14N-R4-R402 Building thermal envelope.

The provisions of Section R402 of IECC-RE are adopted by reference with the following modifications:

1.   Throughout the body of each provision of this section, reset the singular and plural forms of the following terms in italic type: "basement wall," "building thermal envelope," "cavity insulation," "conditioned space," "continuous insulation," "crawl space wall," "dwelling unit," "dwelling unit enclosure area," "dynamic glazing," "fenestration," "infiltration," "insulated siding," "opaque door," "proposed design," and "ventilation air."

2.   Revise Section R402.1.1 to read:

"Wall assemblies in the building thermal envelope shall comply with the vapor retarder requirements of Section 1404.3 of the Chicago Building Code."

3.   Revise Table R402.1.2 to read:

"TABLE R402.1.2
MAXIMUM ASSEMBLY U-FACTORS a AND FENESTRATION REQUIREMENTS

For SI: 1 foot = 304.8 mm.

a.   Nonfenestration U-factors shall be obtained from measurement, calculation or an approved source.

b.   Mass walls shall be in accordance with Section R402.2.5. Where more than half the insulation is on the interior, the mass wall U-factors shall not exceed 0.065.

c.   [Reserved.]

d.   The SHGC column applies to all glazed fenestration."

4.   Revise Table R402.1.3 to read:

"TABLE R402.1.3
INSULATION MINIMUM R-VALUES AND FENESTRATION REQUIREMENTS BY COMPONENT a

For SI: 1 foot = 304.8 mm.

ci = continuous insulation.

a.   R-values are minimums. U-factors and SHGC are maximums. Where insulation is installed in a cavity that is less than the label or design thickness of the insulation, the installed R-value of the insulation shall be not less than the R-value specified in the table.

b.   The fenestration U-factor column excludes skylights. The SHGC column applies to all glazed fenestration.

c.   "5ci or 13" means R-5 continuous insulation (ci) on the interior or exterior surface of the wall or R-13 cavity insulation on the interior side of the wall. "10ci or 13" means R-10 continuous insulation (ci) on the interior or exterior surface of the wall or R-13 cavity insulation on the interior side of the wall. "15ci or 19 or 13&5ci" means R-15 continuous insulation (ci) on the interior or exterior surface of the wall; or R-19 cavity insulation on the interior side of the wall; or R-13 cavity insulation on the interior of the wall in addition to R-5 continuous insulation on the interior or exterior surface of the wall.

d.   R-5 insulation shall be provided under the full slab area of a heated slab in addition to the required slab edge insulation R-value for slabs. as indicated in the table. The slab-edge insulation for heated slabs shall not be required to extend below the slab.

e.   [Reserved.]

f.   [Reserved.]

g.   The first value is cavity insulation; the second value is continuous insulation (ci). Therefore, as an example, "13&5ci" means R-13 cavity insulation plus R-5 continuous insulation.

h.   Mass walls shall be in accordance with Section R402.2.5. The second R-value applies where more than half of the insulation is on the interior of the mass wall.

i.   To reduce the possibility of condensation within walls during cold weather, the ratio of the R-values of continuous insulation to cavity insulation should not be less than 0.30 without hygrothermal analysis."

5.   Revise Section R402.2.1 by deleting the first sentence.

6.   Revise Section R402.2.2 to read:

"R402.2.2 Low-sloped roofs. 

For low-sloped roofs, installing R-42 insulation over 100 percent of the ceiling area requiring insulation shall satisfy the requirement for R-60 insulation. For low-sloped roofs with above-deck insulation, installing R-42 continuous insulation above the roof deck shall satisfy the requirement for R-60 insulation. This reduction shall not apply to the U-factor alternative approach in Section R402.1.4 and the Total UA alternative in Section R402.1.5."

7.   Revise Section R402.2.3 by replacing "permitted" with "allowed."

8.   Revise the exceptions to Section R402.2.4 to read:

"Exception: Vertical doors providing access from conditioned spaces to unconditioned spaces that comply with the fenestration requirements of Table R402.1.3."

9.    Revise Section R402.2.6 to read:

"R402.2.6 Steel-frame ceilings, walls and floors.

Steel-frame ceilings, walls, and floors shall comply with the insulation requirements of Table R402.2.6 or the U-factor requirements of Table R402.1.2. The calculation of the U-factor for steel-framed ceilings and walls in an envelope assembly shall be determined in accordance with AISI S250 as modified herein.

1.   Where the steel-framed wall contains no cavity insulation and uses continuous insulation to satisfy the U-factor maximum, the steel-framed wall member spacing is allowed to be installed at any on-center spacing.

2.   Where the steel-framed wall contains framing at 24 inches (600 mm) on center with a 23% framing factor or framing at 16 inches (400 mm) on-center with a 25% framing factor, the next lower framing member spacing input values shall be used when calculating using AISI S250.

3.   Where the steel-framed wall contains less than 23% framing factors the AISI S250 shall be used without any modifications.

4.   Where the steel-framed wall contains other than standard C-shape framing members the AISI S250 calculation option for other than standard C-shape framing is allowed to be used."

10.   Revise Table R402.2.6 to read:

"TABLE R402.2.6
STEEL-FRAME WALL INSULATION R-VALUES

 

WOOD FRAME R-VALUE REQUIREMENT	COLD-FORMED STEEL-FRAME EQUIVALENT R-VALUE a
Steel-frame Wall, 16 inches on center
R-13&10ci	R-0&20ci or R-13&15ci or R-15&14ci
R-20&5ci	R-13&12.7ci or R-15&12.3ci or R-19&11.6ci or R-21&11.3ci or R-25&10.9ci
Steel-frame Wall, 24 inches on center
R-13&10ci	R-0&20ci or R-13&13ci or R-15&12ci or R- 19&11ci or R-21&11ci
R-20&5ci	R-13&11.5ci or R-15&10.9ci or R-19&10.1ci or R-21&9.7ci or R-25&9.1ci

 

ci = continuous insulation.

a.   The first value is cavity insulation R-value; the second value is continuous insulation R-value. Therefore, for example, "R-30&3ci" means R-30 cavity insulation plus R-3 continuous insulation."

11.   Revise Section R402.2.7 by replacing "permitted" with "allowed."

12.   Delete the exception to Section R402.2.9.

13.   Revise Section R402.2.9.1 by replacing "permitted" with "allowed."

14.   Revise Section R402.2.10.1 by deleting "or International Residential Code, as applicable" and replacing "6 inches (153 mm)" with "12 inches (305 mm)."

15.   Revise the exception to Section R402.2.12, item 1 to read: "The minimum ceiling insulation R-value shall be R- 24."

16.   Insert a new Section R402.2.13 to read:

"R402.2.13 Balconies and parapets.

See Section R605."

17.   Revise Section R402.3 and its subsections by replacing each "permitted" with "allowed."

18.   Revise the exception to Section R402.3.5 by deleting "In Climate Zones 2 through 8."

19.   Revise Section R402.4.1.1 by deleting the last sentence.

20.   Revise Table R402.4.1.1 by replacing the following rows to read:

 

Rim joists

Rim joists shall include an air barrier. b

Rim joists shall be insulated so that the insulation maintains permanent contact with the exterior rim board. b

 

 

Basement crawl space and slab foundations

Exposed earth in unvented crawl spaces shall be covered with a Class I vapor retarder/air barrier in accordance with Section R402.2.10. Penetrations through concrete foundation walls and slabs shall be air sealed. Class 1 vapor retarders shall not be used as an air barrier on below-grade walls.

Crawl space insulation, where provided instead of floor insulation, shall be installed in accordance with Section R402.2.10. Conditioned basement foundation wall insulation shall be installed in accordance with Section R402.2.8.1. Slab-on-grade floor insulation shall be installed in accordance with Section R402.2.9.1.

 

21.   Revise Section R402.4.1.2 to read:

"R402.4.1.2 Testing.

The building or dwelling unit shall be tested for air leakage. The maximum air leakage rate for any building or dwelling unit under any compliance path shall not exceed 5.0 air changes per hour or 0.28 cubic feet per minute (CFM) per square foot [0.0079 m3/(s × m2)] of dwelling unit enclosure area. Testing shall be conducted in accordance with ANSI/RESNET/ICC 380, ASTM E779 or ASTM E1827 and reported at a pressure of 0.2 inch w.g. (50 Pascals). A written report of the results of the test shall be signed by the party conducting the test and made available to the building official. Testing shall be performed at any time after all penetrations of the building thermal envelope have been sealed.

Exceptions: 

1.   For additions, alterations, or repairs to existing buildings, building envelope tightness and insulation installation shall be considered acceptable when the items in Table R402.4.1.1, applicable to the method of construction, are field verified.

2.   For heated, attached private garages and heated, detached private garages accessory to Group R-5 occupancies, building envelope tightness and insulation installation shall be considered acceptable where the items in Table R402.4.1.1, applicable to the method of construction, are field verified. Heated, attached private garage space and heated, detached private garage space shall be thermally isolated from all other habitable, conditioned spaces in accordance with Sections R402.2.12 and R402.3.5, as applicable.

R402.4.1.2.1 Procedure.

During testing:

1.   Exterior windows and doors and fireplace and stove doors shall be closed but not sealed beyond the intended weatherstripping or other infiltration control measures.

2.   Dampers including exhaust, intake, makeup air, backdraft and flue dampers shall be closed but not sealed beyond intended infiltration control measures.

3.   Interior doors, where installed at the time of the test, shall be open.

4.   Exterior or interior terminations for continuous ventilation systems shall be closed and sealed.

5.   Heating and cooling systems, where installed at the time of the test, shall be turned off.

6.   Supply and return registers, where installed at the time of the test, shall be fully open.

Exception: When testing individual dwelling units, an air leakage rate not exceeding 0.30 cubic feet per minute per square foot [0.008 m3/(s × m2)] of the dwelling unit enclosure area, tested in accordance with ANSI/RESNET/ICC 380, ASTM E779 or ASTM E1827 and reported at a pressure of 0.2 inch w.g. (50 Pa), shall be allowed for:

1.   Attached single and multiple-family building dwelling units.

2.   Buildings or dwelling units that are 1,500 square feet (139.4 m2) or smaller.

R402.4.1.2.2 Mechanical ventilation.

Mechanical ventilation shall be provided in accordance with Section 403 of the Chicago Mechanical Code."

22.   Revise Section R402.4.1.3 to read:

"When complying with Section R401.2.1, the building or dwelling unit shall have an air leakage rate not exceeding 3.0 air changes per hour, when tested in accordance with Section R402.4.1.2."

23.   Revise Section R402.4.4 to read:

"R402.4.4 Rooms containing fuel-burning appliances.

Where open combustion air ducts provide combustion air to open combustion fuel-burning appliances, the appliances and combustion air opening shall be located outside the building thermal envelope or enclosed in a room that is isolated from inside the thermal envelope. Such rooms shall be sealed and insulated in accordance with the envelope requirements of Table R402.1.3, where the walls, floors and ceilings shall meet a minimum of the basement wall R-value requirement. The door into the room shall be fully gasketed and any water lines and ducts in the room insulated in accordance with Section R403. The combustion air duct shall be insulated where it passes through conditioned space to an R-value of not less than R-8.

Exception: Direct vent appliances with both intake and exhaust pipes installed continuous to the outdoors."

24.   Revise Section R402.4.6 to read:

"R402.4.6 Electrical and communication outlet boxes (air-sealed boxes).

Where air-sealed boxes are required by Table R402.4.1.1, electrical and communication outlet boxes shall comply with all of the following:

1.   Be tested in accordance with NEMA OS 4.

2.   Have an air leakage rate of not greater than 2.0 cubic feet per minute (0.944 L/s) at a pressure differential of 1.57 psf (75 Pa).

3.   Be marked "NEMA OS 4" or "OS 4" in accordance with NEMA OS 4.

4.   Be installed per the manufacturer’s instructions and with any supplied components required to achieve compliance with NEMA OS 4."

25.   Revise Section R402.5, excluding the exception, to read:

"The area-weighted average maximum fenestration U-factor allowed using tradeoffs from Section R402.1.5 or R405 shall be 0.48 for vertical fenestration and 0.75 for skylights."