Arkansas HVACR NewsMagazine November 2025

HVACR NewsMagazine November 2025

State National Chapter News

covering—either an IB or TB—as required for SPF in the surrounding space. • Flexible Ducts and Duct Board: SPF may also be applied to the exterior of ducts constructed from flexible ducts or duct board materials. These duct materials are typically tested and approved under UL181. However, the application of SPF to their exterior is generally not included in the UL181 approval scope and may fall outside standard compliance. Always check with the duct material manufacturer for specific approvals. • Interior Surface Requirements: Building codes mandate that all interior surfaces of ductwork and plenums achieve a flame spread index of ≤25 and a smoke developed index of ≤50, as tested per ASTM E84/UL 723. SPF and other foam plastic insulations do not meet these criteria unless covered by a prescriptive thermal barrier, such as ½-inch gypsum board. • Air Distribution Limitations: Supply and return air must be conveyed through approved duct materials. Attics and crawlspaces insulated with SPF must not be used as return or supply plenums under any circumstances.

SPF offers high R-values, air sealing, moisture control, and structural benefits, but its airtight nature demands precise HVAC sizing and balanced ventilation — typically via ERV or HRV systems. SPF also introduces fire protection requirements: thermal or ignition barriers must separate it from living spaces, especially near combustion appliances. In attics and crawlspaces, SPF must not be used as a return or supply plenum, and ductwork must meet flame and smoke spread codes. Early collaboration between HVAC and insulation professionals is essential to ensure safety, code compliance, and optimal performance. 1 ASTM E779-19 Standard Test Method for Determining Air Leakage Rate by Fan Pressurization , ASTM International, Conshohocken, PA 1 ASTM E1827-17 Standard Test Methods for Determining Airtightness of Buildings Using an Orifice Blower Door, ASTM International, Conshohocken, PA 1 2024 International Energy Conservation Code (IECC), Section R402.5.1.3, International Codes Council, www.iccsafe.org 1 2024 International Building Code (IBC), Section 2603 or International Residential Code (IRC), Section R303 (R315 in prior IRC versions), International Codes Council, www.iccsafe.org 1 SPFA Technical Document SPFA-126, Thermal and Ignition Barriers for the SPF Industry. Spray Polyurethane Foam Alliance https://www.sprayfoam.org/technical-documents/ 1 2024 IBC Section 2113 or IRC Section R1005.8 1 2024 International Mechanical Code (IMC) Section 604.3 or IRC Section M1601.4.6 or 1 UL181 Factory-Made Air Ducts and Air Connectors , 2021, UL Standards and Engagement, Underwriters Laboratories, Bensenville, IL 1 2024 IMC Section 602.3 or IRC Section M1601.3 All references made to ICC documents refer to the 2024 versions. Prior versions of these codes may be used in different jurisdictions. These earlier code versions may have different section numbers and content. References

Summary

Integrating high-efficiency HVAC systems with spray polyurethane foam (SPF) insulation creates durable, energy efficient buildings with superior comfort.