Stone Wool or Glass Wool? What are the advantages of stone wool compared to Styrofoam? Why is vapor-permeable foil important? How does the price of materials affect insulation quality? Does the rule “more is better” apply to insulation?
Investing in building insulation continues to “pay off” for many years, supplementing the household budget through lower heating and cooling costs. Insulation can be implemented in many ways, varying in both cost and quality. Below are answers to some of the most common questions:
Is stone wool better than Styrofoam?
Both materials have their advantages and disadvantages. Stone wool has several key benefits over EPS panels, also known as Styrofoam. The thermal insulation properties of stone wool are slightly better, but this does not significantly impact the quality of insulation in real conditions.
The first significant advantage of stone wool is its vastly superior vapor permeability. Stone wool allows walls to “breathe,” while Styrofoam creates a hermetic barrier that prevents moisture from escaping the walls.
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Another important advantage of stone wool over EPS panels is its non-combustibility. Stone wool is made from natural stone and only begins to melt at temperatures above 1800 degrees Fahrenheit (aprox. 1000 degrees Celsius).
Thus, in the event of a fire, a facade made of stone wool will not contribute to the spread of the fire. Another advantage of stone wool, though perhaps less obvious in practice, is better sound insulation.
The lower price of Styrofoam is one of its significant advantages, but not the only one. Another is that EPS panels are much quicker and easier to work with. They are perfectly flat, adhere to the facade easily, and it is easier to achieve a smooth surface.
In short, working with Styrofoam is faster and achieves excellent aesthetic results more easily, which is why more craftsmen offer this service.
When you add up the lower material cost and easier installation, it becomes clear that most craftsmen will offer this option to be more competitive, and in both cases, you get a well-insulated building.
Does the rule “more is better” apply to insulation?
In short, yes. The thicker the insulation, the better the building will be insulated. However, this does not mean that there are no standards and that it is not worth exceeding them, as the quality of insulation will only improve slightly, while the installation cost will be too high.
When and why is internal wall insulation used?
Internal wall insulation is only used when external insulation is not feasible. The best way to insulate a building is by applying insulation to the exterior walls. There must always be a specific reason for internal insulation, and there are many. For example, if the apartment is on the 15th floor of a building, or if you live in a smaller building but not all residents agree to insulate the entire building.
Additionally, internal wall insulation is the only solution if approval for external insulation cannot be obtained, such as for buildings of special significance or in certain locations.
Is stone wool a good choice for sound insulation?
One of the advantages of stone and glass wool over EPS panels, or Styrofoam, is their ability to provide sound insulation. Lower density stone and glass wool are used for sound insulation as they absorb sound better.
However, experts agree that installing a sound-insulating layer or incorporating sound insulation into partition walls requires highly skilled craftsmen, as a large amount of sound-insulating material will be ineffective if other mistakes allow sound transmission.
Do thick walls need thermal insulation?
A common comment is that old buildings with thick walls do not need additional sound insulation. Experts rightly disagree with this assessment. The thickness of the wall is not as important as the material it is made of.
A well-constructed building with thinner walls made of appropriate materials will be much more energy-efficient than an old house with thick walls that are efficient heat conductors, constantly “sucking” heat from the house. Old buildings and thick walls are only an advantage during the summer months, as they resist heat waves longer.
Can stone wool be applied over Styrofoam insulation?
Yes, if the building is insulated with Styrofoam, for example, two inch thick, it is possible to improve thermal insulation by adding stone wool. The only requirement is that the building is in good condition, meaning that the existing Styrofoam contact facade is in good condition.
This means there is no peeling, chipping of the facade, or damage to the mesh. If the facade is in good condition, a facade installer can determine the type of adhesive needed to connect the new facade layer with the existing one, and longer fasteners must be used to secure the new facade layer to the underlying walls.
If the existing Styrofoam facade is damaged, it is more cost-effective to remove it before installing stone wool.
Is vapor-permeable foil mandatory and why?
The importance of vapor-permeable foil is often overlooked. It is crucial, and improper installation or omission can nullify the effect of even the thickest layer of quality insulation. Another common mistake is using standard PVC foil instead of vapor-permeable foil.
Vapor-permeable foil is not the same as standard PVC foil. High-quality membranes allow vapor to pass through, while blocking water, whereas standard PVC foil blocks both water and vapor. This is a fundamental and significant difference.
In inhabited attics and other living spaces, a large amount of moisture is produced. When warm air rich in moisture from the living space finds its way to the interior of the roof structure and reaches colder zones, it cools and releases moisture, causing condensation, or water droplets.
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Therefore, during attic adaptation, insulation material is first installed, followed by foil, and finally, plasterboard or other final covering. The foil acts as a membrane between the moist air in the living space and the insulation itself. It is also crucial to install the vapor-permeable foil correctly, with the printed side facing the interior space.
What is the difference between stone wool and glass wool?
Due to different production technologies and materials, stone wool and glass wool have different mechanical and insulation properties. Stone wool has better mechanical properties due to its denser structure. Because of its greater firmness, stone wool is produced and sold in panels of various thicknesses.
On the other hand, glass wool is less dense and can be compressed, making it easier to transport. It is packaged and sold in rolls.
This difference in mechanical characteristics leads to different applications. Glass wool, being softer, is suitable for various fills where significant mechanical properties are not required, such as sloped roofs and partition walls.
Glass wool adapts better to different shapes, filling spaces more effectively and preventing thermal and sound bridges. Stone wool, with its better mechanical properties, is used for flat roof insulation and external wall insulation, making it a better choice for external facades.