Analysis of construction joints and thermal bridges
The thermal bridge may be defined as an area of the building envelope (a physical point or a linear section) which has a thermal behaviour clearly different than that of the surrounding areas, with reference to the distribution of the temperatures and to the propagation of heat.
The mandatory standards requiring the "correction" of thermal bridges, for all new buildings and for retrofitting interventions. The widespread malpractice in construction industry, in the presence of thermal bridges, is instead to simply provide a greater amount of heat.
The damage done by thermal bridges, in addition to a greater dispersion of heat, is certainly in the reduction of thermal comfort. This necessarily happens when, for some portions of the building envelope, surface temperatures of at least 3°C lower than indoor air temperature are observed. But, even more, the presence of spots in which the surface temperature of a wall or a floor considerably varies with compared to the surrounding area facilitates the risk of surface and interstitial condensation, then creates moulds, and consequently the rooms' unhealthiness and an early impoverishment of materials and construction elements.
Strictly avoid thermal bridges is the only design and construction approach permissible today.
At the construction joints, the risk is obviously higher, so is a good idea to study the hygrothermal behaviour of the suspected critical spots.