How to insulate a roof with foam plastic without disassembling it. Is it possible to insulate a roof with foam plastic? Closed truss structure

The constructed house is already protected by the roof from seasonal precipitation and wind loads. If the roof is insulated, thermal insulation is added to the functions of the roof. The uninsulated ceiling of the upper level of a residential building and its roof causes the loss of a fifth of the building’s heat. Roof insulation helps to avoid energy losses, save on heating costs, and get additional square meters comfortable space for all-season living.

With a wide range of bulk, roll, sprayed and produced insulation boards, the most popular and affordable is roof insulation with foam plastic.

Expanded polystyrene is superior to polystyrene in all respects and is therefore more expensive

Both materials are produced from polystyrene using different technologies. The classic foam plastic we are familiar with is obtained by steaming in the form of microgranules, which increase in size from high temperature and fill out the volume of the block form. The result is a lightweight material from polystyrene shells sintered together and filled with air.

Expanded polystyrene, produced by extrusion, is a material with a solid structure, including small gas-filled cells. Thanks to the technology, a more dense, waterproof, durable material is obtained. Insulating a roof with expanded polystyrene will cost more, but will allow you to get a thinner layer of thermal insulation with good sound absorption, better fire resistance and a longer service life. This material is practically irreplaceable when thermal insulation of a flat roof and floors is being used. Expanded polystyrene is good not only for roofing, but also for insulating the gables of a gable roof without large losses of useful living space.

The operating technology is the same for both materials. In the future, insulation of building roofs with foam plastic will be considered.

Features of the material

Advantages of polystyrene foam:

Foam boards come in different thicknesses

light weight, reducing the load on the load-bearing elements of the roof structure;
ease of installation and processing with working tools;
resistance to temperature changes and certain mechanical loads;
low thermal conductivity due to 98% air content in the material;
long service life;
retains its properties and shape in a humid environment, is not afraid of mold and mildew;
affordable price;
environmental friendliness;
fire safety (the material melts without ignition);
hypoallergenic.

Flaws:

release of harmful substances when exposed to open fire;
the ability to accumulate a small amount of moisture, which can cause the formation of mold and mildew on rafters, sheathing, finishing materials and corrosion of metal fasteners;
the impossibility of completely filling the niche between the rafters due to rigidity; this leads to the appearance of condensation and cold bridges;
the material is almost impervious to air;
rodents can live in polystyrene foam (this does not apply to extruded polystyrene foam);
afraid of contact with solvents, alcohols and petroleum products;
ultraviolet radiation destroys the foam.

Standard foam sheets have dimensions:

500 mm x 1000 mm;
1000 mm x 1000 mm;
2000 mm x 1000 mm.

The thickness of the insulation falls within the range of 10-100mm. In the marking of foam plastic, the number indicates the density in kg/m³. When insulating a roof from the inside or outside, the PSB-S-15 and PSB-S-25 brands are more often used.

After studying the characteristics and comparing them with other types of heat insulators, each owner independently decides whether it is possible to insulate the roof with foam plastic, or whether another material is suitable in his case.

Methods for fastening foam boards

The set of insulation sheets depends on the chosen installation method. necessary materials, devices and tools that will be required for the job.

Polystyrene foam can be:

Fastening polystyrene foam using regular polyurethane foam

glue with special frost-resistant glue, liquid nails, mastic;
lay - when insulating attic floor or flat roof outside;
put battens into the niche;
secure mechanically using wooden slats, umbrella nails or anchors.

For greater reliability, ease of operation, or if necessary, it is possible to combine the proposed fastening methods.

Advice: Several spare slabs are added to the calculated amount of foam upon purchase, taking into account possible damage to the mechanically sensitive material during transportation and installation.

Required materials and tools

To work you need to prepare:

waterproofing material;
polystyrene foam of the selected brand with the required thickness and size of the plate;
vapor barrier film or membrane;
self-adhesive tape for gluing joints or overlaps of vapor and waterproofing fabrics;
polyurethane foam;
construction stapler;
scissors, knife;
wooden blocks;
hammer;
material for finishing insulation places.

Now you can start insulating the roof with foam plastic.

Insulation of a flat roof

Insulating a flat roof with foam plastic and bypassing communications

The waterproofing film is first laid on the previously prepared, clean and dried surface of the flat roof.
Then the foam plastic slabs are tightly laid (for a roof that will be loaded during operation, it is advisable to choose polystyrene foam) and the joints are taped with special tape. If there is a second layer of insulation, its slabs must overlap the joints of the lower layer during installation.
The insulation is covered with geotextile, on which a layer of gravel, expanded clay or crushed stone (at least five centimeters) is poured.
A screed is being made on which the finishing roof covering will be laid.

If you plan to lay out a lawn on a used flat roof or flower bed, then another layer of geotextile is laid on top of the gravel. Now a layer of soil is poured onto it (within 20 cm) and grass or other plant crops are planted.

Roof insulation with foam plastic can also be done from the inside. Most often, foam plastic is glued to the ceiling, so the surface of the latter must be prepared for good adhesion. After fixing the slabs, fill the voids at their joints with sealant. The finishing of the insulated ceiling can be systems of suspended or suspended ceilings. If the foam will be covered with sheets of plasterboard or other materials, a lathing is attached to the ceiling in advance.

Insulation of a pitched roof

eliminate possible damage and leaks of the roof;
treat wooden structural elements with a special antiseptic to prevent rot and mold; rafters, beams, slats already damaged by microorganisms - replace with new ones;
treat metal parts and fasteners with anti-corrosion compounds;
it is desirable to treat the entire wooden structure with fire-resistant impregnation;
if the width of the rafters is less than the thickness of the foam boards used, it is increased using wooden beams.

A layer of waterproofing is attached to the sheathing using a stapler. The overlapping areas of the canvases are glued with a special tape for tightness. If a layer of waterproofing has already been laid under the roof on the sheathing, then this point should be skipped.
Measuring and cutting insulation boards for tight installation in a niche.

Tip: If the decision to use polystyrene foam is made before building the roof, it is advisable to provide a distance between the rafters equal to the size of the slab used.

Laying prepared foam boards between the rafters and securing them using the chosen method.
Small gaps between foam sheets are filled polyurethane foam or other sealant. This operation should be performed carefully and efficiently. Otherwise, there is a high probability of cold bridges occurring with the obligatory formation of unwanted condensation.

Important! When insulating the roof of a residential attic with foam plastic, you should not lose sight of the material of its roof. If the covering is metal tiles or profiled a metal sheet, in addition to the insulating layer, it is imperative to provide a soundproofing layer. This compensates for the weak noise-proofing properties of foam, especially during rain or thunderstorms with hail.

For additional insulation, a layer of mineral wool can be installed on the foam.

If additional sound insulation is provided, it is laid on foam plastic. Otherwise, move on to the next point.
The insulation is separated from the internal attic or attic space by a vapor barrier film, the sheets of which are also taped with special tape at the joints. The vapor barrier is secured to the rafters with staplers and wooden guides for future cladding. The thickness of these guides or profiles will provide the necessary ventilation gap between the vapor barrier and final finishing. When stretching the film, leave a slight sag to avoid tearing due to temperature changes.

Important! For a comfortable stay in insulated attic room it is necessary to take care of high-quality ventilation, since due to the vapor barrier barrier, moisture vapor will remain inside.

Sheathing work is being completed inside insulated attic space with selected finishing materials.

Mistakes when insulating with foam plastic

Use of low-quality slabs - with manufacturing defects or damage during installation.
Violation of technology and work order.
Using ordinary polyethylene film as a vapor barrier.
Incorrectly chosen width of the installed slabs - this leads to a violation of the tightness of the insulation layer.

Knowing how to insulate a roof with foam plastic, it would be useful to study technologies using other materials. After comparing all the pros and cons, you can make an informed choice.

Video: how to insulate the roof of a building with polystyrene slabs

The process of insulating a roof with foam plastic is a very popular way to insulate a house. Both pitched and flat roofs can be insulated in this way. Also, foam plastic for insulation can be laid in the attic floors.

Roof insulation with foam plastic has many advantages: it is easy to install and process, it is not afraid of moisture, it does not rot or be destroyed by microorganisms, and it can provide reliable thermal insulation without weighing down the structure.

But the material also has disadvantages - vapor permeability and flammability. Therefore, when using polystyrene foam as insulation, it is necessary to install ventilation in the attic space and strictly observe all fire safety standards.

Difficulties with foam insulation

Many developers often have a question: are foam vapors poisonous? Is it worth using this material to insulate the roof from the inside? The benefit of polystyrene foam is the fact that polystyrene foam (PSB) used for thermal insulation in residential premises is self-extinguishing - it does not catch fire. The flammability class of polystyrene foam is category G1, that is, it is a fireproof material.

When working on a pitched roof, many experienced builders use mineral wool or basalt slabs. This choice is determined by the rigidity of the foam, due to which the material cannot be located in the entire space under the roof. Voids appear into which cold penetrates, resulting in the formation of condensation. Due to condensation, the rafter system is destroyed and the metal elements in the roof rust.

To avoid condensation, when choosing foam plastic for thermal insulation of the roof of a private house, it is necessary to clarify such an indicator as the thickness of the thermal insulation layer for the area in which you live. When making calculations, you need to focus on the type of roofing material used and the climate zone. The choice of foam has one thing in common: it is not recommended to use foam with a thickness of less than 10 cm for work.

Expert opinion

Konstantin Alexandrovich

Ask a question to an expert

In cases where the insulation needs to be laid in two layers, and the thickness of the rafters does not allow it, it would be correct to lay a 50mm by 50mm beam horizontally, step under the covering material (plasterboard, OSB and various moisture-resistant boards).

Characteristics of foam plastic

Foam plastic has the following advantages among other materials:

light weight, which reduces the load on the load-bearing parts of the roof;
ease of installation and processing with tools;
resistance to temperature changes and certain mechanical loads;
low thermal conductivity due to high air content - 98 percent;
long service life;
preservation of properties and shape at high humidity, it is not afraid of mold and mildew;
affordable cost;
environmental friendliness;
fire safety (foam plastic can only melt and not ignite);
hypoallergenic.

Of course, foam plastic also has disadvantages:

if the material is exposed to open fire, it releases harmful substances;
is able to absorb moisture, albeit in small quantities, which is why rafters, lathing, finishing materials become covered with mold and mildew, and metal fasteners become covered with rust;
it is impossible to completely position the foam between the rafters, as it is too rigid; in this case, condensation and cold bridges form;
has low breathability;
polystyrene foam can be chewed through and colonized by rodents (extruded polystyrene foam is an exception);
Solvents, alcohols, gasoline are dangerous for him;
destroyed by exposure to ultraviolet radiation.

Attention! Despite the fact that high fire resistance is one of the advantages of polystyrene foam (it does not spontaneously ignite), if the material burns, toxic substances are released. That is why the installation of polystyrene foam must be accompanied by compliance with all fire safety rules.

A standard foam sheet can be of the following sizes (mm):

500×1000;
1000×1000;
2000×1000.

The thickness of the insulation varies from 10 to 100 mm. The number contained in the insulation marking indicates the density (kg/m3). For internal or external roof insulation, polystyrene foam of the PSB-15 or PSB-S-25 brands is usually used.

Having studied the characteristics of foam plastic and comparing them with other materials for thermal insulation, each builder himself decides whether to use this material for insulation or replace it with another.

Do-it-yourself roof insulation with polystyrene foam

Before work you should prepare:

material that will be used for waterproofing;
polystyrene foam of the selected type (taking into account the required thickness and size);
vapor barrier film or membrane;
self-adhesive tape to seal the joints and overlaps of vapor and waterproofing materials;
polyurethane foam;
construction stapler;
scissors and knife;
wooden blocks;
hammer;
material that will be used for final finishing in areas of insulation.

After preparing the necessary materials and tools, you can begin to insulate the roof using polystyrene foam.

This happens in the following order:

How to insulate a roof with foam plastic from the outside?

Foam boards are often used to insulate flat roofs from the outside. To do this, the roof is well cleaned and covered with waterproofing. Polystyrene boards can be laid as flooring, glued, or secured with dowels. An important condition is to lay the slabs as tightly as possible so that gaps do not form.

The vapor barrier membrane can be laid at the bottom of the heat insulator, placing it on a concrete base, then the installation of polystyrene foam boards begins, they are covered with expanded clay, on which a cement-sand reinforced screed is laid. Also, using polystyrene foam, you can create a roofing “pie” consisting of:

reinforced concrete base;
bitumen-polymer waterproofing;
slab heat insulator;
geotextiles;
gravel backfill.

This combination creates a serviceable roof that cannot be destroyed by high loads.

External thermal insulation technology:

This option is the most common method of attaching material to a surface. concrete slabs. This method is suitable for insulating a flat roof. Moreover, you can insulate both a new roof and a restored one.

Conclusion

Regardless of the choice of insulation by the master, the so-called protective “pie” always includes foam plastic and waterproofing. Careful adherence to the required rules during installation will allow you to live in any home comfortably and without additional heating costs.

Video on roof insulation with foam plastic

The roof is an integral element of any building that protects the construction site from the effects of atmospheric phenomena: wind, dust, rain, snow.

It is necessary to produce in order to keep it warm in the cold season, and in the hot season summer days no overheating occurred.

It depends on the literacy of the choice of material for insulation, the professionalism of the work performed, and compliance with all rules for arranging the roof. life time roofs.

It seems possible even to a layman. Before you start directly insulating the roof, you need to have a clear idea of where it will be located. attic, residential area or non-residential place for the attic. The consumption of insulation material depends on this.

select the appropriate material, suitable in terms of characteristics and meeting the requirements of a particular building, indicate the scheme and order of work;
Necessarily check the rafters for strength, quality, possible fungal damage. If defects or moisture are detected, unsuitable elements must be replaced;
to increase service life treat with an antiseptic all elements of the roof frame, including wires, water pipes, rafters. Both antipyretic and antiseptic agents can be used as impregnation for wooden structures.

When all preparatory work done, you can start insulating the roof.

Main types of insulation

Of the many materials available on the construction markets for installing thermal insulation, the most popular are:

Styrofoam;
glass wool(fiberglass);
basalt slabs.

Thermal insulation materials must have high thermal insulation qualities, including good water resistance, low thermal conductivity, environmental friendliness, low flammability.

The longer a material can maintain these properties, the more reliable and durable it is.

Foam plastic: advantages and disadvantages

Polystyrene foam is a foam material that consists mainly of gas, enclosed in microscopic cells of material. Due to its good thermal conductivity, foam plastic is often used for roof insulation.

This material, unlike cotton analogues, has more high thermal protection properties, which allows you to lay it in a thinner layer.

In addition, polystyrene foam has advantageous characteristics that characterize it as a worthy heat insulator. The use of foam plastic for roof insulation is due to some characteristic advantages:

no water absorption;
low thermal conductivity;
strength;
is not subject to stretching and compression;
good performance soundproofing;
ease of installation;
no rotting;
not susceptible to microorganisms;
good performance wear resistance: not subject to temperature changes;
does not weigh down the structure;
durability(service life up to 80 years);
relatively low price;
According to hygienic standards, it is harmless to humans and the environment, as it does not emit harmful substances.

CAREFULLY!

Polystyrene foam has fairly good fire resistance (not subject to spontaneous combustion), however, releases toxic substances when burned, therefore, during installation, all fire safety rules must be observed.

Given that foam plastic has a fairly rigid structure, this indicator can be both an advantage and a disadvantage, since rigidity is also accompanied by fragility. In this regard, when insulating a large volume of roofing, a lot of waste may remain, so you should purchase material in reserve.

The disadvantages of polystyrene foam as insulation include::

instability to mechanical stress;
susceptible to destruction when exposed to varnishes or nitro paints;
does not allow air to pass through(it is necessary to install additional ventilation);
has a lower thermal insulation coefficient compared to modern insulation materials;
does not pose an obstacle to rodents, therefore it requires additional protection.

Despite its disadvantages, polystyrene foam is widely used in thermal insulation work.

How to choose the optimal foam thickness?

Climatic indicators of the region are the starting point for calculating the thickness of foam for roof insulation. There are special tables that display the thermal heat transfer parameters of each region.

In addition, the value of the thermal conductivity coefficient of the insulation is indicated on the packaging (sometimes in the certificate) of the foam.

The product of the values of the thermal conductivity coefficient and the thermal heat transfer of the region will be equal to the thickness of the insulation layer.

There are average material density indicators that experts focus on when choosing expanded polystyrene:

on flat or attic roofs use PSB-35 material (density - 35 kg/m3, thickness - from 50 to 100 mm);
for pitched and attic- PSB-15 ( density – 15 kg/m3, thickness – from 50 to 100 mm);
on the walls— PSB-25 ( density – 25 kg/m3, thickness – from 50 to 100 mm).

Sometimes you have to lay the foam in two layers. In this case, the thermal insulation layer may be thicker than the width of the rafters, as a result of which it is necessary to build up frame boards.

With the technology of laying polystyrene foam, the gap between the rafters can be avoided additional work to increase the width of the wooden frame, but then installation can become significantly more complicated.

Insulating a non-residential attic with foam plastic

If there is a non-residential attic, insulation of only the ceiling with the building or the floor of the attic itself.

Sometimes they resort to . In this case, the roof is insulated with foam plastic from the inside.

Before you start insulating the roof with foam plastic, you need to know what work must be carried out:

provide the perimeter of the insulated surface with a continuous heat-insulating circuit;
make rafters, in we talked about the insulation of metal roofing (corrugated sheeting and metal tiles);
provide space between the insulation and the roof for ventilation.

It is this work that ensures high-quality thermal insulation.

Insulation procedure attic foam is carried out as follows:

the amount of material required for the work is calculated. In this case, it is necessary to take into account the surface area that needs to be insulated and surface unevenness. The fragility of foam plastic contributes to an additional increase in the batch of purchased material;
slatted ones are also purchased in the form of bars (for lathing);
assemble and attach the sheathing to the roof;
install insulation.

Flat roof roofing pie

Installation of insulation for an attic roof is carried out in several stages:

wooden structure treated with an antiseptic, cracks are eliminated using polyurethane foam, silicone glue or other sealants;
cover the entire surface waterproofing layer;
lay down lathing from bars(section 10x10mm) in steps equal to the width of the material slab.
lay foam plastic around the entire perimeter of the roof, while making sure that between the panels no gaps were formed;
the insulation is covered;
at the end, the entire “pie” is covered with a material that will completely hide the entire structure (plasterboard, plywood, plastic panels) and cover the entire coating.

The final stage of laying insulation

When the attic is insulated, the heat is retained much longer in the building itself and is not wasted in the attic space.

Insulating the attic roof with foam plastic

It involves insulating the entire area of the attic floor. Initially, the roof is insulated, then the walls and floor. It should be remembered that there must be a gap between the slabs for ventilation.

Insulation mansard roof polystyrene foam is produced quite often, and the sequence of actions must be followed:

before starting work it is necessary to calculate the amount of material consumed. Thin blocks of polystyrene foam are often used, which are laid in a double layer in a checkerboard pattern so that the joints of the bottom layer are covered with the top layer. Due to the fragility of foam plastic, you should take the material with reserve;
then it is applied to the rafters using nails or staples waterproofing film, which is attached using bars up to 5 cm high. On the roof slopes, the waterproofing is laid crosswise with an overlap (the width of the overlay of the edges of the material is about 10 cm). It is allowed for the film to sag a little, but not be taut;
further between the rafters lay foam plastic, in this case, the material and the rafters should not come into contact, otherwise the insulation will cool much faster. Foam sheets should be fasten with self-tapping screws or special glue. It is recommended to seal the joints between the rafters and the wall, as well as between the rafters and the foam plastic, with polyurethane foam;
space window openings sealed with pieces of foam plastic and waterproofing film;
then the entire area is covered vapor barrier film, securing it with staples;
the final stage is laying the sheathing: plasterboard, plywood or other finishing material, which is then puttied and prepared for applying decorative materials (paint, wallpaper, wood finishing). The sheathing is attached to a profile or wooden beam, which provides a gap of about 5 cm between the sheathing and thermal insulation.

Roofing pie pitched roof

Combination of insulation - polystyrene foam + mineral wool

This option for insulating an attic roof with polystyrene foam is the most common. If you follow all the recommendations, you can achieve good thermal insulation of the roof for many years.

Common mistakes when insulating with foam plastic

It is advisable to insulate the roof with foam plastic in conjunction with the insulation of all walls of the building. However, if the roof is insulated wrong, then soon the consequences of unprofessional insulation will clearly make themselves felt.

The most common mistakes, which are important to avoid during the installation of insulation:

the occurrence of gaps between foam plates. These gaps are cold bridges, which appear in the cold season. In addition, they can cause moisture to form in the insulation;
use of polyethylene film as waterproofing. After a few years, its properties will be lost and cellophane will begin to allow moisture to pass through;
errors in calculating the thickness of the thermal insulation layer can lead to the appearance of depressions and disruption of the seal of the insulation.

Correctly selected thermal insulation material and properly equipped roof insulation will keep the house warm for many years.

Useful video

We invite you to watch a video about insulating your roof yourself:

In contact with

Market modern materials for the insulation of low-rise buildings is actually divided into two camps - adherents of mineral fiber insulation and those who prefer foam materials. If many years of experience insulating roofs and floors with mineral fiber speaks for itself, then roof insulation with foam plastic is not yet so popular among developers and construction companies, although this attitude is clearly undeserved. There are many reasons for a reserved attitude towards foamed polymers, therefore, before answering the question for yourself whether it is possible to insulate a roof with foam plastic, it is worth understanding them in more detail.

Why use foam plastic for roof insulation?

From time immemorial, thick mats made of pressed mineral fiber have been used to insulate roofs. Anyone who has worked with mineral wool at least once in their life will confirm my words: even when using protective equipment, working with such insulation is far from easy. In addition, if a hole forms in the roof, the waterproofing is damaged, or condensation flows into the body of the fiber insulation, all the work is in vain.

In this sense, roof insulation with foam plastic is simply a gift of fate:

Lightweight and durable foam boards can be laid under rafter sheathing two to three times faster and easier. Even if the polystyrene foam was caught in a rainstorm or lay in an unheated attic for a couple of years, it has not lost its qualities and can last for several more decades;
Allows you to obtain higher thermal insulation parameters; even with a sheet thickness of 15-17 cm, heat loss through the roof slopes can be reduced by up to 97%;
Repair and replacement of insulation on the roof, if necessary, is carried out five times faster than when using mineral wool.

For your information! The cost of insulating one square meter of roof will be 30% cheaper than using mineral slabs.

The material is easy to cut with a knife or a hand saw, does not delaminate, and in its normal state does not absorb or emit volatile substances or odors. It can be glued, painted, treated with special primers and even plastered with cement-sand or gypsum mixtures.

Logic dictates: if polystyrene foam is used to insulate walls both inside and outside the room, houses are built from sip panels based on polystyrene foam and expanded polystyrene, so why can’t foam plastic sheets be used to insulate the roof?

The answer sounds quite simple - polystyrene foam has its own characteristics and disadvantages that must be taken into account when planning roof insulation.

Features of arranging roof insulation made of foam plastic

Foamed polystyrene, which is polystyrene foam, has its own hidden disadvantages that must be taken into account before insulating the roof with polystyrene foam:

Foamed polymer practically does not conduct water vapor, therefore, to prevent watering of wooden elements rafter system the roof will need to be covered with a layer of insulation from the attic side with a vapor barrier film;
Similarly, the plane of the foam sheets on the side adjacent to the roofing material of the roof must be covered with a waterproofing sheet or film;
The main disadvantage of polystyrene foam, which prevents the widespread use of foam material as a basis for insulation, is its poor thermal resistance and flammability.

For your information! The manufacturer of foam materials tried to minimize the susceptibility of the foam to ignition using special additives in the form of iron and chromium salts.

Such brands of polystyrene melt even when in contact with an open flame, releasing polystyrene decomposition products, but a stable combustion front does not form at temperatures up to 370-400 o C. Wood, widely used for the manufacture of roof rafters, begins to char and steadily smolder even at 270 o C. Therefore, for roof insulation, it is recommended to use foam grades with index C.

To equip insulation systems, foam plastic with a density of 20 to 45 kg/m 3 is used. The heaviest brands have always been the most durable and, accordingly, the most expensive. The lower specific gravity, the lower the thermal conductivity coefficient, but the strength of the material also decreases.

Since the foam sheets laid in the rafter roof insulation system do not experience loads, as, for example, when installing a concrete floor, there are no special requirements for contact or bending strength. But this does not mean that almost any material can be used to insulate the roof, for example, sheets from foam packaging or thermal insulation of industrial refrigerators. This foam will crumble into granules in the second or third year of service. For insulation, use foamed polystyrene grade C with a density of 30 kg/m 3 or more.

Technology for arranging roof insulation based on foam plastic

The sequence of installation of an old house, built a long time ago, may differ slightly from the insulation arrangement scheme for just now assembled system rafters of the new building. The difference lies in the use and location of the waterproofing film or membrane. Of course, work on laying a foam insulation system is carried out only after processing all, without exception, wooden parts of the roof rafter system.

Arrangement of insulation for an old building

Most often, the issue of effective insulation is raised specifically for houses where the roof is assembled ready-made and has been serving properly for quite a long time. Such a roof, as a rule, already has its own insulation layer laid during construction. If the audit showed the good condition of the materials used, the absence of soaking or destruction of steam and waterproofing, then you can simply supplement the existing layer with upholstery with OSB boards and an additional layer of polystyrene foam 70 mm thick. The installed insulation can be covered with a layer of aluminized film.

The remains of the roof waterproofing and insulating material are removed;
The surface of the wood of the rafters and sheathing is thoroughly cleaned with an electric brush, after which it is treated with protective antifungal compounds;
A new layer of waterproofing is applied to the sheathing and rafters; even the rafter beams must be wrapped in insulation and secured with a stapler;
Foam blocks are cut with a width equal to the pitch of the rafters, polyurethane glue is applied to the end surface, and the material is laid on the inside of the roof like bricks.

At the bottom of the roof it is necessary to lay foam plastic with minimum quantity seams, in the area adjacent to the ridge, you can collect insulation from pieces and scraps, but be sure to glue and foam the seams. Foam plastic up to 50 mm thick can be easily cut with a knife; for thicker slabs it is best to use a carpenter's saw with teeth ground on the sides. In this case, the cut is thin and neat.

When cutting, tiny dust and foam balls become highly electrified and stick to your hands, so when cutting the material, a vacuum cleaner is usually used to collect the chips. It is advisable to work in an apron and sleeves, since dust, balls and tiny pieces of foam are very difficult to remove from the surface of clothing.

Excess foam is trimmed and protected. After laying the insulation layer, a vapor barrier material is applied to the surface. It is best to use rolled material with an aluminized surface such as penofol or isopol. The vapor barrier is covered with clapboard sheathing or moisture-resistant plywood treated with a fire-retardant compound.

Roof insulation with foam plastic for new buildings

The technology for constructing insulation for a newly constructed building differs only in the method and location of attaching the top layer of waterproofing. The film or membrane is rolled out in horizontal strips on the roof rafters after filling the sheathing. Laying the canvas begins from the lower edge of the roof slope, each subsequent row is laid out overlapping the previous one. The material is stapled to the rafters; the joints must be taped. A counter lathing is placed on top of the membrane to form vents. The remaining insulation elements are performed similarly to the previous case.

The most important point in building an insulation system is the arrangement of the roof covering passage unit chimney. It doesn’t matter what material the chimney pipe is made of, it will have to be insulated with basalt fiber and closed protective casing made of thin sheet metal. The box in which the pipe is attached to the rafters is also filled with a mineral thermal insulator; the lathing or cladding covering the layer of foam plastic in close proximity to the pipe, at a distance of 40-50 cm, must be sewn up with a metal sheet.

Polymer heat insulators are among the most popular materials for insulating roofs of various designs. Roof insulation with foam plastic allows short time Install the thermal insulation yourself.

Features of the material

Polystyrene foam is foamed polystyrene - a lightweight material, 98% consisting of air bubbles glued together, which are enclosed in a polystyrene shell. The advantages of polystyrene foam include:

minimum weight (insulation does not add serious loads to the roof structure);
low thermal conductivity coefficient due to the high air content, which is an excellent heat insulator;
resistance to moisture (can be used in a humid environment without loss of thermal insulation properties);
resistance to temperature changes;
fire safety (the material does not ignite, but upon contact with an open fire it begins to melt);
environmental safety and hypoallergenicity;
resistance to biological damage (fungus does not develop, is not damaged by rodents);
ease of processing with tools and installation;
lack of tendency to deformation;
long service life(25-80 years old);
affordable price.

Foam plastic is one of the materials that is sensitive to external influences. It must be transported with care. The material should be protected from mechanical damage and exposure to direct sunlight.

When choosing polystyrene foam for insulating roofs and building structures, it is important to consider specifications material of various brands. Manufacturers recommend using polystyrene foam:

PSB-15 (density 15 kg/m3) 50-100 mm thick for thermal insulation of pitched roofs, including attic roofs, as well as ceilings;
PSB-25 (density 25 kg/m3) 50-100 mm thick for wall insulation;
PSB-35 (density 35 kg/m3), or extruded polystyrene foam - for thermal insulation of flat roofs, attic floors, floors. This material can withstand high mechanical loads.

Disadvantages of polystyrene foam as insulation

The question often arises: is it possible to insulate a roof with foam plastic? Polystyrene vapors are toxic, but the finished material does not emit harmful substances. Expanded polystyrene boards can pose some danger when melted under the influence of an open flame. But it is worth noting that self-extinguishing foam is used to insulate residential buildings - it does not support combustion and is a fireproof material.

For insulation pitched roofs sheets of expanded polystyrene can be used, but in terms of functionality they are inferior to cotton wool insulation: rigid slabs of polymer material cannot always tightly fill the space between structures, as a result of which cold bridges form in places where there are voids and moisture condenses. Processing of joints construction foam or sealant do not guarantee 100% protection. Condensation causes destruction of wooden structures and metal fasteners.

The soundproofing qualities of polystyrene foam are rated quite highly, but it is not entirely suitable for thermal insulation of “noisy” metal roofs, since it dampens sound worse than cotton insulation.

Thermal insulators made of polystyrene

What is the difference between roof insulation with extruded polystyrene foam and foam insulation? There are no particular differences in the installation principle, since both materials are polymer foamed slab insulation. But, despite the similar chemical composition, extruded polystyrene foam and polystyrene foam differ in their performance characteristics.

Polystyrene foam is made by repeatedly exposing polystyrene to steam. The initial granules increase significantly in volume and sinter together. It is worth noting that the physicochemical bonds between the granules are quite weak, as a result of which the foam has low fracture strength and can crumble into granules under external influence.

The extrusion method involves first melting polymer pellets and then treating them with freon and carbon dioxide. Thanks to this, extruded polystyrene foam has a strong, solid microstructure, which consists of small closed cells filled with gas molecules. The walls of the cells form a continuous mass of substance. Extruded polystyrene foam - modern high-tech durable material, which is superior to traditional foam in its functional parameters. This should be taken into account when choosing a material for roof insulation.

"Penoplex" is one of many brands of extruded polystyrene foam. Today, the term “penoplex” has become a household name and is often used to refer to expanded polystyrene produced by extrusion.

Basic principles for installing foam insulation

The foam should be laid on a clean and dry surface. In principle, this material can only be installed in conjunction with waterproofing, but in order to ensure long-term operation of the roof, it is advisable to add a vapor barrier layer, otherwise condensation will begin to accumulate on the insulation from the inside. The foam itself will not suffer from it, but wooden structures may begin to rot and become moldy.

Roof insulation with polystyrene foam can be done different ways, including:

gluing (on liquid nails, facade frost-resistant adhesives, mastics);
mechanical fastening (anchors, wooden slats, umbrella nails);
flooring;
investment in the sheathing.

If necessary, fastening methods can be combined. For example, sheet insulation is inserted into the sheathing and additionally secured with a dowel with a thermal head (umbrella nail). Or the material is glued to the surface and secured with screws.

Insulation of a pitched roof

It is recommended to select a heat insulator at the roof design stage so that the pitch of the rafters corresponds to the width sheet material. If we insulate the roof with foam plastic, then this approach can significantly reduce material consumption. The construction market offers sheet polystyrene foam insulation, which can be laid without gaps between rafters with a step width of up to 2 meters.

In addition, it is important to perform a thermal calculation taking into account the climatic characteristics of the area in order to determine the required thickness of the thermal insulation layer. The minimum recommended parameter is 100 mm.

Foam boards are laid along the sheathing between the rafters. To secure the fastening, you can use glue and dowels. There are often small gaps between the slabs and rafters. They should be properly blown out with polyurethane foam or filled with sealant, otherwise cold bridges will form in these places, where condensation will accumulate and have a detrimental effect on the wood of the elements of the rafter system. At the next stage, it is recommended to lay a vapor barrier, and then finish it with plasterboard, clapboard or wood board.

Flat roof insulation

Expanded polystyrene boards are a popular option for external insulation of flat roofs. The roof base should be thoroughly cleaned and covered with waterproofing film. Expanded polystyrene slabs can simply be laid as a flooring, glued, or secured with dowels. It is very important to lay the slabs without gaps, as tightly as possible.

The vapor barrier membrane can be laid under the heat insulator on a concrete base, then polystyrene foam slabs are mounted, covered with a layer of expanded clay, on top of which a cement-sand reinforced screed is laid. Expanded polystyrene as insulation can also be included in such a roofing pie:

reinforced concrete base;
bitumen-polymer waterproofing;
slab heat insulator;
geotextiles;
gravel backfill.

This allows you to create a serviceable roof designed for high loads.

There are more complex options roofing pie, the top layer of which is the soil for planting. Roof insulation with penoplex is widely used to create such inversion roofs.

Insulating a flat roof from the inside

During operation, it may become clear that a flat roof needs additional insulation. In order not to dismantle the roofing pie, it is recommended to insulate the roof with foam plastic from the inside. You should select insulation of the required thickness.

Foamed polystyrene sheets can be attached to reinforced concrete ceilings using glue and dowels. It is important to prepare the base surface to ensure high adhesive adhesion. When laying slabs, the elements should fit tightly to each other. It is advisable to use a sealant during the process so that there are no voids at the joints between the sheets and at the points where they meet the walls.

To finish such a ceiling, you can use a tension or hanging system. If it is planned to cover it with plasterboard or other materials, first attach it to the ceiling wooden sheathing, the thickness of which should be no less than the thickness of the insulation.

The most common mistakes when insulating with polystyrene foam

Installation of sheets with defects or damage to mounted slabs - depressions and cavities contribute to the formation of cold bridges.
An incorrectly selected width of the heat insulator also causes a leak.
Using polyethylene film instead vapor barrier membrane provokes the formation of condensation.
Use of low-quality materials, violation of work technology.

Roof insulation with foam plastic (expanded polystyrene) from the inside, video

Watch how to insulate a roof with polystyrene foam and extruded polystyrene foam from the inside in the video. Advantages and disadvantages of polystyrene foam, is it possible to insulate a roof with it?

Roof insulation with foam plastic: types and classification of insulation materials. Thermal insulation of a gable roof

Today, when building houses, and later finishing them, the question arises of how to make it warm. After all, building is only half the battle; it is important to reduce heat loss as effectively as possible. Moreover, by insulating not only the walls and floor, but also insulating the roof with foam plastic from the inside, or choosing another insulation.

Avoid heavy weighting of the roof modern technologies insulation. A reliable degree of protection against heat loss is provided by the fairly lightweight thermal insulation materials that exist today.

Completed view of attic insulation

The insulation process depends on its type and plans for using the attic space. So it makes sense to insulate the roof slopes if the attic will be frequently used or equipped as a living space.

For these purposes, various insulation materials have been used that effectively cope with this task. And at this stage, the question usually arises: is it possible to insulate the roof with foam plastic or use another material for this purpose, such as mineral wool.

Some prefer the first option, others the second, based on their work experience or the advice of friends. Still others simply doubt and do not know what to give preference to. So what is better to insulate the roof with foam plastic or mineral wool? Let's try to figure it out and decide what to choose.

Types and classification of insulation

Let's consider all types of insulation that are used for these purposes. Various materials are used in roof insulation.

The most commonly used insulation materials are:

light weight;
easy to install;

Considering all the disadvantages and advantages, we can say that polystyrene foam is the best option, for insulation that will keep the house warm.

mineral wool insulation;

expanded clay

All of the listed materials have their pros and, of course, cons. Let's figure it out and determine which material has the best qualities.

Expanded clay is an environmentally friendly material with good thermal insulation properties and an inexpensive price. The big disadvantage is that it is difficult to work with. The main difficulty is that it is difficult to fix and distribute evenly on non-horizontal surfaces.

Expanded polystyrene has good thermal insulation and sound insulation properties, a strong and durable material. But it does have its drawbacks: it melts, releasing harmful substances upon contact with an open fire, and has a low vapor barrier coefficient.

Mineral wool has a low material density and therefore it is considered that its thermal insulation abilities are lower than those of polystyrene foam. Also, its water-repellent properties are not great. Otherwise she is good material for insulation.

Polystyrene foam is a lightweight material that consists of ninety-eight percent air bubbles enclosed in a polystyrene shell.

Its advantages are as follows:

light weight;
low thermal conductivity coefficient;
easy to install;
has good sound insulation properties;
it is an environmentally friendly insulation material;
optimal price-quality ratio;
does not burn on contact with open fire.

Also, the advantages of foam insulation include its moisture-repellent property - you do not have to additionally install moisture- and vapor-protective membranes. Insulation with foam plastic is much cheaper than with mats mineral wool, but requires more accuracy and experience.

In conclusion

We tried to tell you about all the ways to insulate a roof with foam plastic. We hope that you have learned a lot of useful things from this article and now you can independently insulate the roof with foam plastic without resorting to the services of construction organizations, and most importantly, you can save money that you will subsequently spend on your needs.

Do-it-yourself insulation of the roof from the inside with polystyrene foam, how and what is the best way to insulate the roof, is it possible to use mineral wool, instructions, photo and video tutorials, price

How to insulate a roof with foam plastic: answers to all questions

The constructed house is already protected by the roof from seasonal precipitation and wind loads. If the roof is insulated, thermal insulation is added to the functions of the roof. The uninsulated ceiling of the upper level of a residential building and its roof causes the loss of a fifth of the building’s heat. Roof insulation helps to avoid energy losses, save on heating costs, and gain additional square meters of comfortable space for all-season living.

With a wide range of bulk, roll, sprayed and produced insulation boards, the most popular and affordable is roof insulation with foam plastic.

Are polystyrene foam and polystyrene foam the same thing?

Expanded polystyrene is superior to polystyrene in all respects and is therefore more expensive

Both materials are produced from polystyrene using different technologies. The classic foam plastic we are familiar with is obtained by steaming in the form of microgranules, which increase from high temperature and fill the volume of the block mold. The result is a lightweight material from polystyrene shells sintered together and filled with air.

The operating technology is the same for both materials. In the future, insulation of building roofs with foam plastic will be considered.

Features of the material

Foam boards come in different thicknesses

light weight, reducing the load on the load-bearing elements of the roof structure;
ease of installation and processing with working tools;
resistance to temperature changes and certain mechanical loads;
low thermal conductivity due to 98% air content in the material;
long service life;
retains its properties and shape in a humid environment, is not afraid of mold and mildew;
affordable price;
environmental friendliness;
fire safety (the material melts without ignition);
hypoallergenic.

release of harmful substances when exposed to open fire;
the ability to accumulate a small amount of moisture, which can cause the formation of mold and mildew on rafters, sheathing, finishing materials and corrosion of metal fasteners;
the impossibility of completely filling the niche between the rafters due to rigidity; this leads to the appearance of condensation and cold bridges;
the material is almost impervious to air;
rodents can live in polystyrene foam (this does not apply to extruded polystyrene foam);
afraid of contact with solvents, alcohols and petroleum products;
ultraviolet radiation destroys the foam.

Standard foam sheets have dimensions:

Methods for fastening foam boards

The set of necessary materials, devices and tools that will be required for the work depends on the chosen method of installing insulation sheets.

Fastening polystyrene foam using regular polyurethane foam

glue with special frost-resistant glue, liquid nails, mastic;
lay - when insulating the attic floor or flat roof from the outside;
put battens into the niche;
secure mechanically using wooden slats, umbrella nails or anchors.

For greater reliability, ease of operation, or if necessary, it is possible to combine the proposed fastening methods.

Required materials and tools

To work you need to prepare:

waterproofing material;
polystyrene foam of the selected brand with the required thickness and size of the plate;
vapor barrier film or membrane;
self-adhesive tape for gluing joints or overlaps of vapor and waterproofing fabrics;
polyurethane foam;
construction stapler;
scissors, knife;
wooden blocks;
hammer;
material for finishing insulation areas.

Now you can start insulating the roof with foam plastic.

Insulation of a flat roof

Insulating a flat roof with foam plastic and bypassing communications

The waterproofing film is first laid on the previously prepared, clean and dried surface of the flat roof.
Then the foam plastic slabs are tightly laid (for a roof that will be loaded during operation, it is advisable to choose polystyrene foam) and the joints are taped with special tape. If there is a second layer of insulation, its slabs must overlap the joints of the lower layer during installation.
The insulation is covered with geotextile, on which a layer of gravel, expanded clay or crushed stone (at least five centimeters) is poured.
A screed is being made on which the finishing roof covering will be laid.

If you plan to lay out a lawn or flower bed on a used flat roof, then another layer of geotextile is laid on top of the gravel. Now a layer of soil is poured onto it (within 20 cm) and grass or other plant crops are planted.

Insulation of a pitched roof

Produce necessary preparation and revision of the roof structure frame and the roof itself:

Scheme for insulating a pitched roof with foam plastic

Roof insulation with foam plastic

Laying prepared foam boards between the rafters and securing them using the chosen method.
Small gaps between sheets of foam plastic are filled with polyurethane foam or other sealant. This operation should be performed carefully and efficiently. Otherwise, there is a high probability of cold bridges occurring with the obligatory formation of unwanted condensation.

For additional insulation, a layer of mineral wool can be installed on the foam.

If additional sound insulation is provided, it is laid on foam plastic. Otherwise, move on to the next point.
The insulation is separated from the internal attic or attic space by a vapor barrier film, the sheets of which are also taped with special tape at the joints. The vapor barrier is secured to the rafters with staplers and wooden guides for future cladding. The thickness of these guides or profiles will provide the necessary ventilation gap between the vapor barrier and the final finish. When stretching the film, leave a slight sag to avoid tearing due to temperature changes.

The work is completed by covering the inside of the insulated attic space with selected finishing materials.

Mistakes when insulating with foam plastic

Use of low-quality slabs - with manufacturing defects or damage during installation.
Violation of technology and work order.
Using ordinary polyethylene film as a vapor barrier.
Incorrectly selected width of the installed slabs - this leads to a violation of the tightness of the insulation layer.

Knowing how to insulate a roof with foam plastic, it would be useful to study technologies using other materials. After comparing all the pros and cons, you can make an informed choice.

Roof insulation with foam plastic: can it be used, all the pros and cons

Answers to all questions about roof insulation with foam plastic. How to properly and whether it is possible to insulate a roof with polystyrene foam. The advantages of this method of thermal insulation.

Roof insulation with foam plastic: 5 main questions for an independent master

Are you attracted to roof insulation with foam plastic as the cheapest and easiest option, but you are worried about some opinions about its toxicity, and you don’t really know how to get started with this material? In this article we will reveal the 5 most important questions about polystyrene foam as insulation and help you understand the technology of its installation with the help of detailed master classes. It will be interesting!

What is hidden under the name “foam plastic”?

Foam plastic is the popular name for expanded polystyrene. But it is worth distinguishing between simply expanded polystyrene and extruded polystyrene foam.

Polystyrene is a product of the polymerization of styrene, which is quite clear from the name alone. In appearance, polystyrene is hard, elastic and colorless. It does not have high mechanical bending or tensile strength, and low density. Even lenses are made from this substance, not to mention dishes and other household items.

Expanded polystyrene is foamed polystyrene, which is produced in the form of sheets up to 20 cm thick and can vary in density. It costs much less than extruded polystyrene foam, is more friable and has more limited area applications.

The name of extruded polystyrene foam comes from its production method - extrusion, when the raw material is squeezed out through certain holes of the same size. Even more precisely: extruded polystyrene foam is a gas-saturated melt of polyethylene. It is produced in the form of sheets with a thickness of 30 to 70 mm, and varies not only in density, but also in color. Much more durable than conventional foam, it has a tongue-and-groove system along the edges and is easy to install - there is no need to fill the joints. In addition, its thermal conductivity is even lower - in fact, the lowest of all existing insulation materials.

Extruded polystyrene foam is made by extrusion, due to which it has a uniform, closed-porous structure. Each cell has a diameter of no more than 0.1-0.2 mm.

Extruded polystyrene foam in English is called XPS, in Russian - EPPS. They are also insulated with polystyrene as a sandwich panel when this insulation is closed on top OSB board or metal sheet:

Moreover, working with this material is quite simple:

But one of the most popular XPS products on Russian market– light blue Primaplex slabs. This is a fairly durable material with extremely low water absorption, dimensional stability and high frost resistance.

Why is foam plastic better than other thermal insulation?

Now let's look at the popular myths about polystyrene foam.

So, the first and most important quality for which this insulation is valued is its high thermal insulation. This coefficient is 0.035-0.048 W/mK at 25C, and 0.20 W/mK for its individual types, according to manufacturers. But absolutely all foamed plastics are afraid of water and quickly absorb it. And expanded polystyrene, which is made using the non-press method, has a water absorption of up to 350% of its mass. And even this is not the limit! And the more moisture in the insulation, the lower its thermal insulation properties.

But in practice, ordinary polystyrene foam lasts only 10-15 years as roof insulation, after which its heat-protective qualities sharply decrease. But extruded polystyrene foam, abbreviated as EPS, is more durable.

But polystyrene foam has the lowest thermal conductivity among all existing roof insulation materials. Even in severe frost, the temperature of 50 mm thick foam and EPS sheets will be +5°C. Plus the following advantages over other heat insulators:

Soundproof.
Stable dimensions throughout the entire time.
Easy to install and cut to required sizes.
No need for wind protection.
Resistance to chemicals of various kinds.

And quite interestingly, in factory conditions they test the strength of extruded polystyrene foam: they lower it into water, heat it to +40°C and cool it to -40°C. Each such cycle is equivalent to one year of operation. Therefore, manufacturers confidently declare that extruded polystyrene foam can serve as under-roof insulation for 50 to 80 years.

And the most important advantage of extruded polystyrene foam is that it does not reduce its thermal insulation properties even when in contact with water. Whereas conventional insulation works properly for only a few years, and then, if mistakes were made in roof insulation, they gradually reduce their thermal insulation qualities and the house has to be heated more and more. This is not to mention other related problems.

But in roofing pie expanded polystyrene can be damaged by rodents: they will not live in it, but they will make moves. Unless you hide these sheets outside:

Is polystyrene foam safe as insulation?

Officially, this material is classified as environmentally friendly, i.e. those that do not pollute environment and are not dangerous to humans. But let’s initially determine what influence on the human body can be considered dangerous, and what can be considered prejudice and unnecessary anxiety. You will be very surprised!

Such different concepts

Thus, in the world it is customary to refer to two main concepts for assessing the harm to the human body of certain substances: threshold and linear.

The threshold concept states that all harmful substances in a residential building must be reduced to a certain level for each of them, a threshold, which is fixed by the MPC value (maximum permissible concentration). Those. this is the quantity harmful substance in the air, which can already harm a person. Exceeding this threshold always leads to negative consequences such as illness or even death. Let's give an example: the cheapest foam plastic was chosen as insulation, it was installed incorrectly, there is no normal ventilation in the home. Result: sick liver in the household. But in a well-ventilated house, no one feels harm for a long time. Those. we are talking about the fact that the concentration of a harmful substance below the established threshold does not have a dangerous effect on a person, and a healthy body can easily cope with small toxins. It's like inhaling cigarette smoke from your interlocutor once.

In all countries former USSR And modern Russia building codes and the rules are based on the threshold concept. But in Japan, Canada, Germany, the USA and Belgium, the linear concept is at the forefront, the essence of which is that the harmful effect on the human body linearly depends on the total absorption of a certain substance. Those. at one time cigarette smoke really will not have a significant effect negative influence on the body, but constant smoking – yes. The same applies to polystyrene foam: if such insulation is used both on the roof and on the walls, then every day a person absorbs the permissible amount of styrene through the lungs, which is not so little in a year. In a word, small concentrations of poison with long-term use are also harmful. This is easy to show using the example of modern megacities: all transport exhausts and factory emissions do not individually exceed the sanitary threshold, but still life is not sweet for the city residents.

If, when insulating, we adhere not to the first concept, but to the second, then the value of the maximum permissibility of styrene in a residential area will have to be reduced by 594 times!

Of course, polystyrene is also used in Food Industry our country, and in medicine. But remember that its toxicity is calculated according to the same concept - threshold. Just note that polystyrene foam and polystyrene are already being phased out in many countries, and in some even banned.

A substance that is not excreted from the body

Now let us recall that styrene is a condensed aromatic compound that contains benzene in its molecule and is bad because it is not excreted from the human body. And, according to modern scientists, in residential construction the threshold for the presence of styrene in the air should be reduced to such minimum values that any polymerization products (including polystyrene foam) should be prohibited.

Therefore, we conclude: styrene is toxic to humans primarily because it accumulates in the liver. After all, the problem is that the human body can really cope with an ordinary toxin by simply processing it with the help of the liver and throwing it away naturally, but styrene is not removed from the body - it only accumulates. Therefore, a threshold concept cannot be applied to foam insulation - only a linear one.

In addition, according to modern SNiPs, toxicity indicators of combustion products must be determined for combustible materials. And for high-quality expanded polystyrene this value is T2, which means “moderately dangerous”.

99% polymerization

There is one more point that not everyone knows about. The fact is that 100% polymerization of EPS is only a theory, but in practice it does not even reach 98%. In addition, even the polymerization process itself is reversible, because polymers are easily destroyed by ultraviolet rays, ozone, water, oxygen, heat and mechanical stress. Then free styrene begins to separate from the EPS and penetrates into the living room, albeit in a small concentration, but it affects the heart and women’s health quite a bit. And the most common problems from this element are toxic hepatitis, and all because of the cumulative properties of styrene, it accumulates in the liver, but is not excreted.

And finally, special studies of the Russian Academy of Sciences have shown that during its period of operation, polystyrene foam decomposes up to 10-15%, and 65% of the decomposed part consists of styrene.

The solution is ventilation!

But how can the foam used to insulate the roof harm it? If this is insulation from the outside, then, of course, no way. If from the inside, but the attic is not used, then it is necessary to carefully consider ventilation. But if we are talking about a residential attic with such insulation, then things are bad. At least we don't advise you to do this.

Or it’s good to cover the foam in front with other insulation, as in this project:

How to insulate a roof with foam plastic inside and outside?

Basic methods of attaching foam to a surface:

But mainly two methods of fastening are popular. Adhesive:

This is how to properly insulate an attic roof:

As insulation for a concrete roof:

What difficulties may arise during insulation?

But there are many such difficulties, so get ready to study all the nuances of such insulation.

Point 1. Expansion joints

Here is the first stumbling block that may frustrate you when insulating your roof with foam plastic. This is the concept of expansion joints. Seams form over time between thermal insulation materials due to temperature changes, as well as along the perimeter and in places where beams pass. You can notice such problem areas in winter - by a thin strip of ice or snow that does not roll off. And there is a limit for deviations from the norm for these seams, and for pitched roofs it is one, but for flat roofs it is completely different.

Although some home craftsmen simply cut out the foam to the size of the rafters and insert it without any seams:

Point 2. Weathering

But the most alarming thing is that polystyrene foam undergoes weathering, during which gas-containing mixtures are formed. And weathering in an ordinary attic with its ventilation through opposite dormer windows is inevitable. It is not advisable to decorate even a residential attic with polystyrene foam, so that in the heat you simply do not inhale the so-called persistent organic pollutants, which, by the way, Western countries under the strict prohibition of the Stockholm Convention.

Point 3. Preliminary plan

Unlike the installation of conventional insulation, before installing foam sheets, you should carefully consider the plan and make sketches. There are other difficulties: for example, such panels cannot be cut and processed mechanically, they cannot be secured with screws - only inserted into the finished structure. Moreover, if you need to carry out certain communications under the roof (electricity, for example), then you will have to organize another mounting layer under the panels, at least 50 mm thick.

Point 4. The need for waterproofing

Despite the fact that polystyrene foam and expanded polystyrene are waterproof, covering roof slopes or flat roof waterproofing cannot be considered. All because of the large number of seams. That's why waterproofing layer required: it can be bitumen roll materials, oiled paper, fiberglass or kraft paper.

Have you decided to insulate with this material? Think it over proper ventilation roofs and take care of your health!

Roof insulation with foam plastic: detailed analysis all pressing issues

Myths and truth about foam insulation: how easy, safe and practical it is. Step by step instructions with examples of work done correctly.