Hey Heidi

Q: How are fire ratings of Concrete Masonry assemblies calculated, and for fire code compliance, are listing services such as UL® required?
-Fire Rating Expertise Desired

A: Dear FRED: Section 721 of the IBC recognizes several methods to calculate the fire resistance for CMU walls. The equivalent thickness method is the most commonly used, and the most cost effective. It takes into account extensive industry research, the results of ASTM E-119 testing and aggregate type. Equivalent thickness...Read More

Q: Why are Type I (N-1) moisture control units no longer available?
-Moisture Unit N-1: Can you Help Investigate the Elusive?

A: Dear MUNCHIE: Prior to 2000, ASTM C-90 included two designations: Type I moisture-controlled units, and Type II non-moisture controlled units. Type I (N-1) units were stipulated to have a maximum moisture content at the time of delivery. In theory, limiting the moisture content of the units reduces dry shrinkage, which...Read More

Q: We’re required by code to have an R value of 26. If I were to use Concrete Masonry cavity wall construction, the wall will be way too thick. Help!      
-Cavities Always Lead to Efficient Buildings 

A: Dear CALEB: A structural Concrete Masonry back up wall with an Architectural CMU veneer is a great choice for resilience, fire resistance, thermal comfort, water penetration, and durability.   An essential component of a cavity wall is, well, the cavity.  The cavity includes a space for ventilation and drainage as well...Read More