fire doors

• Fire windows

• Fire shutters

• Rated glazing

• Fire dampers

• Through penetration firestop

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Structural Ratings

• Provided by encasement

• Concrete or masonry

• Gypsum

• Approved spray on material

• Asbestos was widely used

• Impact protection must be provided

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Fire Blocking

• Method of controlling fire spread through small concealed spaces

• Formerly called “fire stopping”

• Not a rated assembly

• Fire blocking requirements are prescriptive not performance requirements

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Draft Stopping

• Method of controlling fire spread through large concealed spaces in combustible construction

• Attics, floor, ceilings

• Not a rated assembly

• Draft stopping requirements are prescriptive not performance requirements

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Draft Stopping

• Typically, 3,000 ft² for attics in apartments

• Attics must have access for maintenance and inspection

• Openings in draft stops self closing and latching

• Often damaged by tradesmen

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Summary

• Building code requirements are generally performance versus specification

• Specify ratings in hours for structural elements

• Assemblies are tested in accordance with the STTC tests

• Approved assemblies are listed