You may have heard the term thermal bridging before, but do you know what it means? In the same way, a bridge gives people easy access across a waterway, a thermal bridge gives energy an easy path to travel through a building envelope.

What is Thermal Bridging?

It is said that the building envelope has one of the most important jobs within a structure. One of the primary goals of a building envelope is to separate two environments: the conditioned interior and the un-conditioned exterior. A building envelope consists of several layers of materials that offer support and climate control. Securing and attaching all the building envelope layers is just as necessary as the materials themselves. Controlling thermal energy and moisture through the building envelope plays a significant role in a successful and effective structure.

To maintain the temperature of interior space, it is essential to use a best practice continuous insulation or building enclosure system to slow down the temperature flow into or out of the building. Continuous insulation and building enclosure systems perform well, but you must follow best practices for fasteners and sub-framing materials. Using improper components and materials can lead to thermal bridges.

Thermal bridging can occur when highly conductive materials create a passageway, allowing thermal energy or moisture to travel through the layers of building envelope material. An example may be using a metal screw with metal sub-framing on a building with metal studs. As the metal screws cool down due to exposure to cold air outside, that cool energy can travel through the connected metal building envelope components. When this cold exterior energy travels through the thermal bridge within the building envelope and is met with warmer interior energy, an exchange occurs. Condensation can then form at the point at which the exchange of hot and cold energy occurs. As condensation collects, a drop of water forms within the building envelope. One drop of water may seem like no big deal, but severe damage can result if this occurs over time.

Thermal bridging and the moisture issues it can cause have detrimental effects on the building’s life expectancy and the overall health of its occupants. To make matters worse, these issues can develop long before they become visible in some cases.

Common Effects of Thermal Bridging:

• Reduced building envelope effectiveness

  • Creating passageways within the building envelope decreases its effectiveness in separating two environments.

• Increased energy loss and costs

  • If thermal bridging occurs within a building envelope, energy can easily escape or enter a building. The energy you are consuming to either heat or cool your building is wasted when this happens. In the end, you will expel more energy, thus increasing your operating costs.

• Increased risk of moisture damage

  • If energy can travel through a building envelope due to thermal bridging, moisture can, too. So whether it is water, condensation, or vapor, thermal bridges are a highway for moisture.

• Decreased life expectancy of building

  • Moisture can build up within your building envelope, forming mold or mildew before you may be able to even see it. As a result, your building will likely have a decreased life expectancy and may need to be repaired or replaced sooner if this occurs.

• Increased risk of negative effects on occupant health

  • If mold or mildew occurs, occupants may be at a health risk and at risk of occupying a building with unidentified structural issues.

• Increased in building material waste sent to landfills

  • If buildings require more frequent replacement or repair due to thermal bridging and moisture damage, the amount of building material waste sent to landfills increases over time.

• Decreased comfort of interior space

  • Controlling a building’s conditioned interior climate becomes increasingly tricky. If thermal energy from the unconditioned exterior can easily pass through the building envelope, this results in a more uncomfortable internal environment.

How Can Sub-Framing Material Affect Thermal Bridging?

Preventing thermal bridging within your building envelope is vital in avoiding the common building envelope issues listed above. So, how do you prevent thermal bridging? To stop a thermal bridge, you need a thermal break. A thermal break is a barrier that blocks energy flow. Incorporating materials and components with thermal breaks and low conductivity within your building envelope can make or break the success or effectiveness of your structure.

Thermal Bridging (Metal)                                        Thermal Break (GreenGirt CMH™)

Standard Metal Z-Girt Sub-Framing

There are two common types of material used for continuous insulation and building enclosure system sub-framing. These two materials are metal or fiber-reinforced polymer (FRP). Figure 1.1 below shows a standard metal sub-framing Z-girt with a steady and highly conductive pathway for thermal energy or moisture to travel from the exterior cladding through a metal fastener, metal Z-girt, and metal framing. This sub-framing material is highly conductive, as the system components consist of all metal materials.

Standard FRP Z-Girt Sub-Framing

GreenGirt CMH™ Z-Girt Sub-Framing

Advanced Architectural Products, creators of GreenGirt CMH™ Z-girt sub-framing, has the best practice, thermally-broken,  sub-framing solution for your continuous insulation or building enclosure system. GreenGirt CMH™ consists of  a composite metal hybrid material. GreenGirt CMH™ offers a complete thermal break with the use of FRP without compromising the structural strength of metal.

Figure 1.3 below demonstrates how the FRP component of GreenGirt CMH breaks the passageway for energy to travel through conductive components, while offering a structurally sound surface for fastener attachment and retention.. The GreenGirt CMH continuous insulation and SMARTci® building enclosure systems include GreenGirt sub-framing, making GreenGirt CMH and SMARTci the overall, best practice continuous insulation and building enclosure solutions for your building envelope.

Utilizing GreenGirtCMH Z-Girt Sub-Framing:

• Eliminates thermal bridging
• Increases your building envelope effectiveness
• Decreases thermal energy loss and operating costs
• Decreases the risk of moisture damage
• Increases the lifespan of your building
• Decreases the amount of building material waste sent to landfills
• Decreases occupant health risk
• Increases the comfort of the interior environment

Download our Structural Engineering Study on GreenGirt CMH™ vs. Generic FRP

To learn more about our GreenGirt CMH™ sub-framing, GreenGirt CMH™ continuous insulation, or SMARTci® building enclosure systems by Advanced Architectural Products, visit our website or contact  us today.

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