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IRC Section M1505 — HVAC Ducts and Plenums

Updated Apr 3, 2026

Addresses ductwork materials, construction, and sealing for mechanical systems.

Section M1505 specifies ductwork construction and installation. Sheet metal ducts must be properly sealed and supported. Fiberglass ducts provide insulation and sound attenuation. Ductwork must be sized for proper air distribution without excessive noise. Duct sealing with mastic or metal-backed tape prevents air leakage. Returns must be sealed to prevent infiltration of unconditioned air.

TAGS

irc hvac ductwork

DETAILS

section

M1505

category

Mechanical Systems

code body

IRC

code year

2021

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