SoffitDuct: An Easy and Innovative Retrofit Distribution Solution

SoffitDuct is a lightweight, prefabricated HVAC ductwork system designed to replace invasive site-built soffits in multifamily retrofits. Demonstrated at the Corona Del Rey apartments in California, the system uses foil-faced foam to provide a 'finish-ready' exterior that can be painted, reducing contractor time and duct leakage. While the project identified challenges in passing through structural wall framing, it estimates that the solution is applicable to 6.3 million residential units (45%) in California, excluding studios, one-bedroom units, and single-story homes with attics.

• SoffitDuct addresses the high cost and disruption of multifamily mechanical retrofits by providing a prefabricated, lightweight HVAC distribution system with a "finish-ready" exterior, eliminating the need for traditional site-built soffits, drywall work, and extensive sheet metal fabrication.
• The system offers several technical advantages, including design flexibility regarding aspect ratios and insulation levels, a lightweight foil-faced foam construction that requires minimal structural support, and improved air sealing that lowers duct-leakage rates compared to sheet metal, leading to carbon and energy savings.
• Demonstration at the Corona Del Rey apartments revealed that passing the ductwork through walls with structural framing remains a challenge; adding flanges to bypass framing members increased the complexity and time required for design, fabrication, and transport.
• The market potential for SoffitDuct in California is estimated at 6.3 million residential units, or 45% of the state's units, excluding studios, one-bedroom units, and single-story homes with attics where ductless upgrades or attic installations are more cost-effective.

APA

RMI (2025). SoffitDuct: An Easy and Innovative Retrofit Distribution Solution. https://rmi.org/resources/soffitduct-an-easy-and-innovative-retrofit-distribution-solution/

Chicago

RMI. SoffitDuct: An Easy and Innovative Retrofit Distribution Solution. 2025. https://rmi.org/resources/soffitduct-an-easy-and-innovative-retrofit-distribution-solution/.

Wikipedia

{{cite report |author=RMI |title=SoffitDuct: An Easy and Innovative Retrofit Distribution Solution |date=15 April 2025 |url=https://rmi.org/resources/soffitduct-an-easy-and-innovative-retrofit-distribution-solution/ |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{rmi2025soffitduct, author = {{RMI}}, title = {{SoffitDuct: An Easy and Innovative Retrofit Distribution Solution}}, institution = {RMI}, year = {2025}, month = apr, url = {https://rmi.org/resources/soffitduct-an-easy-and-innovative-retrofit-distribution-solution/}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }