Publish on Voirvert.ca | Voir autrement Expanded polystyrene: effective, environmentally friendly insulation
26 Oct, 2020

Designed for the insulation of older buildings, the new EPS injection technology offers more for the environment, with unrivalled benefits for the renovation sector.

What are these microbeads?

These EPS microbeads are the same as those used in the thermoforming of rigid expanded polystyrene insulation panels. These are high-performance insulating materials, widely used in construction, which have their own specific characteristics due to their composition, shape and density. However, the transformation stage into a rigid panel brings about a significant change in the technical properties of these EPS microbeads. Loosely packed one on top of the other, they present truly different, unique and utterly surprising characteristics. These are the very characteristics that inspired the creation of EPS insulation in situ, directly on the building site. Injected into the site with an acrylic binder, they congeal in place to form a high-performance, practical rigid insulator for construction and renovation.

Composed of just 2% plastic, EPS microbeads are water-resistant and almost as light as air. All it takes is a small draught or gap to disperse them. This is why, logically, it was never intended to use them in this way in the construction field, for reasons you can imagine.

Thermoforming EPS microbeads into panels or rigid insulating blocks was the de facto solution, but not for injection molding. Ultralight, round microbeads in a variety of sizes (between 1 and 3 mm) circulate under a jet of air in the smallest nooks and crannies inside walls. They pile up like opaque bread, perfectly covering all the regular and irregular shapes they contain.

The microcellular appearance of the injected product appears watertight, but in reality it is permeable to air and water. When set, microbeads can withstand a compression equivalent to type 1 EPS (for rigid), ensuring long-term dimensional stability.

Energy-efficient performance

When injected, the shape and lightness of the microbeads provide all the fluidity required for perfect wall filling, with no thermal bridging. Inserted into every small gap of 1 to 3 mm, they target leaks, significantly seal off air infiltration and eliminate all air movement in the walls. We could then speak of an assembly of materials forming a sandwich wall. Combined with the high thermal value of EPS, they ensure the performance and energy efficiency of buildings. Another special feature is the atypical shape of the tiny crevices between each microbead, giving the insulation the property of being non-capillary. In other words, it does not absorb water from adjacent building elements.

What’s more, this characteristic makes it highly permeable to water vapor. Knowing that it’s difficult to prevent the migration of moisture from draughts between the inside and outside of the building envelope, it would therefore be appropriate to speak of a hydrophobic insulation that doesn’t encourage its accumulation, but on the contrary improves its migration to evacuate it. This is a useful feature for maintaining the energy performance of insulation at all times, since the accumulation of moisture irreparably reduces the thermal resistance of materials. This is particularly true for older buildings, where a vapour barrier is usually ineffective or completely absent from the structure. In such cases, you’ll be advised to apply vapour-barrier paint, to avoid any need for demolition.

Environmental value

Despite what many people may think, EPS in microbead form offers many environmental benefits. With only 2% material and more, they contribute to reducing greenhouse gas emissions. Mainly because the injection of EPS microbeads makes it possible to incorporate between 25% and 50% recycled material. Post-consumer EPS is recovered mechanically and without chemicals. On the other hand, virgin EPS microbeads in bulk require no further processing. They can be used as they are just a few days after expansion.

What’s more, the injection of these microbeads offers a new solution: the possibility of insulating an existing building without demolition. This thermal improvement preserves the built heritage and produces virtually no waste. This significantly increases the building’s energy efficiency, with far less environmental and financial impact.

Not to mention the fact that this insulation gives off no harmful vapors or dust. It is therefore harmless to health. The microbeads agglomerate during injection, but do not stick to the materials in contact with them, ensuring their fluidity. When deconstructed, they are easy to recover and 100% recyclable.

Considering that every insulating material that goes into the design of a wall assembly is intended to deliver performance, durability, with low ecological impact, the unique characteristics of in-situ injected polystyrene microbeads offer an interesting solution for this purpose.

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