How to use polystyrene foam to insulate the facade of a house with your own hands? Overview and Material Selection Tips + Video

How to use polystyrene foam to insulate the facade of a house with your own hands? Overview and Material Selection Tips + Video Foam insulation of outer walls is quite a popular practice among those who want to save money on high-quality insulation.

The first thing to do is to figure out what are the features of the foam, for what purposes it is best suited, and what to expect after a certain period of operation.

Polyfoam is primarily attractive for its cheapness, because for little money you can sheathe a house completely. In addition, the lightness of the material makes it possible to work independently, without anyone's help.

Any business has its own nuances, and the process of insulating a house with foam plastic also has its own characteristics.

Thermal insulation of residential buildings

How to insulate

Various materials are used for thermal insulation of residential buildings, among which the most popular use:

  • Polyurethane foam;
  • Expanded polystyrene sheet;
  • Glass fiber, mineral wool;
  • Fill-in thermal insulation;
  • Styrofoam.

Each of these materials has its own advantages and disadvantages. Minvata has a good percentage of heat conductivity, does not lend itself to putrefactive processes, does not deteriorate under the sun's rays, and most importantly, it does not burn. Backfill insulation is very cheap and does not need any preparatory work before use. Expanded polystyrene has an excellent level of heat conductivity, which makes it possible to make installation in thin layers.

In addition, the material does not absorb moisture, water vapor or condensation.

Characteristics of polystyrene

If you dig deeper and understand the intricacies of installing facade foam, you can come to the conclusion that this material is the best suitable for thermal insulation of building walls in terms of economic benefits and technological characteristics.

  • How to use polystyrene foam to insulate the facade of a house with your own hands? Overview and Material Selection Tips + Video The thermal conductivity of the foam is higher than that of extruded polystyrene foam, and the cost is lower.
  • Polyfoam does not absorb moisture, as mineral wool does.
  • Due to the lightness of the sheets, the material does not exert additional stress on the building and foundation, respectively.

  • If we compare foam with expanded clay or glass granulate, then the first material is much easier to work with.
  • Foam insulation can be faced with any materials for decorative and protective purposes. To provide protection from fire, the insulation is plastered. This is one of the most reliable and least expensive methods.

At first glance, it may seem that all foam is the same and does not differ.

But, in fact, not all of its types are suitable for wall insulation. For insulation work, foam plastic with PTT and PSB marking is used. The materials have increased density and are coated with a protective film. The numbers on the packaging of the material indicate the density of the foam for insulation of the facade.

Polyfoam with a density of 10 - 20 kg / m 3 is used for the purpose of warming chambers in refrigerators, change houses, windows, balconies, various tanks, drainpipes.

Despite the apparent fragility, the sheets have good thermal insulation performance. They can be used for facade insulation with foam plastic under siding. In order to apply plaster on top, this material is not suitable due to its fragility. If the material is made with a high level of porosity, then there may be cases of moisture absorption under the layer of plaster, and at subzero temperatures, the same layer can fall off with the facing material for a couple.

Styrofoam with a density level marking of 25 kg / m 3 is most suitable for insulating the outer walls of the house.

These are already more durable sheets that are able to withstand the applied layer of plaster, and at the same time provide good thermal insulation of the walls.


On labels with foam markings there are letters that indicate the design features of the sheets.

  • А - ordinary sheets of material without features. The most popular foam due to its low cost. It is used to insulate any surfaces.

  • B - sheets of polystyrene with a cut edge, which makes it possible to insulate the house without the so-called cold bridges.
  • P - foam sheets, which have a melted surface due to cutting with a hot knife in the form of a wire.
  • Ф - foam of a certain style, having a non-standard shape.
  • N - sheets of foam, which are used to insulate walls from the outside.

How to use polystyrene foam to insulate the facade of a house with your own hands? Overview and Material Selection Tips + Video The use of materials with a more complex design has its undeniable advantages, but this does not mean that from just foam with marking A, you cannot build a reliable insulation wall covering.

Note. Thick foam is highly workable. You can cut edges from it, as well as make a melt with your own hands.

As for rumors that the foam produces toxic substances and styrene, experts say that this factor primarily depends on the quality of the product. Chinese-made material is not recommended to be stored in residential premises.

High quality foam can be used to create stucco, various sculptures, floor and ceiling insulation without the use of facing materials. In the production of foam, processing with fire retardants is used in order to increase the material's fire safety class. In the process of insulating the facade of the house with foam plastic with your own hands, you can skip the plastering work.

The disadvantages of foam as a heater for walls include a low level of vapor permeability. If we use foam plastic with a thickness of 35 - 50 mm at a density of 15 - 20 kg / m 3 , the problem will not be so significant.

Simple material marked A, have vapor permeability indicators only 10-15% lower than that of ordinary bricks. It is worth considering that such foam is still better than expanded polystyrene, which does not let steam through at all. Thus, creating an insulating layer, there is no need to make a ventilation gap between the walls and the material. This material can be glued simply to the surface of the walls like tiles.

In harsh climatic conditions, facade foam plastic 100 mm is used, and the technology of its installation in such cases is different.

The polyfoam is mounted on a pre-assembled frame made of a metal profile, which in turn is attached to dowels with caps. It is advisable to choose foam with a profiled surface from the inside. This allows for better vapor permeability.

Insulation of the facade


The technology of insulation of the facade with foam plastic under plaster resembles laying tiles for facing facades and walls premises. The difference lies in the use of foam boards.

Before starting the main work, it is necessary to perform a number of preparatory steps:

  • Remove the cladding materials from the facade;
  • Clean the surface of the walls with mechanical , and then manual grinding in order to clean up irregularities and defects;
  • Voids must be sealed with cement and sanded;
  • Treat the cleaned surface with a primer that can penetrate into deep layers.

Note. Preparatory work before wall insulation with foam plastic must be carried out at above-zero temperatures, in calm and dry weather.

Stages of facade insulation with foam plastic

Glue. Which one to choose?

For installation of insulation on the walls, use a special facade adhesive for foam plastic.

The most popular material is Ceresit CT85 or any other identical in composition. To knead the glue, the mixture is poured into a container with a certain volume of water and mixed with a construction mixer and left to infuse for 10-15 minutes. While the glue is pulling on with moisture, mark along the edge of the wall below. For this purpose, jute or thick cord is suitable.

How to use polystyrene foam to insulate the facade of a house with your own hands? Overview and Material Selection Tips + Video Along the jute insert bars for support, which will help keep the first row of foam from falling.

Instead of a marking cord, a starting profile is sometimes used when insulating the facade with foam, for example, the one that is used when cladding walls with siding. According to the markings, it is necessary to select the required number of foam plates for the first row.

What is an edge overlap?

If you plan to insulate your house for a long period of operation, it is recommended to make an edge overlap. This makes it possible to reduce the negative effect of significant gaps at the joints. The application of glue to the foam is done with a movement that resembles the creation of a large blob measuring 6 - 7 cm.

Along the edges of the foam, spread glue in a strip 5 - 7 mm thick.

In the presence of protruding reinforcement or defects on the surface that rise above the wall at a height of 1 cm, a larger volume of glue is applied to the wall itself, and only along the edges of the insulation. The Styrofoam sheet must be applied to the wall and lightly pressed down so that the adhesive comes out at the edges of the material. It is important to ensure that the installation of the facade foam is carried out smoothly. In the case of uneven walls, the foam is trimmed in the right places, otherwise it will have to be leveled with kilograms of plaster.

What is a mushroom dowel?

If fastening with glue is suitable for lightweight foam sheets, then a mushroom dowel is used for sheets with a large weight. Umbrella dowels are ideal for this purpose as they allow the foam to be securely attached to the wall surface. The fasteners are evenly distributed over the entire sheet. One cap allows you to hold the edges of adjacent sheets together.

Foam insulation of outer walls in two layers

This method is used in practice in cases where the laying of thin sheets of foam is not enough.

This usually happens in regions with a harsh climate, where it is desirable to insulate houses with 100 mm facade foam. Since thick material is expensive and much more difficult to work with, insulation is often laid in two layers. The initial foam sublayer is mounted with glue, then the joints and gaps are sealed, and after several days, reinforced with mushroom dowels.

For laying the second layer, glue is applied to the foam sheets, stretched over all surfaces with a spatula with teeth and mounted on the first layer of insulation. In order for the installation to go well, it is necessary to ensure that the first layer is laid evenly.

Application of leveling plaster to foam plastic

How to use polystyrene foam to insulate the facade of a house with your own hands? Overview and Material Selection Tips + Video Before proceeding with the finishing of the facade of the house after insulation with foam plastic, plastic corners with a mesh are attached to the slopes and corners. The corner must be aligned along the vertical edges of the mesh, then the plaster must be stretched and fixed.

Next comes the turn of the reinforcing mesh. To do this, use a plaster mesh suitable for outdoor use, having a density of at least 140 g / m 2 . The canvas must be rolled vertically and secured with a construction stapler along the upper edge of the foam.

The edges of the joining canvases are laid with an overlap of 5 - 7 cm, the joints are fixed with plaster. After the canvases are leveled, you can start applying the plaster. For this purpose, plastic and dense mixtures are used.

A thin layer of glue is placed on the mesh surface and spread with a spatula. The layer thickness should be at the level of 2-3 mm.

When the plaster is dry, it must be trowelled to give a perfectly flat surface. To do this, use an emery cloth or sander. After that, proceed to the application of a leveling layer of plaster with a thickness of 3 - 4 mm.

Decorative plaster can be applied to a completely dried leveling layer. Before doing this, it is necessary to treat the surface with a primer.

In the case of wall cladding with decorative panels, Ceresit St16 is used, which contains needle sand. If the walls will be painted - Ceresit CT17.