Construction Defects in Insulation and Thermal Bridges

by Cody Farmer

I opened my water and electric bills simultaneously…needless to say, I was shocked.

Ok, ok…bad joke but it still made me laugh because of the truth in it. And a large part of the reason why the typical homeowner’s heating and AC bills are so high is because of thermal bridges.  There seems to be a need for third-party inspection since the GC, Subcontractor delivery system still requires a babysitter! Here’s what often happens on a build site: The subcontractors expect the end user to QA their work and then they have to repeatedly come back until it’s finally correct. My question is – why isn’t it being done right from the start so that there are no repeats or fixes that are necessary? Why do some subcontractors and GCs seem to need someone else to check their work and point out failures?


Well, when it comes to insulation mistakes, the most obvious answer is that many builders simply aren’t taught how to avoid thermal bridges in their training. Eliminating thermal bridges is often something taught in Passive House training, but not typically done in conventional training.

The exclusion of this element of training has resulted in huge problems in indoor air quality and temperature control for many homes, offices, and shops around the world. I especially notice this here in Colorado where our outdoor temperature swings are often so wild and unpredictable. One minute it’s sunny and warm, and the next it’s a blizzard. Welcome to Colorado! Temperature control is one of the many reasons that having airtight construction in Colorado is so important!

Since our typical construction training on this subject is so woefully inadequate, let’s talk about thermal bridging – what it is, why it’s so detrimental, and how to eliminate that problem.

Escaping heat tends to leave using the path of least resistance. Thermal bridging usually happens when there is a break in, or penetration of the building envelope (e.g. insulation). Thermal bridges can be produced by:

  • The joints between the wall and floor
  • The joints between the wall and roof
  • Holes in the building envelope for pipes and cables
  • Windows and doors
  • Steel wall ties used in masonry construction (e.g. cavity walls)

Thermal bridges are detrimental for various reasons, but the main three are: reduced effectiveness of insulation, high energy bills, and increased possibility of mold and rot. We’re talking about a typical 30% loss of heat that can be attributed to thermal bridges when constructing an airtight building. And what happens when you have such a great heat loss? – higher energy costs. Thermal bridging also accounts for condensation indoors and even in interstitial spaces hidden in the walls, all causing perfect conditions for mold to grow or wood rot to occur. If it’s hidden in the walls, it’s especially dangerous because it often goes unnoticed and, therefore, unrepaired which can cause numerous health issues.

All of that sounds awful, so what’s the solution? When you hire us (or complete training with us to become PHIUS certified), we will show you how we create proper thermal barriers using window glaze, Tescon and Extoseal tapes along joints, and continuous insulation producing a tightly sealed building envelope. At Mainstream Corporation, we believe that attention to detail pays off in the end. When you include us on your job site as consultants, we think you’ll agree.

Upload your plan sets so that we can show you how we can help or contact us to begin your training to become certified!