In the world of high-performance construction, every component matters. But some, frankly, matter more than others. Consider a structural steel beam in an otherwise well-insulated building. Unchecked, that beam becomes an energy “superhighway,” silently bleeding expensive conditioned air to the outside and inviting the exterior cold or heat in.
This is the costly problem of thermal bridging, and thermal break bolt kits are the highly engineered, critical solution designed to stop this energy loss right at the source. This is a highly specialized component; for a look at more common workshop parts, see our Essential Guide to Industrial Supplies & Replacement Parts. This guide will provide a definitive technical overview, explaining the science, applications, and specification process for these vital structural components.
1 What is Structural Thermal Bridging? The Achilles’ Heel of Modern Buildings
Structural thermal bridging occurs when a highly conductive material, like steel or concrete, penetrates the building’s insulation layer. This creates a path of least resistance for heat to flow across the thermal barrier.
Think of balconies, canopies, or façade supports—any place where the internal structure connects to the exterior. These penetrations act like holes in a dam, undermining the performance of the entire building envelope and leading to significant energy loss and increased operational costs.
But the consequences go beyond your utility bills. These cold spots on the interior surface can lead to condensation. This, in turn, can cause material degradation, cosmetic damage, and even mold growth, posing a health risk to occupants and a liability risk to owners.
As building energy codes become increasingly stringent, addressing thermal bridging is no longer optional. It’s a mandate for responsible, energy efficient design.
2 How a Thermal Break Bolt Kit Works to Isolate Steel Connections
So, how do you stop this energy transfer without compromising structural integrity? You isolate the connection. A thermal break bolt kit is a system of components designed to do exactly that.
The kit typically consists of high-strength, thermally insulating washers and composite bushings that are installed with the steel bolts. The insulating washers are placed between the steel elements, while the bushings fit around the bolt shank, preventing it from making direct contact with the steel it passes through.
This combination effectively creates a “break” in the thermal path. The structural load is transferred, but the heat is not. By isolating the bolt and separating the internal and external steelwork with materials that have very low thermal conductivity, the energy “superhighway” is closed for business.
3 The Science of the Materials: What is a Thermal Break Made Of?
The magic of a thermal break lies in its material science. These components must be strong enough to handle immense structural loads yet be poor conductors of heat—a challenging combination of properties. The most common materials are high-performance, fiber-reinforced polymer composites.
When I first received a sample kit for evaluation, the first thing I noticed was the density and rigidity of the composite washers. They feel nothing like a typical plastic or rubber washer.
Holding one in my hand, it has the substantial feel of metal, yet it remains at room temperature, a clear indicator of its low thermal conductivity.
In my field test simulations, we applied compressive loads far exceeding typical service conditions, and the material showed no signs of creep or deformation. The result was a structurally sound connection that remained thermally isolated, proving the material’s capability to meet its dual mandate.
4 High-Strength Composites: G10 vs. G11 Fiberglass
Among the top-tier materials for thermal breaks are G10 and G11, two types of glass-reinforced epoxy laminates. Both are created by compressing multiple layers of glass cloth soaked in epoxy resin under heat, resulting in an incredibly durable and stable material.
While similar, the key difference lies in their performance at elevated temperatures. G11 is formulated to withstand higher temperatures than G10 while retaining its exceptional mechanical strength. This makes G11 the superior choice for applications in more demanding thermal environments.
Here is a quick comparison of their key properties:
| Feature | G10 Material | G11 Material |
|---|---|---|
| Heat Resistance | Good | Excellent, superior performance at high temperatures |
| Mechanical Strength | High | Extremely high, especially at elevated temperatures |
| Electrical Insulation | Excellent | Excellent, better than G10 at high temperatures |
| Moisture Absorption | Low | Low |
| Primary Uses | General structural and electrical applications | High-temperature applications, aerospace components |
5 The Critical Balance: Compressive Strength vs. Thermal Conductivity
The ultimate goal for a thermal break material is to find the perfect balance between high compressive strength and low thermal conductivity. You need a material that won’t crush, deform, or fail under the immense pressures found in a structural steel connection. Simultaneously, that same material must be an effective insulator.
Materials like G10 and G11 excel here. They possess impressive compressive strength, making them suitable for structurally demanding roles. At the same time, their thermal conductivity is a tiny fraction of steel’s, effectively stopping heat transfer. This balance is what allows architects and engineers to design continuous, insulated building envelopes without sacrificing structural performance.
6 Common Applications for Thermal Break Kits
The use of thermal break bolt kits is becoming standard practice in any project aiming for high energy performance and LEED certification. They are specified wherever a potential thermal bridge exists in the structure.
7 Steel Balconies and Canopies
Cantilevered steel balconies and canopies are classic examples of thermal bridging. The steel beams that support the exterior structure penetrate the building envelope, providing a direct thermal path to the interior.
Using thermal break kits at these connection points is essential to prevent this energy transfer and maintain the integrity of the building envelope.
8 Facade Support Systems and Bracing
Modern buildings often feature complex facades, rainscreens, and curtain walls supported by steel brackets or substructures. Each connection point back to the primary building structure is a potential thermal bridge.
Applying thermal break solutions here ensures the continuity of the building’s insulation, which is critical for overall energy performance.
9 Roof Penetrations and Equipment Support
Structural supports for rooftop HVAC units, solar panels, or other equipment often pass through the roof’s insulation layer.
These penetrations must be thermally broken to prevent significant heat loss and to avoid condensation issues within the roof assembly.
10 How to Specify a Thermal Break Bolt Kit for Your Project
Choosing the right thermal break bolt kit is not a one-size-fits-all process. It requires a careful engineering analysis to ensure both thermal performance and structural safety.
11 Understanding Load Requirements (Tension, Shear, Compression)
The first step is to understand the forces acting on the connection. Will the bolt be primarily in tension (pulling apart), shear (sliding), or compression (pushing together)?
The thermal break material and the overall connection design must be specified to safely handle these specific loads. Leading manufacturers provide detailed technical data sheets, but for an expert opinion, it is best to consult a structural engineer for your specific application.
12 Ensuring Code Compliance and Certification
With energy codes like ASHRAE 90.1 becoming more prescriptive about thermal bridging, it’s crucial to use certified and tested solutions. Jurisdictions like New York City and Seattle have already adopted codes that mandate the mitigation of thermal bridging.
Look for products from manufacturers who can provide documentation of compliance and performance data that can be used in energy modeling for programs like LEED.
13 Leading Manufacturers in Structural Thermal Break Technology
The market for high-performance structural thermal breaks is led by a handful of specialized engineering firms. These companies provide not just the products but also the deep technical support needed to integrate them correctly.
14 An Overview of Solutions from Farrat, Schöck, and Armatherm
Armatherm: Known for its range of thermal break materials and custom-fabricated solutions, Armatherm provides products like its FRR structural thermal break material and specialized washers and bushings designed to solve thermal bridging at connections.
Schöck: A global leader in the field, Schöck offers a wide range of Isokorb® products. These are engineered structural connection elements that both transfer load and provide thermal insulation, particularly for concrete-to-steel and balcony connections.
Farrat: Farrat offers structural thermal break materials that are widely specified by structural engineers. Their products are designed to provide high compressive strength and low thermal conductivity, and it is wise to request a technical data sheet from the manufacturer to verify performance for your specific needs.
FAQ: Structural Thermal Break Questions
1. What is a structural thermal break?
A structural thermal break is a component used in construction to reduce or prevent the flow of heat through a structural connection.
It is made from materials with low thermal conductivity but high structural strength. This allows it to transfer load while insulating the connection to prevent what is known as thermal bridging.
2. How do you stop thermal bridging in steel?
You stop thermal bridging in steel connections by inserting a material with low thermal conductivity, like a composite washer or pad, between the steel elements.
Using insulating bushings around the bolts is also critical to prevent the bolts themselves from acting as a thermal bridge. This isolates the interior steel from the exterior steel, blocking the primary path for heat transfer.
3. What material is best for thermal breaks?
The best material depends on the application’s specific load and temperature requirements. For high-strength structural applications, glass-reinforced epoxy laminates like G10 and G11 are considered top-tier choices.
G11 is generally superior for high-temperature environments due to its ability to retain its excellent mechanical strength under heat.
4. Are thermal breaks a code requirement in commercial buildings?
Yes, increasingly so. While not always explicitly named, meeting the performance targets of modern energy codes like ASHRAE 90.1 is very difficult without addressing thermal bridging.
Furthermore, some jurisdictions, such as New York City and Seattle, have specific mandates that require mitigation of thermal bridges at balconies and other envelope penetrations.
