Thermal break

Metal moves heat fast. Without a break, a steel or aluminum frame acts like a bridge between outdoors and indoors. A thermal break splits the frame into an inside half and an outside half. A low-conductivity material joins them.

The result is a warmer inside surface in winter, a cooler one in summer and less condensation risk. Any metal window or door that claims good efficiency should have one. Read how it works in steel in our thermally broken steel windows guide, and see thermally broken steel for the term itself. Ask what material forms the break and how it is joined.