Intumescent Head-of-Wall Firestop for Steel Stud Deflection
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Solution Overview
Problem
Current fire blocking and containment systems for head-of-wall construction joints and gaps in buildings are labor-intensive and expensive, and there is a lack of effective solutions for dynamic head-of-wall systems, particularly in steel stud wall constructions, to prevent smoke and fire penetration.
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 and featuring a U-shaped track with slots for secure fastening, which expands to seal gaps when exposed to heat, preventing smoke and fire spread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fire blocking methods (mineral wool stuffed into gaps with elastomeric spray coating) are used to seal head-of-wall joints, then fire resistance is achieved, but labor intensity and cost increase significantly
Solution Approach 1:
The patent employs pre-fabricated firestop blocks made of fire-resistant materials that can be quickly installed as disposable units. These blocks are designed to be inserted into the head-of-wall joints and secured with minimal labor, replacing the time-consuming process of stuffing mineral wool and applying spray coatings. The blocks provide immediate fire resistance without requiring extensive manual labor for installation.
Solution Approach 2:
The firestop blocks are pre-fabricated with the necessary fire-resistant properties and structural features before installation. This preliminary preparation allows for rapid deployment during construction or renovation, eliminating the need for on-site mixing, stuffing, and coating operations. The blocks come ready-to-install with integrated sealing and fire-blocking capabilities.
2Adaptability or versatility
If dynamic head-of-wall systems with ceiling deflection gaps are used, then structural flexibility is improved, but fire penetration risk increases due to gaps
Solution Approach 1:
The firestop blocks are designed with dynamic characteristics that allow them to accommodate ceiling deflections while maintaining fire sealing. The blocks can be installed in a manner that permits vertical movement of the ceiling relative to the wall, yet the fire-resistant barrier remains intact. This may involve using flexible sealing materials within the blocks or designing the block geometry to maintain contact and sealing under varying ceiling positions.
Solution Approach 2:
The firestop blocks incorporate flexible sealing components such as elastomeric materials or expandable foams that can deform to accommodate ceiling movement. These flexible elements maintain the fire barrier function while allowing the necessary structural deflection, creating a seal that adapts to dynamic conditions rather than requiring rigid fixation.
3Productivity
If steel stud wall constructions with gaps are used, then installation efficiency is improved, but smoke and fire spread is facilitated
Solution Approach 1:
The firestop blocks are designed as discrete, pre-fabricated units that can be independently installed at each head-of-wall joint location. This segmentation allows for efficient installation across the entire wall assembly without requiring continuous labor-intensive operations. Each block is a self-contained fire-blocking element that can be quickly secured to the steel framing, maintaining both installation productivity and fire safety.
Solution Approach 2:
The firestop blocks serve as intermediary elements installed between the steel wall framing and the ceiling structure. These blocks fill the gaps created by the framing system and provide a fire-resistant barrier that mediates between the structural requirements (allowing gaps for installation and deflection) and the fire safety requirements (preventing smoke and fire spread).
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, accommodating ceiling deflections and preventing smoke and fire penetration, as demonstrated by passing Underwriters Laboratories' fire resistance tests, with the intumescent strip expanding to fill gaps and maintain a fire-resistant seal.
Implementation Method 1
an 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
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 is disclosed. 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 and above a centrally located and outwardly protruding lengthwise corrugated groove. The intumescent strip comprises expandable graphite and a fire retardant (C2-C8 alkyl diamine phosphate). When exposed to a heat source such as a building fire, the intumescent strip expands so to fill the head-of-wall construction joint or gap, thereby retarding or preventing 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.