How to choose polystyrene and other materials, advantages and disadvantages of such insulation, comparative characteristics, surface preparation, thermal insulation work and finishing of external walls. Insulation of external walls with foam is a technology that allows you to reduce heat transfer between the interior and the street to a minimum. Using this material, you can significantly reduce the cost of heating in the winter season and air conditioning in the warm season. Insulated walls allow you to save up to 30% of the heat that used to go out into the street uselessly.
The need for thermal insulation of external walls with foam
Insulation of walls from the outside with foam plastic from the outside is the most preferable and reasonable solution for many objective reasons. It is the outdoor technology that allows you not to reduce the internal volume of space in the room. In addition, in this case, you can not be afraid of such a phenomenon as the "dew point". She will not be in the wall itself, or inside the room. Therefore, there will be no freezing of the walls with subsequent destruction. And one more nuance: insulated surfaces stabilize the temperature in the home, and even during severe frosts, the air in the room does not cool down so quickly. Today, foam is increasingly preferred as an insulating material. Insulation of external walls with this insulator is used not only for private houses or cottages, but also for individual apartments in high-rise buildings.
When choosing foam, you need to pay attention to its density, since material with an indicator of less than 25 kg per 1 m3 not good. This is due to the fact that it will not give the facade the necessary rigidity. It will be difficult even to plaster it without causing damage. Therefore, you need to buy C-25 grade foam or denser.
There are several systems for insulating the outer part of the building: this is light plaster, and the so-called "wet" method, and well masonry. The principle of wet plaster makes it possible to obtain the most durable and vandal-resistant surface. To give the facade good ventilation, a gap must be left between the outer screen and the thermal insulation layer. For insulated walls, thick sheets of 5 cm or more are used. After the work is done and the finishing is completed, the temperature in the house usually rises by 5-6 degrees Celsius. All existing joints and cracks will be sealed at the same time. The walls will dry out from moisture and will be free of mold, because they are treated with fungicidal compounds. All of the above improves the microclimate in the rooms of the building.
Advantages and disadvantages of exterior wall insulation with foam
The main advantages of facade thermal insulation with foam plastic include the following characteristics:
- Profitability, as well as a quick return on investment. External insulation is always highly effective, and in the near future the owner will be convinced of the savings on utilities.
- Moisture resistance - this indicator suggests that you can forget about the manifestations of fungus or mold. Moisture condensation will occur outside the structure.
- Increased environmental friendliness, because the material does not harm the health of the inhabitants of the home.
- Improving sound insulation, which will create a more comfortable atmosphere inside the house.
- Excellent aesthetic appearance, because with the use of foam, you can achieve any architectural and design solution. It can be painted in any color or shade of color scheme.
There are not so many disadvantages of this material, especially in comparison with its strong qualities. In case of careless handling or contact with an open fire, it can be flammable, and when burning, it releases toxic and unsafe substances into the air. Even domestic rodents can harm the coating, so it requires additional protection.
Myths about the use of styrofoam to insulate exterior walls
This material is considered to be one of the most flammable. This is indeed true, however, with proper adherence to fire safety requirements and high-quality installation, polystyrene is absolutely safe. In addition, it ignites at temperatures much higher than that of paper and even wood. The flammability of this insulation can be significantly reduced by using protective layers.
There is an opinion that the foam is short-lived, however, the studies carried out by scientists indicate that the plates from this heat insulator are able to withstand long-term operation. Its main enemies are mechanical impact, as well as ultraviolet radiation.
Compared to other chemically synthesized materials, it is not toxic to health. Suffice it to recall that food packaging is made from foam plastic, in which there is direct contact with food. The composition contains neither poisonous nor highly hazardous substances, and when working with it there is no need to use additional protective equipment. It has been proven that even after long years of use, the foam does not pose any harm to human health. This is possible due to the biological neutrality and stability of the insulation, as well as the fact that it does not contain any other gas other than air. Therefore, use in everyday life does not threaten the occurrence of allergic reactions.
Someone may suggest giving preference to extruded polystyrene foam or mineral wool. Let's evaluate their comparative characteristics. Rock wool rolls are cheaper, but won't provide as much warmth. And the products made in slabs already differ significantly in price. As for expanded polystyrene, the difference in thermal conductivity compared to a conventional analogue is insignificant, but it costs significantly more.
Another myth is related to the fact that it does not really matter which insulator to use, because the technology of insulating the outer walls with foam is the same in any case, which means that the results will be the same. But the better the raw materials are, the longer and more efficiently the insulated structure will serve. It is necessary to pay attention to the quality of the foam, trusting only trusted manufacturers. The strength of the bond will depend on the adhesive mix as well as the correct surface reinforcement. You should not skimp on the reinforcement mesh. For the reliability of thermal insulation, the foam must be covered with a protective compound. Even paint will provide some protection: for example, from sunlight, from temperature or chemical exposure. However, for a greater effect, it is better to use decorative plaster, which will also serve as mechanical protection.
Thermal insulation technology of external walls with foam
Before insulating the walls from the outside with foam, it is worth learning everything about the technology of work. By the way, it is not particularly difficult. In any case, a careful study of each of the stages is required, the correct selection of consumables and tools.
Surface preparation for foam insulation
The step preceding the insulation must necessarily be the maximum leveling of the wall. It is undesirable that irregularities of any size protrude on it. Since foam is a fairly soft material, any defect will weaken the overall structure.
The surface is first removed with plaster to a level at which the irregularities do not exceed 1-2 cm in size. After that, the texture of the wall is carefully examined. The rougher it is, the better the adhesive bond can be achieved.
In what cases surface priming may be necessary:
- When before that the facade was painted with paint, the vapor permeability of which was negligible;
- If there are chalk marks on the wall;
- If surface shattering occurs with slight contact.
Among other things, the primer is useful in that it contains antibacterial and antifungal additives.
As for working mixtures, adhesives and solutions, it is necessary to carefully select them by marking. For different types of work, different compositions will be required. For gluing and reinforcing foam, the professional adhesive mixture "Moment" is suitable. It will be able to reliably fix heat-insulating plates, and will also be needed when creating an outer reinforcing layer on the facades.
It is necessary to prepare from the tools and devices: a hacksaw, several spatulas, working containers, a level and a plumb line, gloves, a hammer, a screwdriver, a paint brush, a roller, a spray gun, an electric drill or a screwdriver.
Styrofoam installation instructions
Ideally, if the fasteners will be carried out not only with glue, but also with umbrella-type dowels. So you can hope that the foam will adhere perfectly.
We carry out the work according to the following algorithm:
- Attach the starting profile along the bottom edge of the wall. It will provide additional support and keep the foam sheets from slipping.
- A glue mixture is applied along the entire perimeter of the insulation product. Particular attention is paid to the middle. Now the sheet is pressed against the wall surface and held for several seconds. You can go to the next item.
- After this, the insulated surface is allowed to stand for at least 3 days to dry completely. This time is usually enough to cover the whole house with foam, and the glue had time to reliably set.
- Now it's time to fix the foam plastic for the facade with umbrella construction dowels. They should be taken so that at least 5 pieces come out for each square meter of material. When hammering, you need to control so that they enter the wall by at least 5 cm.
- When placing the dowels, make sure that they are placed in the middle of the sheet, as well as at the corners of each of them at the joints. It is necessary to make a small indent from each edge.
- Any noticeable irregularities must be cleaned up immediately with a special float. Every large seam or depression larger than 0.5 cm must be blown out with foam.
- If the sheets are attached in 2 layers, then the upper one must be shifted relative to the lower seam. In other words, there should be some overlap, both horizontally and vertically. All four corners should be placed in different locations for each layer.
- Now you need to glue the reinforcing mesh onto the surface. It will be the basis for the plaster layer and is attached to an adhesive solution containing cement. The glue should be applied abundantly, in sections of about 1 by 1 m.
- A mesh fabric is embedded in the glue and a thick layer of the composition is again applied over it. For horizontal mesh strips, overlaps of up to 10 cm are made.
- To protect the corners of the outer walls, galvanized or plastic corners are used. They will be able to give them maximum strength.
Finishing exterior walls
After the insulation of the outer walls with foam is completed, a protective and decorative layer can be applied. In thickness, it must necessarily be larger than the insulation. It is leveled until the required density is reached.
Structuring the protective layer begins with a plastic float. This should be done both horizontally and vertically or in a circular motion. This is carried out until the desired invoice is received.
All excess that forms on the coating must be thrown aside, but not returned to the container with the working material. All operations are carried out sequentially, without significant interruptions, until the entire facade has been processed. If it so happened that the work seams still became noticeable, they can be hidden behind the hinged elements.
After the entire surface has been trowelled and the wall has dried, the insulated facade should be primed. This is a necessary step before finishing the exterior walls. The quality of these works depends on how the applied decorative coating will look. It is advisable to purchase a grade of primer such as ST-16 or ST-17. Before using it, you should carefully study the instructions on the package - usually there is a detailed description of how to dilute the mixture.
Despite the fact that there are many options for finishing, one of the easiest to perform is the processing of facade paint. It is necessary to determine how many layers of staining will be, for example, 2 or 3. If the base base is perfectly aligned, then 2 layers will be enough. The lower one performs a priming function. Water can be added to the paint, but not more than 5% by volume. After waiting for the final drying of the soil, a couple of layers of the coloring composition are applied on top. When creating a topcoat, the substance can be diluted with a large amount of water (up to 15% of the total volume). The three-layer technology will make the facade insulation with foam plastic more durable and better protect the base from moisture penetration. Wait 10-12 hours between applying different layers.
As for the consumption of paints, a lot depends on the nature of the base, the thickness of the layers and their quantity, the proportion between the coloring composition and the solvent. The more porous the material is, the more material will be needed. Since the cans usually indicate the consumption of material, then, knowing the total area of the wall to be insulated, you can easily calculate the approximate number of liters of paint. In modern technologies for the decoration of external walls, complex systems can be used, which include cleaning, priming, protecting and directly painting. It is advisable to choose systems from trusted manufacturers, which are probably on the shelves of any large building materials store. Compositions from different brands can sometimes be poorly compatible with each other.
Experts recommend not to skimp on paints, since cheap formulations are short-lived and are weakly resistant to weather and other factors. They quickly wash off and fade, which is why, after a few seasons, the facade will have to be painted again.
How to insulate the outer walls with foam - look at the video:
Thus, the facade, insulated with foam, leads to comfort in the home, while having the necessary strength. After a few years, the money spent will pay off due to energy savings. The main thing is to observe all the necessary subtleties when performing technological work.
