Let’s look at this logically…
If a 4″ solid grouted block has an R-2.4 (R-Value) and an 8″ solid grouted block has an R-2.7 and a 12″ block has an R-2.8, all per the nationally accredited testing laboratories of the National Concrete Masonry Association (NCMA), and we want to build a 48″ thick wall, we are allowed to add the layers of the individual block units to derive the total wall assembly R-Value.
If all units are solid grouted, you have for all intensive purposes the same solid 48″ masonry wall with major R-Value differences. Since heat has “energy”, it is what we are trying to control or at least limit its movement.
Question: It would appear based upon the layered R-values that the same 48″ wall would “resist” this heat much differently, but would it?
Conclusion: The heat would move through or be absorbed by the thermal mass of the wall assembly at the very same rate making the variously stated wall R-Values inaccurate. The laboratory results are not substantiated by real world applications.
Therefore: The current ASTM wall R-Value test results for block are providing “misinformation” and are not useful. Actually they very deceiving, causing many that rely on such information to make the wrong decisions as to what exterior wall material to use.
Further discussion of inaccurate analysis can be found at www.omniblock.com/2016/08/01/case-study-muzyka-residence/