Your expert in cavity wall insulation
Isoleaz assists you with the insulation of your cavity walls in Luxembourg
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Your insulation expert
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At Isoleaz, we handle all cavity wall insulation projects in Luxembourg. Our team carefully analyzes each situation to guide you towards the most suitable solution for your home, and supports you from the initial site visit to the completion of the project.
Is your property affected by cavity walls?
Many Luxembourg homes built before the 1980s feature double-walled construction, separated by an air gap known as a cavity wall. This configuration, very common in post-war buildings up until the 1970s, actually presents an interesting opportunity: this empty space can be filled with high-performance insulation without undertaking major renovations or altering the building’s exterior appearance.
Before proceeding, three questions should be considered:
- Are your walls actually hollow and compatible with this type of intervention?
- Which insulating material will be best suited to your configuration?
- Which professional can you trust to guarantee a lasting result?
At Isoleaz, we take the time to analyze your situation in detail before making any recommendations. Our goal is to offer you the most effective solution, achievable under the best conditions and sustainable over time.
What is cavity wall insulation?
Cavity wall insulation involves injecting insulating material into the space between the two walls to eliminate heat exchange. This technique helps retain heat inside the home in winter and limits the penetration of outside heat in summer, resulting in significantly improved thermal comfort and lower energy bills.
The implementation method varies depending on the project.
During a renovation, the injection is generally carried out from the outside. Small holes are drilled in the mortar joints of the facade, through which the insulation is injected under pressure until the cavity is evenly filled. Once the operation is complete, these holes are carefully sealed with a material that matches the color of the existing mortar joints, for a virtually invisible result. This type of work can often be completed in a single day, with minimal disruption to the occupants.
In new construction, the double wall is insulated during the structural phase. The insulating material is placed against the inner wall before the finishing coating is applied, whether it is plaster, wood cladding or other facing.
How can you tell if your walls are hollow?
Identifying the presence of cavity walls is not always easy. However, a few clues can guide the diagnosis:
- The thickness of the wall: A double-walled wall is generally thicker than a conventional solid wall.
- The year of construction: Buildings erected before 1920 generally do not have cavity walls, unlike buildings from subsequent decades.
- The construction plans: If they indicate a double wall with an interstitial space, the presence of a sliding joint is confirmed.
The only way to be certain is to call on a qualified professional, who will carry out a thorough check before any decision is made.
What conditions must be met to insulate cavity walls?
The presence of cavity walls is not enough to guarantee the feasibility of insulation. Several criteria must be checked before starting the work:
- The width of the slide The thickness must be sufficient, ideally at least 5 centimeters, to allow for even distribution of the insulation. Below this threshold, other solutions must be considered.
- The cavity must be clean and free from debris or obstacles that could impede the proper diffusion of the material and promote the appearance of moisture
- The facade must be in good general condition: The system must be free of cracks, chips, or damage that could allow moisture to penetrate. If repairs are necessary, they must be carried out before any work is done on the sliding mechanism.
- Moisture removal
This must be ensured by a vapor-permeable facade coating. Walls regularly exposed to rainfall absorb more moisture and dry more slowly, which can eventually lead to significant problems.
At Isoleaz, our team systematically conducts a thorough assessment before confirming the project’s feasibility, guaranteeing you an efficient and trouble-free construction process.
The advantages and limitations of cavity wall insulation
The strengths of this technique
Cavity wall insulation offers several advantages that make it one of the most sought-after solutions for Luxembourg homeowners wishing to improve their housing without invasive work.
After the roof, walls are one of the main sources of heat loss in a building. Effectively treating this area can lead to energy savings of up to 25% on heating bills, a particularly significant gain in the current context of rising energy prices.
Other notable advantages:
- A quick and minimally invasive implementation, without demolition or modification of the exterior or interior appearance of the dwelling
- The total preservation of living space, unlike interior insulation.
- The cost is generally lower than that of other wall insulation methods (ITI and ITE), making it the most financially accessible solution.
- An increase in the value of the property, thanks to the improvement of the energy performance certificate (EPC), an increasingly important criterion on the Luxembourg market.
- A wide selection of insulating materials, adapted to different cavity wall configurations
Points of vigilance
Cavity wall insulation does, however, have one major limitation to be aware of: the risk of moisture accumulation in the cavity after the insulation is installed. This phenomenon, although infrequent when the site is properly prepared, can lead to long-term problems if it is not anticipated. Solutions exist to address this, such as the injection of suitable waterproofing gels. This is precisely why a preliminary inspection of the walls is an essential step before any work begins..
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What material should I choose to insulate cavity walls?
The choice of insulation directly determines the system’s performance and its long-term behavior. For cavity wall insulation, specific materials are used, as they must be able to be blown or injected into a confined space without losing their properties.
Glass wool
Blown-in fiberglass insulation is one of the most commonly used solutions for this type of project. Lightweight and efficient, it is evenly distributed throughout the cavity using a blowing machine, ensuring complete coverage with no gaps. It offers good thermal and acoustic performance, and has good fire resistance.
Other materials can also be used depending on the site configuration: injected polyurethane foam, particularly well-suited to narrow cavities thanks to its controlled expansion, or polystyrene beads, which are lightweight and moisture-resistant.
Our Isoleaz advisors will guide you toward the material best suited to your home, taking into account the cavity thickness, the building’s orientation, and your energy performance goals.
What budget should be allocated for cavity wall insulation in Luxembourg?
The cost of cavity wall insulation depends primarily on the total surface area to be treated and the chosen material. It is generally the least expensive wall insulation method, particularly because it requires neither extensive scaffolding nor demolition or reconstruction work.
As a guide, the average price is between €130 and €160 excluding VAT per square meter, all services included. This amount may vary depending on the specific characteristics of the project and the accessibility of the walls.
At Isoleaz, we provide you with a personalized and detailed quote within a maximum of 24 hours, so you have a clear understanding of the budget before making any commitment.
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