Plaster for polystyrene – features of the material and its use

Although plastering polystyrene surfaces can be challenging, it’s an essential step in producing a smooth, long-lasting finish. Frequently utilized as an insulating material, polystyrene requires a specific kind of plaster that sticks to its surface well without compromising its insulating qualities. You can choose the best plaster for your project by being aware of its special qualities intended for polystyrene.

Not all plasters are made equal when working with polystyrene. The ideal plaster should not only adhere well, but also offer a shield that improves the surface’s toughness and aesthetics. When compared to standard types, this plaster usually has better adhesion qualities and is more flexible.

The main characteristics of plaster for polystyrene, such as its composition, advantages, and application best practices, will be discussed in this article. Understanding these factors will guarantee the success and longevity of your project, regardless of whether you’re a professional or a do-it-yourself enthusiast.

A specialized substance called plaster for polystyrene is used frequently in insulation to safeguard and improve the longevity of polystyrene surfaces. For both interior and outdoor applications, its superior adhesion, flexibility, and resistance to cracking make it the perfect choice. This kind of plaster enhances the insulated area’s overall thermal performance and offers a smooth, visually pleasant finish.

How to plaster polystyrene

Porous structure characterizes polystyrene. It is composed of firmly bound, gas-filled styrene granules that are pressed up against one another.

But as time passes and the material is exposed to outside elements like sunlight, temperature fluctuations, high humidity, and precipitation, these bonds weaken and the material starts to degrade.

Because of its extremely low mechanical strength, you could easily break or crumble the slab with your hands. Plastering the surface creates the protective shell that the material needs.

Apart from regular polystyrene, related materials are frequently employed in construction. For instance, during the production of extruded polystyrene foam, the granules melt and transform into a homogenous material with potent molecular compounds. Alternatively, concrete blocks made of up to 75% polystyrene granules are known as polystyrene concrete.

Plastering walls composed of polystyrene concrete, regular, and extruded polystyrene involves the use of specific compounds and technology intended for these types of surfaces. With specific additives, they can acquire unique properties.

Suggestions. Avoid taking a chance by attempting to make it yourself or using ordinary plaster for this kind of work. Invest in tested materials whose packaging indicates that they can be used on foam plastic and comparable surfaces.

Mineral plasters

White Portland cement, lime hydrate, and mineral fillers are added to create mineral plaster for polystyrene. The emergence of surface cracks and a limited service life (up to ten years) are among its drawbacks.

The substance has a ton of other advantageous qualities.

• Frost resistance – the ability to withstand frequent freeze-thaw cycles without losing strength and other characteristics;
• Resistance to moisture;
• Good vapor permeability, allowing structures to "breathe", maintaining a favorable microclimate in the premises;
• Fire safety, non-flammability;
• High adhesion – the ability to stick to the surface of the base;
• Low price;
• Environmental friendliness – does not contain toxic substances;
• Easy to care for.

Acrylic plasters

Aqueous dispersion of acrylic resins is the basis for the addition of mineral binders, plasticizers, and modifiers to plasters. They are expensive, but they also require a lot of maintenance because the surface absorbs dust and dirt easily and can only be cleaned with detergents.

• Acrylic plaster is easily applied;
• It has high elasticity and stretchability, which prevents cracks;
• It has high resistance to mechanical stress;
• It adheres securely to the base, does not peel off;
• Creates a vapor-permeable coating;
• It lasts 2-3 times longer than mineral plaster.

The described mixtures may vary in composition and application, as the instructions for plastering polystyrene require the installation of a fiberglass mesh reinforcing layer.

The majority of manufacturers make various materials that are used to glue the mesh together and apply a decorative coating. Here, the decorative plaster’s composition is altered to include a solid granular filler, which creates a relief on the surface when applied and grouted.

However, there are also all-purpose mixes that can be used to create a layer that is both decorative and supportive.

Technology of plastering polystyrene surfaces

Plastering polystyrene concrete blocks and walls insulated with foam plastic involves multiple steps, just like finishing any other kind of surface.

Preparation of materials and tools

Determine the area of the surface that needs to be finished before making any material purchases. This is required in order to determine how much plaster, primer, and reinforcing mesh are needed. The packaging of all building mixtures typically includes information on the consumption per square meter, so pay attention to that.

The following details will assist you in making a decision beforehand:

• Depending on the thickness of the layer, you may need 4-6 kg of universal plaster per square meter. Accordingly, when purchasing adhesive and decorative compounds separately, the consumption of each of them will be 2-3 kg.
• The consumption of primer depends on its type. In case of using universal plaster, a regular penetrating primer is suitable, and for finishing with a decorative composition – a primer such as Betonokontakt with a filler of quartz sand.

• Reinforcing mesh is purchased taking into account that each strip is glued with an overlap of at least 10 cm on the previous one.

Suggestions. Purchase the material with a 10%–15% reserve. This is particularly relevant to building mixes, as all finishing should be carried out using the same brand of material. Insufficient plaster can lower the quality of a surface finished with a different composition if you cannot find any on sale. Keep your receipts so you can return an entire package of unused goods to the retailer.

Using the tools, get ready:

• A set of spatulas;
• Paint roller and brush;
• Grater with sandpaper;
• Building level;
• A container for mixing the solution and a drill with a mixer attachment.

Preparing the solution

Using a construction mixer or a drill with a special attachment, the working solution from the dry mixture is prepared in accordance with the instructions on the package, but at low speeds to prevent the formation of air bubbles.

This is a crucial matter. Pay attention to suggestions regarding the limited viability of a solution’s time of use.

After opening the packaging, pre-made acrylic compositions are sufficient for a simple mixing.

The device of the reinforcing layer

We go straight to the polystyrene plastering process. Prior to being glued on a glue or universal composition, a reinforcing mesh is first affixed to its surface in the following order:

• Cut stripes about 30 cm wide for reinforcing external angles and slopes. Bend it in half along the length;
• Apply plaster to the corners with a layer of no more than 3 mm and stick the net, pressing it into the solution and smoothing it in the direction from the corner and down;
• Apply the solution to continuous sections of the wall and roll out a grid on them, also pressing it into a raw mixture so that it completely “drowned” in it;

• Smooth the surface with a wooden or metal float, removing folds and bubbles and achieving squeezing the solution through the mesh cells for its secure fastening;

• Let this layer dry for 24 hours, then sand the surface with a float with sandpaper attached to it.

Applying the finishing layer

Following grouting, a primer is rolled onto the surface, allowed to dry, and then the finishing coat is applied. The procedure is followed as normal: a small spatula is used to remove the solution from the container, and it is then slid onto the wide working spatula’s blade and spread across the wall.

The layer ought to be just 3 mm thick. If ornamental plaster is being used, the filler grain diameter should roughly match the layer thickness.

In addition, the plaster is left to dry for three to four days before being primed and sanded in preparation for painting or other finishing touches.

The material and application technique must be carefully considered when plastering polystyrene surfaces. This kind of plaster is designed specifically to stick to polystyrene, giving the material an eye-catching and long-lasting finish that can improve its insulating qualities. The correct planning and application methods can turn polystyrene into a robust, visually beautiful surface.

It’s important to select the right plaster for polystyrene. It guarantees good adhesion as well as the finish’s durability. Using the right plaster can help prevent problems like peeling or cracking that can occur when using the wrong products. For optimal results, it’s crucial to mix and apply the plaster according to the manufacturer’s instructions.

All things considered, plastering polystyrene is a workable solution for both external and interior uses. Because it blends style and utility, it’s a popular option for a lot of building and remodeling projects. Whether you’re adding decorative finishes or insulating a house, this method provides a dependable means to accomplish your objectives.

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