Disadvantages of polystyrene foam as insulation. Choosing inexpensive insulation: polystyrene foam, its features and application technology

Advantages and disadvantages. An increasing number of homeowners, frightened by heating bills, decide to insulate their homes and choose polystyrene foam as a thermal insulator.

– pros and cons, how not to make a mistake in choosing, the article is devoted to these issues.

Let us stipulate right away: polystyrene foam and expanded polystyrene are produced from the same raw materials, but this different materials. Polystyrene foam is a fragile, flammable material that decomposes in light and cannot withstand mechanical loads and is intended for packaging. For insulation, polystyrene foam is used - a denser material with completely different characteristics, but in common parlance both materials are called the same, which often leads to confusion.

Foam production process organic matter styrene - technical development 1951 by the American concern BASF. The insulation, called “styrofoam,” consisted of 98% air filling a cellular foam base. The material was characterized by low thermal conductivity, low water absorption and vapor permeability.

As a result of improvements in technology, extruded polystyrene foam appeared - self-extinguishing foam. Their main difference is in the structure of the cells: expanded polystyrene has an open structure, while extruded material has a closed structure, which reduces water absorption and increases fire resistance.

The quality and technical characteristics of foam plastics in Russia are declared by GOST 15588-2014 “Heat-insulating polystyrene foam boards. Technical conditions". To insulate walls in a system with an external plaster layer, in accordance with this document, it is necessary to use polystyrene foam marked F - facade.

The letter G in the marking of the plates indicates the content of graphite, which gives lower thermal conductivity and colors the material in the mass in a silver-black color.

We are for it"!

This is what people say who have recently insulated their home with polystyrene foam. Indeed, the material has a lot of positive qualities:

1. Low weight.
2. Low thermal conductivity.
3. Excellent noise absorption performance.
4. Self-extinguishing property.
5. Ease of use.
6. Low cost.

Yes, indeed, polystyrene foam is second only to polyurethane foam in thermal conductivity; the volumetric weight of the slabs is from 10 to 50 kg per 1 m3, while the best materials from mineral wool it starts at 30-35kg/m3, has excellent noise reduction and fades out in 1 second, and can be used by any homeowner.

And we are “against”

This is what people say who have insulated a house without taking into account the specifics of the material. Let us list the negative qualities of the material:

1. Low vapor permeability.
2. High water absorption.
3. Low resistance to mechanical damage.
4. Instability to light.
5. Rodents love it.

Due to low vapor permeability, it is undesirable to use this material to insulate the outside of a house made of wood - without installing two ventilated gaps, which is difficult and time-consuming. A moisture absorption of 4% with low quality work will ensure that the material gets wet and loses its heat-insulating qualities after 2 seasons.

When insulating as part of a light plaster system, any accidental impact can lead to destruction of the protective layer, and the exposed foam plastic under the influence of sunlight just crumble. And finally, the last thing: mice prefer this material for making nests in the thickness of the insulation - it’s warm, it’s easy to gnaw through passages.

In wet plaster systems, a metal perforated corner - the starting profile - saves from the invasion of rodents, but when installing a ventilated facade, they can easily overcome this obstacle.

Where to use polystyrene foam?

So why, despite everything negative qualities Is polystyrene foam popular? How to use the best qualities of the material to make your home comfortable and reduce the negative to a minimum?

Let's consider. A little bit of thermal engineering in the tape: for the insulation system to work, it is necessary that the vapor permeability of the materials increases from the inside out, and the thermal conductivity of the materials, on the contrary, decreases.

That is, the material on the street side should have greater vapor permeability than the internal material and a lower coefficient of heat transfer resistance.

Comparing the heat transfer resistance of building materials and polystyrene foam, we see that this indicator satisfies the requirement, but when comparing vapor permeability, it turns out that in the case of wood, the indicator of polystyrene foam is lower than that of wood, which means that the dew point will be on the wooden structure, which will lead to to condensation settling on it, getting wet and rotting.

When insulating a wooden house with polystyrene foam from the inside, the requirement is also not met, since the heat transfer resistance coefficient of wood is greater than that of insulation.

conclusions

Polystyrene foam is not suitable for insulation wooden houses, but will cope perfectly with the task of retaining heat with walls made of brick or light cellular concrete. When choosing an insulation system, it is better to choose a wet (plaster) system if the house is located near crop areas where voles are a common occurrence.

Taking into account everything said above and strictly following the manufacturers’ instructions when performing work, the use of polystyrene foam for insulation is justified and will last longer than the guaranteed 50 years.

Despite the emergence of more and more new insulating materials, polystyrene foam continues to be popular among professional builders and home craftsmen. What allows this material to maintain its leading position as an insulation material, and what are the ways to use it?

Characteristics

The production of polystyrene foam began more than eighty years ago. The first block was released in Germany, after which it began to be used everywhere in various territories. The basis for the insulation boards are polystyrene beads. Initially, they are elements with a dense structure that do not even remotely resemble foam plastic. At the first stage of production, they are foamed. Next, the base is dried and cured, which is subsequently immersed in a special chamber, where it is sintered with steam at a certain pressure. At the pre-sale stage, the foam comes in large blocks that are cut to specification.

The size of the standard sheet that is used for insulation is one meter long and wide; there are also options for a foam sheet with half the width. The most popular sheet size is 120 by 60 cm. The difference between types lies not only in size, but also in the density of the material. The normal density for facade insulation is 25 kg per cubic meter. Slabs with a density of 15 and 40 kilograms are also produced. This indicator directly affects thermal conductivity. The higher the number, the lower the thermal conductivity and the higher the price for the foam. Denser insulation can withstand greater loads, so it is often used for floor insulation.

Due to the fact that the balls undergo preliminary foaming, this saturates them with gas, which causes the low thermal conductivity of the foam. Its indicator is within 0.038 W/(m×K). Typically foam is produced white, but during the manufacturing process of polystyrene beads, the manufacturer can add any desired pigment to differentiate their product from other options. In some cases, foam plastic can also be called extruded polystyrene foam and polyethylene foam. These materials differ from polystyrene foam in the production method, as well as in the underlying material.

Properties

Based on the characteristics and experience of using polystyrene foam, it is quite easy to highlight its strengths and weaknesses. The advantages of such an insulator include:

• minimum weight;
• environmental cleanliness;
• low cost;
• possibility of self-installation;
• the possibility of insulating various surfaces;
• ease of processing and adjustment;
• resistance to biological processes;
• soundproofing properties.

The solids in polystyrene foam make up only a few percent of the total volume of gas that is contained in the material. This determines its light weight. Thanks to this, the insulation is ideal for use with frame buildings, because it does not exert significant pressure on the foundation and walls. This feature also simplifies the process of lifting the material to a height and self-installation. Polystyrene is a polymer, which in its structure and composition does not pose any harm to human health and the environment if it is not consumed as food, so you can insulate a building with polystyrene foam without fear that harmful substances will begin to be released from heating over time. The comparative cost of such material is low, so it is suitable for low-budget insulation of temporary buildings.

Installation of the material does not cause any particular difficulties, so it can be carried out without outside help. Due to its versatility, insulation can be applied to any accessible surface. At the same time, polystyrene foam does not react with most building materials, unless you take organic solvents into account. Therefore, when laying polystyrene foam on wooden, brick or concrete surfaces, there are no problems. The insulation can be processed with a regular knife or hacksaw, which simplifies the process of adjusting it to fit various shapes. The material is thin and can take on curved shapes, so insulation is available semicircular bay windows. Polystyrene foam is excellent insulation for plinth and foundation. This is due to the fact that it can be located in the ground long years without changing properties, because it is not subject to rotting processes and mold and mildew do not develop on the surface of the foam. A wall insulated with foam plastic acquires additional soundproofing properties, which is also a positive effect.

It is important to know about the disadvantages, which, however, are offset by the existing advantages:

• instability to organic solvents;
• low mechanical strength;
• fire hazard;
• lack of vapor permeability.

It is not recommended to use insulation during painting works. Certain types of paints that are diluted with solvents can damage the material by decomposing it. A surface insulated with foam plastic requires additional reinforcement by installing a fiberglass mesh to increase its strength, since even a slight mechanical impact can leave a dent in the material. Although fire retardants are added to the insulation during production, this does not make it absolutely fireproof. When exposed high temperatures the material melts with the release of carbon dioxide, but is capable of self-extinguishing. Due to the density of the material, air does not pass through it, which provides insulation from moisture, but creates a barrier to its outflow, which can result in the formation of mold under the insulation.

Note! Rodents can live inside the insulation boards. Mice and rats do not eat it, but simply make passages inside, creating a home. Poultry also like to peck at the foam, damaging its integrity.

Is it worth insulating from the inside?

The question of insulating a house or other building with foam plastic from the inside raises a lot of controversy, since it is difficult to answer this question unambiguously. It is worth saying that this method of foam insulation exists, but it also has opponents. The main argument is that heat-intensive materials should be placed indoors, since they absorb ambient temperature, and thermal insulation materials should be left outside so that they prevent the penetration of cold into building materials. Insulation from the inside with foam plastic is possible if you provide high-quality ventilation of the room, which will promptly remove moisture, which will prevent the formation of mold. It is also important to calculate everything correctly so that the dew point does not shift towards the living space. In this case, due to the difference in air temperatures inside and outside, condensation will occur between the insulation and the wall, which will lead to the destruction of the blocks. A video of the process of internal insulation with foam plastic is below.

Polystyrene foam for attic insulation with polystyrene foam has been and remains one of the most popular for a long time thermal insulation materials. Even the presence on the market of a wide variety of mineral wool insulation, products made from extruded polystyrene foam, and other materials did not affect the leadership of the insulator among inexpensive insulation materials.

In this article we will look at the types of polystyrene foam, their technical characteristics, as well as the pros and cons that this material has.

1 Features of the material

The use of polystyrene foam as a thermal insulation material is widespread in both industrial and private construction.

The main reason for this is the cost of this material with glue for polystyrene foam, which, with technical characteristics comparable to other insulation materials, is an order of magnitude less. Having analyzed all the features of using polystyrene foam as insulation, we can draw the following conclusions:

• The technology allows you to reduce the financial costs of insulation. For example, even if we take into account that the cost of mineral wool and polystyrene foam is identical (in reality, a cubic meter of foam plastic costs about 2 thousand rubles, mineral wool - 4-6 thousand rubles), then for thermal insulation of the same surface, mineral wool will need on average one and a half times more than foam;
• Simplified installation - there is no need to create an additional supporting structure; the sheet is mounted on the walls using an adhesive solution.

Using this material, you can insulate any surfaces - walls, ceilings, floors, facades, roofs, interfloor ceilings.

Polystyrene foam is also often used as the main insulation inside the walls of houses built using frame technology, and free space inside hollow brick walls.

House insulated with foam plastic

2 Types of material and their technical characteristics

Classification of polystyrene foam is carried out depending on the density of the material, according to which the following are distinguished:

There is also foam of increased hardness PS-1 and PS-4.

The technical characteristics of PSB foam are as follows:

• Density, kg/m3: PSB S15 -8, PSB S25 – 15, PSB S35 – 25;
• Compression resistance, MPa: C15 – 0.04, C25 – 0.08, C35 – 0.16;
• Resistance to bending, MPa: C15 – 0.06, C25 – 0.018, C35 – 0.25;
• Percentage of water absorption during complete immersion in 24 hours: C15 – 4, C25 – 3, C35 – 2;
• Fire extinguishing time in the absence of direct contact with fire, sec: C15 – 4, C25 – 1, C35 – 1;
• Flammability class: for all materials – G3 (normally flammable);
• Thermal conductivity coefficient, W/mk: C15 – 0.043, C25 – 0.039, C35 – 0.037;
• Vapor permeability coefficient, mg; C15 – 0.05, C25 – 0.05, C35 – 0.05;
• The normal operating temperature for all types is from -60 to +80 degrees. At the same time, polystyrene foam is not dangerous to human health.

Balls - components of foam plastic that hold air inside

Polystyrene foam of the PS class, with increased density, is manufactured using pressing technology; they can have a density from 100 to 600 kg/m3. The scope of application of such foam plastics is floor insulation concrete screeds, laying under highways and any structures that exert high mechanical pressure on the thermal insulation material.

The technical characteristics of pressed dense foam are, in general, identical to materials manufactured using standard technology.

2.1 Advantages of use

Considering the low cost of the material (even if it is reinforced foam plastic for the facade), its advantages, when used as insulation, are undeniable.

The quality of insulating the facade, attic, or ceiling of a house with the help of such material, no matter what anyone says, it is possible! Insulation with foam plastic will not seem inferior, since the difference in the thermal conductivity of materials at the level of 0.03-0.05 W/mk is simply not felt.

Among strengths insulator, making it a very good insulation, the following main factors can be identified.

2.2 Low thermal conductivity

In terms of thermal insulation properties, the material does not differ much from insulation made from extruded polystyrene foam or mineral wool of average quality, however, it costs an order of magnitude lower.

Thus, the thermal conductivity of foam plastic, depending on the density of the material, ranges from 0.037 to 0.041 W/μ, which allows effective insulation premises made of any material - wood, brick, expanded clay block, or gas silicate blocks. For the same materials, urea foam can be used.

Insulating the facade of an apartment with polystyrene foam

The low thermal conductivity of polystyrene foam makes it possible to high-quality thermal insulation buildings when using relatively thin insulation, so, in practice, foam plastic with a thickness of over 12 centimeters is used extremely rarely.

For comparison, the thermal conductivity of mineral wool is 0.035-0.04 W/mk, and that of extruded polystyrene foam is 0.039 W/mk. At the same time, the cost of these materials exceeds the price of foam plastic by at least 2-2.5 times.

2.3 Hydrophobicity

The hydrophobicity of a material is its ability to absorb liquid. The less hydrophobic the insulation, the better, since when moisture is absorbed, thermal insulation materials are prone to losing their properties. performance characteristics, weight gain, resulting in additional stress on bearing structures, and rapid destruction.

Polystyrene foam, due to its closed-cell structure, has minimal hydrophobicity. As practice shows, in 24 hours of complete immersion in water, the material is able to absorb no more than 3% of the liquid from its mass. At the same time, 3% is the maximum absorption rate; it is not linear and does not increase over time.

Thanks to this, using polystyrene foam it is possible to insulate surfaces exposed to constant contact with water. For example, the material is often used to insulate the foundation, or ground floor, which are constantly affected by groundwater.

2.4 Noise reduction

Polystyrene foam for insulating a house with polystyrene foam from the inside, in addition to thermal insulation, is often used for soundproofing rooms. Insulating a house with polystyrene foam allows you to kill two birds with one stone: in addition to reducing the heat loss of the building, you will also receive high-quality sound insulation, which significantly increases the comfort of living in the city center, or near railways and highways.

Soundproofing the ceiling with foam plastic

The sound-dampening properties of polystyrene foam arise from its porous structure. Inside the numerous cells, air is closed, which dampens all penetrating sound waves.

Of course, for high-quality insulation of impact noise, using foam plastic alone is not enough, but this material dampens noise transmitted through the air quite effectively.

2.5 Chemical inertness

An indicator such as chemical inertness is one of the main factors determining the durability of any thermal insulation material. Polystyrene foam is fine with these parameters - it is not subject to destruction under the influence of alkaline and saline solutions, acids, alcohols, and water-soluble paints.

Polystyrene foam as insulation also has the advantage of microbiological inertness - microorganisms do not grow in it, it is not afraid of dampness and does not mold. The only negative is that rodents love to eat this material, so when insulating with this material, you must first take care of killing mice.

2.6 Compliance sanitary standards

Any thermal insulation material used to perform internal insulation a residential building, first of all, must be environmentally friendly, since in the case of the opposite, its fumes will constantly be breathed by the residents of the house.

The compliance of polystyrene foam with all sanitary standards was confirmed by the Moscow National Institute of Hygiene named after Erisman (conclusion No. 03/PM8), according to which, when air samples were taken in rooms insulated with polystyrene foam, there were no harmful human body no substances were detected.

This is what the foam structure looks like under a microscope

2.7 Disadvantages of use

Significant disadvantages that prevent the use of this material as industrial insulation are not so terrible for household insulation.

First of all, it is worth highlighting the susceptibility to combustion, which does not make it possible to use polystyrene foam as insulation from the inside of industrial buildings and other premises with high requirements for fire safety. According to the flammability class, foam plastic belongs to category G3 or G4, depending on the manufacturing technology.

To solve the issue of fire resistance, when producing polystyrene foam, a fire retardant is added to its composition, thanks to which the material acquires the ability to extinguish independently in the absence of direct contact with fire.

The optimal temperature range at which foam plastic can operate normally is from -100 to +80 degrees.

Practice shows that the material is capable of withstanding a short-term temperature increase of up to 110 degrees without loss of performance characteristics, for example, upon contact with molten bitumen mastic, however, with long-term exposure to temperatures above 80 degrees, deformation of the foam is possible.

The average melting point of polystyrene foam is 270 degrees. The ignition temperature is 440 degrees, and if there is no direct contact with the fire, the foam will extinguish within 4-5 seconds.

For example, the ignition temperature of ordinary paper is the same 440-450 degrees. The melting point of plastic is 220 degrees.

Technical characteristics of polystyrene foam: thermal conductivity

Technical characteristics of polystyrene foam - material properties. Analysis of the technical characteristics of polystyrene foam.

Properties of foam plastic

Expanded polystyrene (foam)- a white insulating material consisting of 98% air, enclosed in billions of microscopic thin-walled polystyrene foam cells. Expanded polystyrene is resistant to moisture, resistant to aging, and not susceptible to microorganisms. As the most effective, insulating materials made of foam plastic (expanded polystyrene) have been used for thermal insulation of roofs, walls, ceilings and floors in residential and administrative buildings for 30 years. Ease of processing using hand saw or knife, low volumetric weight, possibility of gluing with various building materials, simplicity mechanical fastening- undoubted advantages of expanded polystyrene (foam). Products made from expanded polystyrene (foam) are biologically safe and are used for food packaging.

Expanded polystyrene foam is virtually waterproof. The amount of water absorbed in relation to the weight volume of polystyrene foam per year ranges from 1.5-3.5%. On the other hand, the air permeability of polystyrene foam greatly exceeds its water permeability. That is, the wall “breathes”. Ambient temperature has no effect negative influence on the physical and chemical properties of expanded polystyrene. At temperatures up to 90°C, expanded polystyrene does not change its properties even over a long period of time. Atmospheric influence external walls from polystyrene foam blocks are practically not affected.

Purposes of expanded polystyrene (foam) insulation

• reduction of costs for installation and construction work;
• saving thermal energy for heating;
• cost reduction heating equipment(by reducing its quantity);
• increase usable area buildings by reducing the structural thickness of the walls;
• increasing the temperature comfort of the room;
• increasing the environmental safety of a building structure.

Expanded polystyrene (foam plastic) has a high thermal insulation ability, far exceeds known traditional building materials, and can ensure the long life of any building, regardless of climatic conditions.

The need and advantages of using expanded polystyrene (foam) in construction

There is an opinion that polystyrene foam is the most optimal material for construction. Considering everything physicochemical characteristics polystyrene foam and polystyrene foam itself, two groups of characteristics can be distinguished: safety characteristics and operational and technical ones. Let's consider the operational and technical properties of polystyrene foam:

• One of the main properties of foam plastic is its fairly low thermal conductivity coefficient, which allows it to be widely used in various construction works. Due to the evenly distributed air inside the polymer, and, as is known, air does not conduct heat well, expanded polystyrene boards are well suited for basic and additional protection of structures and premises from freezing of walls in all weather conditions.
• Polystyrene foam also has soundproofing and windproof properties, which allows it to be used if necessary.
• The next property is durability. If all basic installation and operating conditions are observed, expanded polystyrene will not change its initial properties and will last for decades. Polystyrene foam is a chemically neutral building material.
• The absolute moisture resistance of polystyrene foam boards allows them to be laid in places where liquid accumulation or leakage is most likely. In this case, the foam does not change its original shape, and the material does not shift or swell.
• Simplicity in installation, fastening and cutting of polystyrene foam sheets and blocks significantly saves developers time and money. You should also take into account the fact that when working with this building material, there is no need to use special protective clothing, equipment and devices for workers.
• Foam is resistant to various types destructive effects of water, alcohol, weak acids and alkalis, thereby extending the service life of expanded polystyrene boards and sheets.

Safety characteristics of expanded polystyrene:

• The main safety indicator of expanded polystyrene is its fire resistance. When polystyrene foam interacts with fire, the melted layers prevent the material from re-igniting and smoldering, which is typical for the wood we are used to.
• Environmental friendliness of the material. The starting product for making foam plastic is styrene, consisting of hydrogen and carbon. Therefore, when polystyrene foam ignites, the same substances are released as when wood or coal burns. Today, foam plastic is the most proven and clean material; it is used in the manufacture of children's toys, for storing and transporting food.
• Temperature endurance. On this moment no minimum temperature threshold has been established at which the use of polystyrene foam is contraindicated. Maximum temperature approximately limited to +100°C. but it is necessary to take into account that such temperature values ​​​​do not occur in construction, and therefore this value can be neglected.
• Resistance to microbiological factors. Foam boards do not contain nutrients for the life of microorganisms, therefore the development and growth of various fungi and bacteria does not occur. This property guarantees cleanliness in the work and operation of polystyrene foam.

With the introduction of new construction standards for thermal protection of buildings in Russia, there is a need for the construction industry to transition to new principles for solving problems. At the same time, architects and designers are increasingly turning to new materials and structures that can effectively meet specified requirements. Expanded polystyrene is one of these materials. Thermal insulation properties expanded polystyrene (foam) in comparison with other materials are shown in the following table and speak for themselves. According to current Russian building codes, the thickness of walls that equally prevent heat loss in a building should be approximately:

• Reinforced concrete - 4.20 m
• Brick - 2.10 m
• Expanded clay concrete - 0.90 m
• Wood - 0.45 m
• Mineral wool - 0.18 m
• Expanded polystyrene - 0.12 m

Calculation of thermal insulation with foam plastic

The required thickness of thermal insulation is determined depending on the climatic conditions of operation and the purpose of the building; in addition, measures to protect against moisture condensation and energy saving should be taken into account.

Safety

The material is produced, used and disposed of without harming the environment and human health. Expanded polystyrene is 100% reusable, the cleanest and safest thermal insulation material. It is also used as packaging material for food, toys, etc.

Good thermal resistance

Expanded polystyrene is 98% static air trapped within its closed cell structure. Static air is known to be the best natural heat insulator. The content of polystyrene plastic in the material is only 2% - this combination provides PSB-S slabs with remarkable heat-insulating properties. Moreover, polystyrene foam retains its heat-insulating properties as in wet conditions, and with low temperatures.

Soundproof and windproof

When insulating with polystyrene foam boards PSB-S does not need additional wind protection. In addition, the sound insulation of structures is improved.

Moisture resistance

Thermal insulation boards PSB-S are not hygroscopic. The moisture absorption of expanded polystyrene is significantly lower than that of mineral wool. Even when immersed in water for a long time, PSB-S thermal insulation boards absorb only a few percent of water from their volumetric weight, this allows them to be used for insulating foundations with direct contact of the insulation with the ground.

Short-term and long-term resistance to stress is one of the most important properties of expanded polystyrene. And it is significantly higher than that of mineral wool.

Maintaining stable dimensions

PSB-S insulation remains stable in building structure, and throughout the entire life of the building: it does not shrink, does not decrease in size and does not move in the structure.

Durability

During the entire life of the building, the quality of the properties of PSB-S insulation does not deteriorate. The minimal moisture absorption of the material ensures that it maintains resistance to stress and heat-insulating ability in humid conditions. Expanded polystyrene does not form a nutrient medium on its surface for the growth of microorganisms, does not rot, does not mold or rot, and is chemically resistant.

Ease of use

Due to their low weight, polystyrene foam boards PSB-S are convenient and easy to handle, they can be easily cut into pieces required sizes using ordinary tools. For a builder, it is extremely important that when using expanded polystyrene in work, it is not necessary to use protective equipment: it is non-toxic, odorless, does not emit dust during processing, and does not cause skin irritation.

Flammability

All PSB-S thermal insulation materials are made from raw materials containing fire-resistant material - fire retardant, and comply with the requirements of GOST 15588-86. The operating temperature of expanded polystyrene is from -200°C to +85°C.

Polystyrene foam as insulation – its advantage and scope of application

Of all the thermal insulation materials available in their arsenal, builders most often choose foam plastic. Polystyrene foam has already been used as insulation for quite some time. for a long time for thermal insulation of both large construction projects and individual construction.

Many believe that this is one of the best materials for thermal insulation of houses and other premises. Almost every material has its own pros and cons; having considered them, we will understand whether polystyrene foam is really the best the best option for insulation of premises.

Characteristics of polystyrene foam as insulation

Polystyrene foam is a foam mass. Polystyrene foam slabs are distinguished by their low weight, since the inside is mainly filled with air. The raw materials from which polystyrene foam is made have even greater density than the original material. The main volume of polystyrene foam consists of still air, which is a good heat insulator.

Advantages of polystyrene foam as insulation

1. According to the hygienic conclusions of the manufacturers and in accordance with the state standard, polystyrene foam is an environmentally friendly material. It is harmless to humans as it does not release toxic substances into the air.

2. In addition, this material has practically no shelf life, since it is not attacked by microorganisms and does not decompose. It has low thermal conductivity and has high vapor barrier properties.

3. Polystyrene foam is fireproof and fire resistant. When the room temperature changes, it does not change its physical and chemical properties. High-quality foam plastic contains a fire retardant that has self-extinguishing properties, as a result of which it does not support combustion.

4. The weight of this material is very low, and this is an additional plus, since it does not weigh down the structure and does not affect the shrinkage of the foundation.

5. It should be noted that this is an inexpensive material, easy to install in a building, and very durable.

Disadvantages of polystyrene foam

In front of everyone positive properties polystyrene foam, it also has a number of disadvantages.

1. Polystyrene foam has low mechanical strength, therefore, it is necessary to create additional protection for it.

2. In addition, it can be destroyed when nitro paints or paint and varnish materials with such a composition.

3. The disadvantages of polystyrene foam include its inability to allow air to pass through.

4. It may be susceptible to rodent attacks, so you need to cover it with a durable layer of plaster.

Insulation of walls with foam plastic

Polystyrene foam is good insulation for walls. The walls are insulated with foam plastic, both inside and outside. But most often, insulation is done from the outside. When insulating from the outside, it is possible to move the highest freezing point to the outside of the wall, thereby preventing the cold from penetrating into the room.

It is not correct to carry out internal insulation of walls that face the street. The fact is that the wall that goes outside must warm up thanks to internal heating. When laying polystyrene foam on the inner surface of the wall, the wall will be insulated on both sides, that is, the wall will not only be insulated from the outside, but it will also be thermally insulated on the inside of the room, which will prevent it from being heated by heating.

As a result, the “dew point” will shift inside the wall, or this point will end up between the wall and the foam layer. Moisture will accumulate in these places and saturate the wall; in addition, this moisture can freeze in cold weather, that is, all this will lead to a disruption in heat exchange, and the walls will gradually collapse.

Therefore, the best option would be to insulate the walls from the outside, but you will definitely need to finish the foam plastic on top with a layer of durable plaster. Polystyrene foam does not have increased mechanical strength, so strengthening the walls is necessary for the durability of the structure.

Floor insulation with foam plastic

Thermal insulation of the floor is also performed using foam boards. The use of foam plastic for floor insulation is very effective method, allowing you to keep the floors warm and reduce noise when walking on the floor or when moving furniture. In this case, foam boards with a thickness of up to 50 mm are used for thermal insulation of the floor. They are laid on a layer of material with insulating properties. Next, the seams are sealed, and only then everything is filled with screed.

Roof insulation

For thermal insulation of roofs in houses and buildings for various purposes, two methods are used: unventilated (warm roof) and ventilated (cold) roof. In the first case, when creating a non-ventilated (warm) roof, the entire roof is covered with 70 mm thick foam plastic slabs, and a bitumen layer is poured on top. With the second method, foam boards are installed on the back of the roof, leaving a ventilated surface to prevent the formation of water vapor. It is very important to properly insulate attic roofs.

Foundation thermal insulation

Insulating the foundation with polystyrene foam requires enhanced protection, since not only does soil pressure occur, but also the load on the foam plastic increases in winter during soil heaving, and this occurs during freezing. Strong reinforcement is required; for this, brickwork is done or concrete is poured.

Thermal insulation of engineering systems

Foam plastic has become very often used for thermal insulation of engineering systems. For example, for thermal insulation of water pipes and sewer pipes during winter freezing, the use of polystyrene foam will be simply irreplaceable, as it will help to avoid the catastrophe of pipe breakage in the winter. Foam plastic is also used for thermal insulation of cold water supply pipes. Thermally insulated with foam plastic and ventilation ducts, telephone lines and buried channels.

Polystyrene foam as insulation, its characteristics and scope of application Video

Polystyrene foam has been used as insulation for quite a long time. However, polystyrene foam, like any other insulation material, has its advantages, disadvantages and a certain scope of application, which will be discussed in this article.

Foam plastic - characteristics and properties of insulation

Foam plastic is a modern building material that is used for thermal insulation of buildings and structures. Can be used for both outdoor and interior works. The foam characteristics of which we will consider in this article have a number of undeniable advantages. This material is extremely popular and is in high demand among developers and construction organizations.

Structure and composition of foam

Polystyrene foam is a white material with a rigid foam structure, which contains 98% air and 2% polystyrene.

For its production, a technology has been developed for foaming polystyrene granules, after which these microscopic particles are treated with hot steam. The procedure is repeated several times, as a result of which the density and weight of the material are significantly reduced.

The prepared mass is dried to remove residual moisture. The process is carried out outdoors in special drying containers. At this stage of production, the structure of the foam takes its final shape. The granule sizes range from 5 to 15 mm.

The dried foam granules are given the appropriate shape in the form of slabs. Pressing is carried out on special installations or machines that “pack” the foam and give it a compact shape.

After pressing the foam, it is again treated with hot steam, resulting in the formation of white blocks with the specified width parameters. The blocks are cut with special tools to the sizes required by the customer. Foam sheets can be standard or non-standard sizes. The thickness of the foam varies from 20 to 1000 mm, and the dimensions of the plates have the following dimensions:

Technical characteristics of polystyrene foam

Thermal conductivity

The undeniable advantage of polystyrene foam is its unique thermal insulation abilities. This is explained by the fact that the polystyrene cells in the form of polyhedrons measuring 0.3-0.5 mm are completely closed. The closed cycle of air cells reduces heat transfer and prevents the penetration of cold.

Windproof and soundproofing properties

Walls insulated with foam plastic do not require additional wind protection. Moreover, the sound insulation of buildings and structures is significantly increased. High sound insulation properties are also due to the cellular structure of the foam. For high-quality insulation of premises from external noise, it is enough to lay a layer of material 2-3 centimeters thick. The thicker the foam layer is used, the better sound insulation can be achieved in the room.

Low water absorption

Compared to other materials, foam is characterized by low hygroscopicity. Even when directly exposed to water, it absorbs minimal amount moisture. This is explained by the fact that water does not penetrate through the walls of the foam cells, but only seeps through separate channels through interconnected cells.

Strength and durability and foam

Foam plastic slabs do not change their physical properties for a long time. They withstand significant pressure, but do not deform or collapse. A clear example serves the construction of runways, where polystyrene foam is widely used. The degree of strength is determined by the thickness of the polystyrene foam board and its correct installation.

Resistance to biological and chemical influences

Expanded polystyrene boards are resistant to aggressive environments, including solutions of salts, alkalis and acids, sea ​​water, lime, gypsum, cement, bitumen, silicone and water-soluble paints. Substances containing animals and vegetable oils, as well as gasoline and diesel fuel.

When using foam plastic as building material contact with aggressive agents should be avoided chemical compounds, among which:

• organic solvents (paint thinners, turpentine, ethyl acetate, acetone);
• saturated hydrocarbons (alcohols) and petroleum products (kerosene, gasoline, diesel fuel, fuel oil).

The cellular structure, which is the basis of the foam, when in contact with the listed compounds, is disrupted and can completely dissolve in them.

Polystyrene foam is an unfavorable environment for microorganisms. However, if it is significantly contaminated, harmful microorganisms may appear and multiply on its surface.

Easy installation and ease of use

Polystyrene foam slabs are distinguished by their unusually low weight, which makes them easy to handle and their installation does not cause difficulties. They are cut into pieces required sizes with ordinary tools.

Expanded polystyrene is recognized as an environmentally friendly material and does not emit harmful substances. Therefore, builders working with it do not need individual means protection. The material is non-toxic, does not generate dust, does not irritate the skin and has no odor.

Fire safety

High-quality building materials must meet all fire safety requirements and be resistant to open fire. Polystyrene foam does not support the combustion process and flares up at a temperature that is twice that of wood. Moreover, when burning polystyrene foam, the energy released is 8 times less than when burning wood. This means that the fire temperature when burning foam is much lower.

Expanded polystyrene can only ignite during direct contact with an open flame. When the exposure stops, the foam self-extinguishes within four seconds. These indicators characterize it as a relatively fireproof building material. Although manufacturers and sellers claim that it is absolutely fireproof.

Foam grades depending on density and their application

The numbers in the foam marking indicate its density; the higher the number, the greater the density.

Polystyrene foam grade PPT-10 is used for:

• insulation of construction cabins, trailers and containers;

Foam plastic grade PPT-15 is used for:

• sound and thermal insulation of internal walls;
• insulation of balconies and loggias;
• insulation of houses, apartments and other premises;
• sound insulation and insulation of structures that do not experience significant mechanical loads;
• thermal insulation water pipes(protecting them from freezing and increasing their service life).

Polystyrene foam grade PPT-20-A is used for:

• thermal insulation of building facades;
• production of decorative and finishing materials.

Polystyrene foam grade PPT-25 is used for:

• sound and thermal insulation of internal and external walls;
• thermal insulation of foundations and floors;
• thermal insulation attic floors and ceilings;
• sound and thermal insulation attic premises and roofs;
• insulation of balconies and loggias, facades of houses and apartments;
• manufacturing structures of multilayer panels (including reinforced concrete);
• arrangement of access areas, heated paths, car bays, parking lots;
• hydro and thermal insulation of underground communications;
• protection of soils from swelling and freezing;
• thermal insulation of water pipes;
• thermal insulation of sewage drains;
• strengthening the slopes of swimming pools, sports grounds, flower lawns.

Polystyrene foam grade PPT-35 is used:

• for internal and external sound and thermal insulation of walls;
• for sound and thermal insulation of foundations and floors;
• for sound and heat insulation of attic rooms and roofs;
• for insulation of facades of apartments and houses, loggias and balconies;
• when arranging the floors and walls of refrigeration chambers in multi-storey refrigerators;
• for thermal insulation of heated soils, ventilated undergrounds in auto repair shops;
• when laying or reconstructing highways in wetlands and moving soils;
• during installation of refrigeration equipment (refrigerated cars, freezing units) and cold insulation of warehouse premises;
• to protect foundations from freezing and increase their strength during the construction of highways and runways;
• when laying and repairing railway lines (protection from frost, protection from distortions and subsidence of roads on marshy soils);
• for covering the soil in the process of strengthening bridge ledges and embankment slopes.

The foam marking is supplemented with conventional letter symbols:

• A – a plate with smooth edges in the shape of a parallelepiped;
• B – the slab has edges in the form of an L-edge;
• R – slab cut to its outer size using a hot string;
• F – slab made to the outer size in a special shape;
• N – foam board intended for outdoor use.

Here is an example of what the foam marking looks like:

Disadvantages of polystyrene foam

#1. The main disadvantage of expanded polystyrene is its flammability. Polystyrene foam sheets are highly flammable and release toxic substances. To counter this, special additives and technologies for the production of self-extinguishing foam have been developed.

#2. Foam plastic structures must be protected from the damaging effects of solvents and ultraviolet radiation. Using polystyrene foam boards outdoors requires protecting them from sunlight.

Foam plastic - characteristics and properties of insulation

Due to its characteristics, foam plastic has become very widespread in modern construction. It is one of the best, and even irreplaceable, heat-insulating and sound-proofing materials.

Who hasn't seen women selling ice cream in polystyrene boxes? Surely everyone saw it. So polystyrene foam is well known to everyone, since it has long been used for thermal insulation. Moreover, not only for protection from the cold, but also from heat.

What is polystyrene foam?

Polystyrene foam is a plastic in which, using a certain technology, pores (bubbles) with air have been created. Thanks to these air bubbles, plastic became insulation. (Actually, the insulation is air, and the plastic only prevents it from evaporating from the insulated structure.)

There are many foams. But the most common is polystyrene foam, which is usually called polystyrene foam.

Pros of polystyrene foam

Polystyrene foam has the following advantages:

• light weight;
• does not rot;
• not afraid of acids and alkalis;
• working with him is not only easy, but also simple. Polystyrene foam is processed (cut) very simple device made of stretched nichrome wire through which an electric current is passed. However, if you really don’t want to tinker with different wires and, especially, under current, you can get by with a simple sharp knife with a thin blade (the author of this article does just that);
• not afraid of moisture (not always, but more on this below);
• accessible, because it is sold in almost any construction supply store;
• and the price is also affordable.

Disadvantages of polystyrene foam

1. Burns at relatively low temperatures (already at 80 degrees!). Therefore, it would be better for him to be between non-flammable materials, for example, between brick walls.

2. Poor strength. Yes, the strength varies: 50...160 kPa. There is even 400 kPa, but - the price! So polystyrene foam is not used as an independent structural material (well, except for the manufacture of those same ice cream boxes :)). Therefore, in construction, hollow blocks are made from foam plastic, into which concrete is poured:

Then the load-bearing function is performed by concrete.

The second way to use polystyrene foam is to attach it to walls:

The third method is in the form of crumbs for dry filling into various voids in structures.

3. Everyone who is not too lazy loves to live in polystyrene foam. Perhaps this will help lovers of hamsters, etc., but this is not for me.

Features of choosing foam

Nowadays everything that is possible is insulated with polystyrene foam (it would be more correct to say: I want to). Even entire houses are built from a hybrid of OSB and polystyrene foam. As you might guess, I'm talking about SIP panels. But here lies one trap that no seller of such houses will tell any buyer: the quality of the foam is often very low. This is because polystyrene foam production is cheap and accessible. Manufacturers produce materials (this applies not just to foam plastic, but to any product in general) not in accordance with GOST ( state standard), and according to technical specifications ( technical specifications, developed by the manufacturer himself, and whatever he fits into these conditions will be released).

Let's compare two photos of foam plastic:

In the first photo, the polystyrene foam has granules in the shape of polygons. Due to this, they fit tightly to each other. And in the second photo the granules are in the form of balls, which is why they cannot fit tightly to each other; there are pores between the granules. This foam is vapor permeable! But it is not blown by the wind. That is, steam penetrates into the foam, but is not drawn out by any drafts, and water accumulates in it. The frost hit - the water froze, the frost released - the water melted, over the winter there will be many such cycles, and in a few years even more. As a result, after 5...10 years, a wall made of such foam crumbles into individual balls. And in dampness, toxins and fungi develop and go indoors. In general, such foams require waterproofing.

Is foam plastic the best insulation?

Let's summarize.

Polystyrene foam is a good insulation material: in terms of insulation capabilities it ranks third after polyurethane foam and extruded polystyrene foam. Reasonably priced and available in many building supply stores. It is easy to process, and lifting a foam plastic board is not difficult even for a not very strong person... But it is afraid of fire and mechanical influences. So it needs to be protected with other, more durable and non-flammable materials. Oh yes, and mice, of course...

To figure out whether polystyrene foam is the best insulation, you just need to read about other insulation materials and compare. This is what I invite you to do in the following articles.

polystyrene foam as insulation

Building materials cannot cope with the task of creating a favorable indoor microclimate, so construction cannot do without additional insulation. Builders often use foam plastic as insulation for the roof, ceiling, attic floor, as well as for the foundation and walls. The material has different technical characteristics for thermal conductivity and thickness, which can be used in accordance with the installation location and needs. Another advantage is the ease of cutting the panels and their installation.

Polystyrene foam, or expanded polystyrene, is a cellular mass of foamed plastic. The characteristic lightness of the material is due to the fact that its main volume consists not of the original polymer, but of air, which, moreover, is a poor conductor of heat.

Marking and density of polystyrene foam

If the letter C (PSB-C) is added to the abbreviation marking according to GOST-15588-86, this indicates that fire retardants have been added to the composition of the foamed polymer and such foam belongs to the flammability group G1 or G2. If this letter is missing, it means there are no fire retardants and it is G3 or G4. The material density indicated in the table means the following:

• PSB-S-15 - the number indicates that the density of the panel is not 15 kg/m3, but up to this mark. This is the lowest indicator among all brands, therefore PSB-S-15 is used in places that do not bear mechanical load: insulation of roofs, ceilings, as well as walls and floors under frame cladding. This brand is also used for soundproofing rooms.
• PSB-S-25 - density up to 25 kg/m 3, and such panels have a universal application - they are used more often than other materials. In addition to places that do not bear mechanical loads, this insulation is used for building facades with the application of ordinary and decorative plasters.
• PSB-S-35 - panel density up to 35 kg/m 3 allows their use in sandwich panels, in reinforced concrete structures (permanent formwork), as well as for arranging waterproofing. This brand is also used for underground work - insulation and waterproofing of basements and foundations.
• PSB-S-50 is the most durable polystyrene foam and can be used both for places with low and high mechanical load. Can be used to insulate floors, heated soils and even highways.

Operational and technical characteristics

Thermal conductivity diagram of building materials

The most basic quality of polystyrene foam is low thermal conductivity; this property of polystyrene foam as insulation in comparison with other building materials is shown in the table above. The effect is achieved due to the uniform distribution of air in the volume of the foamed polymer and its thickness. PSB of any density can be used for indoor and outdoor work with any degree of humidity, as well as with temperature changes (the range is from -200ᵒC to +85ᵒC).

In addition to insulation, polystyrene foam is used for sound insulation of certain objects, for example, PSB is laid inside plasterboard partitions or under metal roofing building. Polystyrene foam is a chemically neutral substance and has a high service life. Even when a leak is observed, for example, when the roofing material (corrugated sheeting, slate, etc.) is damaged, the properties of PSB are not lost, since there is no reaction to moisture.

Foam plastic of different thicknesses

Foam panels are resistant to weak acids, alkalis and alcohol, which significantly increases the scope of application. PSB is easy to cut and you can use the most simple tools– a painting knife or a heated nichrome string. Installation is carried out using glue, on umbrella dowels or between profiles.

Technology of using foam plastic for thermal insulation

The ease of cutting foam, ease of installation and low cost contribute to the popularity of the material for private construction. With proper calculations and correct installation foam plastic boards can provide a normal microclimate in residential and non-residential (outbuildings, attics, etc.) premises.

Which side is better to install foam?

Dew point shift depending on the location or absence of thermal insulation

When insulating a building, including an attic, great importance has the location of the insulation, since this shifts the dew point and the effectiveness of the insulating material. If the stove is installed indoors, the wall still remains cold, therefore, it is necessary to increase the thickness of the polystyrene foam. In addition, the dew point (condensation formation) most often occurs at the point where the foam joins the wall, which leads to the formation of mold.

If the insulation is installed outside, then the dew point shifts to the foam and condensation does not collect due to the lack of moisture inside the foamed polymer. At the same time, the wall warms up from the side of the room and moisture does not get there, therefore, the service life increases. If thermal insulation occurs under roofing material, then it is only internal and condensation cannot form at the junction - the dew point is transferred inside the attic.

Calculation of the thickness of foam insulation

The ratio of thermal conductivity coefficient and required thickness material. (*Indicates the addition of a factor of 1.15 for buildings with monolithic belts made of heavy concrete)

According to SNiP 2.09.84.87-2001, the table shows the minimum coefficient for residential and administrative buildings. In addition, for each region there is a certain value of thermal resistance - this is a constant value, which is denoted by the letter R. To carry out an exponential calculation, you can take average R=2.8(m2*K/W).

The calculation formula looks like this: R=R1+R2, where R1 is the wall (conditionally brickwork), R2 is the insulation (conditionally polystyrene foam).

The total and individual thickness of materials is calculated using the formula R=p/k, where p is the layer thickness in meters, k is the thermal coefficient of the building material (W/m*k). For an indicative calculation, masonry of two bricks and polystyrene foam of the PSB-S-25 brand will be used.

Insulation of the building with polystyrene foam

The length of an ordinary brick (coefficient 0.76 (W/m*k)) is 0.25 m, which means that the masonry has a thickness of p = 0.25 * 2 + 0.01 = 0.51 m. total thermal conductivity brickwork it turns out Rbrick=p/k=0.51/0.76=0.67 (m2*K/W). Therefore, Rfoam = Rtotal-Rbrick = 2.8-0.67 = 2.13 (m 2 *K/W).

For the total thickness of polystyrene foam, you need to substitute the values ​​into the formula Pfoam plastic = Rfoam plastic * kfoam plastic = 2.13 * 0.035 = 0.07455 m. Please note that the calculation is indicative and neither the thickness of the plaster nor the thickness of the cladding with their thermal coefficient was taken into account. For such walls with finishing (external and internal) and waterproofing, the average thickness of polystyrene foam is usually not 0.07455 m, but 0.5 or 0.6 m.

Material cutting technology

When insulating rooms internally and externally with expanded polystyrene, a painting knife with a sharp blade is used to cut it. This factor affects the clarity of the cut - a dull blade tears the foam and as a result a lot of debris is obtained in the form of small polymer granules. They are very difficult to remove, since, having a static charge, they stick to all objects.

The panels are cut “to fit a ruler”, which is replaced by a building rule or a long level. For cutting, use a wooden plane in the form of a plank board, plywood or OSB, so that the blade does not dull so quickly. In this case, the parameters of the cut fragment must exactly match the parameters seat.

Features of installing PSB under plaster

Installation of PSB on umbrella dowels

The most common type of external installation is the installation of foam plastic on umbrella dowels with additional fixation with glue (most often Ceresit CM-11 is used for this). This mount is used for regular or decorative plaster, with preliminary sealing of gaps and gluing of plaster mesh. Taking into account future mechanical loads, the PSB-S-25 grade is needed here.

For such installation, a plane without differences is important, so that the panels laid on it also create a relatively flat plane for the front finishing. In some cases (as a rule, this happens after the walls have been erected), the surface is first plastered and only after that the panels begin to be attached.

Installation of PSB insulation under the frame

Installation of PSB under the lathing for finishing

In the top photo you see the installation of polystyrene foam with virtually no fastenings - here the panels are fixed between the cross beams that support the wooden sheathing. Also, such a sheathing can be attached directly to the wall, but the polystyrene foam is still fixed in an identical way, between the beams (boards). If there are gaps between the panels, then foam is blown in there.

An identical method is used for interior partitions from plasterboard, where foam is tightly inserted between the profiles. But here PSB serves not so much for insulation as for soundproofing the room.

Installation of foam plastic on the ceiling under a metal frame

Wood itself is an insulator, so installing panels between beams is acceptable, but using this method with metal sheathing is unacceptable. In such cases, PSB is laid under the frame, be it a wall or a ceiling, as in the photo above.

First, the brackets are screwed on to hold the metal profiles, and then the panels are strung onto these consoles, thus covering the entire surface of the wall or ceiling. After this, a metal sheathing is mounted on top of the polystyrene foam - this method automatically creates a ventilation gap between the cladding and the foam plastic, and moisture from evaporation in the room does not accumulate on the surface of the polystyrene foam.

Based on the above, the conclusion suggests itself that the properties of foam plastic as insulation are most acceptable not only for the private sector, but also for industrial construction. And if we talk about roof insulation, then this is the best option, since it has low thermal conductivity and convenient installation due to the rigidity of the panels.

Video: roof insulation with foam plastic