Thermal bridges are areas in the building envelope where heat escapes more quickly to the outside than in adjacent, better-insulated components. Typical weak points include corners, roof and ceiling connections, window reveals, or transitions between different materials — such as reinforced concrete and masonry.
Standard Thermal Bridge Supplements by Building Type
Depending on the type of building and the level of detail in the planning, different standard supplements apply:
1. Existing Buildings
For existing buildings without detailed verification, a standard supplement of
0.10 W/(m²·K) is typically applied.
2. New Buildings
For new buildings, the applicable supplement depends on whether and how thermal bridge planning has been conducted:
Category A (Equivalence verification according to DIN 4108, Supplement 2):
0.05 W/(m²·K)
→ Standard value when planning and execution follow usual good practices.Category B (Enhanced equivalence verification):
0.03 W/(m²·K)
→ Applies if all construction details are specifically designed and executed to minimize thermal bridges.
Special Case: Interior Insulation > 50% + Solid Concrete Ceilings
In new buildings with predominantly interior insulation and solid concrete ceilings, the risk of thermal bridging increases.
→ 0.15 W/(m²·K)