Thermal bridges are junctions where insulation is not continuous and causes heat loss. The main problem for fitters, thermal bridges have an impact on the loss percentage if the house is well insulated.

What is a thermal bridge?

A thermal bridge occurs when there is a gap between materials and structural surfaces. The main thermal bridges in a building are found at the junctions of facings and floors, facings and cross walls; facings and roofs, facings and low floors. They also occur each time there is a hole (doors, windows, loggias…). These are structural thermal bridges. These thermal bridges vary in importance according to the type of wall or roof (insulated or not).

In a building that is not properly insulated, thermal bridges represent low comparative losses (usually below 20%) as total losses via the walls and roof are very high (about >1W/m2K).

However, when the walls and roof are very well insulated, the percentage of loss due to thermal bridges becomes high (more than 30%) but general losses are very low (less than 0.3 W/m2K).

That is why in low energy consuming buildings, it is important to have very high thermal resistances for walls and roofs to have low heat losses via the junctions.

Integrated thermal bridges

A wall or floor almost always consists of several components pasted, screwed or mechanically assembled together. If they are not well designed, these assembly systems can produced thermal bridges within the system, hence their name of integrated thermal bridges.

How to act on thermal bridges?

At the design level, it is imperative to choose construction processes and components that reduce surface losses as much as possible and integrate the smallest possible losses in the junctions of these surfaces. Whatever insulation systems are used, there are relevant thermal, acoustic and/or fire safety solutions.
Generally speaking, in the case of individual homes, very good floor insulation is needed and, depending on the wall insulation, the floor should be covered with a floating floor or a bricked system with built-in insulation.

Back to FAQ list