603.10 Joints and Seams of Ducts. Joints and seams for

duct systems shall comply with SMACNA HVAC Duct Construction Standards – Metal and Flexible. Joints of duct systems shall be made substantially airtight by means of tapes, mastics, gasketing, or other means. Crimp joints for round ducts shall have a contact lap of not less than 1 ¹ ⁄2 inches (38 mm) and shall be mechanically fastened by means of not less than three sheet-metal screws equally spaced around the joint, or an equivalent fastening method.

603.10.1 Duct Leakage Tests.HCD] Ductwork shall be leak-tested in accordance with [Not adopted by the SMACNA HVAC Air Duct Leakage Test Manual. Representative sections totaling not less than 10 percent of the total installed duct area shall be tested. Where the tested 10 percent fail to comply with the requirements of this section, then 40 percent of the total installed duct area shall be tested. Where the tested 40 percent fail to comply with the requirements of this section, then 100 percent of the total installed duct area shall be tested. Sections shall be selected by the building owner or designated representative of the building owner. Positive pressure leakage testing shall be permitted for negative pressure ductwork. The permitted duct leakage shall be not more than the following:

Lmax = CLP ^0.65 (Equation 603.10.1)

Where: Lmax = maximum permitted leakage, (ft ³ /min)/100

square feet [0.0001 (m ³ /s)/m ² ] duct surface

Lmax = maximum permitted leakage, (ft ³ /min)/100

square feet [0.0001 (m ³ /s)/m ² ] duct surface area. CL = six, duct leakage class, (ft ³ /min)/100 square

feet [0.0001 (m ³ /s)/m ² ] duct surface area at

CL = six, duct leakage class, (ft ³ /min)/100 square

feet [0.0001 (m ³ /s)/m ² ] duct surface area at 1 inch water column (0.2 kPa). P = test pressure, which shall be equal to the

design duct pressure class rating, inch

Joints and seams and reinforcements for factory-made air ducts and plenums shall comply with the conditions of prior approval in accordance with the installation instructions that shall accompany the product. Closure systems for sealing factory made air ducts and plenums shall be listed and labeled in accordance with UL 181A or UL 181B, and marked in accordance with Table 603.10.

P = test pressure, which shall be equal to the

design duct pressure class rating, inch water column (kPa). 603.10.1.1 Duct Leakage Tests for ResidentialBuildings. [HCD 1 & HCD 2] See California Energy Code Section 150.0(m)(11) for low-rise res- idential; and Section 140.4(l) for duct leakage tests for other residential buildings.