Thermal insulation with polyurethane foam of the inner surface of the walls, its features, advantages, disadvantages and work technology. Wall insulation with polyurethane foam is a good way to create comfort in your home. This material belongs to a new generation of thermal insulation and promises significant economic benefits in its use. You will learn how to insulate walls with polyurethane from the inside in this article.
Features of wall insulation from the inside with polyurethane foam
Polyurethane foam insulation is available in the form of rigid plates or sprayed liquid. In its method of use and composition, the liquid material is very similar to construction polyurethane foam, except that the capacity of the cylinders with it is much larger.
Polyurethane foam can be used for external and internal insulation of enclosing structures. From the outside, material in the form of slabs is quite suitable for wall insulation.
The second case is considered not the best solution. The reason for this is the movement of the dew point deep into the wall when the main part of the structure gets into the area of negative temperatures. In the area between the inner side of the wall and the thermal insulation, water begins to collect, which, periodically freezing, destroys the structure. Therefore, the main task of internal insulation is to minimize the gap between the material and the wall. This can only be done using a spray polyurethane heat insulator.
To apply polyurethane foam, liquid polymers are mixed in a special apparatus - polyol and polysocyanate. These components quickly enter into an exothermic reaction with the gas, resulting in the foaming of the mixture. In the future, it is sprayed along the insulated wall, where the foamy liquid increases in volume and after a while hardens.
The components of liquid polyurethane insulation are manufactured at specialized production facilities and come to consumers ready for consumption and packaged in special labeled tanks. Each batch of the product is supplied with a technical data sheet.
During the application of liquid polyurethane foam to the walls, its temperature is plus 20-25 degrees. Installations, spraying the material, dose the components of the insulation in proportions from 1: 1 to 1: 7. The ratio of the components depends on the requirements for the final product.
Thermal conductivity of polyurethane insulation - 0.023 W / m3… But since this indicator means little for an inexperienced home specialist, such a comparison can be made: polyurethane foam 50 mm is equivalent in terms of thermal insulation characteristics to 150 mm of mineral wool or 80 mm of foam.
The porous structure of polyurethane foam insulation can have a density of 30 to 300 kg / m3… Most often, a material with a value of this parameter of 30-50 kg / m is used.3.
In the hardened form, polyurethane foam for wall insulation is absolutely safe for health. Among the most famous insulation materials, it has the highest thermal resistance and is not able to ignite from a spark or high temperature. The ignition of the material is possible only from the hearth of an open fire, however, when the flame goes out, the combustion of the insulation also stops. True, the smoke that accompanies this process is very caustic and contains substances harmful to the body.
Spraying can be used to protect any surface regardless of its texture and curvature. The resulting coating, due to its outstanding adhesion properties, tightly fits structures with different reliefs, repeating their shape. Foamed insulation in a liquid state is able to fill even the smallest gaps and cracks, and after hardening, form a common structure with the wall, protecting it from penetrating moisture.
From a ton of raw materials, you can make 20 m3 insulation and spray it with a wall area of 500-600 m2 with a layer thickness of 30-40 mm.
The properties of the components of the liquid mixture and their chemical composition must comply with the technical conditions, it is mandatory to comply with the warranty period for storing the material. After its expiration, the components of the liquid insulation are checked for compliance with the requirements of the TU and, with a positive result, can be used for? the original warranty period.
Advantages and disadvantages of wall insulation from the inside with polyurethane foam
If we take into account the use of liquid polyurethane foam, and not only its characteristics, it is possible to identify the advantages of insulation using this material:
- Foam insulation has excellent adhesion to wall materials: concrete, wood, metal, glass and brick. The configuration of the enclosing structures and their mechanical defects in the form of irregularities, small cracks do not matter at all during spraying. Excellent adhesion of polyurethane foam excludes the device of any additional fasteners and pre-treatment of the surface before applying it.
- With the help of mobile devices, the spraying of polyurethane foam insulation can be carried out on-site using a minimum amount of initial components. This fact is an important advantage of this method of processing structures. At the same time, reducing the cost of delivery, storage and installation of polyurethane foam brings an impressive economic effect. It is much more profitable to produce foam insulation at the place of its use than to transport far away the "air" of polyurethane foam products consisting almost entirely of gas. In addition, the costs for fastening materials, organization of storage of the insulator and its protection are reduced.
- When insulating the walls from the inside with polyurethane foam by spraying, the time of work is significantly reduced due to the high manufacturability of this method. A working unit consisting of two people in one work shift is able to insulate a wall area of about 800 m using a mobile installation2.
- The polymerization time for polyurethane insulation can be 24-72 hours. Such a high rate of foam hardening makes it possible to operate the facility almost immediately after the completion of thermal insulation work.
- Polyurethane foam is an unusually light insulation, therefore, it practically does not make the structure heavier and does not put loads on the foundation.
- The polyurethane foam coating does not care about seasonal changes in air temperature.
- Liquid spraying of insulation, in contrast to its sheet or tile counterparts, creates a monolithic connection with the enclosing structure. At the same time, there are no joints in the thermal insulation, through which cold air often penetrates.
In addition to the undoubted advantages, polyurethane foam has some negative properties, they should be remembered when choosing a material for wall insulation:
- The insulation wears out quickly from exposure to sunlight. Therefore, after polymerization, it needs protection, which can be provided by painting the insulated surface, plastering it or installing panels.
- The use of polyurethane foam is limited to the choice of surfaces that are very hot or can catch fire. And although this insulator is a non-combustible material, at high temperatures it can begin to smolder and collapse.
- Among the significant drawbacks, one can include the relative high cost of the foam concentrate components and the work on its application with mobile installations.
Technology of insulation of internal walls with polyurethane foam
Most often, polyurethane foam is used to insulate housing in high-rise buildings from the inside, and not all enclosing structures are sprayed, but only corner ones facing the street, loggias, as well as walls that are located between two adjacent apartments. In addition, due to the low hydrophobicity of the material, foam insulation is often used to protect wet rooms: toilets, kitchens and bathrooms. Let's consider in detail the process of such thermal insulation.
Preparatory work before installing polyurethane foam
Before doing the insulation of the wall surface with polyurethane foam with your own hands, you should free the room from household appliances, furniture and household items.
It is recommended to cover windows and doors with foil. These measures are necessary, since the spraying process takes place under significant pressure, and splashing of foam material cannot be avoided. Having increased adhesion, drops of polyurethane foam can firmly adhere to any surface, and after they have solidified, removing splashes of the material without a trace will become a very difficult task.
In addition to carrying out protective measures, it is necessary to remove the old finishing material from the walls to the very base. If you remove the trim carefully, then after warming it can be reused. Before starting thermal insulation work, the base surface should be cleaned of dust with a damp brush.
In addition, it is recommended to think about security measures. The room in which insulation is planned must have exhaust ventilation. And it is strictly forbidden to work with this material without protective equipment: special glasses, a respirator and gloves.
Spraying polyurethane foam insulation on walls
For thermal insulation of walls by spraying polyurethane foam, it is necessary to purchase special equipment equipped with a spray gun. Such an installation can have a programmed capacity and have the possibility of soft adjustment, which allows you to select the optimal rate of entry of the mixture components into the sprayer.
During the operation of the device, the metered components are supplied by air pressure into the mixing tank of the atomizer. There they are mixed and then thrown onto the wall using a special nozzle that gives the mixture the shape of an aerosol torch. The combined, but not yet foamed, components cover the base with a thin layer, and after 1-3 seconds a reaction occurs - the foam rapidly increases in volume. After hardening, it turns into a monolithic insulating coating.
The density of polyurethane foam can be controlled by selecting the components of the raw materials in the right proportions. Low density insulation is not able to take loads. Therefore, it is used for thermal insulation of walls, where it is planned to protect it from mechanical stress by installing claddings: panels, plasterboard sheets, lining and others. A special frame made of a profile or a wooden bar is preliminarily made for such a coating.
High density polyurethane foam over 40 kg / m3 does not require such protection, since it can well work under load. To protect it from moisture and ultraviolet rays, decorative plaster or a layer of paint is applied over it. In this case, there is no need for a frame.
When working with liquid polyurethane foam, it is necessary to ensure that the sprayed layer lays down evenly, without leaving unfilled gaps and large beads of material. Particular attention should be paid to thermal insulation of corners and places of abutment of walls to other structures.
To make the layer of thermal insulation even, before the foam hardens, you can run a straight rail along it, removing the protruding excess material from the wall. A smooth surface lends itself to further finishing more easily.
It is economically unprofitable to buy an expensive installation for insulation with polyurethane foam at home. The best option would be to rent it for a short term for a couple of days. This can be done in any specialized workshop.
Finishing of interior walls
The layer of polyurethane foam insulation should not be left open due to the loss of its quality by the material due to exposure to solar radiation. If the coating is not protected, over time it turns yellow, then darkens and collapses.
The most economical finishing method is painting. Most often, acrylic paints with a service life of about 3 years are used for this purpose, compositions based on epoxy resins with a durability of up to 30 years, as well as polyurea, which has a service life of more than 50 years. Since the polyurethane foam coating itself can serve for more than 20 years, it is unreasonable to use less durable building materials for its decoration.
Therefore, in recent years, polyurea has become the most popular, which is distinguished by excellent anti-corrosion properties, water resistance, wear resistance, unique durability and a rich palette of colors. The texture of the coating makes it possible to use this polymer as a cladding material.
However, quality costs money. The cost of spraying polyurea is much more expensive than other similar materials.
How to insulate walls from the inside with polyurethane foam - look at the video:
Currently, polyurethane foam from the whole variety of heat-insulating materials is the best example both in terms of price and quality characteristics. Therefore, when choosing a heater for your home, you should pay attention to it. Good luck!
