Features of thermal insulation of external walls with polyurethane foam, the pros and cons of this technology, the choice of suitable equipment for spraying the material, the rules for carrying out work on applying insulation to the facade. Insulation of facades with polyurethane foam is a relatively new method of thermal insulation. The substance is applied by spraying on a variety of surfaces - smooth, embossed, unusual shapes, made of different materials. Polyurethane foam is considered one of the most highly effective insulation materials.
Features of work on the insulation of facades with polyurethane foam
Polyurethane foam as a heater for houses began to be used relatively recently. It quickly gained popularity due to its strength and excellent thermal insulation characteristics. Polyurethane foam is a material that is formed by mixing two polymers. These are polyol and polysocyanate. They have a liquid consistency. These substances are mixed directly in the process of applying to the surface. They are foamed under the influence of carbon dioxide and heated to high temperatures in special equipment. The finished mixture is fed through hoses under high pressure to a special construction gun, which sprays it onto the surface of the walls. After application of polyurethane foam, its volume rapidly increases. In this case, all cracks and voids are filled with insulation. This creates a smooth, seamless finish. The material hardens quickly enough, so you need to work quickly. This heat insulator has high adhesion to almost all building materials. They can insulate facades made of wood, steel, concrete, brick and others. Both residential buildings and industrial buildings are insulated with polyurethane foam.
Advantages and disadvantages of facade insulation with polyurethane foam
Although the installation of polyurethane foam on the facade requires additional costs for the purchase or rental of special equipment, the recoupment of this method of insulation occurs within three years.
In addition to a quick payback, the method of thermal insulation using polyurethane foam has the following advantages:
- Polyurethane foam can be sprayed on any surface due to its excellent adhesion. The material will not fall off, slide or chip.
- A dense, seamless building envelope is created that prevents cold air from entering. In addition, it penetrates into all cracks, filling them completely.
- The house, insulated with polyurethane foam, is reliably protected from extraneous sounds from the outside. The material has good sound insulation properties.
- Metal elements of the building insulated with this method will not undergo corrosive processes.
- A layer of such insulation is very resistant to mechanical and chemical influences.
- Lack of "cold bridges". No other method of insulation is capable of completely and qualitatively eliminating this phenomenon. "Bridges of cold" appear in places where the guides are located. When insulating with heaters in mats or slabs, these areas have to be additionally processed with polyurethane foam assembly foam.
- It is possible to carry out insulation with polyurethane foam even of those buildings that have complex configurations and structures with many carved parts. It is almost impossible to install sheet heat insulators on such houses.
- The fire hazard of this heat insulator is very low. The polyurethane foam contains a polyol component, to which a fire retardant is added. This ensures that the insulation layer will itself fade out even if it enters the open fire zone. Combustion of the material is possible at a temperature of at least 500 degrees Celsius.
- It is possible to spray polyurethane foam even on buildings with an insufficiently strong foundation. The material is quite light, so it will not exert a significant load on the foundation. In addition, the layer of heat insulator after curing will give additional strength and rigidity to the walls.
- With the right equipment, polyurethane foam can be applied very quickly. Within one or two days, you can completely insulate the house and start finishing work almost the next day after installing the insulation.
- There is no need to additionally use a vapor barrier or windproof film. Polyurethane foam is a moisture resistant material that creates an airtight layer.
- The layer of thermal insulation will not rot and mold. It also does not attract rodents and insects.
Polyurethane foam can serve as a heater for a long time - up to 50 years. True, to preserve its optimal thermal insulation properties, it is necessary to protect it with finishing materials from sunlight and atmospheric precipitation. It is important to weigh all the pros and cons before starting to insulate the house by spraying polyurethane foam, so consider the disadvantages of the method:
- To apply material to the facade of a house, you will need to purchase or rent expensive equipment. This is often unreasonably expensive, so it is easier and cheaper to hire a team of professionals.
- It is necessary to work with polyurethane foam using personal protective equipment - respirator, gloves, mask, glasses. You will also need a special suit that will protect exposed skin from uncured foam.
- It is important to strictly follow the fire safety rules near the thermal insulation layer. Although polyurethane foam is not flammable, in contact with fire, it smokes heavily, releasing a large amount of toxic substances that are dangerous to humans.
- If the insulation layer is not protected from the outside with finishing materials, then it will begin to deteriorate rather quickly under the influence of direct rays of the sun and atmospheric moisture. In this case, the polyurethane foam will release monomers, which are also harmful to humans.
In addition, if you are an inexperienced builder, then self-application of polyurethane foam on the walls can take a long time. In addition, no one will give you a guarantee for high-quality work and excellent thermal insulation.
Facade insulation technology with polyurethane foam
External insulation of buildings with polyurethane foam, as a rule, is used for houses with a small number of floors. The procedure for applying material to the facade consists of the following stages: preparation of the base, spraying, wall reinforcement and finishing work.
Selection of equipment for spraying polyurethane foam
The equipment that is used to create two-component polyurethane foam and spray it onto walls is considered quite difficult to use. However, in our time, manufacturers offer to purchase devices that are not professional and are suitable for one-time household use. The polyurethane foam spraying kit includes the following elements:
- Two cylinders with high pressure fluids, which are needed to form polyurethane foam;
- Hoses used to connect cylinders and a special spray gun;
- Spray gun that releases foam;
- A set of interchangeable nozzles for the pistol, which have various modifications;
- Keys used to assemble the device;
- Special technical grease.
Also, this kit is accompanied by instructions that describe the rules for assembling and using the device. It usually takes a few minutes to assemble the device. It is enough to connect the cylinders with hoses, and put the desired nozzle on the gun - and you can start working. Most disposable units do not have a component heating function. Also, the hoses for the supply of substances are not heated. This limits the scope of use of such equipment, since the optimum temperature for applying foam is 20-30 degrees above zero. However, dependence on the temperature outside can be eliminated by "folk methods". Flexible hoses are placed in energy-flex pipe thermal insulation. The cylinders are placed in buckets or barrels with water heated to 30 degrees. The area that can be treated with polyurethane foam depends on the size of the cylinders. It is important to remember that after the start of work on the application of the material and with a forced pause, the equipment, assembled and ready for use, can only be operated for a maximum of 30 days. After this time, the installation becomes unusable.
For this reason, it is not recommended to buy cylinders with a large supply of polyurethane foam than may be needed for thermal insulation. As a last resort, you can use the remnants of the insulation for spraying in household premises - a garage, a greenhouse, a balcony. When working with the apparatus for applying polyurethane foam to walls, the following technical safety rules must be observed:
- For spraying, choose clothing that covers the whole body, as well as a hat. So you will protect yourself from getting the foam on your skin or hair, which is very difficult to remove after hardening.
- Use a respiratory mask to protect the respiratory tract. It will prevent small foam particles from entering the respiratory system. This rule is especially true when working at a height or when the gun is positioned at an angle to the wall.
- Wear gloves on your hands to avoid contact with the foam. Usually, a pair of gloves is included with the installation, but it is recommended to have a few spare with you.
Preparation for the application of polyurethane foam
Before spraying polyurethane foam on the facade of the house, you need to carry out preparatory work. They include a set of measures for cleaning the surface from old coatings, unreliable elements and flaking parts. If finished, it must be dismantled to the building frame. You should also remove all outdoor lighting fixtures, ebbs, ventilation grilles, decorative elements. Existing glazed windows must be covered with paper and its edges must be sealed with tape. Next, we install the crate on the walls. It can be made of wooden beams or metal profiles. The distance between the guides should be approximately 20-50 centimeters, depending on the dimensions of the building and the thickness of the applied polyurethane foam layer.
Sheathing can also play a leveling role for uneven walls. It must be installed using a building level and a plumb line. All openings in the crate will subsequently be filled with foam, and the surface will become even.
Instructions for spraying polyurethane foam on the facade
On average, the thickness of the sprayed layer of polyurethane foam is three centimeters. Depending on the climatic conditions of the area where you live, the layer can be reduced to two centimeters or increased to five. If this is your first time spraying, it is recommended that you first simulate the movements of applying polyurethane foam from a gun to the wall. This will give you an estimate of how many times you will need to reposition and intercept the pistol to cover a specific surface. Since, as soon as you lower the trigger of the device, the foam will harden almost immediately in the nozzle, after that it will need to be changed to a new one. The number of nozzles in the kit is limited, so it is recommended to work with a minimum number of breaks. We carry out insulation of the house outside with polyurethane foam according to the following rules:
- We open the taps, after which the substance is supplied to the gun through the connecting hoses.
- We pull the trigger and the polyurethane foam starts to spray onto the wall.
- We start spraying from the bottom of the wall. We fill, first of all, the gaps in the crate.
- We hold the gun at a distance of about 25 centimeters from the facade.
- Hand movements should be smooth, uniform. So you are guaranteed to be able to get an even layer.
- If necessary, we move to a new place of work. In this case, we turn off the pistol, and replace the nozzle with a new one.
- The intensity of application can be adjusted. If you need a thin layer, adjust the equipment so that the polyurethane foam is applied in a small stream.
- If the thickness of the first layer is not enough for you, then after it hardens, you can apply the second one.
- Keep in mind that the foam grows in size, so the second layer should not protrude too much beyond the sheathing. So you will avoid problems with finishing work in the future.
- Each new layer of insulation must be laid in such a way that its surface is as flat as possible. The second (or third) layer should be applied along the joints of the previous one.
Polyurethane foam hardens in minutes. Therefore, almost immediately after the end of the work on its spraying, you can start trimming the protruding reliefs. This can be done by focusing on the crate. Use a mounting knife when doing this.
Facade reinforcement rules
In order for the finishing materials to smoothly and beautifully lay on the insulated surface of the facade, as well as to avoid the appearance of cracks in the corners of window and door openings, the wall must be covered with a layer of reinforcing mesh. First of all, we carry out the installation of the perforated corners. They are made of aluminum or plastic and have a reinforcing mesh attached at the edges.
We carry out work according to the following scheme:
- Lubricate the corners and the mesh, as well as the corners of the building with assembly glue.
- We apply it to the corners of the house and press it with a spatula to the thermal insulation layer.
- Smooth the glue protruding through the mesh and perforation with a spatula over the surface.
- In the corners, the profiles are closely connected and cut off the mesh and shelves at a 45-degree angle.
After you have processed all the corners on the facade, you can begin to fix the main reinforcing layer. To do this, you need a special fiberglass mesh. It has good chemical and mechanical resistance. To fix the mesh on the wall, you will need a special adhesive solution. It can be purchased at any hardware store.
We work according to the instructions:
- Pre-grind the surface of the polyurethane foam with a special grater or coarse sandpaper.
- We cut the reinforcing mesh into pieces. Their length should correspond to the height of the wall.
- We clean the facade surface with dry brushes and apply a thin layer of glue to the area that corresponds to the width of the mesh. Remove excess mixture with a notched trowel so that grooves remain on the wall.
- We apply the mesh to the surface and embed it in the glue. We use a grater or smooth spatula.
- Smooth the area from the middle to the edge. Spread the excess glue solution along the wall.
- Do not pull the mesh tightly or press it into the thermal insulation layer.
- After you have reinforced the entire facade, do not wait for the adhesive mixture to dry, but apply a new layer about two millimeters thick. When doing this, leave a free edge of about ten centimeters. We put the second strip of mesh on it.
- The top layer of adhesive must completely cover the reinforcing mesh so that it does not show through.
It takes one day for the solution to dry, after which you can start finishing work.
Finishing works
After the house has been insulated with polyurethane foam, it is not recommended to install a finishing material on the building that requires fixing to fasteners. For example, when installing siding on dowels and self-tapping screws on top of a layer of polyurethane foam, the integrity of the layer will be destroyed. Cold bridges will appear in the coating, which will lead to an increase in heat loss and the appearance of condensation. The best option for finishing a house insulated with polyurethane foam is plastering. You can choose any decorative composition that will create an interesting effect on the outer walls.
In addition, the walls can be painted. True, for this, the surfaces must be perfectly flat. This must be taken care of at the reinforcement stage. You will also need to make a layer of finishing plaster. How to insulate a facade with polyurethane foam - watch the video:
Thermal insulation of the walls of the house with polyurethane foam is one of the most effective methods of thermal insulation. Spraying the foam will require special equipment and skills. Therefore, carefully weigh all the nuances before taking on such work with your own hands.
