R302.5.2 Duct penetration

[Marc M]

R302.5.2 Duct penetration. Ducts in the garage and ducts
penetrating the walls or ceilings separating the dwelling
from the garage shall be constructed of a minimum No. 26
gage (0.48 mm) sheet steel or other approved material and
shall have no openings into the garage.

Jerry,
can you explain the last bolded sentence?
Also,
When the duct penetrates the firewall, is the entire duct on the garage side (for example) solid sheet metal? I asume it is for obvious reasons but want to make sure.

[Jerry Peck - Codeman]

Hi Marc,

and shall have no openings into the garage.

The duct is required to be connect to the air handler unit (the typical reason the duct would be in the garage) and run from the air handler unit through the garage space through the separation wall between the garage space and the living space, with; a) no supply openings; b) no cut out openings in the duct; c) no openings of any kind for any reason which open the duct to the garage space (also remember that the system serving the the living space is not allowed to have a supply or return in the garage, and this backs that up).

When the duct penetrates the firewall, is the entire duct on the garage side (for example) solid sheet metal?

Yes, 26 gage sheet metal all the way ... don't forget the "or other approved material" - that sometimes includes ductboard (depends on the AHJ, or in the cases of Florida the Residential code states, "shall be constructed of a minimum No. 26 gage (0.48 mm) sheet steel, 1 inch (25 mm) minimum rigid nonmetallic Class 0 or Class 1 duct board, or other approved material").

[Marc M]

Thank you.