When it comes to applying a facade to a house, commonly known as external thermal insulation composite systems or ETICS, there are two main options – Styrofoam, also known as EPS boards, or mineral wool. Each solution has its advantages and disadvantages.
Material cost and installation price are also important considerations. In the following paragraphs, we’ll attempt to simplify the process of making this crucial decision. Deciding to insulate your home is already a step in the right direction, regardless of the solution you choose.
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Whether it’s mineral wool or styrofoam, the difference between an insulated and uninsulated house during winter is like going outside in a T-shirt versus a winter coat. Likewise, any facade dramatically reduces heating costs and improves indoor comfort. Of course, nuances exist, and each facade brings specific advantages and disadvantages.
Advantages of Mineral Wool
Mineral wool boasts several advantages over EPS boards or Styrofoam. While the thermal insulation properties of mineral wool are only marginally better, this difference doesn’t significantly impact the quality of the building’s insulation. The significant advantage of mineral wool lies in its superior vapor permeability.
Mineral wool allows walls to “breathe,” whereas Styrofoam cladding creates a hermetic barrier preventing moisture from escaping walls. In numerical terms, this translates to the coefficient of µ, where a lower coefficient indicates easier passage of vapor through the material. For instance, air has a coefficient of µ-1, mineral wool µ-1.2, while Styrofoam has a coefficient of µ-30. These figures illustrate how mineral wool facilitates moisture removal and contributes to the building’s overall health.
However, it’s essential to note that this doesn’t mean homes insulated with Styrofoam will necessarily develop mold, while those insulated with mineral wool won’t. In apartments, kitchens, and bathrooms, major moisture generators, are typically lined with ceramic tiles, reducing moisture transfer through walls. Eventually, moisture exits the building through open windows or air conditioning systems. The vapor permeability property becomes particularly crucial in buildings with higher moisture production, such as restaurant kitchens and professional laundries.
To fully utilize this advantage of mineral wool, it’s necessary to use other materials like adhesives and finishing layers with vapor permeability properties. If an impermeable material is used as the finishing coat, one of mineral wool’s primary advantages is diminished.
Fire Resistance and Sound Insulation
Another significant advantage of mineral wool over Styrofoam EPS boards is its non-combustibility. Mineral wool, derived from natural stone, only begins to melt at temperatures exceeding 1000 degrees Celsius (aprox. 1830 degrees Fahrenheit). Therefore, in the event of a fire, mineral wool cladding won’t contribute to its spread. This characteristic is particularly vital for larger residential buildings and multi-story structures.
Similarly, for this advantage to be fully realized, other materials used in facade construction (adhesives and coatings) must also possess fire resistance certification, falling into the so-called A2 class. Additionally, mineral wool offers better sound insulation due to its structure’s ability to absorb sound, whereas Styrofoam reflects it.
While the majority of noise enters through windows, this difference may not be noticeable in practice. However, in specific cases and for buildings with specific purposes, this difference can be significant. Moreover, mineral wool may be the only viable solution for insulating curved walls, for which rigid EPS boards are unsuitable.
Cost Considerations and Ease of Installation
The question arises, then, why most private homes and smaller residential buildings are insulated with EPS, or Styrofoam. Lower cost is indeed a significant reason, but not the only one. When insulating a large area and considering the slight difference in material cost multiplied by the number of square meters, it eventually makes a noticeable difference.
Moreover, EPS boards are much quicker and easier to work with. They are perfectly flat, adhere to the facade without the need for additional anchoring, unlike mineral wool which often requires additional fastening to the wall. In summary, working with Styrofoam is faster, achieving aesthetically pleasing results more easily, making it a more attractive option for tradespeople.
When the lower material cost per square meter and easier installation are combined, it’s clear why most craftsmen offer this option – it makes them more competitive, and in both cases, a well-insulated building is achieved.
Health and Practical Considerations
Unlike mineral wool, which is derived from stone, Styrofoam is a byproduct of oil refining. However, despite its origin, Styrofoam’s composition is not harmful to health. Unlike mineral wool, which withstands high temperatures, Styrofoam retains its properties only up to 80 degrees Celsius (176 degrees Fahrenheit), making it potentially unsuitable for certain applications.
Nevertheless, many builders have found EPS insulation boards in decades-old attic renovations that have not lost their physical and insulating properties. Of course, in specific situations, such as insulating chimneys, Styrofoam is not a suitable choice.
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