The specifics of wall insulation with foam, all the pros and cons of this technology, preparatory work, instructions for installing foam plates, final surface finishing, practical advice. Insulation of walls from the inside with foam is a simple technology that does not require qualifications, but it is quite laborious. Traditionally, external wall or facade insulation is considered more effective, but internal work will also help to keep heat. You just need to carefully read the nuances of the process, select tools and quality materials.
Features of thermal insulation of walls from the inside with foam
Internal wall insulation with foam has gained such wide popularity due to the amazing properties of this heat insulator. Polyfoam is a unique gas-foam material, in which air occupies the main structure. Thanks to this property, it has an amazing thermal insulation.
For internal work, sheets or panels of polystyrene foam are most often used, the density of which is measured in kg / m3… For example, one of the popular brands PSB-S-25 is made of expanded polystyrene, in a press-free way, from a self-extinguishing material, with a density of 25 kg / m3.
In addition to these qualities, you should pay attention to other criteria when buying a material for insulation. It is advisable to purchase it in those places where it is stored protected from rain, wind and frost. Otherwise, its thermal insulation characteristics may be impaired. Styrofoam should be solid white with no yellow spots. They indicate that it was stored in poor conditions or was produced from low-quality raw materials.
It is not enough to simply insulate the walls with foam plastic from the inside in order to count on retaining heat for many years. Additional ventilation must be provided, and work must be carried out to prevent the formation of condensation. Otherwise, the insulator will collapse in the coming heating seasons.
Internal cladding with any heat-insulating material, and especially such as foam, significantly reduces the size of the room. In fact, you should be prepared for the fact that the usable area in the room will decrease by 5-10%. And, finally, work on thermal insulation should be carried out in a room completely freed from furniture and household equipment, which will certainly provoke certain inconveniences. But you can do the insulation of the room from the inside in any weather, without being tied to the season.
Advantages and disadvantages of insulation of internal walls with foam
There are plenty of advantages from using foam as a heat insulator:
- It does not burn and is practically incapable of absorbing moisture.
- The inner wall insulated with this material will have good thermal insulation.
- There will be no foci of fungus and mold on the insulated surface.
- It is very easy to work with foam plates - they weigh a little, but they are conveniently cut and mounted.
- The foam insulation layer can last a long time if done correctly.
- Walls insulated with it from the inside can withstand large frosts, intense heat, and do not require an additional waterproofing layer.
- The material is very cheap in cost.
Among the negative side effects that can cause insulation of the house from the inside with foam, we will focus on the following:
- The material cannot be called particularly durable, therefore, when using it, they must think over additional external protection.
- Polyfoam is highly flammable, and when it burns, it poisons the air with poisonous combustion products.
- Due to the low adhesive qualities of the foam, it is necessary to provide additional fastening to the wall surface.
- Poorly allows oxygen to enter the room.
- Reduces footprint due to its impressive dimensions.
There is another significant disadvantage of internal insulation, which is inherent not only in foam, but also in many other materials. A large amount of moisture accumulates between the insulation and the outer wall. Water vapor constantly present in the air is cooled to a certain temperature and forms the so-called condensate.
This temperature is also called the "dew point". The accumulated moisture gradually penetrates into the wall, freezes during frost and begins its slow destruction. In addition, it disrupts the entire heat transfer process at the facility.
Technology of wall insulation from the inside with foam plastic
Despite the fact that work on insulation with foam plates does not require special qualifications, it is necessary to carefully prepare for them. We need to clean up old walls, buy materials and prepare tools.
Preparatory work before wall insulation with foam
Construction work with this material is distinguished by its simplicity, and yet it is necessary to start insulating walls with foam from the inside with your own hands with the preparation of the working surface. At this stage, the following types of work may be required, the volume of which depends on the condition of the walls in the insulated room:
- Elimination of the remains of the old building material - for example, old wallpaper, the remains of plaster or paint;
- Examination of walls for the detection of visible cracks and other defects;
- Thorough elimination of such defects with putty, alabaster mixtures, sealants and others.
In the case when the house or cottage is lined with bricks, the surface must be plastered. For buildings made of concrete blocks, this item is optional. After each wall has been treated with putty, and the irregularities are covered, they are primed and final leveling is performed.
All areas damaged by the fungus must be cured in order to avoid further spread of foci of the disease. For this, a fully prepared surface is treated with antiseptic and moisture-protective compounds. Remember that most antifungal mixtures are considered toxic, to avoid poisoning the body, work in a ventilated room and wear protective gloves.
As the necessary tools for performing work, we need: a pencil, a sharp knife-cutter, a ruler, a level, a tape measure, a spatula, a paint roller, a paint brush, a hacksaw, an electric drill with a mixer attachment, a brush, a metal grater, containers for breeding and stirring workers solutions.
Of the materials required: polystyrene in plates or panels, plaster reinforcing mesh, ground paint, adhesive dry mix, starting profiles, reinforced corners, fixing dowels.
Instructions for installing styrofoam on interior walls
After you prepare the necessary adhesive solution, you can proceed with the installation of the foam. Follow these instructions:
- First, the required sheet dimensions are measured. To do this, it is applied to the wall to be insulated, marked and carefully trimmed, avoiding damage to the edges.
- To coat the wall with the glue mixture, start from the floor, approximately the size of the intended panel. Each sheet should be applied as evenly and tightly as possible to eliminate irregularities.
- Joints between adjacent panels are made according to the same principle as for brickwork (T-shaped). In order for the glue solution to dry completely, the room is left open for a day or two.
- Now you need to fix the panels with plastic dowels. When fastening, you need to pay attention to what the thickness of the foam will be for insulating the walls from the inside. It is enough to drill 6 holes for each panel, a pair on each side and in the center.
- Particular attention should be paid to the processing of joints. For gluing wide ones - you can use narrow strips of the insulation itself, the rest - fill with polyurethane foam. It should not contain the substance toluene, since it is capable of corroding and deforming the foam. Excess foam is carefully trimmed; it is advisable to treat the cuts with glue, which will protect against the appearance of fungus or mold.
- Now place a reinforcing mesh on top of the insulation. She also sits on the glue solution, which is applied with a spatula over the entire surface of the insulation. After that, a large piece of a pre-cut mesh is embedded in it. All subsequent pieces are glued after the previous ones have completely dried.
- Then the entire glued mesh is covered on top with another layer of glue. It is necessary to achieve its complete leveling and the absence of protruding parts. You can use a piece of coarse sandpaper to clean up. Sanding the wall or similar abrasives will create a massive cloud of dust. Take care of a respirator to protect your lungs.
- After cleaning, it is time to prime the surface. It is produced with a paint roller, after which the wall can be used for further work processes.
A very interesting option is to attach foam panels to walls without using dowels, glue or foam as a fixing base. This method has become widespread in some Western countries. But in this case, you will need a special foam, in which grooves are made along each side of the plate.
For additional convenience, during installation, you can secure with a few drops of glue or small screws. Then the slabs are placed vertically on the wall and adjusted so that the adjacent panels form vertical recesses with a width of 10 cm, along the entire height from ceiling to floor.
Edged boards are inserted into each of these channels, which will be fixed through the insulation to the wall. If it is concrete, then dowel nails will be required, which would go 5 cm deep into it. Before hammering in nails, the joints of the insulation under the board are thoroughly coated with foam, after which the lumber is immediately installed. Such products themselves can act as a lathing on which sheets of drywall or glass magnesite are attached. They will securely fix the styrofoam to the walls.
If it is necessary to leave a gap for communications between the finish and the insulation, then for the lathing you need to take bars of greater thickness or expand the channel so that it includes 2 boards at the same time. This can lead to a decrease in the usable area in the room.
Finishing the walls after foam insulation
To reliably seal the joints at the junction of the foam plates, special sealant compounds are used. Once dry, they form a strong but elastic seam. In the presence of large defects, polyurethane foam will come to the rescue. But construction installers do not advise using adhesive tape, since on rough surfaces it cannot be used to achieve the necessary sealing.
Special attention is paid to the attachment points for electrical outlets and light switches. To do this, a hole is made for each product in the foam plate, which is 20 cm larger than the diameter of the fixing box of the electrical appliance. New boxes are inserted into the holes and fixed with foam or sealant. Especially carefully you should process the joints of the insulation and the wall. The box is allowed to protrude no more than the thickness of the finishing layer.
Instead of a reinforcing mesh, gypsum plasterboards can be fixed to the foam boards. In this case, it is better to use special polyurethane glue instead of foam for fixing. It has proven itself well in fixing wall materials, including drywall, foam panels, expanded polystyrene and others. It sets quickly, but increases less in volume, in contrast to polyurethane foam.
For gluing gypsum plasterboard directly onto thermal insulation products, such an adhesive is best suited. Apply it to the back of the slab and carefully coat the ends of each panel. With its help, the plasterboard sheet is processed before gluing.
After you finish insulating the walls with foam with your own hands, you can start applying the final layer, which will simultaneously perform protective and decorative functions. Most often, they resort to using plaster. Its thickness should be greater than the thickness of the heat-insulating material that forms the texture of the coating.
After applying the plaster, it is leveled with a wooden trowel or float. Movements can be circular, vertical, horizontal, based on the required pattern. This operation should be performed continuously until the entire wall is completely processed, so that stains of different colors do not appear due to different drying times of the layer. In some cases, the plaster, at the request of the owner, can be painted to match the color of the interior.
How to protect foam-insulated walls
Considering that the inner heat-insulating layer "likes" to accumulate moisture in itself due to temperature condensation, you need to pay close attention to protecting the walls so that they remain as dry and warm as possible. The following recommendations will help us with this:
- For vapor barrier, the highest quality film should be selected, and the connecting joints are carefully sealed.
- To reduce humidity in a room or room, forced-type mechanical ventilation is used.
- The material for thermal insulation should not have high vapor permeability. Ideally, the load-bearing wall will be higher in this indicator than the heat-insulating material. This is what will ensure the escape of steam to the outside.
- When attaching the insulation to the glue, it should adhere as tightly to the wall as possible, and for this it is advisable to apply the glue solution with a comb - this will ensure better contact between the material and the wall.
- When calculating the thickness of the insulation layer, you need to take into account the climatic characteristics of your region. The insulation should correspond to them or even be thicker in this value.
- It is necessary to fix the foam plates on the walls only after processing with a composition that will protect them from mold and mildew. It should dry completely on the surface of the walls.
How to insulate the inner walls with foam - watch the video:
The need to perform work on foam insulation today is a proven fact. This is due to energy resources, which are constantly becoming more expensive in price, and the destruction of previously existing heat communications. Working with foam plastic does not require a lot of practical experience, but it allows you to better maintain a favorable temperature in the room.
