There is no credit for cavities that are open to outside air.

Air films do not apply to air cavities within an assembly.

For heat capacity for concrete ((with densities other than these values or other)) and concrete masonry materials with densities other than the values listed in Table A101.5, see Tables A103.3.7.1(1) through (3) or Tables A3.1B and A3.1C in ASHRAE/IESNA Standard 90.1.

a.

It is acceptable to use the U-factors in Table A103.3.7.1(2) for all concrete and masonry walls, provided that the grouting is equal to or less than that specified.

 

- For ungrouted walls, use the partially grouted column.

 

- For metal studs and z-furring, use the continuous-metal-framing category.

 

- For discontinuous metal clips 1 inch square or smaller, use the metal-clip category.

 

- For insulation that is attached without any framing members (e.g. glued), use the continuous-insulation uninterrupted-by-framing category. Continuous insulation may be installed on the interior or exterior of masonry walls, or between stand-alone walls in multilayer masonry walls, or on the interior or exterior of the concrete.

b.

For Table A103.3.7.1(2), the U-factor includes R-0.17 for exterior air film and R-0.68 for interior air film-vertical surfaces. For insulated walls, the U-factor also includes R-0.45 for 0.5 in. gypsum board. U-factors are provided for the following configurations:

 

(1) Concrete wall: 8-in. normal weight concrete wall with a density of 145 lb/ft3.

 

(2) Solid grouted concrete block wall: 8-in. medium weight ASTM C90 concrete block with a density of 115 lb/ft3 and solid grouted cores.

 

(3) Partially grouted concrete block wall: 8-in. medium weight ASTM C90 concrete block with a density of 115 lb/ft3 having reinforcing steel every 32 in. vertically and every 48 in. horizontally, with cores grouted in those areas only. Other cores are filled with insulating material only if there is no other insulation.

c.

For walls with insulation contained in a framing layer, the U-factors in Table A103.3.7.1(2) assume contact (and thermal bridging) between the mass wall and other framing. For wall assemblies with multiple layers where the wood or metal framing layer does not contact the concrete or masonry layer (i.e., walls with an airspace between the stud wall layer and the mass wall layer), it is acceptable to use the appropriate wood or metal frame wall default U-factors in Tables A103.3.1 or A103.3.6.1. Note: It is acceptable to use this approach where the insulation extends beyond the framing and is in contact with the mass wall layer (e.g. a nominal four-inch metal stud containing insulation that is nominally six inches thick and therefore extends two inches beyond the back of the metal stud).

d.

Except for wall assemblies qualifying for note 3, if not taken from Table A103.3.7.1(2), mass wall U-factors shall be determined in accordance with ASHRAE 90.1, Appendix A, Section A3.1 and Tables A3.1A to A3.1D, or Section A9.4.

a.

Exterior insulation values listed above are continuous R-values on the exterior side of the concrete floor.

b.

For conditions with an exterior wall above the peripheral edge of intermediate concrete floor but with no wall below the intermediate concrete floor this table may be used as long as the code minimum insulation is applied to the floor slab below the concrete floor.

c.

Typical conditions where conditioned space building envelope wall thermal insulation values are broken concrete floors include, but are not limited to, the following examples:

 

1. Elevator hoistway shafts that serve the conditioned building and pass through unconditioned floors such as parking garage levels;

 

2. Stairwell enclosures that serve the conditioned building and pass through unconditioned floors such as parking garage levels;

 

3. Walls between interior and exterior building envelope that separate the interior conditioned space from an exterior courtyard or roofdeck;

 

4. Walls between interior and exterior building envelope that separate the interior conditioned space from an exterior unconditioned space on parking garage levels.