Composite House Wrap with Evacuated Foam for Moisture and Insulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing house wraps suffer from high air permeability, low tear strength, and inadequate insulating properties, necessitating a need for a cost-effective solution that provides both moisture vapor transmission and enhanced insulation.
Innovation Solution
A composite house wrap comprising a reinforcing grid layer, a breathable barrier film layer, and an evacuated closed-cell low density polyethylene foam layer, with at least 80% blowing agents dissipated, forming a tortuous path for thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional house wrap materials are used, then moisture vapor transmission is achieved, but air permeability is high and insulating properties are inadequate
Solution Approach 1:
The patent employs a composite structure consisting of a breathable barrier film layer bonded to an expanded closed-cell foam layer. This composite design combines the moisture vapor transmission properties of the film with the insulating and low air permeability characteristics of the evacuated closed-cell foam, thereby achieving both moisture management and thermal insulation while reducing harmful air permeability
Solution Approach 2:
The patent changes the physical state of the foam cells from conventional air-filled to evacuated (vacuum), which fundamentally alters the thermal conductivity and air permeability parameters. The evacuation of blowing agents from closed cells creates a vacuum environment that significantly reduces thermal conductivity (improving insulation) and eliminates air movement (reducing air permeability), while the film layer maintains moisture vapor transmission capability
2Temperature
If house wrap provides adequate insulation, then thermal performance improves, but structural integrity and tear strength may be compromised
Solution Approach 1:
The composite structure combines a thin breathable barrier film with a thicker expanded closed-cell foam layer. The film provides the moisture barrier function, while the foam layer, with its evacuated cells, provides both the insulation performance (R-6 or higher) and the structural integrity. The foam's cellular structure with tortuous thermal paths delivers high insulation, while its bonded construction maintains tear strength and durability
Solution Approach 2:
Different layers of the composite house wrap are assigned different functional qualities: the film layer is optimized for moisture vapor transmission and barrier properties, while the foam layer is optimized for insulation and structural strength. This local differentiation of material properties allows each layer to excel at its specific function without compromising overall performance
3Loss of energy
If house wrap achieves high insulation values, then energy efficiency improves, but material complexity and manufacturing difficulty increase
Solution Approach 1:
The patent achieves high insulation values (R-6 or higher) by changing the fundamental parameter of the foam cells from air-filled to evacuated. This single parameter change (evacuation of blowing agents) creates vacuum insulation that dramatically reduces thermal conductivity through the foam layer, achieving high energy efficiency without requiring multiple complex layers or exotic materials
Solution Approach 2:
The house wrap is segmented into two functional layers: a breathable barrier film layer and an expanded closed-cell foam layer. This segmentation allows each layer to be manufactured using established processes and then bonded together, simplifying manufacturing compared to creating a single homogeneous material with all required properties. The segmentation enables independent optimization of each layer's manufacturing process
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 composite house wrap offers improved insulation (R-6 or higher), moisture vapor transmission, and structural integrity while maintaining cost-effectiveness and ease of handling.
Implementation Method 1
evacuated closed-cell low density polyethylene foam layer, with at least 80% blowing agents dissipated, forming a tortuous path for thermal conductivity
Implementation Method 2
forming a tortuous path for thermal conductivity
Implementation Method 3
a second layer including a breathable, non-perforated barrier film layer... which allows water vapor transmission
Data Source
AI summary
A house wrap for a building comprises a reinforcing drainage plane layer configured to face the outside of the building; a breathable, non-perforated barrier film bonded to the drainage plane layer; and at least one insulating layer including a perforated expanded low density polyethylene foam layer, wherein in the expanded low density polyethylene layer at least 80% of the blowing agents are dissipated from closed cells within the expanded low density polyethylene layer, forming evacuated closed cells whereby a partial vacuum is formed within the closed cells of the low density polyethylene layer.