May 20 2022

Insulation of PU foam: high-quality thermal insulation by spraying

A significant part of the heat produced by heating devices is often wasted due to significant heat loss. This problem is especially common in old houses in which the thermal insulation layer was not provided at the construction stage, and windows and doors serve as a source of cold. The ideal solution to this problem is the insulation of PU foam, the advantages, disadvantages and features of which will be discussed in this article.

Insulation of walls in the house with polyurethane foam

Insulation of PU foam: technology of production and application of material

Such a material as polyurethane foam is obtained by mixing two components – polyol and diisocyanate. Despite the fact that both of these components are toxic and pose a threat to human health, as a result of their mixing, a completely safe polyurethane is obtained, which does not pose any danger and does not react when in contact with other substances. Moreover, the material obtained as a result of two toxic substances is often used even in the food industry.

A characteristic feature of all polyurethane foams is high gas filling

The polyurethane production process is accompanied by active gas release, which results in the formation of a large amount of carbon dioxide. Thus, it turns out to be inside a thin polyurethane shell, which provides a high index of thermal insulation properties of the material.

All this procedure is carried out with the help of a special gun, inside which there is a very high pressure, and the temperature that is maintained in it is 45 ° C. It is as a result of such exposure that fine particles similar to dust are mixed, after which they are sprayed onto the surface, allowing them to foam and harden.

In order for the resulting material to have all the necessary characteristics, its constituent components (polyol and diisocyanate) must be in equal proportions. If the quantity of one of the components is greater, this will negatively affect the characteristics of the material. Excess of the amount of diisocyanate leads to the fact that the foam quickly “sits down” and collapses, not fulfilling its main function – thermal insulation.

Polyurethane foam is not only effective, but also very convenient to install

Polyurethane foam, which has more polyol, is characterized by high fragility, although it is able to fully perform its functions. As you can see, the quality of insulation with this material directly depends on how well the initial components are prepared, as well as on the quality of the equipment used for this purpose.

Mixing of the components can be carried out qualitatively only if there are special high-pressure installations. Therefore, it is necessary to pay attention to what equipment the company you choose uses. The production of polyurethane foam under conditions of insufficiently high pressure leads to a significant decrease in the thermal insulation properties of the material.

A cone jet of mixed components is fed from the barrel of the gun under high pressure

Varieties of polyurethane foam used for insulation

Despite the fact that the manufacturing technology of PU foam is the same, the final product has several varieties that differ from each other in properties and characteristics. Let’s consider each of the options in more detail.

Lightweight open-cell PU foam. The thermal conductivity of this material is often compared with the characteristics characteristic of mineral wool, while it has the same disadvantage – hygroscopicity. The cost of lightweight polyurethane foam is much higher, which makes its use not too justified.

If you want to use lightweight open-cell polyurethane foam for insulation, you need to take care of the presence of layers of waterproofing and vapor barrier materials, as well as think over the facade ventilation system to remove excess moisture. But if we compare this option with the same mineral wool, it is worth noting that the sound insulation performance in this case will be higher.

Structure of polyurethane foam with closed cells

This material is extremely rarely used as insulation for the roof or facade, because it does not cope with its task too well, being susceptible to external factors. But if we are talking about the need for insulation of internal floors or partitions, then its use is fully justified.

Closed-cell polyurethane foam has much more acceptable characteristics: it seizes well on any surface (the exception may be polyethylene) and is absolutely not hygroscopic. Depending on the density index, it is divided into three categories:

low density (28-32 kg/m3). More often than other options, it is used for spraying on walls and ceilings in order to create a thermal insulation layer. The thermal conductivity coefficient of this material is 0.02-0.028, which practically corresponds to the air index (0.022). As for vapor permeability, the indicator is as close as possible to wood – 0.05;

The structure of the hardened foam

medium density material is designed to fill cavities. Its only difference from the previous material is a lower expansion rate, which makes it comfortable to use it to fill the space of layered walls, etc.;
High density PU foam (40-80 kg/m3). Designed to insulate surfaces that are going to be subjected to serious mechanical loads. At the same time, a higher density provides a higher coefficient of thermal conductivity.

How much does polyurethane foam insulation cost, price sq. m.

Considering the issue of prices for insulation of PU foam of 1 sq. m., it is worth noting that the cost directly depends on what type of material was used. The cheapest is a light open–cell PU foam. However, in order for the work to be carried out not in vain, you will also have to spend money on hydro- and vapor-insulating materials, which in total will lead to the same expenses as thermal insulation with medium-density material.

Spray gun for PU foam

The cost of the work, provided that high-quality materials from popular manufacturers are used, starts from 400 rubles. per 1 sq.m. Of course, much depends on the thickness of the applied layer, because this is due to the expense, but such subtleties are discussed individually immediately before the start of the work.

Useful advice! If you want to choose the most profitable material, you can simultaneously request from several firms the calculation of the cost of work, taking into account the required coverage area. This way you will receive information about all current offers and will be able to give preference to the option that suits you best.

Insulation of PU foam: pros and cons of using the technology

The technology of home insulation of PU foam has a lot of very diverse reviews, both positive and negative. Let’s consider what is more, advantages or disadvantages, and whether it is worth giving preference to this type of insulation.

It is necessary to use high-pressure equipment for spraying PUF

Positive characteristics of FOAM insulation: user reviews

The main advantage of this method to provide the building with high—quality thermal insulation is high efficiency. Due to its cellular structure, this material retains heat perfectly. But there are other advantages that should not be overlooked:

the absence of seams and joints eliminates the occurrence of such a phenomenon as “cold bridges”, which has a positive effect on heat preservation;
you can spray PU foam on any surface, even complex in design or texture;
the low level of hygroscopicity of the material has a positive effect on the waterproofing qualities of the surface;
PU foam sets on any surfaces except polyethylene. Interestingly, this is positive at first glance, the quality can also be attributed to disadvantages, since it is almost impossible to wash polyurethane foam, and there is no solvent for it. The only way to get rid of it is to tear it off manually, and this almost always leads to significant damage to the surface on which it was applied;

Insulation of the attic with polyurethane foam

the operational life of PU foam with full preservation of all technical characteristics of the material is 25 years. After that, the thermal insulation continues to operate, although the thermal conductivity of the spraying increases;
spraying is done fairly quickly, so that carrying out all the necessary work will not take much time;
the material is self-extinguishing and does not support gorenje even in case of fire;
the coefficient of vapor permeability is 0.05-0.06, which makes it possible to effectively remove excess moisture after warming the walls with polyurethane foam.

Useful advice! All shortcomings and shortcomings are identified during the first year of operation. If no shortcomings have been identified during this period, you don’t have to worry about it for the next 25 years.

Spraying of rigid PU foam

Disadvantages of polyurethane foam insulation: cons and pros

As you can see, the number of positive characteristics of this material is large, and we can say that all these positive aspects fully justify its use as a heater. However, PPU also has disadvantages, and it is better to know about them in advance:

the cost of spraying PU foam is about 1.5-2 times higher than if you use mineral wool as a heater;
compliance with the spraying technology directly determines the life and quality of its service. Only with the availability of high-quality equipment and the appropriate experience of the duster, it is possible to get the desired result;
insulation of PU foam with your own hands is a very complex and often unjustified process. This is largely due to the high cost of the required equipment, as well as the lack of proper experience in this field;
polyurethane foam does not burn, however, in case of fire it emits a lot of dangerous acrid smoke;

The flammability of polyurethane foam is quite low

as a result of exposure to ultraviolet rays, the foam deteriorates, losing its original appearance, changing color from white to dark brown.

Wall insulation with foam: technology of external and internal cladding

Wall cladding technology. Preparatory stage of work, adhesive compositions, installation of plates on glue and nails, reinforcement of insulation.

Fortunately, most of the proposed disadvantages can be neutralized, for example, by inviting an experienced specialist to work with their equipment and providing the surface with a finishing finish that will further protect the PU layer. But the main deterrent factor for insulation by spraying polyurethane foam is the price, which, nevertheless, is fully justified by the long service life of the coating.

What conditions are necessary for insulation with polyurethane foam: reviews and tips

In order to carry out an expensive procedure for spraying foam was not in vain, it is necessary to carry out all the preparatory work qualitatively and create the necessary conditions. This applies both to the insulation of the walls in the apartment from the inside, and other works: insulation with polyurethane foam of the roof, facade, etc.

For insulation of PU it is better to hire professional employees of a specialized company

First of all, this concerns the preparation of the surface. Even with good adhesion, it is necessary to remove everything that can crumble, for example, old paint.

Useful advice! One of the worst enemies of PU spraying is greasy spots. They must be neutralized and removed before the work begins.

After that, it is necessary to secure all surfaces that are not subject to insulation. As already mentioned, it is almost impossible to wash off the foam, so it is necessary to cover everything with plastic wrap, carefully securing it with tape, leaving no gaps.

Insulation of the roof with the help of PU

If we are talking about insulation of the attic or roof with PU foam, then there are two ways to do this. In the first case, a permanent crate is prepared, on which foam is sprayed. Another option for insulation of the roof with polyurethane foam is a temporary frame, which consists of two planes located in parallel.

If spraying is carried out on the exterior walls of a building, whether it is the insulation of a hangar or a house, the presence of a finishing finish is considered mandatory. By the way, polyurethane foam insulation of a hangar or warehouse is a very common phenomenon. It is only important to make sure that the coating can be fixed on the wall, since the foam will not allow this to be done. To do this, wooden or metal slats are stuffed in advance, which later serve as fasteners.

For example, if you decide to make the insulation of the house with polyurethane foam for siding, the price of the work will be slightly higher, since it will include the installation of fasteners and all necessary fasteners for further fixing of the panels. Although it is worth recognizing that this is an aesthetic, and most importantly – an effective way.

Insulation of the facade of the house PU

How is the process of spraying polyurethane foam

By ordering a company of the appropriate profile to carry out work on the insulation of the building with polyurethane foam, you specify a convenient time at which the minibus arrives with all the necessary equipment. In order to ensure the operation of the high-pressure apparatus, the mains voltage must be 380 V, therefore, a generator is usually started for its operation.

Useful advice! Please note that only low-pressure devices can work from a 220 V mains, which provide a much lower quality of spraying.

A hose is stretched to the surface on which the foam will be sprayed, through which the necessary components will be fed into the gun. At the same time, all people who take part in work or are just nearby must wear special protective suits and respirators. This is necessary to protect the respiratory tract from toxic fumes, as well as to avoid getting foam foam on the skin.

Professional Polyurethane Foam Spraying Equipment

Apply the foam little by little, moving from bottom to top in such a way as to avoid omissions. Due to the fact that the foam expands, it is necessary to monitor the thickness of the resulting layer as it is applied. Although it is worth noting that the excess can be removed by cutting, while it will be impossible to eliminate the deficiency in the future. If we proceed from the technological data, then the layer thickness should be 2-3 cm, however, they almost always do more – about 5 cm.

Having decided to insulate a warehouse, house or any building with polyurethane foam, the most important thing is to find professional specialists who can provide you with really high–quality services. Only in this case your investments will not be in vain and will be able to justify themselves. After all, if all technologies and recommendations for home insulation with polyurethane foam are followed, the price of work will not be low, but it will last at least 25 years, and this is a considerable period during which you will be able to live comfortably without worrying about anything.

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