Ductwork – Sealing

An exert from the 2010 ECCC regarding ductwork and required levels on air sealing.  Certinspectors have the duct testing equipment to test,confirm and supply the necessary documentation the building department will require.

403.2 Ducts.

 

403.2.1 Insulation. Supply ducts in attics shall be insulated to a minimum of R-8. All other ducts shall be insulated to a minimum of R-6.Exception: Ducts or portions thereof located completely inside the building thermal envelope.

403.2.2 Sealing. All ducts, air handlers, filter boxes and building cavities used as ducts shall be sealed. Joints and seams shall comply with Section M1601.3.1 of the Residential Code of New York State, or, in New York City, the New York City Construction Codes. Duct tightness shall be verified by either of the following:
1. Post construction test: Leakage to outdoors shall be less than or equal to 8 cfm (226.5 L/min) per 100 ft2 (9.29 m2) of conditioned floor area or a total leakage less than or equal to 12 cfm (12 L/min) per 100 ft2 (9.29 m2) of conditioned floor area when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the entire system, including the manufacturer’s air handler enclosure. All register boots shall be taped or otherwise sealed during the test.
2. Rough-in test: Total leakage shall be less than or equal to 6 cfm (169.9 L/min) per 100 ft2 (9.29 m2) of conditioned floor area when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the roughed in system, including the manufacturer’s air handler enclosure. All register boots shall be taped or otherwise sealed during the test. If the air handler is not installed at the time of the test, total leakage shall be less than or equal to 4 cfm (113.3 L/min) per 100 ft2 (9.29 m2) of conditioned floor area.Exception: Duct tightness test is not required if the air handler and all ducts are located within conditioned space.

The building duct and plenum system shall meet the requirements above as verified using instruments and procedures specified in ANSI/ASHRAE 152 and ASTM E1554 Test Method A. Tests at other test pressures are permitted to be used if they are converted to equivalent leakage at 25 pascals (Pa) of pressure, and such equivalence is demonstrated to the satisfaction of the code enforcement official. The test shall be conducted by a qualified person, who shall demonstrate competence to the satisfaction of the code enforcement official for the conduct of such tests. For the purpose of this section CFM25 shall mean the leakage from all ducts and plenums in cubic feet per minute measured at 25 pascals of pressure in accordance with ANSI/ASHRAE 152 or ASTM E1554. Test results shall be provided to the code enforcement official and shall include:

1. Name and place of business of the tester;
2. Address of the building which was tested;
3. Conditioned floor area of dwelling, calculated in accordance with ANSI Z65, except that conditioned floor area shall include areas where the ceiling height is less than 5 feet (1524 mm);
4. Measurement of CFM25; and
5. Certification of accuracy of test results and signature of tester.
403.2.3 Building cavities. Building framing cavities shall not be used as supply ducts.