A structural thermal break is a load-bearing, low-conductivity material or assembly placed where steel or concrete passes through the building envelope. It does two jobs at once: it carries the structural loads of the connection, and it interrupts the flow of heat from the warm interior to the cold exterior.
This guide explains thermal bridging, where structural thermal breaks are used and how to choose between the main options.
What Is Thermal Bridging?
Steel conducts heat hundreds of times faster than insulation. Where a beam, angle or post crosses the insulation layer, it forms a thermal bridge, a short circuit that lets heat bypass the insulation. Thermal bridges cause three problems:
- Heat loss: they lower the effective R-value of the whole wall or roof, sometimes dramatically.
- Condensation: the steel inside the envelope can fall below the dew point, so moisture condenses on it.
- Mould and corrosion: repeated condensation leads to mould growth, staining and corrosion of the steel.
Why Structural Thermal Breaks Matter Now
Canadian energy codes are moving steadily toward net-zero energy ready buildings, and energy modelling now accounts for heat lost through thermal bridges at balconies, canopies, shelf angles and other penetrations. Once insulation levels are high, these connections become a larger share of the remaining heat loss, so thermally breaking them is one of the most cost-effective upgrades available to a design team.
Types of Structural Thermal Breaks
- High-strength thermal break pads – plates such as STB-1 bolted between steel end plates or under base plates. Flexible, economical and fast to supply.
- High-R thermal break materials – such as TBF High Density Thermal Break for light loads, cold storage and foundation isolation.
- Proprietary modules – pre-engineered assemblies with stainless load-bearing elements. See pads vs modules.
- Bolt isolation – thermal break washers and bushings that complete a bolted thermal break.
Where They Are Used
- Steel balconies and canopies
- Masonry shelf angles and relieving angles
- Column bases, roof posts and rooftop dunnage
- Parapets, roof-to-wall intersections and roof penetrations
- Curtain wall and cladding supports
- Cold storage and freezer foundations
Frequently Asked Questions
What is a structural thermal break?
A structural thermal break is a load-bearing, low-conductivity material or assembly installed where structural steel or concrete passes through the building envelope. It carries the structural loads while interrupting heat flow, reducing heat loss and condensation at the connection.
What is the difference between a thermal break and a structural thermal break?
Any material that interrupts heat flow is a thermal break. A structural thermal break must also carry significant structural loads, such as compression, shear and moment at a canopy or balcony connection, so it needs high compressive strength and resistance to creep.
Where are structural thermal breaks used?
Common locations include steel balconies and canopies, masonry shelf angles, rooftop dunnage and posts, parapets, column bases on foundation walls, curtain wall supports and cold storage foundations.
How thick should a thermal break pad be?
Most steel connections use 1/2 inch to 1 inch STB-1. Thicker pads reduce heat flow further but lengthen the bolt grip and increase bolt bending, so thickness is set by the engineer of record to balance thermal and structural requirements.
Do I need thermal break washers and bushings?
In most bolted connections, yes. Without them the steel bolts and washers conduct heat around the pad. Thermal break washers and isolation bushings keep the bolts from touching the exterior steel.
Is STB-1 fire rated?
Yes. STB-1 is fire rated to ASTM E84 Class A and Euroclass B (EN 13501-1).
Can TBF High Density Thermal Break be used for balconies?
No. TBF should not be used in moment connections. Use STB-1 for balconies, canopies and other moment or high-load connections, and TBF for light-load supports and cold storage isolation.
How fast can I get thermal break pads?
STB-1 pads cut and machined to your drawings typically ship in 5 to 7 days. TBF parts can be produced in as little as 3 days.
Request a Quote or Data Sheet
Send us your connection drawings, bolt schedule or load requirements and we will quote STB-1, TBF, washers and bushings cut and machined to your specification. Data sheets and design support are available for engineers and architects.
Call 800-580-4195 or use the form below. STB-1 typically ships in 5–7 days; TBF in as little as 3 days.