Some authors of the Dom Praktika website have already written about how harmful polystyrene foam is or where it cannot be used. However, as an editor, over the last week I have received 4 (four) letters in the mail with reproaches that we are in vain considering this material so one-sidedly.
People write that polystyrene foam is very good as insulation, that it is cheap, and that it is indispensable in private construction. And in order to remain within the bounds of objectivity and present all points of view on our website, I asked two authors from Tver, Anatoly Rudenko And German Shevroshevich, write a full article in which foam plastic as insulation will be considered from all sides and in all respects.
Despite everything, polystyrene foam has every chance of remaining the “most popular” insulation material.
Properties of polystyrene foam as insulation - complete list
Expanded polystyrene (EPS) is popularly called “foam plastic” - after the name of the Finnish company that supplied expanded polystyrene to the USSR. Just like “copier”, the name of the company over time was transformed into the name of the material and became a household name.
Currently, hundreds of companies produce foam plastic in Russia and abroad. Equipment for the production of foam plastic is cheap and does not require qualified work force for operation and maintenance.
Let us now consider the main properties of polystyrene foam as insulation:
- Foam is lightweight. This property of foam plastic allows it to be used for insulating light structures, such as facades on light foundations or floors in residential buildings under the screed. Polystyrene foam does not increase the weight of insulated structures at all, and this puts it in first place among all insulation materials when it is necessary to keep the weight of the structure the same or to avoid loading the structure.
- Polystyrene foam is flammable. This property negatively affects all areas of application of foam plastic as insulation. This is especially true for the use of EPS as insulation in ventilated facades. Where there is free access of air to the insulation, polystyrene foam cannot be used. However, in any closed structure, such as a system wet facade, it is possible and necessary to use polystyrene foam as insulation - that’s where it belongs.
- Styrofoam is eaten by mice. What is true is true. Rodents love to make their nests in thick foam plastic. You often see when dismantling basement insulation entire mouse cities in foam plastic, with chambers for storing supplies and long passages between them. You should cover the foam from mice with a metal mesh with a fine mesh to eliminate this incident.
- Styrofoam is cheap. This gives this insulation a big head start over other effective insulation materials. In the conditions of Russian reality, when an individual developer is forced to save every ruble, the cost of insulation sometimes comes first, eclipsing the requirements for fire safety or environmental friendliness.
- The foam is warm. The thermal insulation properties of polystyrene foam are truly excellent. This is one of the most effective insulation materials with a thermal conductivity index of 0.03-0.05 W (m*C), which allows you to get by with a minimum layer of insulation for insulating building envelopes. In order to achieve the thermal resistance of enclosing structures required by the new SNiP, for example, for Moscow, you only need 150 mm of foam on the walls and 200 mm of foam on the floor and ceiling.
- Foam absorbs moisture. This property does not allow the use of foam plastic for insulation of pipes laid in the ground. There are other, more suitable heat insulators for this.
Let us now move on to the area of application of expanded polystyrene in modern private low-rise construction.
Polystyrene foam as basement insulation
It will not be possible to use polystyrene foam as basement insulation due to its hygroscopicity. As mentioned above, expanded polystyrene (EPS) absorbs moisture. At the same time, its thermal conductivity increases sharply, and its thermal insulation properties decrease significantly.
In addition, when the foam gets wet in the spring and autumn period, then when it freezes, the water between the foam balls turns into ice and breaks it. After the first cold season, wet polystyrene foam turns into dust - individual balls that do not retain heat.
Polystyrene foam as insulation for the basement of a house
But using polystyrene foam as base insulation is quite possible. In this case, the PPS is covered on top with a layer of plaster, which is applied to a mesh base. The foam is attached to the base using plastic fastenings"fungi" to which it is then attached metal grid with a fine cell from 0.6 to 0.8 cm.
Then plaster is applied over the mesh and a decorative layer is mounted on it - wild stone, clinker brick, facade tiles.
You can also use a metal profile for plaster to attach the foam to the base. But it is better to refuse to use the wooden block system. As practice shows, wooden blocks on concrete base the base begins to rot from below, moisture also gains access to the foam insulation. And rodents are beginning to show increased interest in such a base.
Foam plastic as insulation in a wet facade system
Let us immediately make a reservation that the use of polystyrene foam as insulation for the walls of a house is only possible in a wet facade system. The use of foam plastic in ventilated facades for any facade material prohibited - it is contrary to fire regulations.
Any stray spark from your or neighboring plot from the barbecue or from chimney baths or houses can be brought into the ventilation gap by the air flow. There this spark can fall on an open or covered with film waterproofing foam. D.C The air in the ventilation gap brings the oxygen required to create an open fire and fan the source of fire. This is how everyone is respected the necessary conditions for a fire to occur inside the ventilation façade, under the façade cladding. The house will burn “inside the walls”; fire crews arriving at the scene of the fire will not be able to help with such a spread of fire.
Polystyrene foam as insulation for exterior walls of a house - only in a wet façade system.
Thus, the place of foam plastic on the facade modern house– under a layer of plaster and decorative solid non-flammable coatings. When there is no access to open fire and oxygen, and there is no direct exposure to moisture, polystyrene foam as insulation exhibits its best properties - light weight, low thermal conductivity and reasonable cost.
Foam insulation of floors and ceilings
Insulating the floor and ceiling with polystyrene foam is only possible if the foam plastic is covered with a screed on top and a layer of concrete below. That is, The best way the use of polystyrene foam for insulation of floors or ceilings is insulation concrete floors in houses made of blocks, bricks or concrete.
Polystyrene foam as floor insulation - only under screed on concrete slabs.
When using this, it is important to protect the foam from moisture that may enter it from the screed. For this purpose, waterproofing is laid on both sides. There is no need to worry about water vapor from the room in such a cake, since concrete has very low vapor permeability.
Where polystyrene foam cannot be used as insulation
It is not at all worthwhile to insulate the following parts of the house with polystyrene foam:
- You cannot use polystyrene foam as insulation in the attic of a house, when laying insulation between rafters or when covering wooden rafter system. This goes against fire regulations when constructing residential premises.
- Expanded polystyrene cannot be used when insulating a bathhouse, since when heated to 90 degrees and high humidity you will receive the emission of styrene into the interior of the bathhouse. And if you also take into account that polystyrene foam burns excellently, emitting greasy black and very poisonous smoke, then think for yourself whether you need such insulation in your bathhouse.
- It is dangerous to use polystyrene foam when insulating rooms from the inside, when a system of metal or wooden profiles and subsequent covering decorative materials. The only acceptable option for insulating foam from the inside is to cover it plaster layer and subsequent decorative finishing plaster.
- You should not insulate window slopes from the inside with polystyrene foam - use better than polyurethane foam. This material is more suitable for insulating residential premises from the inside.
Despite the emergence of more and more new insulating materials, foam continues to be popular among professional builders and DIYers. 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.
Size standard sheet, which is used for insulation, has a length and width of one meter; 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 insulating facades 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 weak sides. 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 perfect for use with frame buildings, since it does not exert significant pressure on the foundation and walls. This feature also simplifies the process of lifting 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 over time it will begin to emit from heating harmful substances. 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 done without outside help. Due to its versatility, insulation can be applied to any accessible surface. At the same time, the foam does not react with most building materials, if you do not take into account organic solvents. 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 a hacksaw, which simplifies the process of fitting it to various shapes. Material of small thickness can take curved shapes, so insulation of semicircular bay windows is available. Polystyrene foam is an excellent insulation material for basements and foundations. 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 work. 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 to high temperatures, the material melts and releases 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. Domestic bird also likes to peck 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 must be located indoors, because they absorb temperature environment, and leave thermal insulation materials 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. Process video internal insulation Styrofoam is below.
The most popular material for insulating any buildings, both walls, floors and ceilings, is extruded polystyrene foam insulation nowadays. But, like most other building materials, along with its advantages, it also has its disadvantages.
In this material we will try to analyze its strengths and weaknesses in as much detail as possible. We will also tell you how to work with this material while observing fire safety measures.
In everyday life, this material can be found under the name “foam plastic,” but this is fundamentally incorrect. These two materials are significantly different from each other. For example, extruded polystyrene foam (EPS) is one of the most deformation-resistant and durable varieties, and its heat-shielding properties are almost not affected by this.
High-strength EPS is produced on special production lines through chemical extrusion of the initial raw materials, which are pure polystyrene granules.
Using special equipment, raw materials are converted into foam, from which, in turn, small granules are produced. During the hardening process, these granules are pressed into layers of the required shapes and sizes, after which they can be used not only for insulating houses, but also for other purposes.
It is precisely due to its fine porosity that EPS is an order of magnitude stronger than ordinary polystyrene foam. Compressed under high pressure and high temperature Such granules give the material greater strength, hardness and reliability
The main difference between extruded polystyrene foam and pressed polystyrene is in the characteristics of its granules. They are smaller, which makes this building material more resistant to physical activity. Granule size thermal insulation material produced by extrusion does not exceed 0.1 mm, while non-pressed granules can reach up to 10 mm.
In foreign interpretation, EPPS may be called XPS. It is produced in several varieties. After the abbreviation “XPS”, the markings of this material contain numbers from 25 to 45, which indicate its density.
The higher the value, the higher the density of the material. Particularly dense extruded material can even be used to insulate asphalt road surfaces, for example, the company's products.
Now that we have figured out what EPS is, we will discuss in detail all its pros and cons.
The main advantages of the material
In fact, polystyrene is the same plastic, only endowed with different qualities. But just because it is somewhat lighter and less dense, it does not cease to be plastic, and therefore it has all the advantages of this material.
Plus, polystyrene is resistant to most chemicals.
In this case, a layer of concrete is formed over a layer of expanded polystyrene, which, in turn, rests on a bed of sand and gravel mixture.
The concrete floor screed is also erected on top of evenly laid EPS slabs.
The blind area, insulated with polystyrene foam, will help protect top part foundation from freezing. Plus, a layer of such material will also work as an additional water-repellent layer.
Since the density of extruded polystyrene foam is an order of magnitude higher than that of regular polystyrene, a number of small problems arise with this. For example, this type of material can still be cut with a knife, but firstly, the blade must be extremely thin and strong, since a thick blade can cause the slab to discolor and crack.
And secondly, the creaking and grinding noise that will accompany such an “event” will be an order of magnitude higher than in the case of ordinary polystyrene foam. Therefore, before starting the procedure, it is recommended to lubricate the knife blade with machine oil.
Some people use a grinder equipped with the thinnest metal wheel to cut EPS blocks. Cutting, in this case, is efficient, but the whistle is so loud that it is better to put plugs in your ears. Among other things, this method is the most “unclean”. After him there will be great amount garbage.
If you decide to use a grinder for cutting polystyrene foam, we recommend that you familiarize yourself with this equipment.
You can easily make a machine or machine for cutting polystyrene foam yourself. To do this, you just need to get some nichrome and a powerful transformer. By connecting the opposite ends of the nichrome wire to the wires coming from the power source, we get a kind of polystyrene foam knife. To make the cut as even as possible, nichrome wire should be kept taut in the device
The most effective and simplest method is considered to be cutting with hot wire. Take two nails, between which a nichrome wire is stretched. Voltage is applied to the nails through a transformer, the wire becomes hot and the process begins. Using this method you can cut out the most precise blocks and shapes high degree difficulties.
But this method is also the most harmful. As already mentioned, phenol vapors released during the cutting process can cause significant harm to the human body, and therefore, this procedure should be performed on outdoors, preferably in a draft or using a special respirator, or even a gas mask.
Few people know, but polystyrene foam makes an excellent formwork for foundations. The material lends itself perfectly to cutting, drilling, etc., and therefore anyone, showing a certain amount of ingenuity and resourcefulness, is able to make a wonderful insulated foundation for their structure
Fire safety measures
When working with extruded polystyrene foam, you must adhere to strict fire safety measures, otherwise extinguishing the fire will be much more difficult than it seems.
That is why, in case work is being done nearby using an open fire, for example, there is a furnace with which bitumen is melted, etc., you should always have a water supply hose, a fire extinguisher, or, at worst, a barrel of water and a bucket at the ready .
It is recommended to do the same when carrying out welding work in close proximity to the EPS. Moreover, it is advised to either shield the material from sparks and scale flying from welding, or pre-moisten nearby polystyrene slabs with water; it is better to do both at the same time. Only in this case will you protect both yourself and your building from fire.
Most fire hazards at construction sites occur precisely because of neglect of safety precautions. If work is carried out in the vicinity of work involving highly flammable materials, welding work, always expect trouble. To prevent this disaster from happening, you should always keep at least a fire extinguisher on hand.
Conclusions and useful video on the topic
You can learn about the criteria by which extruded polystyrene foam should be selected from the following video:
Considering that almost no one pays attention to the weak sound insulation of insulation, sensitivity to ultraviolet radiation is treated by the fact that the material is always protected by a layer of finishing, and low vapor permeability as a minus is eliminated by the presence of good ventilation, of the total number of shortcomings, only “not environmentally friendly” and “high cost” of the material remain, but these shortcomings are also easy to refute.
The very concept of “not environmentally friendly” suggests that that the material is extremely durable, because over time, especially when correct operation, does not break down into components. Isn’t this a criterion for considering the “non-environmental friendliness” of a building material as a plus? Well, regarding the high cost of EPS, there is an excellent proverb: “The miser pays twice.” With all the ensuing morals and consequences.
Have you thought about using EPS as insulation and want to clarify a couple of nuances of its use after reading our material? Ask any remaining questions to our experts below this post - we will try to help you.
If you are professionally involved in the installation of XPS and want to give useful tips for beginners or to supplement the above material with valuable comments, write your comments in the block below.
The problem of insulating a private house or apartment has always had to be solved, while effective ways arose only after the advent of such building materials as polystyrene foam. Insulating the ceiling, floor and walls with its help allows you to retain heat in your home and at the same time save money.
Polystyrene foam
There is pressed and non-pressed foam; it is not too difficult to distinguish them, even if you are not a professional. If you have ever looked at the structure of a material, you have most likely noticed that it consists of small balls that are interconnected, like a honeycomb in a beehive.
Pressless foam can be seen in boxes with household appliances, since it is actively used for packaging.
By thermal insulation properties And appearance the pressed one is practically no different from the second one, its granules adhere to each other somewhat more firmly, due to which it does not crumble. At the same time, pressed foam is more difficult to produce, which means it is more expensive, which is why it is less widespread.
Technical characteristics of polystyrene foam
This breathable material has low specific gravity, does not accumulate moisture, and is not subject to rotting. Its main drawback is its flammability, although by applying plaster the home can be protected from fire.
Polystyrene foam characteristics:
- biological and chemical resistance to sea water, alkali, salt, soap, cement, bitumen, lime, gypsum;
- low thermal conductivity;
- resistance to temperature changes, due to which the material can be used in different climatic conditions;
- it is not a favorable environment for the development of fungi, mold and microorganisms;
- high vapor permeability - thanks to it, the moisture that accumulates in the walls evaporates;
- excellent soundproofing properties.
Basic properties of polystyrene foam as insulation
Expanded polystyrene is popularly called “foam plastic”. This word comes from the name of a Finnish company that supplied expanded polystyrene to the USSR. The name of the company was transformed over time into the name of this material.
At the moment, foam plastic is produced abroad and in Russia by various companies. The equipment for its production is cheap, and does not require skilled labor for maintenance and operation.
Now let's look at the properties of polystyrene foam:
Now let's move on to the use of polystyrene foam in low-rise private construction.
Foam insulation: simple and easy
It is done very simply. The polystyrene foam is attached to the wall of the building using special screws. Initially, you can level the wall using putty, attach the slab, then apply a layer of putty again and paint it. This way you get a completely flat wall.
Insulation of buildings from outside
Polystyrene foam as wall insulation is most often used outside. This method makes it possible to move the freezing point to the outer part of the wall, while preventing the cold from penetrating inside.
For this purpose, sheets with a thickness of 100 millimeters are used. They are attached using dowels and special glue. Performing these works at height is only possible using special equipment.
Internal insulation of the room
This method is less common than the previous one, although it is also effective. It is very convenient that it can be implemented regardless of the time of year and weather. But before insulating the walls inside, they must be pre-treated with special anti-mold compounds.
It should be borne in mind that polystyrene foam as insulation usable area reduces the space. This is explained by the fact that it takes up quite a lot of space, especially considering that drywall is attached to the top.
Insulation of building walls
This method is applicable in the construction of 1- and 2-story houses. A wall 250 mm thick is erected, then sheets of foam plastic are laid, which are protected with plastic film, then the inner wall. This method has the advantage that polystyrene foam as wall insulation is completely protected from open fire and mechanical damage.
Insulation of floors
If we consider foam plastic as a floor insulation (reviews about this use can be seen mostly positive), it is important to take into account that its sheets are laid in a cement-sand liquid mortar during the screed. Air bubbles are expelled using vibration. A 50 mm screed is also made on top of the material.
These measures are especially necessary for residential buildings with damp basements. But in middle-floor apartments, foam plastic as floor insulation will also provide good sound insulation. In addition, this procedure is performed when laying a water-heated floor.
Insulation of ceilings
Such insulation is performed in the same way as with walls. The difference lies in the thickness of the sheets used: it should be no more than 50 mm. In a typical residential building, most apartments have low ceiling heights. Of course, if possible, you can increase the thickness of the foam.
This measure allows you to insulate the apartment, while reducing the noise level and making the home more comfortable.
Basement insulation with foam plastic
It will not be possible to use polystyrene foam in this case due to its hygroscopicity. At the same time, its thermal conductivity increases sharply, and its thermal insulation greatly decreases.
When polystyrene foam in autumn and spring period gets wet, the water in it turns into ice when it freezes, after which it breaks the material. After the first frost, wet polystyrene foam turns into dust, turning into separate balls that are unable to retain heat.
Base insulation with polystyrene foam
But for this it is quite possible to use this material. In this case, foam plastic as insulation is covered with a layer of plaster on top. The foam is attached to the base using plastic “fungi”, to which a fine metal mesh is then attached. Then plaster is applied to it and a decorative layer is applied on top - clinker brick, wild stone, facade tiles.
In this case, you can also use a metal profile for plaster to attach the foam. In this case, it is advisable to abandon the use of a system of wooden blocks. Practice shows that on the concrete base of the base, wooden blocks begin to rot from below, and moisture also gains access to the insulation.
Foam plastic for insulation of a wet facade system
On the facade of the house, the place of foam plastic is located under a layer of continuous decorative non-combustible coatings and plaster. When there is no access to oxygen and open fire, and there is no direct exposure to moisture, this material exhibits its best properties. Don’t forget about the reasonable cost, low thermal conductivity, and light weight.
Roof insulation
Here you need to understand where and what width of material to use. The “non-ventilated roof” is covered with 70 mm thick foam plastic, then a bitumen waterproof layer is laid on its surface. “Ventilated roof” involves installing slabs on the back side of the roof, while the ventilated cavity remains, preventing condensation.
Attic spaces can be great living rooms. At the same time, thermal insulation gable roof brings great benefits at low cost. To do this, you need to install foam plastic in the cracks between the rafters.
Thermal insulation of pipelines
Until recently, thermal insulation engineering communications was not given special significance, while due to them the share of heat loss is about 30%. For pipelines of ventilation ducts, cold water supply, buried cables and telephone lines, foam plastic is now increasingly being used as insulation. This material is also used to protect sewer and water pipes from freezing. The undoubted advantage of using polystyrene foam for these purposes is the ability to give this material various shapes.
Where is it prohibited to use polystyrene foam as insulation?
- Expanded polystyrene cannot be used when insulating a bathhouse, since increased humidity and heating result in the emission of styrene.
- There is no need to insulate window slopes from the inside - for this it is advisable to use polyurethane foam. This material is more suitable for insulating rooms from the inside.
- This material when insulated interior spaces It is dangerous to use when using a system of wooden or metal profiles and further covering with various decorative materials.
It is important to know
Laying foam sheets directly on the ground is not allowed: waterproofing work must first be carried out, and then a layer of screed must be poured. Otherwise, the floor may be damaged by rodents.
If all rules of use are followed, the service life of foam plastic as insulation reaches 100 years. This is its undoubted advantage.
Compliance with the rules for using polystyrene foam as insulation makes it possible to save money on heating your home, and also get rid of excess noise. It can also protect from the sun's hot rays, while preventing the outside walls from heating up. Therefore, there is no need to regularly use the air conditioner, which allows you to save on electricity.
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.
Process for the production of organic foamed 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.
Quality and specifications foam plastics in Russia is declared by GOST 15588-2014 “Heat-insulating polystyrene foam boards. Specifications" 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:
- Low weight.
- Low thermal conductivity.
- Excellent noise absorption performance.
- Self-extinguishing property.
- Ease of use.
- 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:
- Low vapor permeability.
- High water absorption.
- Low resistance to mechanical damage.
- Instability to light.
- 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 the destruction of the protective layer, and the exposed foam plastic simply crumbles under the influence of sunlight. 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 best qualities material to make your home comfortable and reduce negativity 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 internal material, vapor permeability and lower heat transfer resistance coefficient.
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 at wooden structure, which will lead 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.