Brent Chancellor

RDH on Thermal Bridging at Balconies and Slab Edges

This may be a bit Engi-nerdish, but as an engineer, one thing I appreciate is good data communicated in a clear, concise way. If you want to understand the problem of thermal bridging at balconies and exposed slab edges and how design choices impact building performance and cost, then I recommend taking a look at this series of reports by RDH, a consulting firm specializing in building science.

Click here to access The Importance of Slab Edge & Balcony Thermal Bridges, a 4-Part Series of Research Reports from RDH

 

Their set of four reports – titled The Importance of Slab Edge & Balcony Thermal Bridges – cover everything from how much impact exposed slab edges have on effective wall R values (a lot…almost as much as a window), to the impact on thermal comfort and the potential for interior condensation, to comparing the thermal performance and cost performance for a number of insulation and thermal break strategies.

Schöck’s Isokorb thermal break solution was included in the study and came out looking pretty good. Isokorb consistently had the best thermal performance of all the thermal break strategies considered and was shown to be more cost effective than traditional solutions, such as wrapping the balcony in insulation.

Another interesting finding of the study is that the more thermally efficient the wall assembly is at a balcony, the greater impact a thermal break has on the effective R value of the wall assembly. For example, when a wall assembly uses R-5 exterior insulation, adding an Isokorb thermal break increases the effective R value for the wall assembly by as much as 30% over a wall assembly with an uninsulated balcony. However, if R-20 exterior insulation is used, then adding an Isokorb thermal break can increase the effective R value for the wall assembly by more than 100% over a wall assembly with an uninsulated balcony.


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