Significant changes to the commercial provisions in 2012 IECC


Air leakage

Figure 3: Fans set up in the doorway of a building to perform a full-building blower test, a compliance option listed in Section C402.4.1.2. Courtesy: Retrotec Inc.Except for climate zones 1 through 3, a continuous air barrier is required around the thermal building envelope (C402.4). Subsection C402.4.1.1 details the construction requirements of the air barrier and subsection C402.4.1.2 lists three compliance options, one of which is required to be met: materials, assemblies, or full building testing (see Figure 3). A table of maximum fenestration assembly leakage rates is provided in Section C402.4.3.

Unless required to comply with IBC Section 715 or 715.4 or UL 1784, doors and access openings from conditioned spaces into shafts, chutes, stairways, and elevator lobbies shall meet the fenestration requirements or be sealed per a newly added section (C402.4.4). Stairway, shaft, and outdoor air intakes and exhausts shall be provided with motorized dampers limited to a leakage rate of 4 cfm/sq ft. Gravity dampers meeting a 20 cfm/sq ft leakage rate are permitted as an exception for outdoor intakes and exhausts in climate zones 1 to 3, buildings less than 3 stories, as exhaust and relief dampers, and where the design outdoor air intake or exhaust capacity is ≤ 300 cfm. Dampers smaller than 2 ft in either dimension are permitted a leakage rate of 40 cfm/sq ft (C402.4.5).

Building envelope

Figure 4: Low-sloped roofs (<1/6 grade) directly above conditioned spaces in climate zones 1 through 3 must comply with roof reflectance and emittance requirements listed in newly added Table C402.2.1.1. Courtesy: A S Klein Engineering

Exposed outdoor piping insulation must now be protected from degradation, and use of adhesive tapes is not permitted (C403.2.8.1). Some exceptions to piping insulation requirements (C403.2.8) were also modified. The temperature range in exception 3 was decreased from 55 to 105 F to 60 to 105 F. Exception 5 no longer applies to piping 4 ft or less in length but instead to strainers, control valves, and balancing valves on piping with a diameter of 1 in. or less. Exception 6 was added that applies to buried piping conveying fluids ≤ 60 F.

Table C403.2.8, Minimum Pipe Insulation Thickness, was expanded, and the insulation thicknesses for very hot fluids and steam were increased tremendously; however, a footnote was added allowing a thickness reduction for direct-buried heating and hot water system piping. An exception was added to Section C404.5, Pipe Insulation, for heat-traced piping systems, specifying that they must meet the insulation thickness requirements per the manufacturer’s installation instructions.

A minimum insulation of R-3.5 is now required for radiant panels, associated U-bends and headers, and the bottom surfaces of structures incorporating radiant heating (C402.2.8).

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