by Jay Bowen
BPI Energy Analyst
ASNT NDT Level 3 Thermographer
Building conversations in training this week brought up the subject of thermal bridging in the structure. Defined by a material of less insulation or greater conductivity. This material bridges or short circuits the better insulation and reduces its effectiveness. This reduces the overall R value rating of the whole assembly. The following website, http://web.ornl.gov/sci/roofs+walls/AWT/home.htm , addresses this whole wall rating concept. This isn’t a debate of test methods or approaches. It is enough to say that anything put in the wall that reduces the energy of that wall should be addressed in the construction process.
My input on this subject is finding these, before construction begins and discussion with a builder, methods to reduce or eliminate these bridges. Verification of the design or confirmation as building progresses would be where a thermographer can enter the process and provide proof that the building project has conformed to this concept of design.
The images from a qualified thermographer provide detailed analysis of construction detail typically hidden from the inspectors or builders.
Taking a set of images to compare this approach can clearly see the advantage of reducing the vertical framing typical of stick built construction. Even the wide wall of 2x6 framing to increase the side wall dimensions for increased insulation. This is an increase in the R value but the thermal bypass of the stud is still there.
Using SIP to reduce bridging
Standard stick frame wall
Looking at a SIP wall can visualize the reduction in the bypasses by reducing the vertical framing. The corners and joints are still present but can be reduced by the same methods of stick built using exterior insulated sheathing.
Making the bridge elimination or reduction a conscious thought in the whole building process can have substantial rewards in energy saving in the home.