Lake Flato on Twitter
Corey Squire

Thermal bridging is not a huge deal, right??

Posted by on 8/7/13 at 04:24pm

What happens when you drive a metal screw through an insulated wall? It is well known that the assembly U-Value will decrease due to thermal bridging, but over all, how much of an effect can one screw really have?

To answer this question we looked to the thermodynamic simulation software, Therm.  Over the last few weeks our sustainability software guru, Joseph Dugan, has been working with Therm to help us better understand the effects of thermal bridging on our building envelopes. Today our first test results are in and that one screw is causing more problems than we ever thought.

We ran a simulation for an R-30 insulated wall, 10’ high and 6” thick. In the first test we added two 2×6 wooden studs, which lowered the assembly R-Value by 7% – pretty standard.  For the second test, we penetrated the wall with two ¼” steel bolts and attached a steel plate on either side. The total insulation value of the wall was reduced by 57%!! The next step: start testing out details on some real projects. Stay Tuned!

  • Edward

    Very interesting! #followingkeenly

  • Matthew Jarsky

    Hi. I have heard similar claims from the manufacturers of those fancy fibreglass clips for supporting sub-girts (e.g. http://www.cascadiawindows.com/products/series53.php)

    One small point: U-value would increase (not decrease) with increased thermal bridging.