Is the price the only advantage of installing Styrofoam as floor insulation? For which spaces is Styrofoam suitable as floor insulation? What kinds of screeds are suitable for installation on Styrofoam insulation? What are the disadvantages of Styrofoam when used for floor insulation?
Styrofoam is one of the most popular insulation materials, and for good reason. Its thermal insulation quality, ease of installation, and affordable price make it a top choice for thermal insulation needs. While we often see Styrofoam used for insulating façade walls through the installation of so-called “external thermal insulation composite systems” (ETICS), it’s worth noting that Styrofoam is also excellent for insulating floors.
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However, it’s important to note that Styrofoam is used for insulating floor coverings in areas where significant loads are not expected. Therefore, Styrofoam can be used for floor insulation in residential spaces, including garages, but not in commercial spaces where, for example, forklift or truck movement might be anticipated.
Advantages of Styrofoam as Floor Insulation
One advantage of Styrofoam is its compatibility with various types of flooring. Styrofoam does not react chemically to concrete, lime, plaster, asphalt, or most chemical agents that may be encountered during or after construction.
Therefore, Styrofoam can withstand both dry and wet screeds. This means that liquid concrete screeds can be poured over Styrofoam insulation, or dry screeds can be installed. Dry screeds can be made from gypsum and fiberboards, as well as various wood-based panels.
Of course, the appropriate type of Styrofoam should be selected for floor installation. Styrofoam is manufactured in different densities, or hardnesses. Unlike other types of insulation materials, the mechanical rather than insulating characteristics of Styrofoam depend mostly on its density. Harder, higher-density Styrofoams are used in floors.
To distinguish between different types of Styrofoam, packaging is marked with color-coded bands. Blue bands indicate softer and semi-hard Styrofoam, suitable for sandwich walls, ceilings, sloping roofs, and attics. Red bands on packaging denote Styrofoam intended for facade insulation, while black bands signify hard-pressed Styrofoam, which has greater strength and is used for floors.
Styrofoam is a good choice for floors due to its vapor permeability. This property allows floors to “breathe,” reducing the risk of moisture and mold. Styrofoam is classified as B1 for flammability.
Disadvantages of Styrofoam as Floor Insulation
Of course, there are some weaknesses associated with this material, leading to certain limitations. Styrofoam is not durable when exposed to water for extended periods, so its installation should be avoided in areas prone to high moisture levels and potential water ingress.
Therefore, when insulating basement areas, Styrofoam is replaced with extruded polystyrene (XPS). Additionally, Styrofoam does not tolerate prolonged exposure to sunlight well, but this does not pose a problem for floor insulation applications.
Foto: Bosch, Austrotherm