Thermal bridges can occur at several locations within a building envelope; most commonly, they occur at junctions between two or more building elements. Common locations include:

Floor-to-wall or balcony-to-wall junctions, including slab-on-grade and concrete balconies or outdoor patios that extend the floor slab through the building envelope
Roof/Ceiling-to-wall junctions, especially where full ceiling insulation depths may not be achieved
Window-to-wall junctions[13]
Door-to-wall junctions[13]
Wall-to-wall junctions[13]
Wood, steel or concrete members, such as studs and joists, incorporated in exterior wall, ceiling, or roof construction[14]
Recessed luminaries that penetrate insulated ceilings
Windows and doors, especially frames components
Areas with gaps in or poorly installed insulation
Metal ties in masonry cavity walls
https://en.wikipedia.org/wiki/Thermal_bridge