SoffitDuct: An Easy and Innovative Retrofit Distribution Solution

The document is a case study on SoffitDuct, a prefabricated, lightweight HVAC distribution system designed by Thermaduct and RMI to simplify mechanical retrofits in multifamily buildings by eliminating the need for traditional site-built soffits.

• SoffitDuct is a prefabricated, rectangular HVAC ductwork system made primarily of foil-faced foam, designed to provide air distribution and potential chases for plumbing and electrical wiring. It features a "finish-ready" exterior that can be mudded and painted to match drywall, removing the need for invasive and costly site-built soffits.
• The system offers several technical and operational advantages over traditional sheet metal ductwork, including design flexibility regarding aspect ratio and insulation levels, reduced installation time due to prefabrication and a clip install mechanism, and lower duct-leakage rates which contribute to energy and carbon savings.
• A demonstration of the product in a two-bedroom unit at the Corona Del Rey apartments in Corona, California, revealed that passing the ductwork through walls with structural members remains a challenge. In this specific instance, flanges were added to the exterior to avoid interfering with framing, which increased the complexity and time required for design, fabrication, and transport.
• SoffitDuct has a potential market in California covering 45% of residential units, or approximately 6.3 million units. This estimate excludes studios, one-bedroom units (better suited for ductless upgrades), and single-story homes with attics or vented attics where installation is typically cheaper.

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} }