Specification History
| SWS Version | Created | Specification ID | Title | Specification | Objective | Supporting Materials | Rationale | Status |
|---|---|---|---|---|---|---|---|---|
| Version 2025 | 09/24/2023 - 17:17 | 4.0104.2e | Install backing | Install an airtight vapor permeable backing material in full contact with the existing cavity insulation Secure backing material using mechanical fasteners that penetrate the sub framing a minimum of 1" Installation must have a minimum of a 30-year service life |
Airtight, vapor permeable, and durable insulation protection |
The backing of knee walls with an air barrier is required by the IRC, Energy Star, and most all above code building standards. https://basc.pnnl.gov/resource-guides/attic-knee-walls This addresses attic knee wall insulation, which should have an air-tight barrier on both sides to be effective due to the vertical position of the insulation vs. horizontal installations on the attic floor. Clarifying that vapor permeable material cover the insulation will prevent such things as poly being used which could trap moisture. | Red Line | |
| Version 2020 | 08/14/2020 - 14:23 | 4.0104.2e | Install backing | Install airtight backing material in full contact with the existing cavity insulation Secure backing material using mechanical fasteners that penetrate the sub framing a minimum of 1" Installation must have a minimum of a 30-year service life |
Airtight, durable insulation cavity |
Black Line | ||
| Version 2020 | 08/14/2020 - 14:23 | 4.0104.2e | Install backing | Install airtight backing material in full contact with the existing cavity insulation Secure backing material using mechanical fasteners that penetrate the sub framing a minimum of 1" Installation must have a minimum of a 30-year service life |
Airtight, durable insulation cavity |
Black Line |