Minimizing thermal bridging

Thermal bridges are areas of the building envelope with more transmission heat loss than elsewhere and with lower temperatures on the inside than in the rest of the structure. In the worst case heat loss through thermal bridges can account for up to 30 % of transmission heat loss.

If, when the temperature outdoors is low, the inside surface temperature sinks below approx. 13 °C, water vapour will condense in these areas (assuming normal room temperature and humidity). As a consequence of moisture accumulating, mould can develop in these areas.

Mould development in corners where thermal bridges take effect (source: GrAT)

One can distinguish between

structural thermal bridges (through building components with differing thermal conductivity, e.g. at the junction between a reinforced-concrete floor and an external wall),
geometric thermal bridges (e.g., at projections and corners) and
material thermal bridges (due to different materials).