Why insulate an interior wall? Which material should you choose for long-lasting thermal performance? What regulations apply to wall insulation? Find all the essential answers you need to insulate an interior wall in our guide.
Reminder of the fundamentals of effective thermal insulation
To ensure effective thermal insulation of an interior wall, several key elements must be taken into account. First,the continuity of the thermal envelopeis essential. This means ensuring that the insulation is uniform across all surfaces to avoid thermal bridges, i.e., areas where heat can easily escape. These thermal bridges, often located at the junctions between walls, floors, and ceilings, can significantly reduce the effectiveness of the insulation.
Secondly,moisture managementplays a crucial role in the longevity and effectiveness of thermal insulation. Poor moisture management can lead to the deterioration of insulation materials, reduce their performance, and cause problems such as mold. To remedy this, it is essential to use suitable materials and install a vapor barrier, especially in moisture-sensitive rooms such as kitchens and bathrooms.
Finally, another key point isthe thermal resistanceof insulation materials, often referred to as the R-value. The higher this value, the more effective the insulation is at slowing heat transfer. It is recommended to choose materials with a thermal resistance suitable for the region and current regulations in order to optimize the building's energy efficiency.
These three elements—continuity of the thermal envelope, moisture management, and thermal resistance of materials—are the pillars of effective thermal insulation.
Why insulate an interior wall?
Thermal insulation of an interior wall has many advantages, both in terms of energy and cost savings. First and foremost, itsignificantly reduces heat loss. It is a fact that a poorly insulated wall can be responsible for 20 to 25% of a building's heat loss. Improving insulation therefore limits this loss, which helps to maintain a more stable indoor temperature without the need to constantly overheat or cool rooms. This results in a significant reduction in energy consumption.
Financially, this reduction in energy expenditure has a direct impact on heating and air conditioning bills. In the long term, the savings made on energy costs makeinsulation work profitable. It is a sustainable investment that improves the overall performance of the building.
In addition, insulating interior wallsimproves thermal comfort. In winter, it keeps heat inside, while in summer, it prevents outside heat from entering. This ensures a pleasant environment throughout the year, without sudden temperature fluctuations.
From an environmental perspective, improving interior insulation alsoreduces thebuilding'scarbon footprint. Less energy consumption means lower CO₂ emissions, thereby contributing to greenhouse gas reduction targets.
Finally, thermal insulation of an interior wall is a significant asset inenhancing the value of a property. A well-insulated building achieves better energy ratings, an increasingly important criterion in real estate transactions. In short, insulating an interior wall is an economical and environmentally friendly measure that also improves the comfort of the home.
What materials should be used for interior wall insulation?
The choice of materials for interior wall insulation is essential to ensure optimal performance.Conventional materials include glass wool and rock wool. These are very popular, offering good thermal and acoustic insulation, while being economical and easy to install. These materials are particularly appreciated for their value for money.
In terms ofbio-based materials, which are increasingly popular due to their low environmental impact, there are insulators such as wood fiber, hemp, and cellulose insulation. cellulose insulation. These natural materials are durable, recyclable, and offer excellent thermal insulation properties. In addition to contributing to areduced carbon footprint, they regulate humidity better, which improves indoor air quality.
The choice of material depends on the specific requirements of the building, the budget, and ecological preferences. For a sustainable and high-performance building, bio-based insulation materials are an ideal solution, while conventional insulation materials remain a reliable and economical option for many interior wall insulation projects.
What types of materials should be used to insulate walls?
In accordance withRE2020 requirements, the choice of insulation type is crucial to achieving optimal thermal and acoustic performance.Loose-fill insulation, such as cellulose insulation blown rock wool, stands out for its ability to fill every nook and cranny perfectly, thereby reducing thermal bridges. Although they are more technical to install, these insulators offer better thermal and acoustic performance, which fully meets RE2020 expectations in terms of energy efficiency and comfort.
Rigid panels, made of polystyrene or wood fiber, are easier to install and are suitable for flat surfaces, but can leave gaps in uneven areas.Insulation rolls, such as glass wool, are an intermediate solution, combining flexibility and efficiency for large wall surfaces.
What regulations apply to the insulation of interior walls?
Regulations for thermal insulation of interior walls are governed by strict standards, notablyRE2020for new buildings andRT Existantfor renovations. In new construction, RE2020 imposes highenergy efficiency criteria. It aims to reduce energy consumption and limit the carbon footprint of buildings. Wall insulation must therefore complywithstrictthermal performance coefficients, with a minimum thermal resistance (R) of 3.7 m²K/W for walls.
In renovation projects, thermal regulations for existing buildings (RT Existant) require that, during energy efficiency improvements, interior walls be insulated to achieve specific performance levels. The minimum threshold is set at a thermal resistance of2.9 m².K/Wfor opaque walls. In addition, financial assistance such as theCITE(tax credit for energy-efficient renovations) or eco-renovation grants are available to encourage this work, provided that the insulation materials and installation comply with current standards.
What precautions should be taken before and during the installation of insulation in walls?
To ensure effective thermal insulation, it is essential to take rigorous precautions before and during the installation of insulation in walls. First, it is imperative toproperly prepare the surfaceof the walls. Walls must be clean, dry, and free of moisture or mold, otherwise the durability and effectiveness of the insulation will be compromised.
Next, installers must pay particular attention topersonal protective equipment (PPE). When handling certain insulation materials, such as glass wool or rock wool,gloves, masks, goggles, and long clothingare essential to prevent irritation and inhalation of particles. Good ventilation of the workspace is also recommended to minimize risks.
During installation, it is crucial tofollow the installation techniques for insulation materialsaccording to their form (panels, rolls, loose fill). Careful installation reduces thermal bridges and ensures uniform coverage of surfaces. It is also important to ensure that the wall is airtight (by installing a vapor barrier, for example) to prevent moisture infiltration and preserve the thermal performance of the insulation over the long term. In all cases, refer to French standards such as technical notices or DTUs in force to find out all the steps involved in installing insulation in an interior wall.
Following these precautions ensures high-quality insulation that complies with standards and extends the life of the structure.
How long does the thermal insulation of an interior wall last?
The longevity of thermal insulation in an interior wall depends mainly on the quality of the materials used and the rigor of the installation.
Bio-based insulation materials, such as wood fiber, hemp, or cellulose insulation, offer superior longevity compared to conventional insulation materials, provided they are installed correctly. Unlike glass wool or rock wool, which have an average lifespan of 30 to 40 years and are more sensitive to moisture, bio-based materials stand out for theirability to regulate humidity. This allows them to better resist degradation over time and maintain their thermal and acoustic performance for several decades, sometimes up to50 years or more.
These natural insulators, in addition to being environmentally friendly, are capable of absorbing and then releasing moisture without altering their insulating properties, which prevents condensation and mold problems often encountered with conventional insulators. Thanks to this moisture management, bio-based insulators guaranteegreater stability and durabilityover time.
Finally, regular inspection of interior walls and the condition of the insulation ensures that the materials maintain their performance over time. Careful installation and compliance with standards ensure durable, high-performance insulation for decades to come.
Insulating an interior wall is key to ensuring sustainable energy performance. Insulating a building's walls from the inside reduces energy loss by 20 to 25%. While panel and roll materials are easier to install, loose-fill insulation significantly reduces thermal bridges. Bio-based materials, thanks to their hygroscopic properties, are ideal for sustainable and effective thermal insulation.
Photo credit for article: Phoenix (17)
