Title 16 - Buildings and Construction

16.370 ENGERGY CONSERVATION CODE

16.370.C402.6.2

Section C402.6.2 of the International Energy Conservation Code is hereby amended to read as follows:

C402.6.2 Air leakage compliance. Air leakage of the building thermal envelope shall be tested by an approved third party in accordance with Section C402.6.2.1. The measured air leakage shall not be greater than 0.35 cubic feet per minute per square foot (1.8 L/s x m²) of the buiilding thermal envelope area at a pressure differential of 0.3 inch water gauge (75 Pa) with the calculated building thermal envelope surface area being the sum of the above- and below- grade building thermal envelope.

Exceptions:

1.

Where the measured air leakage rate is greater than 0.35 cfm/ft² (1.8 L/s x m²) but is not greater than 0.45 cfm/ft² (2.3 L/s x m²), the approved third party shall perform a diagnostic evaluation using a smoke tracer or infrared imaging. The evaluation shall be conducted while the building is pressurized or depressurized along with a visual inspection of the air barrier in accordance with ASTM-E1186. All identified leaks shall be sealed where such sealing can be made without damaging existing building components. A report specifying the corrective actions taken to seal leaks shall be deemed to establish compliance with the requirements of this section where submitted to the code official and the building owner. Where the measured air leakage rate is greater than 0.45 cfm/ft² (2.3 L/s x m²), corrective actions must be made to the building and an additional test completed for which the results are 0.45 cfm/ft² (2.3 L/s x m²) or less.
2.

Buildings in Climate Zone 2B.
3.

Buildings in Climate Zones 0 through 4, other than Group 1 and R occupancies, that comply with Section C402.6.2.3.
4.

As an alternative, buildings or portions of buildings containing Group I-1 and R-2 occupancies shall be permitted to be tested by an approved third party in accordance with Section C402.6.2.2. The reported air leakage of the building thermal envelope shall not be greater than 0.27 cfm/ft² (1.4 L/s x m²) of the testing unit enclosure area at a pressure differential of 0.2 inch water gauge (50 Pa).

C402.6.2.1 Whole building test method and reporting. The building thermal envelope shall be tested by an approved third party in accordance with ASTM E3158 or an equivalent approved method. A report that includes the tested surface area, floor area, air by volume, stories above grade, and air leakage rates shall be submitted to the code official and the building owner.

Exceptions:

1.

For buildings less than 10,000 square feet (929 m2), the entire building thermal envelope shall be permitted to be tested in accordance with ASTM E779, ASTM E3158, ASTM E1827 or an equivalent approved method.
2.

For buildings greater than 50,000 square feet (4645 m2), portions of the building shall be permitted to be tested and the measured air leakage shall be area weighted by the surface areas of the building thermal envelope in each portion. The weighted-average tested air leakage shall not be greater than the whole building air leakage limit. The following portions of the building shall be tested:

2.1 The entire building thermal envelope area of stories that have any conditioned spaces directly under a roof.

2.2 The entire building thermal envelope area of stories that have a building entrance, have a floor over unconditioned space, have a loading dock or that are below grade.

2.3 Representative above-grade portions of the building totaling not less than 25 percent of the wall area enclosing the remaining conditioned space.

C402.6.2.2 Dwelling and sleeping unit enclosure method and reporting. The building thermal envelope shall be tested for air leakage in accordance with ASTM E779, ANSI/RESNET/ICC 380, ASTM E1827 or an equivalent approved method. Where multiple dwelling units or sleeping units or other spaces are contained within one building thermal envelope, each shall be considered an individual testing unit, and the building air leakage shall be the weighted average of all tested unit results, weighted by each testing unit enclosure area. Units shall be tested without simultaneously testing adjacent units and shall be separately tested as follows:

1. 1.
  
  Where buildings have less than eight total dwelling or sleeping units, each testing unit shall be tested.
2. 2.
  
  Where buildings have eight or more dwelling or sleeping units, the greater of seven units or 20 percent of the units in the building shall be tested, including a top floor unit, a middle floor unit, a ground floor unit and a unit with the largest testing unit enclosure area. For each tested unit that exceeds the maximum air leakage rate, an additional three units shall be tested, including a mixture of testing unit types and locations.
3. 3.
  
  Enclosed spaces with not less than one exterior wall in the building thermal envelope shall be tested in accordance with Section C402.6.2.1.

Exception: Corridors, stairwells, and enclosed spaces having a conditioned floor area not greater than 1,500 square feet (139 m2) shall be permitted to comply with Section C402.6.2.3 and either Section C402.6.2.3.1 or Section C402.6.2.3.2.

C402.6.2.3 Building thermal envelope design and construction verification criteria. Where Section C402.6.2.1 and C402.6.2.2 are not applicable the installation of the continuous air barrier shall be verified by the code official, a registered design professional or approved agency in accordance with the following:

1. 1.
  
  A review of the construction documents and other supporting data shall be conducted to assess compliance with the requirements in Section C402.6.1.
2. 2.
  
  Inspection of continuous air barrier components and assemblies shall be conducted during construction to verify compliance with the requirements of Sections C402.6.2.3.1 and C402.6.2.3.2. The air barrier shall be provided with access for inspection and repair.
3. 3.
  
  A final inspection report shall be provided for inspections completed by the registered design professional or approved agency. The inspection report shall be provided to the building owner or owner’s authorized agent and the code official. The report shall identify deficiencies found during inspection and details of corrective measures taken.

C402.6.2.3.1 Materials. Materials with an air permeability not greater than 0.004 cfm/ft2 (0.02 L/s × m2) under a pressure differential of 0.3 inch water gauge (75 Pa) when tested in accordance with ASTM E2178 shall comply with this section. Materials in Items 1 through 16 shall be deemed to comply with this section, provided that joints are sealed and materials are installed as air barriers in accordance with the manufacturer’s instructions.

1. 1.
  
  Plywood with a thickness of not less than 3/8 inch (10 mm).
2. 2.
  
  Oriented strand board having a thickness of not less than 3/8 inch (10 mm).
3. 3.
  
  Extruded polystyrene insulation board having a thickness of not less than 1/2 inch (12.7 mm).
4. 4.
  
  Foil-back polyisocyanurate insulation board having a thickness of not less than 1/2 inch (12.7 mm).
  Closed-cell spray foam having a minimum density of 1.5 pcf (2.4 kg/m3) and having a thickness of not less than 1 1⁄2 inches (38 mm).
5. 5.
  
  Open-cell spray foam with a density between 0.4 and 1.5 pcf (0.6 and 2.4 kg/m3) and having a thickness of not less than 4.5 inches (113 mm).
6. 6.
  
  Exterior or interior gypsum board having a thickness of not less than 1/2 inch (12.7 mm).
7. 7.
  
  Cement board having a thickness of not less than 1/2 inch (12.7 mm).
8. 8.
  
  Built-up roofing membrane.
9. 9.
  
  Modified bituminous roof membrane.
10. 10.
  
  Single-ply roof membrane.
11. 11.
  
  A Portland cement/sand parge, or gypsum plaster having a thickness of not less than 5/8 inch (15.9 mm).
12. 12.
  
  Cast-in-place and precast concrete.
13. 13.
  
  Fully grouted concrete block masonry.
14. 14.
  
  Sheet steel or aluminum.
15. 15.
  
  Solid or hollow masonry constructed of clay or shale masonry units.
16. 16.
  
  A final inspection report shall be provided for inspections completed by the registered design professional or approved agency. The inspection report shall be provided to the building owner or owner’s authorized agent and the code official. The report shall identify deficiencies found during inspection and details of corrective measures taken.

C402.6.2.3.2 Assemblies. Assemblies of materials and components with an average air leakage not greater than 0.04 cfm/ft2 (0.2 L/s × m2) under a pressure differential of 0.3 inch of water gauge (75 Pa) where tested in accordance with ASTM E2357, ASTM E1677, ASTM D8052 or ASTM E283 shall comply with this section. Assemblies listed in Items 1 through 3 below shall be deemed to comply, provided that joints are sealed and the requirements of Section C402.6.1.2 are met.

1. 1.
  
  Concrete masonry walls coated with either one application of block filler or two applications of a paint or sealer coating.
2. 2.
  
  Masonry walls constructed of clay or shale masonry units with a nominal width greater than or equal to 4 inches (102 mm).
3. 3.
  
  A Portland cement/sand parge, stucco or plaster not less than 1/2 inch (12.7 mm) in thickness.

(History: Ord. No. BC-3499, §171, 2026)

Effective on: 1/1/1901