Q: I’ve heard that concrete masonry structures have low embodied carbon, is this true? Just checking…
-Green Washing Always Rejectable
A: Dear GWAR: Yes, this IS true, but not all concrete has the same embodied carbon. Concrete Masonry Units (CMU) are made with dry-cast concrete (zero-slump) which use less water and cement than poured-in-place concrete (typically referred to as wet-cast concrete). The unique structure of dry-cast concrete enables increased rates of...Read More
Q: Single wythe insulated concrete masonry passes energy code, but how can we keep the walls leek free? And do we need a vapor barrier?
-Leaks Are Really Sad
A: Dear LARS: Single wythe CMU walls have been around for a long time, and with proper detailing, they can be completely leak free. To accomplish this, we recommend a “belt and suspenders” approach. Flashing, weeps, integral water repellent and crack control are key. For extra protection a field applied, breathable,...Read More
Q: I’m considering options for the interior on our new project. What Concrete Masonry aesthetic options are available?
-Concrete Aesthetics Masonry Interiors
A: Dear CAMI: Concrete Masonry Units have come a long way since the term “cinder block” was coined and there’s a variety of aggregate colors available to us here in the Northeast. Deep blacks, grey speckled granites, stones that range from peachy to brown and others that range from pink to...Read More
Q: How are concrete masonry units made?
-Curious About Manufacturing
A: Dear CAM: At our facility we manufacture both structural grey and architectural units. Most architectural finishes expose the beauty of local aggregates and we have a variety of aggregate colors available to us. Deep blacks, grey speckled granites, stones that range from peachy to brown, and others that range from...Read More
Q: Is using a RILEM tube test the best way to determine the water repellency of a concrete masonry structure?
-Water And Leakage Test
A: Dear WALT: No. The short explanation is that a RILEM tube test measures the water repellency of a surface, making it suitable to evaluate the efficacy of non-water permeable coatings. While today it is generally used by the coatings industry, it originated as a way to provide the initial absorptive...Read More
Q: We are using COMcheck™ to have a bit more flexibility passing the energy code. What’s the best way to enter insulated CMU?
-Capacity of Heat Using Comcheck™
A: Dear CHUC: I’m so glad you asked! The default option for concrete block in COMcheckTM does not take into account alternative web configurations, so it’s generally not the best way to go when entering insulated CMU systems such as Hi-R® or Hi-R-H®. These systems have reduced webs which minimize thermal bridging...Read More
Q: Is continuous insulation required to meet the energy code?
-Continuous Insulation Myth Busted Again
A: Dear CIMBA: It is not. There are several options to pass the energy code; prescriptive, trade off (COMcheck™) and whole building analysis. Within the prescriptive method there are 2 tables which can be used to pass the code, the R-value and the U-factor table. Only the R-value table has the CI...Read More
Q: We are designing a building using 4x8x16 polished CMU anchored veneer. In addition to the anchors, do we need to include joint reinforcement?
-Joint reinforcement In Masonry
A: Dear JIM: YES! Concrete Masonry anchored veneers follow similar recommendations for crack control that structural CMU walls do. Movement caused by temperature changes, moisture-volume changes, de lection and/or shrinkage needs to be accommodated. Shrinkage cracks in concrete masonry aren’t a structural concern but an aesthetic one, though they could potentially...Read More
Q: For pre-insulated single wythe concrete masonry wall systems, where would the vapor barrier go?
-Vapors Impacting Concrete
A: Dear VIC: For special circumstances, such as an indoor pool or museum quality storage, a vapor barrier could be needed and the variables for each scenario would need to be considered. For general use, pre-insulated CMU mass walls don’t require a vapor barrier. Mass walls behave differently from other structural...Read More
Q: After having Environmental Product Declarations (EPDs) done for each one of your Concrete Masonry Unit mix designs, is there anything in particular that you learned?
-Environmentally Lowering Impacts
A: Dear ELI: Having EPDs for each of our mix designs has really helped us see what factors affect the environmental impacts of our products. One interesting thing we uncovered was that previously valued sustainable attributes, such as recycled content and regional materials, didn’t matter as much as we thought for environmental...Read More
Q: For our school project, the structure must be cost effective, resilient, durable, have interior walls with great STC ratings, and must contribute to LEED v4. Is Concrete Masonry Construction a good option?
-Construction for Economy, Durability And Resiliency
A: Dear CEDAR, We manufacture A LOT of Concrete Masonry Units for school construction, for all of the reasons you asked about, Cedar. Concrete Masonry units come in countless color options, featuring beautiful exposed natural aggregates. They are available with several architectural finishes such as polished, textured polished, ground face and split...Read More
Q: For pre-insulated Concrete Masonry systems, what is the difference between code based R-values & effective R-values?
-Misleading Effective R Values
A: Dear MERV, For concrete masonry, effective R-values typically mean that the R-value is adjusted to account for the thermal mass of a CMU wall system. It can also take into account other variables, such as thermal lag or annual averages. Code based R-values are calculated based on either test data or...Read More
Q: Is the compressive strength (PSI) of Concrete Masonry Units effected by density and what are the main performance variations associated with the different densities?
-Are Lightweights Better In the Envelope?
A: Dear ALBIE, For architectural units, aesthetics are a major consideration. The light weight aggregate available in the Northeast is a very dark grey, which is visible in ground face & polished units. For standard grey block, mix designs can have different densities, depending on the amount of light weight aggregate used...Read More
Q: We are designing a large health care facility. What role can Concrete Masonry play in creating a resilient structure?
-Resilient Construction Has Extreme Longevity
A: Dear RaCHEL, Concrete masonry construction has strength, durability, longevity, fire resistance, seismic and blast resistance, all of which contribute to the resiliency of the built environment. The durability of concrete masonry construction is well known and vital during the more visible aspects of natural disasters such as floods, hurricanes and tornadoes....Read More
Q: We have a project which is over budget and has limited space. Is it possible to eliminate catch basins and retention ponds if we use a Permeable Articulating Concrete Block (P-ACB) paving surface?
-Stormwater Alternatives are a Must-have
A: Dear SAM: Depending on the soil type and specific site conditions, it is possible to eliminate traditional storm water infrastructure, such as catch basins and retention ponds, by using a high performance permeable articulating concrete block (P-ACB) paving surface. These systems allow for a more natural, vertical infiltration path, recharging local...Read More
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
