How to plaster polystyrene foam: consider what is better to choose

Although plastering polystyrene foam may appear difficult, it is completely manageable with the appropriate technique. Its smooth surface can make it difficult to apply plaster properly, but its light weight and good thermal qualities make it a popular choice for insulation.

For a finish that is both long-lasting and aesthetically pleasing, selecting the appropriate plaster is essential. There are numerous choices, each with pros and cons of their own. You can choose the ideal one for your project by being aware of these.

This post will discuss the most popular plaster types applied to polystyrene foam and offer helpful application advice. This guide will assist you in achieving a seamless, long-lasting finish whether you’re a do-it-yourself enthusiast or taking on a professional project.

Features of foam plastic for building insulation

Foam plastic is a sustainable material that offers dependable fire safety and efficient thermal insulation. A polymer material that resembles natural compositions and contains microscopic cells that are filled with gas or air is called polystyrene foam.

Because of this structure, polystyrene foam has exceptional thermal insulation qualities, which is why it is so well-liked worldwide. One of the least expensive ways to guarantee adequate thermal insulation is to use the material when building a house.

Foam plastic has the following benefits over other materials:

  • Environmentally friendly and clean, what is regulated by the hygienic conclusions of manufacturers and state standards.
  • Low thermal conductivity. The material is 98% air, and this is the best natural heat insulator.
  • Fire safety. Can stably withstand temperature changes in a wide range, without changing physical and chemical properties. It belongs to plastics, which, when burning, like wood, release water and carbon dioxide. But good quality foam plastic does not support combustion: the fire retardant included in its composition gives the foam plastic the property of self-extinguishing.
  • Good sound insulation, which is ensured by low dynamic rigidity.
  • Resistance to microorganisms. Foam plastic does not release water-soluble substances, does not decompose when it gets into the ground or groundwater, does not have a negative effect on natural resources.

Advice: This type of insulation, which is used in construction, needs to be shielded from chemicals such as alcohol, turpentine, paint thinner, acetone, kerosene, gasoline, and different resins because they can dissolve the foam entirely and damage its cellular structure.

  • Resistance to bacteria and mold.
  • Low weight. Minimal density of foam plastic, has virtually no effect on the foundation of the building and its supporting structures.
  • Low price.
  • Easy to process and easy to install.
  • Durability. Its service life is virtually unlimited.

When using foam plastic to insulate a building,

  • The costs of heating the house during operation are reduced.
  • Useful space is saved.
  • The costs of loading and unloading operations are reduced.
  • The costs of using complex construction mechanisms and tools for processing materials are reduced.
  • The time frame for construction work is reduced, while the building is warm and comfortable.

Among foam plastic’s drawbacks are:

  • Low strength. Any point impact on the surface or other mechanical impact leaves a dent, and sometimes the slab is completely destroyed.
  • The material requires protection from the influence of certain external factors:
  1. ultraviolet rays;
  2. humidity.
  • From an aesthetic point of view, leaving a wall that is covered with only slabs is unacceptable. In this case, external finishing of the house is necessary.

What can be used to plaster polystyrene foam

Plastering is an inexpensive and comparatively easy way to finish polystyrene foam by hand.

Advice: The slabs that are glued together can be covered with the polystyrene foam plaster mixture. A supporting frame is installed before the sheathing’s cells are laid in, and clapboard or other panels are used for the surface’s final cladding.

You can use the following to finish polystyrene foam:

  • Universal facade plaster, resistant to temperature changes and moisture. The use of a reinforcing mesh allows you to achieve maximum adhesion of the coating to the surface of the insulation.

Tip: Use a plastic float with an emery cloth attached to it to improve the adhesion of the foam and finishing material.

  • Mineral mixtures (see. Mineral facade plaster: features of the material). Such compositions are made on the basis of white Portland cements, lime hydrate and fillers. The solutions are very durable, adhere well to many types of surfaces, protect the interior of the room from fungi and other harmful microorganisms.

These arrangements enable the creation of a superb texture and visually appealing walls. Their benefits

  1. low cost;
  2. long service life;
  3. good vapor permeability, which allows the composition to be used on surfaces with low diffusion resistance;
  4. resistance to mold, fungi and other harmful microorganisms;
  5. no effect of sudden temperature changes on materials;
  6. natural origin of the coating, does not pose a danger to humans and the environment;
  7. This type of plaster composition goes well with foam thermal insulation.
  • Acrylic compounds (see. Acrylic plaster for the facade: how to use).

These solutions have a longer service life than foam plastic, but they have the drawback of not allowing steam to pass through, which makes it impossible to create a comfortable microclimate inside of spaces without the assistance of specialized equipment. The material is delivered as a ready-to-use mixture for dispersion in water.

  • Silicone solutions. Made on the basis of liquid glass. The high cost of the material limits its use, but it is indispensable for buildings located in industrial and other areas with increased pollution.

Look for cracks between the slabs before plastering the foam. What and how should be used when plastering polystyrene foam externally? The entire procedure is shown in detail in the video.

Recommendation: Keep in mind that the composition cannot be applied in thick layers, so the surface needs to be made fairly smooth.

How to prepare a solution for plaster

The operating instructions on the composition’s packaging must be carefully followed in order to prepare the plaster for use on foam plastic.

Advice: Bring compositions for plastering foam plastic to the consistency of thick "jelly" before working with them.

You should not use products made by different manufacturers for the same building. Different components in similar materials’ compositions "behave" differently. Their applications also vary.

Some examples of compositions are:

  • Universal.
  • With a limited scope of application.

Preference should be given to the first type of coating.

Plaster Type Advantages
Cement-Based Plaster Durable, resistant to moisture, ideal for exterior surfaces
Acrylic Plaster Flexible, easy to apply, good for both interior and exterior
Mineral Plaster Breathable, eco-friendly, suitable for interior use
Silicone Plaster Highly elastic, weather-resistant, perfect for exterior applications

Adding polystyrene foam to your insulation is a good way to improve its look and longevity. You can achieve a smooth, long-lasting finish that both protects and enhances the appearance of your home by selecting the appropriate materials and applying the right techniques.

Adhesion, flexibility, and weather resistance are important considerations when choosing plaster for polystyrene foam. The plaster will adhere well and endure external stresses over time when a good base coat and an appropriate finishing coat are used.

In the long run, it will be beneficial to invest in the right products and take the time to properly prepare the surface, whether you choose to do the work yourself or hire a professional. Plastered polystyrene foam can offer superior insulation and a neat, appealing appearance for many years to come if done correctly.

The selection of appropriate materials and techniques is crucial for achieving a long-lasting and aesthetically pleasing plastered polystyrene foam finish. This post will walk you through the steps, explaining the best plaster types, their advantages, and effective application techniques. You can guarantee the aesthetic appeal and good protection of your polystyrene foam surfaces by using the right products and applying them according to the instructions.

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Dmitry Stepanov

Professional decorator with 10 years of experience. I know everything about renovating apartments, houses and offices. I will be happy to share my knowledge and experience with you.

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