UNDER CONSTRUCTION

This resource of deemed-to-comply above-grade wall assemblies is provided as a tool to help quickly identify a practical selection of appropriate wall assemblies that meet (i.e., are deemed-to-comply with) model building code and energy code requirements. The focus is on appropriate FPIS ci insulation specification coupled with vapor retarder specification for a given climate zone and level of cavity insulation (other wall assembly components must be specified according to the code as usual).

The featured deemed-to-comply wall assembly solutions comply with the vapor retarder provisions of the 2024 International Building Code (IBC) and International Residential Code (IRC) and with minimum R-value or U-factor requirements of the 2024 International Energy Conservation Code (IECC), including Chapter 11 of the IRC as applicable. In some cases, the energy code minimum requirements are exceeded in order to satisfy the building code’s vapor retarder provisions.

These deemed-to-comply solutions were developed using ABTG's calculators for wood-frame and steel-frame above-grade wall assemblies. The user may apply these tools to help evaluate many other code-compliant wood or steel frame wall solutions.

Basic Wall Assembly & Components
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Key Terms to Know:

  • FPIS = foam plastic insulating sheathing (or foam sheathing / rigid board insulation)
  • ci = continuous insulation
  • perm = a measure of the ability of water vapor to move through a material (a lower perm rating increasingly retards vapor flow and a higher value increasingly allows vapor flow)
  • responsive vapor retarder = a vapor retarder as defined by code that increases in vapor permeance as humidity increases (also known as "smart" vapor retarder). A Class I(r) vapor retarder is not a "vapor barrier" in the classic sense because its  vapor permeance increases with humidity and becomes vapor permeable (i.e., not a barrier to vapor). When used per code it does not create a "double vapor barrier" condition and actually promotes inward drying potential.
  • vapor retarder class = categories of vapor retarders based on different ranges of "dry" cup vapor permeance. Lower vapor permeance means greater vapor retardance. (See Note 3 in table below regarding use of vapor retarder classes and also further classification as a responsive vapor retarder).
  • WRB = water-resistive barrier
  • AB = air barrier
  • VR =  interior vapor retarder (warm-in-winter side of wall)

1 & 2 Family Dwellings & Group R Buildings (3 stories or less)

2024 IECC-R / IRC Ch 11 DEEMED-TO-COMPLY WOOD FRAME WALL ASSEMBLIES WITH FPIS ci

General Notes:

  1. Max U-factors and applicable climate zones are based on 2024 IECC-R / IRC Ch11.
  2. U-factor calculations comply with code using parallel-path method (as executed by ABTG's wall calculator).
  3. Vapor retarder options comply with code (also using ABTG's wall calculator) and in CZ 7 and 8 may require additional FPIS ci R-value to control moisture resulting in a lower wall assembly U-factor and better performance than the energy code alone may require.
  4. The deemed-to-comply solutions are not exhaustive of code-compliant solutions for insulation R-values and vapor retarders. They represent practical, cost-effective solutions. To consider additional options, refer to ABTG's wall calculator and the code.

Climate Zones:

0, 1, 2   3   4   5   6   7   8   

Commercial Buildings & Group R Buildings (>3 stories)

2024 IECC-C & ASHRAE 90.1-2022 Deemed-to-Comply Wall Assemblies with FPIS ci

General Notes:

  1. Max U-factors and applicable climate zones are based on 2024 IECC-C (and are equal to or exceed ASHRAE 90.1-2022 requirements).
  2. U-factor calculations comply with code using parallel-path method (as executed by ABTG's wall calculator).
  3. Vapor retarder options comply with code (also using ABTG's wall calculator) and, in CZ 7 and 8 may require additional FPIS ci R-value to control moisture resulting in a lower wall assembly U-factor and better performance than the energy code alone may require.
  4. The deemed-to-comply solutions are not exhaustive of code-compliant solutions for insulation R-values and vapor retarders. They represent practical, cost-effective solutions. To consider additional options, refer to ABTG's wall calculator and the code.

Climate Zones:

0, 1   2   3   4   4 Marine   5   6   7   8   

DISCLAIMER: This information is provided "as is." It is the user's responsibility to determine suitability for use and compliance with locally applicable building and energy codes, and to seek professional assistance as appropriate.