Foam plaster – secrets of the right choice

Selecting the appropriate plaster for your walls can have a significant impact on their longevity and aesthetic appeal. Specifically, foam plaster has special advantages that can improve your area. Because of its portability and ease of use, it is a preferred option for a lot of remodeling projects.

But how can you choose the foam plaster that will best suit your needs when there are so many options available? Having a better understanding of the main variables affecting its performance will enable you to make an informed choice. We’ll go over the key components of foam plaster in this guide, along with advice on how to choose the best kind for your job.

Which foam is suitable for plastering

To avoid pronouncing the lengthy term "polystyrene," it was condensed to "foam." Additionally, write it in three letters: PPS.

These are some of the benefits of this material:

• low thermal conductivity (lower than that of mineral wool);
• small weight;
• resistance to settlement by microorganisms;
• environmental friendliness;
• Small cost.

Among the drawbacks are:

• small mechanical strength;
• low vapor permeability;
• attractiveness for small rodents, birds, OS, bees;
• low heat resistance;
• susceptibility to decay under the influence of UV radiation;
• lack of fire resistance.

The production technology indicates that there are:

• pressed EPS (porous sheets with a smooth surface);
• non-pressed EPS (oval or round granules glued together during sintering).

Although the granules in non-pressed foam are vapor-permeable and delicate, they do not take in water. The plaster will then degrade more quickly if moisture seeps in between the granules. Such an annoyance can be avoided by using pressed EPS.

• more durable;
• has a fairly low thermal conductivity;
• convenient for transportation;
• does not burn;
• cheap;
• durable.

Under plaster, there are two distinct types of insulation: PSB-S-15 and PSB-S-25.

Is it possible to plaster foam and why is it done

Foam is a commonly used insulator. But over time, the structure starts to deteriorate because of ongoing changes in the environment’s temperature and humidity as well as UV radiation. Plaster layers are an easy way to protect against these factors. The most effective way to insulate a building’s walls from the outside is to finish the facade with plaster and foam plastic to safeguard the delicate material.

• a reinforced plaster layer protects the fragile material from mechanical impacts;
• blocks access to sunlight;
• blocks access to moisture;
• increases fire safety, since the plaster coating does not ignite;
• forms a barrier for insects and rodents;
• the resulting layering absorbs noise better and prevents heat from escaping.

Naturally, different plaster mixtures handle this task in different ways. You must select the ideal combination.

What to plaster foam plastic with

Plaster is selected with compositions in mind, taking into account the tasks that plastering can accomplish:

• durable;
• sticky (highly adhesive);
• durable;
• for outdoor work or universal, if external finishing is performed (if insulation is performed indoors, any types are suitable, primarily for indoor work).

Admixtures that promote adhesion with EPS are included in plaster for polystyrene foam, which are specifically designed compositions for coating polystyrene foam materials, such as Ceresit, Ekomix, and Stolit. Different kinds of mixtures are made to do particular tasks:

• for gluing polystyrene foam sheets to the base;
• for protective plastering of EPS sheets;
• universal.

It is preferable to purchase mixes from a single manufacturer. Selecting universal ones is better since they can be applied to any level of finishing work.

Even though they are less expensive, basic plaster compositions with a regular cement foundation are not elastic and are prone to cracking. A house requires long-lasting monolithic coatings for insulation. Ordinary compositions on a synthetic or mineral base are also used in addition to special ones.

Base-specific plaster mixtures are:

• mineral (quite durable, non-flammable, resistant to UV, vapor-permeable, environmentally friendly and cheap compositions based on gypsum, clay, lime, cement);
• acrylic (strong compositions based on acrylic resins, more expensive, less resistant to fire, water-repellent, with a rich color, easily fade in the sun, do not give shrinkage cracks);
• silicone (the most expensive, durable, very elastic, vapor-permeable, resistant to UV, the most durable).

Features of plastering on polystyrene foam

We have already become acquainted with the initial characteristic, which is the presence of unique combinations. Plastering polystyrene foam constitutes the second feature. Reinforcing mesh is utilized in this work. Without it, it is unlikely that the soft EPS coating will have adequate mechanical strength.

The lack of primer on the insulating boards’ surface represents the third "oddity." Plastering over polystyrene foam is an easy task that yields good results. The supplies are affordable and simple to use.

Plastering the facade and internal thermal insulation involves subtleties as well.

On the facade

The development of buildings with cladding composed of various materials began with the introduction of foam plastic.

The most effective technique is known as "wet facade"; it involves building a multi-layered "pie" where the components of each layer serve a specific purpose:

• facade primer under plaster;
• adhesive plaster mass;
• sheet insulation layer;
• plaster (adhesive) mortar;
• reinforcing mesh;
• leveling plaster layer;
• primer layer;
• finishing coating.

Foam plastic external cladding is the most sensible and appropriate course of action in this situation because

1. Dew point (the place where condensation forms) is removed from the premises, being placed inside the sheet insulation, where there is nothing for condensation to form from.
2. In this case, the room also does not lose its volume.
3. Heat accumulation occurs, the premises cool down much more slowly.

Foam sheets, however, may not always be able to be positioned beneath the facade’s plaster.

Inside the premises

Within the building, walls are plastered over foam plastic and insulated if:

• the wall is not accessible from the outside, for example, there are other buildings nearby, or this is insulation and plastering of a balcony (loggia) located at a great height;
• the building is recognized as a historical monument;
• it is prohibited by the rules for the design of houses in the center of the settlement.

Furthermore, if it is not possible to insulate the slopes of the apartment windows from the outside, foam plastic may be required inside the house to insulate the entrance door.

The preparatory work for insulating interior walls is done in the same manner as it is for traditional plastering. Next, in the same manner as on the facade, the foam plastic is adhered to, the mesh is fastened, and plastered. The finishing step may make a difference in this case; if the walls are painted or have wallpaper glued to them, a very smooth surface is needed. After applying a layer of leveling plaster to the EPS, it is puttied and allowed to dry.

It’s important to take into account aspects like foam plaster’s compatibility with existing surfaces, ease of application, and thermal insulation qualities when selecting it for your walls. The correct foam plaster guarantees a smooth finish and long-lasting durability in addition to improving energy efficiency and lowering noise. You can make an informed decision that satisfies your practical requirements and aesthetic preferences by paying attention to these important factors.

Plastering technology

Now is the time to explain the plastering of polystyrene foam. Plastering work is done at temperatures no higher than +30 °C and no lower than +5 °C, and humidity levels up to 60% due to the hardening conditions needed for plaster compositions. When plastering facades, dry, windless weather is preferred.

The plastered surface is protected from the elements by a canopy. Sockets and switches on plastered walls should be de-energized when working inside. Fans and heaters cannot be used to dry a plastered wall.

Workplace safety gear is utilized.

1. Make measurements, calculate the need for materials (safety factor – 1.2).
2. Purchase materials: primer, plaster mix, reinforcing elements.
3. Prepare tools, devices.
4. Prepare the surface.
5. Prepare the solution.
6. Install the foam.
7. Apply the plaster (adhesive) composition, attach the reinforcing elements.
8. Apply the leveling plaster layer.
9. Rub down.
10. Putty.
11. Prepare the surface for finishing.
12. Perform the finishing with decorative compositions.
13. Paint.

It is recommended that a novice learn how to use a spatula with both hands. In this instance, you can continue working without stopping to rest your hand when it grows tired. Hold the spatula at an angle against the wall and apply the solution without applying too much pressure. The pressure affects the mixture layer’s thickness. Using a narrow spatula, apply the solution to the center of the work surface. Additionally, it is employed to remove any leftover mixture or residue from the wall using the wide spatula.

The working surfaces of the spatula and trowel should be routinely cleaned with a damp cloth to remove any leftover plaster mixture when using decorative plasters. This stops captured lumps from forming and the striped smear that results from them. Throwing extra mortar that was removed from the wall into many decorative compositions causes the plaster mixture to crystallize more quickly in the excess areas. If there is extra mixture, it is either thrown away or immediately applied to the wall.

Tools and materials for work

You ought to get ready beforehand:

• short-haired roller (needed for priming);
• construction mixer;
• spatulas with a metal plate;
• trowel or trowel;
• plastic float with attached sandpaper;
• plastic corners with reinforcing mesh;
• notched trowel;
• scissors for cutting the mesh;
• level;
• containers for the solution and water;
• brush;
• plaster mixture (or several types);
• primer;
• fiberglass mesh;
• masking tape.

Plastering supplies are bought in bulk to complete the project (plus a contingency). Purchasing goods from a single company is essential, ideally from a single batch (decorative color compositions require this in particular).

Using a trowel and spatula with rounded edges is preferable. This is particularly crucial when using ornamental plasters.

Preparing the mixture

Usually, the manufacturer includes a thorough description of the solution preparation procedure on the product packaging. Prior to application, the solution is made from the dry mixture.

• all the powder that is in the package is poured into a container with cold water (so that all the mixtures have the same content of components);
• mix the mass with a mixer until a homogeneous dough is formed;
• cover, leave to infuse for 5-15 minutes (after this, neither liquid nor dry substances can be added);
• mix again.

To lift the heavy particles that have settled, the completed mixture needs to be mixed again before being plastered onto the foam plastic.

You can switch the mode by rotating the mixer nozzle in a different direction if spray gets scattered inside the container while mixing the solution. After that, the mixture will be threw back into the container’s center.

Preparation of the base

A crucial phase. The quality of the work done determines the evenness and longevity of the plaster "shell."

The wall is prepped as normal before the insulation sheets are adhered to:

• remove the unusable old coating, knock down large protrusions;
• "heal" chips and cracks;
• clean the base from stains of various origins (wash with water, dry, treat with special agents);
• remove dust from the surface, insulate the remaining metal objects with oil paint;
• install the base profile according to the level;
• mount the foam sheets (on glue with dowel fastening).

The steps involved in making the foam base:

• check the evenness of the entire surface (the joining EPS sheets should be at the same level), running a rule along the wall;
• cut off the protrusions carefully, clean the joints with sandpaper;
• Remove dirt, dust from the surface;
• to increase adhesion, the top of the foam is rolled with a needle roller (the solution will penetrate into the holes formed during plastering).

A common question among novices is whether priming the foam is required before plastering. A primer is not necessary if plastering is done using Knauf company mixtures or special EPS mixtures.

However, a foam primer won’t be unnecessary in situations where mechanical loads can be raised (at a person’s maximum growth). Concrete contact or Ceresit can be used to cover the walls themselves. Primering is applied to the insulated wall following plastering (below finishing).

Closing the seams

In order to avoid the development of cold bridges, mounting foam needs to be inserted into the spaces created by the EPS sheets. The mounting foam in the joints is cut off if it extends above the EPS (the seams need to be filled all the way). Large seams are filled with foam strips that are set on foam and have the desired width.

Selection and fastening of reinforcing mesh

The reinforcing mesh ensures the strength and longevity of the plaster shell. In a strict sense, the purpose of the reinforcing mesh is to make the plaster shell stronger physically. Furthermore, the precise location of potential mechanical impacts. This is the portion of the wall that is 1.5–2 meters above the floor (indoors) or the ground (on the facade). Using the reinforcing mesh above this is unreasonable since it is a needless waste of time, money, and effort.

The plaster has the ability to adhere firmly, shielding the EPS from UV rays and avian pecking. However, the mesh is essential in a problem area where human activity can cause damage to the plaster layer.

Here, a regular serpyanka is inappropriate. Additionally, metal meshes are not used because their rigidity makes it impossible to align them, increasing the plaster layer’s thickness. Depending on the thread thickness and cell size, different densities of fiberglass mesh are used for reinforcement.

All EPS fastening dowels with caps, or "parachutes," are sunk so that the foam surface is free of protrusions prior to mesh installation. The recesses are sealed with adhesive mortar once they have sunk. Another small detail is that a line is drawn on the wall to indicate the height at which mesh reinforcement will be installed before any work is done. To preserve the adhesive mixture, this is done.

The first step in reinforcing a building is to install mesh-perforated corners on its corners. Complexly geometric areas are also reinforced.

1. Prepare the corners (cut to length).
2. Prepare the mortar.
3. Using a spatula or trowel, apply a continuous strip of mortar on both sides of the corner (do not level it). Apply the corner, slightly press down, check verticality with a level. Press the corner, aligning it, into the solution, smooth the mesh on its sides with a spatula (downward and from the corner – to the sides). Ensure that the corner and the adjacent mesh are evenly embedded in the mortar (add the mortar where necessary), remove excess plaster mixture.
4. Having processed the corners, they begin reinforcing the slopes – measure and cut the corners to the required size. If the width of the slopes is correct, reinforce as described above. Otherwise, the corners are applied separately (similar to what is described for the mortar with verticality verification), and the mesh is cut into a strip, 1-1.5 cm narrower than the slope. “Glue” onto the mortar, not reaching 5-7 mm to the corner edge. Smooth the strip of mesh along, then from the center.
5. Flat sections of the wall are reinforced last. Since it is difficult to glue and level large sheets, the mesh is cut into strips one to one and a half meters long. It is easier for beginners to work with small sheets, then they have time to apply and smooth before the mortar dries grid. If you act slowly, the solution will dry out, it will have to be removed and a new one applied. A continuous strip of mortar is applied to the wall, starting from the corner (from the drawn line downwards). The dimensions of the strip are the same as that of the mesh fabric. Plaster layer thickness ~ 2-3 mm. A grid is applied to the solution, guided by the line drawn on the PPS and the vertical angle.

Attaching the subsequent overlapping mesh layer

The mesh must be positioned precisely so that its joints do not rest on the PPS seams.

Sections of the mesh that are not recessed or under which there is no solution may not be left in place.

Grouting the surface

Allow the layer to dry for one day after attaching the mesh. Then the surface is rubbed, but not in the same manner as on a barely set layer following the application of leveling plaster. Wet the wall? Not necessary. Sanding down the sharp protrusions is all that is necessary to prevent them from getting in the way of further finishing.

Use a grater with sandpaper attached for this purpose.

The grain size is chosen based on the kind of coating that will be applied later:

• for decorative structural plaster – sandpaper with a large grain;
• for painting, wallpaper and thin-layer plaster coating – fine-grained.

The float is set flat against the wall, lightly pressed, and then moved in a circle while applying constant pressure, never remaining still for an extended period of time. The wall is cleaned of dust once the entire surface has been grouted.

Finishing leveling

Thicker solution is mixed for this operation. Using a wide spatula, evenly apply a layer to the wall up to 3 mm thick. Following application, the layer is dried and rubbed once more. Dust is then cleared away after that.

Preparation before applying the decorative layer

When using a roller is not convenient, apply the primer with a brush instead. Primers can be applied in one or two layers. This is dependent upon how severe the weather is. A minimum of one day is spent drying each layer of primer. The mixture for plastering and the material of the finishing coating are taken into consideration when choosing the primer composition.

Paint compositions that have the potential to destroy foam cannot be used for finishing such a thin layer of plaster.

The following ingredients should not be included in paint compositions:

• benzene;
• toluene;
• drying oil;
• acetone;
• xylene;
• coal tar or polyester resins;
• gasoline or kerosene.

Application of decorative plaster

The directions should be followed when preparing the decorative plaster solution. It is applied thinly using a trowel or wide spatula. Typically, the diameter of the filler grains and the plaster layer thickness are the same. Since foam plastic wall cladding lacks the necessary strength, it is not advised to use heavy compositions like stone chips.

After it has been freshly applied, the decorative mixture is processed as desired.

Use figured rollers, readily available materials, such as a brush, crumpled plastic bags, etc., or plastering tools (using specific techniques) to create a decorative effect.

Fur coats, travertine, ripped stone, and bark beetle plaster are common finishing techniques for facades. Read the articles under the "Decorative plaster" section for comprehensive instructions on how to achieve different effects.

For illustration, consider how the "bark beetle" décor was done.

Special compositions containing a specific fraction of filler are required for this pattern. The key to the process is rolling filler granules into the set solution to create figured grooves that resemble bark beetle passageways. Using a trowel, apply the mixture in a layer the thickness of which matches the fraction of large granules. This is 2.5–3.5 mm for the facade and less for the rooms (the manufacturer specifies the size). Allow the layer to dry for five to ten minutes after applying it.

A plastic float is placed on the layer and moved in the desired direction as soon as the hand stops adhering to its surface. Grain filler that has been slightly compressed and rolled over the layer using a float creates grooves.

Different patterns can be produced by the rectilinear or (wobbling) direction of the float movement.

The solution is allowed time for the pebbles to fix in the mixture’s body after the entire surface has been uniformly covered in a pattern. A trowel is used for smoothing after thirty minutes. Sharp protrusions are smoothed out in this instance. The layer is painted in one or two colors (typically for facades) once it has dried.

Rooms with decorative plasters are also coated in wax or varnish. Generally speaking, only vibrant compositions are utilized outside. These ought to be exterior paints. They create a strong film because they are more resilient to UV rays and temperature changes.

Selecting ornamental effects for foam plastic finishing is a more sensible choice because they are easily repairable in the event of damage. This number does not include bark beetles.

The decorative plaster finish requires little upkeep. The majority of compositions can be washed, even with detergent.

Plastering of doorways and slopes

The application of foam plastic slopes with plastering will provide the best insulation for the apertures created between window or door frames and the facade after the frames have been replaced. The mounting foam can be allowed to dry completely before creating slopes.

The work is similar to hanging drywall in terms of simplicity. EPS sheets are used to create blanks, which are then glued to the wall around the frame’s perimeter (foam plastic must also be installed beneath the window sill). Fungus-filled dowels are inserted after the glue has dried. The process of plastering foam plastic is also carried out as previously mentioned (corners are placed on the solution, strips of reinforcing mesh are attached, etc.d.).

Before beginning the foam work, the frames are covered with masking tape to prevent staining.

Aspect	Details
What is Foam Plaster?	Foam plaster is a type of plaster that incorporates foam particles, making it lightweight and easy to apply.
Why Choose Foam Plaster?	It"s great for reducing weight on walls, improving insulation, and speeding up the application process.
Choosing the Right Foam Plaster	Look for a product with good adhesion, suitable density, and appropriate setting time for your needs.
Application Tips	Ensure the surface is clean and dry. Apply with a smooth, even layer and allow it to cure properly.
Common Mistakes	Avoid using too much or too little plaster, and ensure it"s well-mixed for a consistent finish.

Selecting the appropriate foam plaster is essential to attaining optimal outcomes in your wall finishing endeavors. You can make sure the plaster you choose satisfies your practical and aesthetic needs by being aware of the different types and their uses.

Recall to take into account elements like application ease, insulation qualities, and durability. As different products have different advantages, it’s critical to match the plaster to the particular needs of your project and space.

In the end, making an informed decision will improve your walls’ appearance as well as their long-term functionality. To guarantee a successful and fulfilling outcome, take your time in your research and choose the best foam plaster.

Video on the topic

Choosing foam without fooling around How to choose foam

Reinforcement of foam plastic, bark beetle

be careful facade workers! or how not to make a wet facade SFTK

Do not make this mistake when insulating the facade, do not ruin the insulation