Intumescent Strip Head-of-Wall Fireblock Assembly
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Solution Overview
Problem
Current fire blocking and containment systems for dynamic head-of-wall construction joints and gaps in buildings are labor-intensive and expensive, with limited effectiveness in sealing smoke and fire penetration, particularly in steel stud wall constructions.
Innovation Solution
A fire retardant head-of-wall assembly comprising an elongated sheet-metal footer and header track with an intumescent strip affixed to the sidewalls, allowing for ceiling deflections while expanding to seal gaps when exposed to heat, enhancing fire and smoke containment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fire blocking materials (mineral wool, spray coatings, caulk) are used to seal head-of-wall gaps, then fire and smoke containment is improved, but labor intensity and installation cost increase significantly
Solution Approach 1:
The intumescent strip is pre-installed in the header track during manufacturing or preliminary construction phases, positioned to automatically expand into the gap when fire occurs. This eliminates the need for labor-intensive manual installation of traditional fire blocking materials at the head-of-wall joint, while maintaining effective fire and smoke containment through the automatic expansion mechanism
Solution Approach 2:
The intumescent strip functions autonomously by automatically expanding when exposed to fire heat, sealing the gap without requiring manual intervention or additional installation steps. This self-activating mechanism replaces traditional methods that require workers to manually stuff mineral wool or apply spray coatings and caulk, dramatically improving installation efficiency while ensuring reliable fire containment
2Reliability
If rigid fire blocking materials are installed to seal head-of-wall gaps, then fire resistance is improved, but adaptability to ceiling deflections (seismic activity, overhead loads) is reduced
Solution Approach 1:
The intumescent strip provides a dynamic solution by remaining flexible and adaptable during normal ceiling deflections caused by seismic activity or overhead loads, then automatically expanding to seal the gap when fire heat is detected. This dynamic behavior allows the system to accommodate building movement while maintaining fire resistance, unlike rigid traditional materials that would crack or fail under deflection
Solution Approach 2:
The intumescent strip changes its physical parameters (volume and density) in response to temperature changes. During normal conditions, it remains in a compressed, flexible state that accommodates ceiling deflections. When exposed to fire heat, it undergoes parametric change by expanding volumetrically to seal the gap, providing both adaptability to movement and fire resistance through temperature-triggered parameter transformation
3Adaptability or versatility
If larger gaps are left between wallboard and ceiling to accommodate deflections, then adaptability to seismic activity is improved, but fire penetration risk increases
Solution Approach 1:
The intumescent strip is pre-positioned in the header track to occupy the potential fire penetration path. When fire occurs, it expands to seal the gap, proactively preventing smoke and fire penetration before they can exploit the larger deflection accommodation gap. This preliminary positioning ensures that larger gaps can be safely used for seismic accommodation without increasing fire risk
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The assembly effectively seals head-of-wall construction joints, preventing smoke and fire penetration, and accommodates ceiling deflections, meeting Underwriters Laboratories standards for fire resistance, thus improving fire protection efficiency and reducing costs.
Implementation Method 1
an elongated intumescent strip affixed lengthwise on at least one of the outer sidewall surfaces of the pair of sidewalls, the intumescent strip being positioned on the upper sidewall portion
Data Source
AI summary
The invention disclosed herein is directed to a fire retardant head-of-wall assembly configured to seal a linear head-of-wall construction joint or gap when exposed to a heat source such as a building fire. The inventive fire retardant head-of-wall assembly comprises a header track having an elongated intumescent strip affixed lengthwise on at least one of the outer sidewall surfaces of the header track. When exposed to a heat source such as a building fire, the intumescent strip is able to expand so as to at least partially fill the head-of-wall construction joint or gap; and in so doing, retard or prevent the spread of smoke and fire. The inventive fire retardant head-of-wall assembly has been certified as complaint with respect to Underwriters Laboratories, Inc.'s standards set forth in its Tests for Fire Resistance of Building Joint Systems—UL 2079.