Composite WRB Sheathing With Resealable Flaps at Mate Lines
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Solution Overview
Problem
Existing wall sheathing assemblies with vapor-permeable water-resistant barriers (WRBs) face challenges in maintaining integrity and sealing at mate lines, which are repeatedly accessed and closed during building construction, leading to deterioration and air infiltration.
Innovation Solution
A composite structural board with a vapor-permeable WRB sheet attached to a structural board using a discontinuous adhesive, allowing for unattached areas that enable liquid movement and featuring flaps that can be demountably attached, ensuring effective sealing and access without excessive deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the WRB sheet is repeatedly opened and closed to access mate lines during construction, then service lines can be installed and inspections carried out, but the WRB sheet suffers deterioration in integrity and performance due to staple holes and wrinkles
Solution Approach 1:
The WRB sheet is segmented into movable flaps at the mate lines that can be independently opened and closed. This allows access to service lines without repeatedly opening the entire WRB sheet, reducing deterioration from repeated handling.
Solution Approach 2:
The WRB sheet is pre-installed on the wall sheathing before the building is enclosed. Service lines are then accessed through pre-designed openings in the mate lines, eliminating the need to repeatedly open and close the WRB sheet after installation.
2Reliability
If the WRB sheet is made more durable to resist deterioration, then integrity is improved, but the cost and complexity of the material increases
Solution Approach 1:
Rather than making the entire WRB sheet more complex and durable, only the critical areas at the mate lines are segmented into protected flaps. This localized approach improves durability where needed without increasing overall system complexity.
Solution Approach 2:
The WRB sheet has different properties in different areas: the majority of the sheet remains simple and lightweight, while the flaps at the mate lines are designed with specific durability features. This local differentiation improves reliability without unnecessarily increasing overall complexity.
3Reliability
If the WRB sheet is fully attached to the structural board, then sealing is improved, but access to mate lines becomes difficult and requires cutting through the attached sheet
Solution Approach 1:
The WRB sheet is attached to the structural board in a discontinuous manner, with segments or flaps left unattached at the mate lines. This allows these segments to be moved for access while the rest of the sheet remains securely attached for sealing.
Solution Approach 2:
The WRB sheet transitions from a static fully-attached state to a dynamic system where specific flaps can be moved. The flaps are attached in a way that allows them to be opened and closed repeatedly, providing dynamic access while maintaining overall sealing integrity.
4Reliability
If discontinuous adhesive attachment is used to allow liquid movement paths, then water resistance is improved, but the number of attached and unattached areas increases complexity
Solution Approach 1:
The adhesive attachment is applied in discrete segments or zones rather than continuously across the entire WRB sheet. This segmentation creates natural pathways for liquid movement while maintaining water resistance through the discontinuous adhesive bonds.
Solution Approach 2:
Different areas of the WRB sheet have different attachment characteristics: some areas are fully attached with adhesive for water resistance, while other areas (particularly at mate lines) are left unattached or partially attached to allow liquid movement and access. This local differentiation optimizes both water resistance and functionality.
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 solution provides a continuously sealed building envelope, reduces WRB deterioration, and enhances sealing at butt joints and mate lines, improving the integrity and performance of the wall system while allowing for easy access and resealing.
Implementation Method 1
a vapor-permeable water-resistant barrier (WRB) sheet
Implementation Method 2
a hydrostatic head of 55 cm or greater
Data Source
AI summary
A composite structural board having a structural board and a water-resistant barrier (WRB) sheet, and a wall system comprising same, wherein a face of the structural board is discontinuously attached to the inner face of the WRB sheet solely by a first adhesive, the WRB sheet fully covering the face of the structural board; wherein the unattached areas between the face of the structural board and the inner face of the WRB sheet define paths by which a liquid can move between the face of the structural board and the inner face of the WRB sheet; in some instances the WRB sheet material extends beyond at least one edge of the structural board forming a WRB sheet flap.