Alternate code- approved means of determining R-values of concrete masonry walls include two-dimensional calculations and testing (ref. The method is fully described in TEK 6-1C. The method accounts for the thermal bridging (energy loss) that occurs through the webs of concrete masonry units. The R-values/U-factors listed in this TEK were determined by calculation using the code-recognized series-parallel (also called isothermal planes) calculation method (refs. Cavity wall R-values are listed in TEK 6-1C, R-Values of Multi-Wythe Concrete Masonry Walls (ref. This TEK lists thermal resistance (R) and thermal transmittance (U) values of single wythe walls.

These steady-state values can be used in conjunction with factors such as thermal mass, climate, and building orientation to estimate a building envelope’s thermal performance, typically using software. U-factors and R-values are used to estimate heat flow under steady-state conditions (neglecting the effects of thermal mass). This construction method allows insulation and reinforcement to be used to increase thermal and structural performance, respectively, without increasing the wall thickness. Single wythe concrete masonry walls are often constructed of hollow units with cores filled with insulation and/or grout.

Cmu block fire wall r value