The data for covered in this section are provided in Table IV.12 and Table IV.13 under the PDF "Masonry Properties" and Table IV.19 under document the PDF "Effective R-Value of Insulation". Data Tables IV.12 and IV.13 give thermal transmittance (U-factor), total thermal resistance (R-value), and heat capacity (HC) for typical concrete and masonry wall constructions. The U-factors include surface air films. If there is no insulation on the outside of the wall or no furring on the inside of the wall, U-factors can be selected directly from the tables and used to show compliance with the requirements of the California Standard. Likewise, the HC values can be used to establish the design criteria for the wall, since the requirements in the Standard depend on HC.
If your wall has an exterior insulation finish system (EIFS) or if it is furred on the inside, then use the total R-Value from the table and add the R-value for the additional layers. The U-value is the sum divided into the number one (its reciprocal in mathematical terms).
Effective R-values for Interior Furring Systems or No Furring Systems
Furring is an effective way of providing additional wall insulation and consists of providing a layer of insulation and then a layer of gypsum board (or drywall) as a new inside finish surface. The space between the mass wall and the gypsum board can be framed with wood studs at various thickness or metal framing members. Metal framing can consist of conventional metal wall studs, but a more common system, used with rigid insulation, is to use "Z" channels.
If there is no metal or wood framing in the furring space, the thermal resistance of the interior furring system is equal to the R-value of the insulation plus the R-value of the gypsum board (about 0.5). A furred wall with no framing is not very common, but can be achieved through the use of adhesives. When there is framing, the framing (especially metal framing) reduces the effectiveness of the insulation. The effective R-Value with no furring is the R-Value minus 0.5. For example, a masonry wall the R-5 insulation with have an effective R-Value of 4.5.
Table IV.19 under "Insulation" documents has data for the effective R-Value of interior wall furring systems, including the gypsum board and the effect of framing, but not the interior or exterior air films. The columns of the table contain the R-Value of the insulation alone. The rows of the table are organized first by the thickness of the furring space (the distance between the mass wall and the gypsum board) and second, by the type of framing (either wood or metal). Based on this information the R-Value of the interior furring system is selected and added to the R-Value of the concrete or masonry wall. The "Frame Type" describes the type of furring that is used for the interior or exterior insulation.