The thermal bridging group is
progressing on their next publication through ASCE. One new point of focus in
this publication is thermal bridging through other materials. One common
building material that is often overlooked as a thermal bridge is concrete.
Although concrete isn’t nearly as conductive as steel, where it acts as a
bridge it can still cause substantial energy loss. One of the most common
examples of this is at balconies. Often the balcony is merely a cantilever of
the main floor slab. Because of this, there is no continuous envelope or
insulation barrier. In high rise condos and apartments, these can almost be
visualized as fins on a radiator, as they behave in much the same way.
One way
to avoid or reduce this bridge is with a proprietary break. These systems are
designed to still transfer the cantilever forces (shear and moment), while
reducing the bridging to isolated stainless steel bars. Although widely used in
Europe, these systems are not commonly found in the states. The Thermal Bridging
group will be looking at these cantilever concrete conditions more closely in
the next publication.
Thermal Bridging Working Group update by web liaison Raquel Ranieri, P.E., LEED AP BD+C. Read more recent articles about thermal bridging here.
