Choosing the right insulation

Choosing the right insulation for your building can have a big impact on energy consumption, cost, maintenance and longevity. In this guide, we will look at insulation by function, material, type and location as well as technical performance.

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  • How do I choose the right insulation?

    JOHNS MANVILLE Thermal Insulation

    JOHNS MANVILLE Thermal Insulation

    Correctly insulating a building helps to save energy and improve thermal comfort for the occupants. The best type of insulation to choose will depend on a number of elements such as the surface to be insulated, the space available and the type required (thermal, acoustic or both).

    The key criteria to consider include:

    • The surface to be insulated
    • The material
    • The format and dimensions
    • The technical performance (thermal, fire, acoustic)
  • What do I need to know about the performance of insulation?

    ETERNO IVICA Acoustic insulation panel

    ETERNO IVICA Acoustic Insulation Panel

    The total performance of insulation will depend on a number of factors such as thermal resistance (the R-value). The R-value can be influenced by the type, density and thickness of the material, so it is important to use a consistent R-value when comparing different products. There are many thermal insulation products that also have acoustic properties, helping limit sound transmission through air or resonance through materials.  Listed below are some of the key characteristics to take into account :

    • The λ-value is the thermal conductivity of the insulation, measured in W/mK (Watts per meter-Kelvin). The lower the value the better.
    • The R-value is the thermal resistance of the insulation of a given thickness, calculated by the thickness(in metres) / thermal conductivity, measured in K.m2/W (Kelvin square meters per Watt). The higher the R-value the more resistant the insulation is against heat loss.
    • The U-value is the calculation of thermal transmittance – how much heat is lost through the building material. The lower the U-value the better. The overall U-value of a building envelope is calculated taking into consideration the thermal transmittance of each layer.
    • Fire ratings such as the Euroclasse 13501-1 in the EU is used to rate the combustibility and smoke emissions of materials. The classification and rating required can vary depending on geographical area.
    • The sound insulation in “dB Dw” describes the sound transmission lost between two spaces in Db. The overall sound reduction from one space to another will depend on the assembly of the elements that make up the floor, wall or partition and the sound absorption capacity of each material.

    It is important to make sure that other products used in the building envelope (such as vapor barriers, connections, waterproofing etc.) are compatible and correctly installed, as this will have an impact on the overall effectiveness and longevity of the insulation.

  • Where can insulation be installed?

    There are four main types of insulation: roof, facade, wall and floor. While the roof insulation might be considered the most important, as the roof can allow heat loss at a higher percentage, all four areas of insulation need to be properly done.

    IKO - Flat Roof Insulation

    IKO – Warm Flat Roof Insulation

    Roof Insulation – Uninsulated roofing can result in a 25% heat loss in a building. The type of insulation to choose and installation method to implement will depend on factors such as the type of construction, roof pitch, local climate and building regulations. Ensure that the insulation chosen is compatible for the type of roof system, or building envelope. Always consult a professional in case of doubt.

    Here are a few examples of installation methods :

    • Cold pitched roof installation: The insulation is installed in between and above the ceiling joists with a ventilation gap. The area under the roof pitch will also remain uninsulated, so water tanks and plumbing in this area might need to be insulated to protect from freezing.
    • Warm pitched roof installation: The insulation is fixed between the roof covering and the roof rafters, as well as on gable walls, and protected by the waterproof membrane. While this method is more expensive than a cold installation, the space under the pitched roof is insulated and can be finished with plasterboard to convert into a living space.
    • Cold flat roof installations: The insulation is placed between the joists above the ceiling. This method of insulating is less efficient than warm flat roof installations because it is more prone to incorrect installation, which could lead to cold bridging, condensation problems or even roof damage.
    • Warm flat roof installations: The insulation is installed over the roof support below the waterproof layer. Rigid insulation boards are sometimes used in this type of installation.
    • Inverted flat roof installation: The insulation is installed over the waterproof layer of the roof.


    MITTEN Facade Insulation Panel

    MITTEN Facade Insulation Panel

    Façade insulation – Insulating from the exterior is generally more effective than the interior, as it is easier to avoid cold bridging or dew points, and also helps maximize interior space. However, it can be up to 50% more expensive to install and might not even be permitted if the existing facade needs to be maintained, such as in protected historical areas.

    Wall Insulation The type of installation chosen will depend on the state and location of the wall – for example the level of dampness and evenness. Very damp walls may require a stud wall with a cavity between the exterior wall to allow for ventilation.

    Floor insulation – There are many different types and formats. Insulation can be installed between wooden floor joists in traditional wood constructions, or under the finished floor also to reduce resonance or noise in apartments underneath carpets, parquets or tiling. Underfloor heating systems can have insulation built into the system to protect piping.

  • What insulation formats and materials are available?

    KRAIBURG RELASTEC Rubber Sound Insulation

    KRAIBURG RELASTEC Rubber Sound Insulation

    The material used for insulation often depends on the format. Loose or blown insulation generally uses mineral wool, for example, wood fiber or a few others; while roll insulation uses mineral wool or fiberglass with the option of supplementary materials for acoustic purposes. We’ve listed the main formats here with a description of materials used.

    Loose or blown insulation is good for awkwardly shaped areas and floor and wall cavities where roll insulation may not be able to evenly cover. It is easy to install, but the insulation may settle over time. Common materials for this type include mineral wool, cellulose, wood fiber, or polyurethane.

    Roll insulation is popular for thermal insulation for walls, floors, ceilings and roofs and ducting. Roll insulation materials such as mineral wool and fiberglass insulation are naturally non-combustible, uv and mould resistant with good thermal acoustic properties. They are often available in standard sizes for easy installation between framing, joists and rafters. Synthetic foam roll insulation for acoustics such as rubber, epdm can be used to provide supplementary acoustic insulation for floors, walls or ceilings

    Panel insulation can be costly but tends to be fast and easy to install. It is important to ensure that edges and obstacles are properly finished to avoid gaps which could cause cold bridging, sound transmission or dew points. Some products might include multiple material layers to improve the overall performance of sound insulation, breathability or reflectivity.
    Vacuum insulated panels (VIPs) are insulated using a vacuum system. Air is removed from the inside of the panel to create a vacuum. While vacuum insulation panels are very expensive, they have a high U-value and are much thinner than other forms of insulation.

  • What are the options concerning natural insulation?

    SIG PLC sheep's wool insulation

    NATUREPRO Sheep’s Wool Insulation

    Using natural insulation materials over synthetic materials can have a number of advantages such as biodegradability, breathability, as well as avoiding the use of toxic chemicals and VOCs. Some natural products require less energy to produce than synthetic equivalents, such as hemp (some of them are even waste products from other markets such as straw bale).

    However, many natural materials are more expensive than synthetic alternatives and might need supplementary treatments against insects or moisture. Examples of popular natural insulation materials include hemp, sheep’s wool, wood fiber, cotton and Straw bale. If you do decide to use natural insulating materials, make sure that it is adapted for use, meets local regulations, and that the construction firm is qualified to install it properly. While hemp batts can often be installed in a similar way to mineral wool between rafters and joists, some natural insulation materials require special construction techniques, and treatments such as straw bales and might not be suitable for humid environments.

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