The Shortfalls of Thermal Bridging in a Building Structure
October 26, 2016
A thermal bridge is a surface area (mostly in a building structure), which has a higher potential for "heat transfer" than adjacent materials. Thermal bridges contribute to the overall reduction of insulation performance, oftentimes throughout the entire building structure. Often referred to by the professionals as a "cold" bridge or a "heat" bridge, thermal bridging occurs in three ways:
- When a material has higher conductivity than an adjacent material
- When there are openings and penetrations in the building envelope
- When there are breaks or gaps in the installed insulation materials
Thermal bridging, in a building or home, will have negative effects on the indoor environment. To begin with, energy efficiency is reduced because of undesirable "heat transfer". As well, moisture accumulation and natural condensation will occur. And finally, there could be significant indoor air quality issues, indoor comfort issues, and the potential for building materials to deteriorate. Often overlooked, particularly when insulating a residential home, thermal bridging can be easily prevented with a proactive approach to installation. Here, a professional insulation contractor will apply and install materials designed to create continuous and uniform thermal resistance. In short, every effort is made to nullify the various ways that thermal bridging occurs in a structure. Understanding thermal bridging in a residential home is mainly about understanding the home's wall assembly, and the construction materials that were used to build the home. For the most part, a home's exterior walls provide a barrier between the inside and outside environment. With insulation, the walls prevent unwanted air infiltration and moisture from entering the home. Most homeowners rely on their home insulation to keep things warm and cozy in winter and cool and comfortable in summer. There's also a reliance on the R-Value of the insulation - the measure of how well the insulation resists "heat transfer". The problem here is that R-Values will vary in every home, depending on the conditions of the building envelope, and other structural variables. Thermal bridging is one big reason that R-Values can't be relied on entirely. In fact, wall assembly in the majority of homes universally suffers from thermal bridging. And with traditional wall stud construction, thermal bridges are pervasive in a building envelope. Bottom line: the advertised R-Values differ dramatically from the "effective" R-Values - what professionals regard as "real". The cure for thermal bridging is basic - it must be reduced, and preferably eliminated. In newly built homes, advanced framing systems do reduce the number of potential thermal bridges, while ensuring that all openings and penetrations are sealed tight. As well, high performance insulation is installed in order to seal and insulate in away that practically eliminates any thermal bridges. For homeowners who are upgrading or retrofitting old insulation, one of the very best long-term solutions for thermal bridging is Spray Foam Insulation. With SFI, a professional installation will prevent unwelcome air movement and moisture accumulation, while creating thermal insulation that delivers higher R-Value performance than any of the other product applications available.