Technology of facade plastering on foam: choosing what and how to plaster the insulation

Foam is a popular choice for home insulation because of its superior thermal qualities. But insulation by itself is insufficient; facade plastering provides the necessary finishing touch and protection. Although plastering over foam may seem like a difficult undertaking, done correctly, it can be a durable and successful process.

Selecting the appropriate plaster type and knowing the right methods are essential to guaranteeing that the insulation holds together and producing a long-lasting, visually appealing finish. This post will walk you through the process of choosing the best plaster for foam insulation and show you how to apply it properly step-by-step.

Advantages and disadvantages of foam when insulating a house

Gas makes up the majority of the material in polystyrene. This establishes its primary benefits: light weight and effective thermal insulation. Since foam’s structure reduces sound vibrations, it is also a good sound insulator. Furthermore, the following are some benefits of the material:

• environmental friendliness – complies with environmental standards and does not harm humans and the environment;
• durability — resistant to mold, rot and corrosion;
• light weight — easy to transport, no additional load on the foundation;
• easy to process and install;
• affordable price.

Along with the benefits, there are drawbacks as well:

• Low strength. This is the main reason why the insulation layer is covered with additional material, since under mechanical impact its structure is easily damaged, and it loses its thermal insulation qualities.
• Incompatibility with nitro-based paints and varnishes. These substances can corrode the foamed mass.
• Does not allow air to pass through. Poor vapor permeability does not allow it to be used in interior decoration of residential premises. Without good ventilation, the house turns into a thermos.
• Rodents and insects are partial to polystyrene foam that is not protected by plaster or durable finishing.
• Fire hazard — burns and emits hazardous substances.

Characteristics, scope and price

The material’s density determines its cost. Russia produces the foam plastic grades listed below.

• PSB-S 15. Density 8-13 kg/m3. Insulation of walls, floors, non-load-bearing roofs. Price from 1300 rubles/m3.
• PSB-S 25. Density 15-22 kg/m3. More dense and durable than C 15. Same areas of application. Price from 2100 rubles/m3.
• PSB-S 35. Density 25-30 kg/m3. Durable and inexpensive material. Can already be used for thermal insulation of load-bearing roofs. Price from 3600 rubles/m3.
• PSBS 50 — Density 35-37 kg/m3. High-strength. Has the highest density and strength. Used for insulation of foundations of industrial and residential buildings, load-bearing roofing. Prevents freezing and swelling of the soil. Price from 4700 rubles/m3.

A fire retardant is present in all brands of foam plastic, encouraging self-extinguishing. However, the substance is still classified as highly flammable fire resistance class G4.

Choosing plaster for the facade

The external finishing option you select will determine how long the insulation lasts, so you should consider it carefully. Plaster enables problem-solving:

• Protection from mechanical damage. The fragile foam is easily crumbled and crushed, so it must be protected from blows.
• Waterproofing. Although polystyrene foam absorbs moisture poorly, it still does (up to 2% by volume when fully immersed). However, it takes a very long time to dry. Wet polystyrene foam retains heat much worse. Its strength decreases.
• Sun protection. Ultraviolet rays dry polystyrene foam. Over time, it begins to crumble.
• Improving fire safety. A plaster layer will protect the insulation from fire.

Depending on the final finish, you will need two or three different types of mixtures to finish external walls insulated with polystyrene foam:

1. Adhesive mortar with additions of polymers, sand, and cement. It is utilized to build a base layer with reinforcing mesh and to install insulation sheets on external walls. On top of it, decorative finishing will already be applied. Examples of adhesive mixtures that you can use are Ceresit CT 83, Weber.Therm S100, Unis Teplokley, and Knauf Sevener.

2. Sand-and-cement mortar. It will guard against harm to the foam. It will be covered with the final layer of decorative plaster or facade paint.

With a mixer, you can make this mixture yourself. Depending on the type of cement, the material proportions will vary. For the M400 brand, for instance, four parts of sifted dry sand are used to make one part. For plasticity, surfactants and lime are added. Plastering can be done much more affordably with independent mixing.

There are ready-made CSP mixtures in practically every hardware store. These are a few well-known brands: Volma Aquasloy, Osnovit Startwell PC2, Forman (Forman) No. 61, Knauf Unterputz, etc. Depending on the manufacturer, ready-made mixtures cost between 200 and 300 rubles per 25 kg.

3. Ornamental plaster. There are various binding bases for it, such as silicate, silicone, and acrylic. You can select any decorative arrangement because polystyrene foam has a low vapor permeability and is covered in a layer of cement plaster. Customers only care about preferences and price.

A foam-insulated facade put on your house is a great way to keep it safe and look good at the same time. You can guarantee an eye-catching and long-lasting finish by selecting the appropriate materials and applying them according to the right procedures.

When choosing plaster, take your project’s particular requirements into account. Varying degrees of flexibility, breathability, and weather resistance are provided by different plasters. To get the best results, match the type of foam insulation used and the plaster to your climate.

It is essential to apply and prepare carefully. Cracking and detachment can be prevented by properly priming the foam surface and applying the plaster in even, consistent layers. It will pay off to take your time and do the task correctly if you want a polished facade.

In the end, protecting the exterior of your home and improving its curb appeal can be achieved by spending money on high-quality materials and adhering to tried-and-true plastering techniques. Knowing the science behind facade plastering on foam, whether you’re a do-it-yourself enthusiast or collaborating with experts, will empower you to make wise choices and accomplish long-term success.

The secret to ensuring longevity and adequate insulation when plastering a foam-insulated facade is choosing the appropriate materials and methods. This post will walk you through the process of selecting appropriate plaster varieties and correctly applying them to foam to ensure that your external walls are both aesthetically pleasing and well-protected. These pointers will assist both professionals and do-it-yourself enthusiasts in producing a long-lasting, high-quality finish.

Video on the topic

How to properly warm the house with foam. Errors and nuances

How to make a reinforcing layer on polystyrene foam/Wet facade/Garage repair part 5

SECRETS of the masters in one video! Fiberglass mesh, kerchiefs, swallows, corners, etc…

how I putty a house (reinforcement with mesh) how to putty polystyrene foam