How to work with expanded polystyrene when insulating a building wall from the inside, its main advantages and negative properties, how to prepare a wall for thermal insulation, stages of work. Insulation of walls from the inside with expanded polystyrene is one of the simplest and at the same time reliable ways of keeping warm in residential and non-residential premises. Every year the price of the thermal insulation service increases, but for many categories of our fellow citizens it is still in demand. Among the huge variety of insulation materials on the market, expanded polystyrene does not lose its relevance, because each of us is familiar with it. We will analyze what other advantages it has, and also consider the features of its use for internal wall insulation.
Features of thermal insulation of walls from the inside with expanded polystyrene
The main problem in carrying out internal work can be called the phenomenon of increased freezing of an insulated wall. This is due to the fact that the dew point, which is the center of the accumulation of condensate, shifts to the inner edge of the structure, and sometimes even reaches the surface. The spread of condensation leads to the destruction of not only the finishing layer, but also the wall itself. The result is high heat loss and high room humidity.
Traditional expanded polystyrene is produced by manufacturers in the form of even, smooth and dense sheets, the dimensions of which can be either 100 by 100, or 100 by 50 cm.
The installation of this material requires the utmost attention. But you still can't get rid of the problem of joints. The main solution should be the most tight fit, and the ends of the adjacent sheets are coated with a sealant for a better connection with each other.
The master applies a mortar to fix this material in a special way. Traditional cakes, which are suitable for outdoor use, are not suitable for internal thermal insulation. They will lead to the appearance of gaps, in which subsequently condensation will accumulate. Therefore, when it is necessary to insulate the walls from the inside with expanded polystyrene, apply the adhesive mixture to the entire sheet and achieve its uniform distribution. This will ensure that it adheres securely to the wall surface.
In order to economically and correctly distribute the glue solution, we will use a special needle-type paint roller. It pierces the surface of the material, as it were, which gives a more reliable connection. It is for this mounting method that it is important to ideally prepare a working wall plane. Conventional cement mortar is not very suitable for these purposes.
It is advisable to acquire mixtures that form a moisture-protective layer. The same applies to anchoring - instead of them, you should prefer T-shaped profiles, which will be fixed not only to the floor, but also to the ceiling. This is necessary, especially in cases where mesh reinforcement will be applied over the insulation.
Advantages and disadvantages of wall insulation with expanded polystyrene
Among the many advantages that wall insulation has from the inside with expanded polystyrene, we will dwell on the following:
- The cheapness of the material, which makes it accessible to a wide range of users.
- According to its characteristics, it is not inferior to expensive and fashionable heaters.
- Polyfoam has excellent thermal insulation properties.
- It is very simple and affordable in terms of installation.
- The material is lightweight.
- It is easy to dock it when insulating, simply removing the excess with a knife.
- It is characterized by durability.
- Stable at a comfortable temperature.
And that is not all. Customers may ask whether classic foam is suitable for arranging an insulating layer. Of course, yes, but expanded polystyrene extruded to insulate walls from the inside outperforms traditional polystyrene in its qualities: it has a higher strength, is easy to install, since it does not crumble and can be cut with an ordinary sharp knife, it has a lower water absorption, which guarantees it a long and effective operation.
Among the negative qualities of such a heater, experts note the following:
- Expanded polystyrene can be called, without exaggeration, a rather fragile material.
- When insulating, they need to provide additional ventilation in the room.
- The material should be protected from direct sunlight, which causes it to disintegrate.
- It is a combustible material and, in addition, emits toxic substances when ignited.
Despite the fact that, according to the manufacturers, the operational period of expanded polystyrene can reach 10-20 years, much depends on the observance of technological nuances during installation. If it was violated in some way, the service life will immediately decrease.
One of the dangers is the appearance of fungal mold on the walls of premises insulated with foam. It serves as a source of allergic manifestations. This happens because the dew point shifts to the middle of the wall, and after it dampness and humidity come into the house.
Foam fires produce hazardous and toxic gas. Although the material does not burn, it begins to melt when exposed to high temperatures. In this case, not only suffocating black smoke gets into the air, but also a gas called phosphene, which causes paralysis of the respiratory tract.
Internal wall insulation technology with expanded polystyrene
After you have chosen the technology for attaching expanded polystyrene and calculated all the costs, you can start the insulation work. It is necessary to observe a number of nuances that can affect the quality of the finished coating. Experts do not recommend saving on materials or skipping individual jobs from the technological chain.
Preparatory work before insulation from the inside of the walls
First of all, the wall that will be insulated must be leveled. Even an unskilled builder understands that on an uneven surface, one should not expect high-quality fastening of the insulator and all subsequent layers. Ultimately, this will lead to heat loss and waste of funds.
If we are talking about a newly built building, then the wall should be plastered first. After that, it is treated with primer paint and any irregularities are repaired with a putty. In other cases, the same actions will be required, only without the obligatory application of plaster mortar.
It is a different matter when it comes to renovating premises. Until the moment you insulate the walls from the inside with polystyrene foam with your own hands, be sure to remove the old paint or wallpaper. After that, each wall is thoroughly diagnosed for detecting grooves, cracks or concrete chips on it.
Any defects are eliminated with plaster or store putty. In some cases, you can resort to polyurethane foam. After that, the surface is carefully leveled. As soon as the working wall is completely flat, it is again treated with primer paint.
However, before laying the foam sheets, we still need to take care of the waterproofing. This is explained simply: in any case, at low air temperatures outside the building, moisture will pass through the wall and get onto the insulation, under its influence the expanded polystyrene loses its characteristics, and over time it simply starts to rot. The waterproofing material will just serve as a protection in the path of moisture.
After the waterproofing is installed, they begin to install the insulation. If in the old days its sheets were necessarily fastened using screws and dowels, then modern industry has simplified this process. There are special adhesive solutions that greatly facilitate installation work.
Thus, the basic requirements that must be met before starting thermal insulation:
- The surface should be as flat and dry as possible.
- The wall should be separated from the thermal insulation layer by waterproofing and vapor barrier.
- The insulation itself should not have cracks, joints or any gaps.
- It should be distinguished by the maximum permissible moisture resistance.
It is required to prepare tools such as a knife, emery cloth, gloves, a hammer, a puncher, a pencil, a corner ruler, a container for diluting glue and other liquids.
Instructions for installing polystyrene foam on walls
You should start with the calculations of the required material. The value of the height of the walls is taken and multiplied by the width. From the obtained value, it is necessary to subtract the window and door openings, but add a small tolerance in connection with the slopes. As for the type of insulator, it is not at all necessary to chase the thickest foam. It will be enough to make a choice in favor of the 10-centimeter PSB-S-25.
As for the glue, you should give preference to the special one, which is designed for such materials. Although it is more expensive, it will be able to provide the desired result, namely a heat insulator securely fixed on the wall. To carry out work on reinforcing polystyrene foam, you will need a separate grade of glue, so you will also have to worry about this in advance.
From other materials and devices, we need special umbrella dowels, which provide additional fastening to the wall. By their number, you need to take about 5 pieces for each attached sheet. The length of the fastener should be 2 times thicker than the thickness of the sheet itself. To reinforce the glued polystyrene foam, you need to stock up on a mesh with cells of 5 by 5 cm. The corners and slopes will be pasted over with special painting corners.
If such a cycle of work will be carried out for the first time, then it is better to take care of a small surplus of materials. This will insure against the need for repeated trips to the store.
Do-it-yourself insulation of internal walls with expanded polystyrene is carried out in the following order:
- A new sheet of material is taken, on which a layer of glue with a thickness of about 10 mm is spread. The composition must be distributed evenly over the entire area.
- It is necessary to glue products to the wall in a checkerboard pattern, like laying a brick. The size of the gaps should be minimal.
- After gluing, we will fix the sheets with umbrella dowels. They are driven into each corner of the slab, and one is attached in the very center. This can be done immediately for each glued product or for all of them in total. In this way, it is possible to achieve a tight fixation of the heat insulator.
- Now you can proceed to the reinforcement stage. There is another rule here: for the mesh to hold well, it must be filled with a thick layer of glue. Before gluing, you can slightly moisten the wall by sprinkling it. For reinforcement, you should buy a mesh with a certain density indicator, not less than 140 g / m2.
- After you fix the mesh to the foam, it is smoothed over its entire area. Protective corners are attached to all corners of the product using the same glue.
It is necessary to carry out all types of insulation work at a temperature of at least + 5 ° C. It is imperative to achieve complete drying of the wall, as well as an acceptable level of humidity. At each stage, the surface must be dried, for which you can use heaters or heat guns, building hair dryers.
Final finishing of the wall insulated with expanded polystyrene
Giving the final appearance to the insulated wall is the last stage of the work. This process can be attributed to the longest and most laborious in the entire algorithm. Since a single layer of plastering is not enough, the work can be carried over to the next day. The last layer must be made as neat and even as possible, since with its help we create a base for high-quality wall decoration.
After the leveling layer has dried, it is smoothed with sandpaper in order to eliminate all irregularities. The wall is covered with a primer paint, which is able to ensure perfect adhesion between the heat insulator and the topcoat.
Plastering work on an insulated wall should be started with the choice of a mixture that is designed to cover polystyrene foam materials. The most famous products are Ceresit, Worth, Ecomix. They are a universal mass that forms a protective layer on the insulation. The mixture is used not only for leveling the wall, but also for gluing the mesh. Material consumption will be approximately as follows: 4 kg per 1 m2 for the mesh and 6 kg for the protective final layer.
The use of a mesh is necessary so that the leveling compound can adhere to the expanded polystyrene surface. The denser the product, the stronger the whole structure will turn out, but it will be more difficult to paste over the corners with it. To glue the corners, we cut off a strip of mesh with a length equal to the length of the slope and a width of 30 cm. The universal mass is spread with a spatula at an angle, after which a piece of mesh is applied and ironed thoroughly.
For the installation of the mesh, it is cut off in pieces of about 1 meter. The mass is applied to the work surface, the product is applied to it and smoothed from top to bottom, as well as in the direction from the center of the wall. In the process of smoothing, you need to take a little mixture on the spatula to completely close the structure. This is how each vertical strip is glued, and the joints are made according to the "overlap" principle, so that each partially overlaps the neighboring one.
After the mesh is dry, grout it. To do this, you need a plastic float with a piece of emery cloth attached to it. Rub in counterclockwise, with gentle circular motions.
It remains to fix the leveling layer, for which we will use the same universal mixture. The mass is poured onto the wall with a spatula, while its thickness should be approximately 3 mm. The dried finish layer must be trowelled, in the same way as in the case of the mesh.
Grouting should be done no earlier than one day, but no later than four days after application. It is at this stage that the surface becomes as smooth and even as possible. Now it can be painted with colored primer based on the customer's preference.
How to insulate walls from the inside with expanded polystyrene - look at the video:
Thus, the internal insulation of walls with expanded polystyrene will reduce the cost of heat supply by almost one third. Moreover, you can do all the work yourself, without any special experience. It is enough to carefully study the above instructions and stock up on materials with the tool.
