A thermal break is a low-conductivity material inserted between thermally conductive building components (typically metal) to interrupt the pathway for heat transfer and reduce thermal bridging. Thermal breaks reduce heat flow by 50-90 percent through structural connections, window frames, and curtain walls.
Materials and Applications
Thermal breaks use polyamide, polyurethane, foam, or fiberglass with thermal conductivity values of 0.1-0.3 W/m·K. They are commonly installed in aluminum window frames, metal studs, and building attachments. Minimum thermal break thickness is typically 0.5-1 inch for effective performance. Structural thermal breaks must meet building code requirements for structural continuity and load transfer.
Performance and Building Code Compliance
Thermal breaks improve window U-factors by 20-30 percent and reduce condensation risk on metal frames. They are required by IECC and ASHRAE 90.1 in most climate zones. Thermal breaks in aluminum frames reduce linear thermal transmittance (PSI value) from 0.05-0.15 W/m·K down to 0.01-0.05 W/m·K. Cost typically adds $3-8 per linear foot to window assemblies, significantly improving overall building envelope performance.