House insulation by spraying polyurethane foam: pros, cons, comparison, prices

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What is polyurethane gunning really is – is it another example of unjustified technological complexity, or is it really a rational method of insulation that justifies its cost? Let’s understand the cost of services, the benefits of technology and possible problems.

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

The basis and essence of technology

There are two main problems in building insulation. Using materials based on mineral wool, the developer has to take care of protecting the porous material from getting wet, and the polymeric foam insulation boards require careful adjustment and sealing of the joints. Both of these drawbacks do not appear as such when installing seamless insulation belts applied by gunning, that is, by spraying.

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

Foamed polyurethane (PPU) is the main material for such insulation today. In a broad sense, this is the same substance that is found in polyurethane foam cylinders. The only difference is that aerosolized polyurethane foams and hardens when exposed to oxygen and water vapor. When using shotcrete technology, the composition is used two-component, that is, it does not require wetting the surface before application, which has the best effect on adhesion.

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

Another advantage of a two-component foam is its high reaction rate: the composition sets and reaches its final dimensions almost immediately after application. Due to this, the speed of work performance becomes very high, you do not have to return to the treated surfaces again, even when a layer of more than 100-150 mm is sprayed.

Application takes place by means of a special shotcrete machine, which feeds the foam components under very high pressure and automatically doses them with very high precision. Mixing takes place in the chamber of the operator’s console, that is, immediately before contact with the treated surface. At the exit, a very fine fraction is formed, which, together with the high adhesiveness of the material, provides excellent adhesion to any materials other than polyethylene film and some types of plastic.

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

The result is a monolithic insulating cover that fully corresponds to modern ideas about passive buildings. Virtually all polyurethane grades have the highest known resistance to heat transfer. In terms of its heat-saving properties, PPU is second only to foam glass, and even then with a small margin.

Differences in foam formulations

The structure and characteristics of the sprayed foam vary from object to object. The polymer formula, color, density, nuances of preparation and application of the composition can be different. Most of the practical benefits of foam are determined by the size, type and quantity of pores.

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

First of all, it is worth knowing that the time, that is, the foam polymer cell, can be hermetically sealed or open. The closed cells of polyurethane foam contain not air, but an inert gas, which works both to prevent the transfer of heat and to ensure self-extinguishing of the material during combustion. Closed polyurethane foam is charred, while the thicker the crust, the worse it conducts heat, thus, inside the massif the insulation remains intact (there is no oxygen for combustion), which makes the polyurethane foam extremely useful when insulating buildings on a steel frame.

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

Foam with open cells has a sufficiently high vapor permeability, at the same time, its flammability increases. Polyurethane harmlessly survives saturation with moisture, therefore, it is customary to plaster rooms with high (80-100%) relative humidity, such as steam rooms or bathrooms with similar compositions. Foam is able to absorb a sufficiently large amount of water vapor and gradually release it without losing its heat-saving characteristics.

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

These are the main details a customer needs to know about the types of polyurethane foam. Usually, the selection of material and its preparation is undertaken by the performer, because it is almost impossible to carry out such work himself. If we compare sprayed polyurethane with other types of insulation, it is inferior to them only in cost, although in the end such an insulation system may be even cheaper..

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

A reasonable question is how safe is this chemical compound? In the process of spraying, there are many suspended foam particles in the air, which are harmful to the lungs, plus volatile toxic compounds are released. It is possible to stay in the treated area only with respiratory protection. But after complete polymerization, the foam does not react with chemical compounds in any way, has no residual emissions (unlike expanded polystyrene), does not produce dust and does not contain radioactive impurities.

Application options

Mainly gunning with polyurethane foam is used for thermal insulation of attics and attics. The details of the lathing and rafter system have a complex shape, and it is rather difficult to fill the space between them tightly. When spraying, all voids are filled, no supporting crate and vapor barrier are required.

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

By analogy, almost any belt of internal insulation can be sprayed. Starting with covering the enclosing walls with a layer of 3-5 cm and ending with filling the voids of the floors, although in the latter case it is more practical to use filling foam. Since the composition can be sprayed even with a very thin layer, the insulation performs a preliminary leveling of the walls, which is subsequently processed with a finishing putty or cement-sand plaster.

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

The surface of fully polymerized foam itself has good adhesion, but usually, to be sure, either a plaster mesh is additionally attached to it, or pasted over with a fiberglass mesh for gypsum compositions. Separately, it should be said about the insulation of hangars and frame buildings. The foam is applied directly to the inside of the outer coating, does not load the structure, adheres well and does not become covered with condensation.

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

There is one important nuance in PU foam insulation. You already know the difference in the vapor permeability of closed and open cells, and this must be taken into account, following the main rule of drawing up a pie of enclosing structures. It states that the porosity and vapor permeability of the materials that make up the wall must increase from the inside out. Thus, only polyurethane foam with closed cells is used for internal insulation, and for facade decoration – with open cells, but necessarily less hygroscopic than the wall material..

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

Please note that when determining the thickness of the insulation belt according to the thermal engineering calculation, it is necessary to correctly determine the dew point displacement depending on the temperature delta. Polyurethane itself is not afraid of water, but it can be detrimental to a permeable supporting structure. Therefore, PU foam insulation is selected and placed in such a way that it takes over the condensation point.

How much is pleasure

The service of spraying polyurethane foam is estimated by the total volume of foam spent in the production of work. The average price is about 10-12 thousand rubles per m23 foam composition, which is equivalent to 15-20 m2 total treated area. Consumption may increase when it comes to uneven surfaces with deep pores and seams (lathing under the roof or, for example, rubble brickwork).

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

Additionally, the density of the foam must be taken into account. Above, we indicated the cost of covering with lightweight foam (30-35 kg / m3), heavier foam rises in price in proportion to the consumption of chemicals by weight. It should be noted that almost all performers have a system of volume discounts, thus, when insulating large objects, the price of gunning PPU can be equal to the cost of a cheaper insulation..

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

Additionally, services for antiseptic treatment of walls and structures, installation of an appropriate vapor barrier when using foam with an open cell and other related work can be offered.

Installation difficulties

People who have dealt with polyurethane foam-shotcrete, the merits of this material as a heater are not questioned. It is a practical, durable and safe material that fully justifies its cost. But spraying polyurethane foam has a number of unpleasant features..

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

First of all, the whole process, from the preparation of the mixture to its supply and application, has an extremely complex technology. It is unrealistic to reproduce the high quality obtained with the use of expensive professional equipment in homemade practice, otherwise the whole point of buying expensive raw materials is lost.

Home insulation by spraying with polyurethane foam: pros, cons, comparison, prices

Another difficulty can be called a few, but strict requirements for the state of the treated surface. It must be dry and free from dirt and oil stains. Although polyurethane foam is very tenacious to almost all materials, the presence of impurities can reduce adhesion to zero..

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