Thermal bridging reduces the energy performance of a house. It is often found in the connections of building elements and leads to the development of mould and increased energy costs.
However, it is not a fatality, as it can be detected, corrected and removed. There are many tricks to help reduce the damage caused by a thermal bridge at the ceiling level.
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What is a thermal bridge?
A thermal bridge can be defined as an insulation defect that causes heat loss and a decrease in the thermal resistance of a house.
This type of failure is usually caused by poor design of the dwelling. The installation of poorly performing equipment and the use of poor quality materials can also be the cause of this problem. In addition to these causes, humidity and excessive heating or air conditioning can also be a problem.
Generally speaking, thermal bridges are found in walls, roofs, ceilings, balconies and floors. They can be identified by means of a thermal camera at the various openings in your house (doors, windows, veranda, etc.).
You can also find them at electrical outlets or cable outlets where there is an air hole.
How to identify a thermal bridge?
It is difficult for an individual to identify thermal bridges in his or her home, except when mould is already apparent.
You can perform a manual test on all areas that are considered sensitive. These are nothing more than junctions between two or three walls, the edges of windows and doors.
To detect thermal bridges, simply place your hand on a wall or area. If you notice a significant difference in temperature in that area, you may have a thermal bridge.
The most effective way to identify this problem is to call in a professional, who may be an architect or an insulation contractor. The latter will offer to carry out an in-depth energy assessment of your home's envelope using thermographic analysis.
This is a simple and straightforward method of identifying and highlighting building defects. To do this analysis, the professional uses a thermal camera to visualise the house as a heat emitting entity.
The different types of thermal bridges
We have three main types of thermal bridges:
- Linear It appears at the junction of two walls. This thermal bridge is frequently found at the junction of wall/low floor, balcony/slab, external wall/roof. It is visible at the intersection of horizontal floor walls and horizontal wall surfaces. Linear thermal bridges can be found around door frames and door thresholds;
- One-off This type of thermal bridge is found at junctions between three different walls, such as corners;
- Structural This type is generated as a result of the installation of the insulation, especially after gluing or screwing, and is inherent to the installation method.
What are the risks of a thermal bridge?
Thermal bridging is responsible for the formation of mould and heat loss which leads to increased energy costs.
A risk of mould
Areas subject to thermal bridges are usually damp. This is what encourages the growth of mould. You should know that indoor air contains a lot of moisture. When this warm air touches the thermal bridge, it cools down suddenly and the vapour contained in it condenses. This condensation area is conducive to the development of fungi and moulds.
Additional energy costs
High energy bills are caused by high heat loss. In addition, there is a high demand on heating systems in winter and air conditioning in summer. These variations caused by thermal bridges lead to higher energy bills.
Solutions for removing a thermal bridge in the ceiling
There are various techniques for overcoming thermal bridges. The installation of a thermal bridge breaker, the installation of a floating screed on insulation and the insulation of roller shutter casings are all solutions to be considered.
Installation of a thermal bridge breaker
The installation of a thermal bridge breaker eliminates linear thermal bridges. It is an insulating device that connects the exterior wall or the partition wall to the floor via a steel structure.
It is positioned at the end of the slab to ensure the continuity of the insulation. Widely used in renovation, this device can also be integrated during the construction of your home. It is generally recommended for intermediate floors.
The thermal bridge breaker helps you to restore the evenness of the insulation on your building envelope. This device has a positive impact on the performance of the house. It is important to note that a particular type of breaker is needed for each variety of thermal bridges. You have to deal with them one by one if you want to get a homogeneous thermal insulation.
You can also map them using infrared thermography. However, it is best to install the device when your home is being built. In fact, the integration of thermal breakers can be complex in renovation. It is therefore essential to integrate them into the structure of the house.
Laying a floating screed on insulation
The screed is a thin layer of mortar between 4 and 6 cm thick. It is poured between the slab and the floor covering to level the floor and provide a smooth finish. The screed also serves as a support for the flooring. It is called a floating screed in the case of insulation under screed. With this technique, coupled with thermal insulation from the inside of the walls, it is possible to eliminate thermal bridges in the low floor.
Insulation of roller shutter housings
A practical solution for eliminating thermal bridges is to insulate the roller shutter box with rock wool or solid foam. You can find kits specifically designed for insulating roller shutter boxes in DIY stores.
Focus on the RT 2020 standard and the end of energy flats
The Thermal regulation 2020 (also known as Environmental Regulation 2020) is a standard for positive energy housing or buildings and passive houses.
Note that a positive energy house produces more energy than it consumes. Passive houses are dwellings that use little energy and recycle the energy they produce.
This standard applies from 2021 and requires homes to produce their own energy to meet their needs. It uses the same criteria as the RT 2012 standard, but increases their requirements. The standards to be respected are mainly :
- Bioclimatic energy efficiency ;
- Consumption measured in kWh/m²/year ;
- The maximum temperature that should not be exceeded in your home.
In addition, since 2011, the government has introduced the RGE (Reconnu Garant de l'Environnement) label. It is aimed at craftsmen and companies specialising in energy renovation work. In addition, thanks to the RGE label, you can obtain financial aid.