Buried Ducts TechSpec

This TechSpec provides an overview for transitioning to a buried duct system.

TechSpec: HVAC Ducts Buried within Ceiling Insulation in a Vented Attic (Buried Ducts)

A buried duct system is a practical and cost-effective alternative to installing ducts inside conditioned space or constructing unvented (semi-conditioned) attics for housing the HVAC system. If constructed in accordance with the recently-approved provisions of the 2018 International Residential Code (IRC), buried ducts provide an effective and energy-efficient air distribution system that ensures comfort and savings for the homeowner.

This TechSpec provides an overview of key attributes and implementation details for transitioning from a traditional duct design to a buried duct system. The focus is on using conventional materials and practices that do not rely on spray foam. The described system uses fiberglass insulation (loose fill and/or batts) and any code-compliant air sealing solutions.