I still get surprised when I see companies lie in their advertising. We are building a 12 unit condo project in Lititz called PilgerHaus and need to construct an exterior elevator shaft. After purchasing the elevator, I saw that hydraulic elevators want to be between 60 to 90 degrees F. I hadn’t thought about insulating the 8″ block wall, but decided we could foam the cores. I knew I’d seen some good R values from that system. I found a manufacturer’s data sheet that showed R values of 14 and 9 for various density 8″ concrete blocks.
I talked to my old buddy and masonry expert Harold Haldeman of New Holland Concrete to determine which density block we use. He informed me that nobody makes a block with the aggregate light enough to achieve R 14. Maybe the foam manufacturer was confused, thinking they were using some block available only in heaven.
Harold also showed me the National Concrete Masonry Institute TEK Manual website that his company helps support. That website provides all the most current masonry technical reports for free. These are useful and practical reports, full of information that comes in handy for anyone working around masonry. I had purchased a set of these reports 10 years ago for over $100, but hadn’t recently updated. I was thrilled to find all these updated reports for free online.
When I looked at the Energy section, under R values, I found that normal weight concrete block (about 130 lb/cf) have an R value of 4 and lightweight concrete block (under 105 lb/cf) have an R value of 5.6. Since we need the normal weight block for the strength, I realized that foaming wasn’t going to be a good option, we need to wrap the shaft in rigid insulation, than put our finish material over the insulation. It’s great to be able to find a value like that so easily and for free.
Definitely check out the NCMA TEK website and bookmark it. You will want to consult it with other masonry problems as well. I know I often use it to find quick masonry retaining wall designs, fire ratings or noise control designs.