Thermal conductivity and density of penoplex, comparison with polystyrene foam PSB

Foam density is an indicator that determines the strength characteristics of thermal insulating polystyrene foam. This thermal insulation material consists of 98% air bubbles and 2% pure polystyrene. Polystyrene is the basis of expanded polystyrene.

It is obtained by the polymerization of styrene. Expanded polystyrene has become widespread due to a number of advantages:

1. No toxic compounds.
2. High thermal insulation properties, thermal conductivity in a dry state – 0.029-0.036 W/(m.k).
3. Light weight.
4. Polystyrene foam does not enter into chemical reactions with building materials (cement, bitumen, acrylic, gypsum putty).
5. Resistance to microorganisms, algae, mold, fungus.
6. Durability.

The physical and mechanical properties of polystyrene foam may vary. They depend on the quality of the raw materials and the method of polymerization of styrene.

Calculation of the required insulation thickness

The thickness of the insulation layer depends on the following factors:

• thickness, design, thermal conductivity of the wall material;
• climatic zone of the building;
• the presence of additional layers in the structure (for example, a layer of internal plaster).

For simplicity, we will calculate the thickness of the insulation for the wall of a house made of foam concrete blocks 30 cm thick with internal plaster 20 mm thick, built in the Moscow region.

The normalized heat transfer resistance of walls for different regions of the Russian Federation is determined from the table:

The heat transfer resistance of the wall should be 3.16 m2 °C/W.

Using the table, we find data for the wall - 0.703 m2 °C/W and the plaster layer - 0.035 m2 °C/W.

We subtract individual data from the standard value:

3.16–0.703–0.035= 2.422 m2 °C/W

The thickness of polystyrene foam for wall insulation should provide such resistance to heat transfer.

We determine the thickness using the formula

• δ – insulation thickness, m;
• λ – thermal conductivity of the material, W/m2 °C.

Calculation example

Let's assume that for thermal insulation we purchased PPS20 F RG material. The density of the foam is 20 kg/m3, thermal conductivity under the worst operating conditions is 0.033 W/m2 °C.

δ = 2.422x0.033=0.079, or rounded 80 mm

Since slabs up to 50 mm thick can most often be found on sale, it makes sense to use two 50+30 mm or 2x40 mm slabs for insulation.

Wall insulation

As we learned from the material above, it is necessary to use different materials for different parts of the walls. If you do not want, for example, rotting and destruction processes to begin in your wooden bathhouse constructed with XPS, the installation of extruded polystyrene foam is excluded. Correctly, it is very simple and it is not difficult to stick to it.

The density of traditional polystyrene foam for wall insulation is 25, extruded polystyrene is 15. When working with traditional polystyrene foam, it is best to use slabs with a thickness of 50 mm; extruded polystyrene foam requires the same indicators. You can get by with a thickness of 30-40 mm.

How does the density of foam affect its cost?

There are several points of view related to the concept of density. The unit of measurement for this parameter is kilogram per cubic meter. This value is calculated from the ratio of weight to volume. It is impossible to determine with one hundred percent accuracy the qualitative characteristics of polystyrene foam related to its density. Even the weight of the insulation does not affect its ability to retain heat.

When thinking about purchasing insulation, buyers are always interested in its density. Based on these data, one can judge the strength of the material, its weight and thermal conductivity. Foam density values ​​always fall within a certain range.

During the production process of expanded polystyrene boards, the manufacturer determines the cost of production. Based on the formula for determining density, the weight of the insulation will affect this value. The greater the weight of the material, the denser it is, so its cost is higher. This is due to the fact that polystyrene, as a raw material for heat insulation boards, plays an important role. It accounts for about 80% of the total cost of finished products.

How does changing the thermal conductivity of foam affect its density?

Polystyrene foam is made from polystyrene foam balls containing air.

Any thermal insulation material contains air in its pores. The improved thermal conductivity index depends on the amount of atmospheric air contained in the material. The higher it is, the lower the thermal conductivity coefficient. The production of polystyrene foam is carried out from polystyrene foam balls containing air.

From this we can conclude that the density of polystyrene foam does not affect its thermal conductivity. If this value changes, then changes in thermal conductivity occur within percentages. One hundred percent air content in the insulation is associated with its high heat-saving ability, since air is characterized by the lowest thermal conductivity coefficient.

Due to the low thermal conductivity of the insulation, a high degree of energy saving is ensured. If we compare polystyrene foam with brick, their energy-saving ability will differ significantly, since 12 cm of thermal insulation thickness corresponds to 210 cm of thickness of a brick wall or a 45-centimeter wooden wall.

The thermal conductivity coefficient of foam plastic, expressed in digital values, belongs to the range 0.037 W/mK - 0.043 W/mK. This value can be compared with the thermal conductivity of air equal to 0.027 W/mK.

Scheme of application of various brands

The following key types of expanded polystyrene are produced, differing in density and other characteristics:

• PSB-S-15, the density of this brand of foam is up to 15 kg/cu.m.
• PSB-S-25, from 15 kg/cu.m. up to 25 kg/cu.m.
• PSB-S-35, from 25 kg/cu.m. up to 35 kg/cu.m.
• PSB-S-50, from 35 kg/cu.m. up to 50 kg/cu.m.

The thermal conductivity component of foam plastic, expressed in digital values, refers to the range 0.037 W/mK - 0.043 W/mK. The indicated value can be correlated with the thermal conductivity of air, which is equal to 0.027 W/mK.

Use of polystyrene foam PSB-S-15

Polystyrene foam PSB-S-15 can be used for insulation of house facades. This type of insulation is practically not used in construction. It is used in structures that are attached to structures. These can be open balconies or verandas that serve a decorative function. Using PSB-S-15 foam plastic, shapes for facades are formed, and this allows :

• frame the corners of the house, windows;
• separate floors by creating cornices.

What is PSB-S-25 suitable for?

The density of the foam is calculated by analogy with determining the density of brick. For example, if 1 cube of foam has a density of 25, then its weight will be 25 kg. The flexural and compressive strength of foam depends on its density. The density of polystyrene foam and its brand are completely different characteristics. For example, if we take into consideration SPB-C25 or SPB-C50, the density parameter will fluctuate between 35−50 or 15−25.

Plates with a density of 25 are used to insulate the facades of a house. The standard is foam plastic, the thickness of which is 5 cm. This type of insulation is used for many purposes. Its thickness can be changed - this will depend on consumer preferences.

Polystyrene foam of maximum thickness can be used to insulate walls that are exposed to atmospheric agents. They can also be used to insulate walls, since such material perfectly prevents the appearance of fungus.

Based on the designation of the material, it is used in various construction structures, and this does not impair its quality characteristics.

Application of polystyrene foam PSB-S-35

In order to perfectly align the walls, you can change the thickness of the polystyrene foam tiles. It is not recommended to abuse the size of the thickness of the material, since this will provoke certain problems with fixing the drainage system at the corners of the building.

Before choosing insulation of the required thickness, it is recommended to find out in advance what the amount of gas pipe stock is , because it should never be covered, as this may disrupt the aesthetics of the appearance of the building. In this case, it is advisable to prefer PSB-S-35 material with a thickness of 5 cm over material with a density of 25 and a thickness of 10 cm, especially since their prices are practically the same.

Insulation with a density of 35 can be used to insulate the slopes of windows and doors, and the facades of buildings. As a rule, it costs twice as much as the same polystyrene material with a density of 25. With a thickness of 5 cm, it can be used to insulate non-residential structures and garages. With a thickness of similar insulation of 7 centimeters, it can be used for thermal insulation of residential premises.

Due to the normal level of density, it is possible to use a heat insulator with a minimum thickness , which does not imply a deterioration in the quality of insulation. If the polystyrene foam heat insulator turns out to be harder, then it can be used to provide ideal insulation of basement walls and foundations.

Types of polystyrene foam and how it is classified Video

Classification of polystyrene foam

According to the production method, this material is conventionally divided into two large classes, which have completely different characteristics. The first is produced at high temperatures by sintering granules. The second involves mixing the granules at elevated temperatures with the further addition of a special foaming agent and removal from the extruder.

The first class is called pressless, it is easy to determine by eye. The material looks like balls interlocking with each other, somewhat similar to a beehive. Suffice it to recall the polystyrene foam in which any household appliance was supplied (microwave oven, refrigerator). The second class is called pressed, since the granules are connected to each other much more firmly. It is much more difficult to break or crumble. According to this, different brands are distinguished.

Foam brands

The marking of polystyrene foam from domestic manufacturers is indicated by two letters - PS. If the material is pressless, then three letters are used - PSB. Other numbers and letters can be additionally added to them through a dash. For example, PSB-S means self-extinguishing foam. So, we will describe the main existing brands so that you can know which polystyrene foam to choose.

• PSB-S-15 - has a low density and is used for insulating those structures where special mechanical strength is not needed. This type of material is used to insulate attics, attic roofs, containers, carriages, and to fill the space between rafters. It is environmentally friendly, not susceptible to any microorganisms, and has high moisture resistance.
• PSB-S-25 is the most popular and universal brand. Used for insulation of walls, floors, building facades, loggias. It is not susceptible to microorganisms, is environmentally friendly, and has high resistance to aging and moisture.
• PSB-S-35 - used to a greater extent for insulating foundations and underground communications (including parking lots). It is also used to prevent soil swelling when constructing swimming pools, sports fields, and lawns. Plus, it is an ideal material for unfavorable climatic conditions. It is biologically safe, has high mechanical strength, and is resistant to aging, moisture and the development of microorganisms.
• PSB-S-50 - has the highest density compared to all other brands. Used in environments where mechanical strength is important. It is used in the construction of roads in swampy areas and in the construction of interfloor floors. It is also well suited for insulating floors in barns, garages, and industrial areas. The material is biologically safe, resistant to aging and moisture.

Types of foam

The first ones are made by pressed and non-pressed methods, the brands are described above. The second ones are polyurethane (PPU), common in everyday life in the form of ordinary foam rubber. Still others are polyethylene (PPE), which have the form of an elastic material in which the product is wrapped so that it does not break (film with air bubbles).

The fourth are polyvinyl chloride (PVC), very similar in appearance to extruded polyethylene foam. They are also very elastic and have the same properties. Plus, they do not contain highly toxic mixtures and are recognized as a self-extinguishing material.

In fact, there are more species. If you are interested in a particular material, then you should find out the information at a hardware store, where all varieties are listed in the catalogs.

What density foam is best for different types of insulation?

High-density PSB is best used for insulating industrial facilities, utilities, parking lots, roads and sidewalks. It is used in industry and the highway sector. It is able to withstand high static and dynamic loads on the plane.

This begs the question, what is the best characteristic of polystyrene foam for insulating a house? Density 35 kg/m³ is the volumetric weight of polystyrene foam for insulating walls outside. Polystyrene PSB-S-35 and PSB-S-25 correspond to this density and are suitable for thermal insulation of facades of residential buildings . Its structure will not be destroyed by mechanical impact on the plane of the slabs.

The slabs are easy to install and process, allowing you to obtain a thermal insulation effect at low material costs. This is the most popular type of slab.

PSB-S-15 foam plastic slabs can also be used to insulate house facades. It is important to exclude static and shock loads on the surface of the insulation during operation of the building. It can also be used to fill voids in structures, insulate attics, insulate underground spaces and voids in ceilings.

Classes, thickness and grades of PPP, how to choose, which one is better to use

At first glance, all foam plastic is the same, but this is only for those who first decided to insulate the house from the outside. Polyurethane foam is divided into classes and grades, and for this purpose the following characteristics are used:

• production features;
• material density;
• edge design method.

Expanded polystyrene classes

The material is divided into 2 classes:

1. Pressed - the sheet will be marked PS. The insulation is produced using press installations. The structure of the material is smooth and it is almost impossible to distinguish polystyrene granules.
2. Pressless - in this case, the PSB marking is left on the foam. To create such products, high-temperature sintering of the substance is used. Although press installations are also used. The slabs consist of round or oval granules that are easy to distinguish from each other.

Letters or numbers are added to these markings, which will help determine the density of the material, where it is best to use it and the shape of the edge. Additional letters are:

• A – the correct shape of the slab.
• B - the edge cut is similar to the letter L.
• R - slabs were cut using a hot string.
• F - the product was created using a form, or a façade purpose.
• C – polystyrene foam extinguishes on its own.
• N – suitable exclusively for outdoor use.

PPP brands

Now let's look at the grades of material. To determine the brand, manufacturers indicate a digital value. For non-press and press representatives these values ​​are different. Let's look at each class separately in detail.

Brands of pressless polystyrene foam

On the construction market, this class of insulation is represented by the following brands:

• 15 – low-density foam. The cheapest. Most often used for packaging household appliances or fragile items. It is easy to damage;
• 25 - if the letter F is added to such numbers, then the material is suitable for finishing the facade. The density is much higher, which means the strength is improved. It is often chosen to create decorative elements in the interior or landscape - the density of the material allows;
• 35 - foam with this marking can be used for various purposes. It is a good insulation material for facades, as a component for multilayer panels (thermo, sandwich, reinforced concrete);
• 50 is the densest and most durable material, and also the most expensive. It is used for insulation of underground structures and communications.

Brands of pressed polypropylene

Using the pressing method, PVC foam is produced. Polyvinyl chloride resin is added to the composition. The material is very durable and reliable. It is used in all areas of construction and insulation. A number from 1 to 4 is added to the letters PS. The higher the numerical value, the higher the density, and therefore the strength, of expanded polystyrene.

The material of the press production method is suitable for creating containers for aggressive substances. It is resistant to most known chemically active liquids.

Advantages and disadvantages

Polystyrene foam has many more advantages than disadvantages, but first things first. The first advantage that allows the use of polystyrene foam as insulation is its excellent thermal insulation properties. In addition, this material is not able to absorb moisture, and therefore no vapor barrier is needed, and in the future this useful property will allow you to avoid problems with the development of mold and mildew.

Polystyrene foam is a fairly lightweight material, so no work will be required to strengthen the foundation, and it is very easy to work with. This is a durable material that does not deform or change its properties over time. The low price of this type of insulation is a decisive argument for its choice.

But it doesn't come without its drawbacks. The main one is flammability: polystyrene foam easily supports combustion, while emitting acrid toxic smoke. That is why, to insulate a house, it is better to choose a material impregnated with an antiprene composition, which prevents spontaneous combustion. In addition, rodents often make burrows in polystyrene foam, which is a common reason for refusing this type of insulation, but if the installation is carried out according to all the rules, then this trouble can be avoided.

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 have standard or custom sizes. The thickness of the foam varies from 20 to 1000 mm, and the dimensions of the plates have the following dimensions:

• 1000x500mm;
• 1000x1000mm;
• 2000x1000mm.

This is interesting: Sheathing a house with foam plastic

Main brands of foam plastic

After foaming the polystyrene, the raw materials for the finished products are loaded into a container. Steam is injected into it under pressure. The granules foam and become saturated with air. At the next stage, the finished granules are dried from moisture; hot air is used for this.

When drying, the granules are shaken periodically. The finished granules are placed in bins that are calibrated according to foam grades. Molding occurs under pressure. When molding, the following types of foam are obtained, which differ in density:

The last number in the marking determines the density of the foam for insulation. Many developers do not know what the specific gravity of foam is. Density (specific gravity) is the mass of a product in its volume. The density of polystyrene grade PSB-S-15 is 15 kg/m³. Accordingly, one cubic meter of PSB-S-15 polystyrene boards weighs 15 kg.

The question arises of how to independently determine the density of foam plastic without special equipment. This is easy to do: you need to calculate the cubic capacity of the finished product and weigh it on the scales. To make a claim, the store must have in hand a state verification certificate of the scales. Weighing can be carried out directly in the store or at the construction warehouse of the materials supplier. This technical calculation of foam density will be the most optimal.

Where are polystyrene foam of different sizes used?

This durable, moisture-resistant insulation is used for outdoor work. To insulate a wall with polystyrene foam, you first need to determine what density, size, and type of polystyrene foam you will need for the job. The choice depends on the expected loads that this material will bear during operation. When insulating a vertical wall, the loads will be minimal; sheets of any brand will do. Even PSB-S 15 will give the same result as PSB-S 25 when it comes to wall insulation in areas with mild winters. This is due to the fact that the principle of operation of the foam is based on gluing polystyrene balls, between which and inside there are multiple air chambers. It is known that the less mass and more air, the better the thermal insulation effect. It is inconvenient to work with low-density sheets, which are more fragile and break. PSB-S 25 has a higher density, making finishing easier.

Properties of expanded polystyrene.

Expanded polystyrene 25 is often used for external insulation of walls of non-residential premises. They are used to decorate balconies, loggias, garages, shopping centers, and various institutions. For northern regions with cold winters, it is believed that a sheet thickness of 5 cm is enough to keep the room warm on the coldest nights. Polystyrene foam grade 100 is used for thermal insulation of industrial freezers, as well as for insulation of houses in the harsh climate of the Far North. A sheet size of 10 cm will ensure maximum thermal protection. When choosing a brand of expanded polystyrene, you can choose a sheet that has various parameters. A non-standard sheet 500x500 is sometimes much more convenient to work with than a standard long one with dimensions of 2000x1000 mm.

For insulating the walls of a house, sheets measuring 1000x1000 and 1000x500 mm are suitable. They are convenient to work with and result in fewer joints that will have to be sealed hermetically. To fill smaller areas, existing sheets are cut into suitable pieces. In all non-standard situations in finishing, it is better to use a sheet of large sizes to make it easier to cut configurations. During the installation process, such sheets are adjusted to the required parameters by cutting polystyrene foam into pieces. This material is easy to cut.

Expanded polystyrene, having dimensions of 2000x1000 mm, is more difficult to install. When working alone, it is easier to lay two sheets of 1000x1000 each than one sheet measuring 2000x1000 mm.

Expanded polystyrene is a popular material in the construction market because its thermal insulation ability is much better than that of other building materials. It ensures long life for buildings in any climatic conditions.

https://youtube.com/watch?v=Ea94bC7aIp0

Comparing its thermal conductivity with other materials, we obtain the following results: 80 mm thick foam is equivalent to 100 mm of mineral wool, 274 mm of wood, 760 mm of brickwork and 1720 mm of concrete. This characteristic and low cost make this material especially popular in construction.

Foam plastic for wall insulation

Polystyrene foam is an economically advantageous material. Economic benefits manifest themselves not only at the construction stage, but also at the subsequent operation stage. This is achieved due to high heat retention rates for insulating walls and other structural elements, as well as a reliable level of fire resistance.

During installation, slab thickness standards must be observed. For external walls this figure is 50 mm, and for internal walls 30 mm. Density - 25.

Using this material, you can carry out work on external and external insulation of walls. Outside, the installation process takes place using cement mortars, various mounting devices, glue and other things. When installing foam plastic, the inner side will have a good level of noise protection. It is necessary to use plasterboard sheets. You can use an alternative option - plaster.

The plates that are involved in the fastening process for the outer part must meet a thickness of 50 mm. The inner side will require 30 mm. The wall, which is located on the outside of the room, must first be treated with cement mortar. It is applied using a special metal mesh. After completion of the work, we can assume that the foam has been successfully installed.

Density. Index

When working on wall insulation, polystyrene foam has a density index of 25. An external wall with a 50 mm sheet will have high heat retention rates, as well as additional sound insulation.

Polystyrene foam with a density of 25 looks quite advantageous compared to its counterpart, whose density is 15. The main differences are in quality. You can feel a big difference in the quality of foam with a density of 25 and 15 without even starting to use them.

The extruded polystyrene brands presented earlier in the article have the following density indicators:

• 31C (from 28.5 to 30.5 kg).
• 31 (from 28 to 34 kg).
• 45 (from 38.1 to 45 kg).

Vapor permeability properties

The vapor permeability indicator directly affects the efficiency of air exchange that occurs between the inside of the premises and the outside. This happens due to the fact that the air outside has a lower temperature than the inside.

When there is an exchange of air from the inside to the outside, the level of permeability should increase. In terms of vapor permeability, traditional foam plastic is superior to extruded foam.

• Traditional foam has 0.063 mg/(m*h*Pa).
• Extruded foam has 0.013 Mg/(m*h*Pa).

Why is this so? If you use extruded polystyrene foam for external insulation, this will lead to undesirable consequences. Its low vapor permeability has a high level of insulation; this will lead to the accumulation of moisture, which will not allow the materials to dry out and ventilate.

Types of expanded polystyrene

As we have already said, this material is divided according to the production method. Figuratively speaking, the following options are distinguished: polystyrene, polyurethane, polyethylene, PVC expanded polystyrene.

The first ones are made in a pressed and non-pressed manner, the brands are described above. The second ones are polyurethane (PPU), which are popular in domestic conditions as usual foam rubber. Still others are polyethylene (PPE), which have the form of an elastic material in which the product is wrapped so that it does not break (film with air bubbles).

The fourth is PVC (PVC), similar in appearance to extruded polyethylene foam. They are also very flexible and have the same qualities. In addition, they do not contain highly toxic mixtures and are recognized as a self-extinguishing material.

In fact, there are a decent number of species. If you are concerned about a specific material, then it makes sense to find out information at a building materials store, where all the different options are listed in the catalogs.

Video about the production of various polystyrene foam options

Is vapor barrier and waterproofing necessary?

Polystyrene foam is a material that has fairly good resistance to the passage of vapors. When insulating walls made of block materials or brick, there is no need to install vapor barrier membranes.

When insulating the facade of a wooden building, a vapor barrier membrane is needed. It is attached between the wall and the foam plastic so that a ventilation gap is formed.

Waterproofing is not installed under foam plastic.

IMPORTANT!

If walls are insulated with foam plastic under siding, then a diffusion membrane is used, not a vapor barrier.

These two materials differ in their ability to pass vapors.

Thermal conductivity coefficient of foam plastic boards

Insulation of a house can be done in various ways, for example, using polystyrene foam, which has high performance characteristics. These include: practicality, environmental friendliness, light weight, ease of installation, immunity to temperature changes, as well as an affordable price. But the main advantage is the low thermal conductivity of polystyrene foam, which allows for excellent energy saving.

What determine the characteristics of the material?

The ability to conduct heat is influenced by many factors, in particular:

• Layer thickness. Sometimes, in order to achieve high-quality energy savings, it is necessary to use a large amount of insulation. For example, the thermal conductivity of 5 cm foam plastic boards will be lower than 1 cm with the same density.
• Structure. The porous structure leads to increased insulating properties, because the cells contain air that perfectly retains heat.
• Humidity. During storage, slabs must be protected from moisture. This is due to the fact that liquid does not have a very favorable effect on the characteristics of thermal insulation foams: the more it accumulates, the worse it is.
• Average layer temperature. Its increase leads to a deterioration in the efficiency of the insulator.

Types of foam plastic and their indicators

There are a huge number of insulation boards on the construction market. In general, polystyrene foam has low thermal conductivity, but this varies depending on its type. Examples: sheets marked PSB-S 15 have a density of up to 15 kg/m3 and a thickness of 2 cm, while the described indicator is up to 0.037 W/(m*K) at an ambient temperature of 20-30 °C. Its value for sheets 2-50 cm marked PSB-S 35, with a density of no more than 35 kg/m3 and 16-25 kg/m3 marked PSB-S 25 of the same size is 0.033 W/(m*K) and 0.035 W/ (m*K) respectively.

The dependence of the thermal conductivity of foam insulation on its thickness is best seen when comparing it with various materials. Thus, a sheet of 50-60 mm replaces twice the volume of mineral wool, and 100 mm is equivalent to 123 mm of expanded polystyrene foam, which has approximately similar characteristics. Basalt wool also loses greatly. But the thermal conductivity of Penoplex is slightly lower than that of polystyrene foam: in order to obtain normal temperature conditions in the room, you will need 20 and 25 mm, respectively.

How do you know which sheets to buy?

In order to most effectively apply this or that insulation method, it is necessary to select the correct dimensions of the material.

When trying to find the best option for insulation and heat conservation in the house, you should not lose your head - when choosing expanded polystyrene, you cannot rely only on its brand. Polystyrene foam grade 15, in terms of its characteristics, is in no way inferior to foam plastic grades 25 and 35

1. Polystyrene foam – brand and specific gravity per cubic meter

A common misconception is that the specific gravity of the foam must match the brand. That is, if polystyrene foam is grade 35, then its specific gravity per cubic meter should be 35 kg. However, in reality, the figure indicated in the foam brand only indicates the maximum possible weight of one cubic meter, according to the criteria prescribed in GOST.

This means that grade 15 includes polystyrene foam with a specific gravity of up to 15 kg/m3, which in reality is 11-12 kg/m3. In the case of the popular 25th grade, foam with a density of 15.1 kg/m3 to 25 kg/m3 is considered, but in practice, slabs with a specific gravity of 16-17 kg/m3 are produced.

You can also consider the 30th grade with a weight of polystyrene foam boards from 25.1 to 35 kg/m3, where the foam is produced with a real density of 26-27 kg/m3.

Is it worth calling polystyrene foam manufacturers unscrupulous in this case? In no case, because every manufacturer tries, while complying with GOST requirements, to provide the consumer with the best price while maintaining the competitiveness and quality of the polystyrene foam boards produced.

You cannot determine the quality and brand of polystyrene foam by density. This characteristic is only one of several when determining the brand of polystyrene foam boards produced in production. These characteristics are specified in GOST 15588-86, they include: thermal conductivity, water resistance, burning time of polystyrene foam boards, compressive strength, bending strength and structural stability.

Density is not the most important characteristic on this list.

For example, for the 25th grade GOST stipulates a compressive strength of no less than 0.08 MPa, while for the 15th density it is 0.04 MPa.

It is very important that according to GOST, if the foam does not correspond to its brand in any characteristic, it must be defined as expanded polystyrene of a brand of a lower class. Thus, if you buy foam plastic with a density from 15.1 to 25 kg/m3, which corresponds to grade 25, but its compressive strength is less than 0.08 MPa, it must be classified as grade 15.

2. Is polystyrene foam warmer due to its density?

Should we strive for high density? There is an opinion that dense foam is warmer. However, GOST again helps to understand this issue, according to which different brands differ in thermal conductivity only by thousandths:

grade 15 – thermal conductivity within 0.043 W/(m K);

grade 25 – within 0.041 W/(m K);

grade 35 – within 0.038 W/(m K).

In fact, modern production technologies maintain the thermal conductivity coefficient at almost the same level within 0.038 W/(m K) regardless of the density of the foam. Thus, the insulation of the house will be the same using the 15th grade or the 35th. The only difference between them is the compressive strength, which allows the use of denser polystyrene foam for insulating floors or surfaces with constant load.

Experts recommend that insulation of walls from the outside be carried out with good grade 15 polystyrene foam or grade 25 polystyrene foam of average quality, with an appropriate cost. You should not blindly chase strength for the reason that when thermally insulating walls, the technology provides for the need for protection from mechanical damage with a reinforcing mesh and a layer of plaster. The low density of the material only helps to simplify the work.

In the case of floor insulation, it is necessary to use polystyrene foam of the 35th grade, and the compressive strength must be at least 0.14 MPa. The indicator is less indicative of the 25th grade and they want to pass it off as higher quality foam. Also, the density should not be less than the values ​​​​established by GOST - from 15.1 kg/m3 to 25 kg/m3.

3. Important characteristics - what to pay attention to?

Density is not the main feature of polystyrene foam. Many characteristics serve as a pleasant bonus when insulating, as the sound insulation and wind protection of the building improves.

In practice, water absorption of polystyrene foam does not play an important role in wall insulation. This characteristic is taken into account only when carrying out underwater work. While under operating conditions of the façade, there is no constant contact with water.

When choosing a material, many people pay great attention to the resistance of polystyrene foam to low and high temperature levels. Foam plastic easily withstands low

temperatures up to -180 °C. However, in the case of high temperatures, things are not so simple. Experts have found that polystyrene foam can withstand temperatures of 95–110°C for several minutes, which technologically makes it possible to cover the slabs with a layer of molten resin or bitumen.

Polystyrene foam will shrink and deform with constant contact with materials whose temperature exceeds 80°C.

4. Does styrofoam burn?

Polystyrene foam is often referred to as a combustible material that is easily ignited. However, this hypothesis is a myth; anyone can test it; just try to set fire to a small piece of polystyrene foam and you will get the answer to this question.

Were you able to ignite the material? No! Indeed, today, according to the requirements of GOST, any brand of polystyrene foam contains fire retardants in its composition, such foam is designated as PSB-S. The prefix “C” means self-extinguishing.

This means that even if you manage to light PSB-S polystyrene foam, it will burn in a matter of seconds. It is also worth noting that melted residues also do not support combustion.

It is worth taking into account the use of polystyrene foam in the external insulation of houses, in which the material is located in the middle layers of facade structures under fiber cement boards or plaster and a layer of paint; in this case, only the destruction of the outer layer and the presence of a constant source of fire can lead to a fire.

It is known that when polystyrene foam burns, about 1000 MJ / cubic meter is released. m. How much heat does wood release when burning? 7–8 times more! So, no matter how much foam is blamed, it is no more dangerous than other building materials.

The Achilles heel of polystyrene foam is ultraviolet rays. With constant exposure to them, the foam loses its structural strength, the surface of the plates turns yellow and becomes brittle. Subsequently, under the influence of wind and rain, erosion of the material occurs. To completely eliminate these consequences, it is necessary to take measures to protect polystyrene foam. Such measures include applying a layer of plaster and further painting, or a more durable and durable method, using fiber cement panels. Under the protective layer, foam plastic can last more than 50 years.

Technology of thermal insulation of external walls with polystyrene foam

There are several ways to install polystyrene foam on the facade:

1. On glue.
2. Mechanical fastening using dowels.
3. Combining method. Both glue and fasteners are used. It's more reliable.

Everyone can choose the appropriate option for themselves, but professionals recommend using the latter method. In order for the entire structure to remain securely adhere to this plan.

Preparatory work

It all starts with preparing the foundation. This stage is as important as fixing the insulation or finishing it. Here they do the following:

1. If the building was previously covered with finishing, it is removed.
2. Remove fasteners and hanging structures.
3. The wall is cleaned of dirt, grease stains, solution build-up, and dust.
4. Prime the surface. For porous materials, such as foam or gas block, choose a deep penetration primer and apply it in 2 layers. It is also desirable that the composition be antibacterial. Then the main structure will be protected from harmful microorganisms. The soil allows you to increase the adhesion of the material from which the load-bearing walls are made, and therefore securely fix the insulation to the base.
5. Next, install the starting profile at the border of the base and the beginning of the wall. It will serve as a support for the foam. The profile is fixed immediately along the perimeter of the entire building. Be sure to check the horizontal position using a building level.
6. Now we begin to prepare the adhesive solution. The glue should only be suitable for polystyrene foam; other brands will not work. Cooking instructions are on the package. Be sure to adhere to the proportions, otherwise the material will not stick to the wall.

Bonding boards

The finished solution must stand for some time so that all components react with each other. Next, proceed to gluing the insulation boards:

• A thin layer of the solution is applied around the perimeter of the foam board. In these places, the mixture must be rubbed into the material - this increases adhesion.
• Make 2-3 small blots in the center.
• The slabs are installed in the starting profile from the lower left corner of the house.
• The foam is pressed tightly against the wall so that the solution is evenly distributed under the sheet. If excess adhesive solution is visible, remove it with a spatula. The evenness of the installation is checked using a building level.
• Glue is also applied to the next plate and pressed tightly against both the wall and the previous sheet.
• In the second row, the vertical joints should not coincide. To do this, the foam is shifted 15–20 cm to one side.
• After all the walls are completely covered with insulation and the adhesive solution has set, begin mechanical fixation. Make holes using a hammer drill and install disc-shaped dowels.

Installation of the reinforcing layer

When the glue is completely dry, begin reinforcing the surface of the foam. For this use:

1. An adhesive solution, perhaps the same one that was used to fix the slabs to the wall.
2. Fiberglass mesh.

There is also a special technique for gluing the mesh:

• First of all, apply a thin layer of glue using a spatula.
• Pieces of mesh 15–20 cm wide are glued to the corners. The mesh element is laid in such a way that the two walls have identical segments. Using a clean spatula, press the fiber into the adhesive solution.
• If it doesn’t work out, add glue on top and smooth it out.
• Next, we begin to reinforce the wall.
• A mesh is placed on the corner element with an overlap of 10 cm. It is also pressed into the solution with a spatula.
• When this layer has dried, apply the finishing layer to completely hide the mesh under the glue.

Applying a decorative layer

After applying the last layer of glue, wait until it dries completely. Next, it is customary to cover the foam insulation with plaster. This may be a decorative option with an original pattern or a regular, even layer painted in a suitable color.

After all the work is completed, the house will be warm and updated at the same time.
And this is a solution to two problems at once. Of course, whether to choose polystyrene foam for insulating a house or not is everyone’s business. The nuances of choice and technical characteristics listed above are quite enough to make the right choice. Polystyrene foam is considered a particularly effective building material used to insulate buildings inside and out. The reason for the widespread use of foamed polystyrene foam (or polystyrene) in the construction industry is the density of the foam and its excellent heat and sound insulation properties of the material. Many brands of material open up great opportunities for selecting the most suitable option.

Which is better - polystyrene foam or polystyrene foam?

Among specialists and home craftsmen, disputes often arise about what is better to use for insulation: polystyrene foam or expanded polystyrene. Advanced portal visitors will say that these are one and the same. And they will be right. Indeed, from the point of view of a chemist, expanded polystyrene (aka styrofoam) is not only a classic representative of foam plastics, but also the founder of the class of foamed plastics.

At the household level, not everything is so simple, since expanded polystyrene is associated with materials such as Penoplex, TechnoNIKOL, Styrofoam, URSA, which in structure are almost indistinguishable from polystyrene foam, but are made from extruded polystyrene foam. It’s easy to figure out where the foam insulation is and where the extruded polystyrene foam is: the first is always white, the second is colored (painted). Moreover, each manufacturer uses its own color scheme: TechnoNIKOL (yellow), Penoplex (orange), Styrofoam (blue), etc.

When it comes to their performance characteristics, there are differences, but they are minor:

• Polystyrene foam has a higher thermal conductivity, which requires a thicker layer of thermal insulation. And this is the loss of usable area of ​​the room when insulating from the inside;
• extruded polystyrene foam has higher strength and rigidity;
• polystyrene foam costs much less (approximately 2,000 rubles/m3 versus 4,500 rubles/m3).

Wall pie device

When insulated with foam plastic, the classic version of the wall pie looks like this:

• bearing wall;
• adhesive base;
• base profile;
• insulation;
• reinforcing mesh;
• adhesive base;
• primer;
• finishing layer.

The finishing layer can be facade plaster, paint or other facing material chosen when determining the design of the wall.

Wet facade

Differences between polystyrene foam and manufacturing methods

Before we begin to consider the types of polystyrene foam, it is necessary to clarify the terminology. Many people call polystyrene foam a lightweight white material consisting of a huge number of white compressed balls, in general this is true, but one point needs to be clarified.

Foam plastic is a general name for a whole group of materials obtained by foaming plastics. Since various plastics can be foamed, there are a huge number of foams. For example, if polystyrene is used as a raw material, the material obtained is polystyrene foam; if polyurethane is used as a raw material, the material is polyurethane foam (one type is polyurethane foam); polyvinyl chloride foam is obtained from polyvinyl chloride.

The production technology for all foam plastics consists of three main stages:

1. Mixing the components used.
2. Foaming.
3. Structuring.

The main technological link is foaming; at this stage, polymers are filled with gas, which determines the technical characteristics of the material.

The ratio between open and closed cells with air plays an important role in the physical and mechanical properties of polystyrene foam. Closed cells guarantee low hygroscopicity. The less the foam absorbs water, the better its thermal characteristics, the longer the material lasts.

The structure of the foam depends on the manufacturing technology and the raw materials used. Polystyrene foam, polyurethane and polyvinyl chloride have a large number of closed cells.

According to production technology, there are two main types of polystyrene foam:

• expanded polystyrene foam - (EPS)
• extruded polystyrene foam - (XPS).

Expanded polystyrene foam - (EPS)

Foamed polystyrene foam is most often used in everyday life. It is used as thermal insulation, material for packaging equipment and furniture. During its manufacture, polymers are filled with gas using foaming components.

Foamed polystyrene foam.

The technological chain consists of several stages:

• Mixing polystyrene, which is sometimes replaced by polymonochlorostyrene or polydichlorostyrene.
• Adding foaming components, which are low-boiling hydrocarbons - dichloromethane, pentane or isopentane.
• Adding additives that improve the properties of the finished material - plasticizers, fire retardants and dyes.
• Formation of granules with uniform distribution of low-boiling liquids in polystyrene.
• Treatment with steam or hot air.
• An increase in granule size as a result of sudden evaporation of low-boiling liquids.
• Structuring foam cells, giving it shape.

As a result of boiling of the foaming components, the granules increase in size by more than 50 times. The walls of the forming cells harden and merge, trapping air inside - an ideal heat insulator. The material turns out to be light, homogeneous, and retains its given shape well.

Enlarged expanded polystyrene foam granules.

Extruded Polystyrene Foam - (XPS)

The main differences in the production technology of extruded polystyrene foam are the absence of steam treatment and structuring by extrusion from a flat-slot extrusion head. Freons were used as a foaming agent in the first decades of material production; today carbon dioxide is used.

This expanded polystyrene has a continuous structure with closed-porous cells with a diameter of 0.1 - 0.2 mm.

Extruded polystyrene foam.

Extruded polystyrene foam has good thermal insulation properties and is more dense than expanded polystyrene foam. This allows the use of extruded polystyrene foam to insulate those objects for which expanded polystyrene foam is too soft. It is possible to produce extruded polystyrene foam, which will withstand loads of up to 35 tons per 1 m2.

Types of material and their differences and features

As we have already said, polystyrene foam differs in its manufacturing method. Conventionally, it can be divided into three types.

The first type is polyurethane foam (PPU). The most common example of such foam is ordinary foam rubber. This type of material is very elastic and is characterized by the presence of open pores, due to which air and water vapor are perfectly permeable. That is why it is used in furniture production and the construction industry, producing polyurethane foam. The disadvantages of such polystyrene foam include the fact that it is short-lived and with prolonged exposure to sunlight, the material turns yellow and slowly deteriorates. It is also worth noting that, despite the fact that such foam can be self-extinguishing, its smoke is very toxic and dangerous.

The second type is polyethylene foam (PPE). This type of foam is quite elastic. You've most likely seen it in stores many times - polyethylene foam is often used to wrap fragile items when moving. The material is produced in the form of sheets of different sizes. The advantages of the material include its durability and environmental friendliness due to the absence of toxic substances.

The third type is polyvinyl chloride foam (PVC). It is elastic and contains no toxic substances. However, it is worth noting right away that PVC can only burn when surrounded by fire - it will not ignite on its own. But if this happens, the material will begin to release hydrogen chloride, which, when combined with a liquid, leads to the formation of hydrochloric acid. Because of this, smoke from PVC can be very dangerous.

We told you about the most famous types of materials used in domestic construction. We hope our information will help you choose the most suitable foam for the type of work being carried out.