Polymer heat insulators are among the most popular materials for insulating roofs of various designs. Insulating the roof with foam plastic allows you to install thermal insulation yourself in a short time.
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);
- 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 foam plastic for roof insulation and building structures it is important to take into account the technical characteristics of the material various brands. Manufacturers recommend using polystyrene foam:
- PSB-15 (density 15 kg/m 3) 50-100 mm thick for thermal insulation pitched roofs, including attic, 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 poisonous, but ready 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 Expanded polystyrene sheets 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 physico-chemical bonds between the granules are quite weak, as a result of which the foam has low fracture strength, under external influence may crumble into granules.
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, integral 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 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. Basically, this material can only be installed complete with waterproofing, but 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 in various 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 thermal insulator at the roof design stage so that the pitch of the rafters matches the width of the 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 rafter legs. 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 rafter system. On 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 layer is laid reinforced screed. 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 also more complex versions of the 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 turn out 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, a wooden sheathing is first attached to the ceiling, 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.
- The use of polyethylene film instead of a 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.
Modern insulation technologies allow you to avoid heavy weighting of the roof. 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 they began to use various insulation materials 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 these purposes, for example 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, which 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 environmental material with good thermal insulation qualities and 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 properties thermal insulation and sound insulation, 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 mineral wool mats, but requires more care 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 your roof with foam plastic without resorting to services construction organizations, and most importantly, you can save money that you will later 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
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 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, it becomes more dense, waterproof, durable material. Roof insulation with polystyrene foam will cost more, but will allow you to get more thin layer thermal insulation with good sound absorption, better fire resistance and 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 gables 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
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 term operation;
- 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;
- ability to gain large quantity 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:
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 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.
Necessary materials and tools
To work you need to prepare:
- waterproofing material;
- polystyrene foam of the selected brand with required thickness and the size of the slab;
- 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 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.
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 floor can be systems of hanging 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
- 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 compulsory education 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”?
Polystyrene foam is popular name 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 a more limited scope of application.
The name of extruded polystyrene foam comes from its production method - extrusion, when the raw material is squeezed out through certain holes same sizes. 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 abbreviation 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 the Russian market is the 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 period.
- 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 a roofing pie, polystyrene foam can be damaged by rodents: they will not live in it, but they will make passages. 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 amount of a harmful substance in the air that can already harm a person. Exceeding this threshold always leads to such negative consequences, like illness or even death. Let's give an example: the most suitable insulation material is cheap foam, installed incorrectly, there is no normal ventilation in the home. Result: sick liver in the household. But in a well-ventilated house there is no harm for a long time no one feels. Those. we are talking about the fact that the concentration of a harmful substance below the established threshold does not affect dangerous influence per 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 on both the roof and the walls, then every day a person absorbs through the lungs permissible norm styrene, 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, which 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 actually 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 space, albeit in a small concentration, but on the heart and women Health influences quite a bit. And the most common problems from this element - toxic hepatitis, and all due to the cumulative properties of styrene, it accumulates in the liver, but is not excreted.
And finally, special studies Russian Academy 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 with 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 insulate correctly mansard 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 concept expansion joints. Seams form over time between thermal insulation materials due to temperature changes, as well as along the perimeter and in the places where the 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 so-called persistent organic pollutants, which, by the way, are strictly prohibited in Western countries by 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 finished design. 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. This is why a waterproofing layer is necessary: 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: a detailed analysis of 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.
Today, there are many materials that can be used to insulate the roof of a residential building.
One such material is polystyrene foam. It is rightfully one of the most popular because it has a number of advantages, such as light weight, ease of processing, and long service life.
Polystyrene foam is also used for thermal insulation of floors attic floor. Further in the article we will talk about how to insulate a roof with foam plastic.
Polystyrene foam is used for insulation of walls, ceilings, foundations, roofs and other areas of buildings. This material has the following advantages:
- long service life;
- does not cause allergies;
- polystyrene foam does not burn, but only melts;
- light weight;
- low thermal conductivity;
- resistant to temperature changes;
- easy to process;
- does not lose thermal insulation properties when used in a humid environment.
Many people wonder whether it is possible to insulate a roof with polystyrene foam and is polystyrene foam harmful to health? Polystyrene vapors are toxic, but the finished material does not emit substances harmful to health at all. It can be dangerous if melted by an open flame. However, the insulation of residential buildings is carried out using self-extinguishing foam, which does not support combustion and also belongs to the category of fireproof materials.
Preparation for installation
When insulating the roof of a house with polystyrene foam, you must first purchase the required amount of polystyrene foam, self-tapping screws, vapor barrier film, and wooden planks for fixing thermal insulation material.
When purchasing polystyrene foam, you should pay attention to its density. In construction stores, as a rule, they sell polystyrene foam of the PSB-S-15.35 and 25 brands. Their prices are almost the same. The number at the end shows how much one weighs cubic meter material in kilograms (material density).
Foam with more high density used for:
- Finishing of building structures exposed to physical stress;
- External façade finishing;
- Concrete screeds.
You can use expanded polystyrene brand PSB-S-15.
It should be noted that roof insulation with polystyrene foam is carried out without the use of complex equipment. You need to prepare the following tools:
- Screwdriver with attachments;
- Roulette and corner;
- Wood hacksaw;
- Marker;
- Furniture stapler for fixing the hydro- and vapor barrier layer;
- Pincers and pliers;
- Construction knife.
Choosing polystyrene foam and installing a roofing pie
When insulating a roof with foam plastic, you need to mandatory install vapor barrier and waterproofing. In this case, the vapor barrier is laid on the side attic room, and the waterproofing layer - from the roof side.
Foam plastic for roof insulation is resistant to moisture, but the penetration of water vapor and moisture into the thermal insulation layer is undesirable. After all, in this case they begin to rot wooden elements roofing structure.
In general, it consists of the following steps:
- Installation of waterproofing on rafters. This work can be done before or during installation roofing material;
- Installation of foam boards in the space between the rafters;
- Sealing the resulting seams using polyurethane foam;
- Elimination of cold bridges;
- Installation of a vapor barrier layer;
- Finishing the ceiling and walls of the attic space.
Polystyrene foam is also used to insulate attic floors. In this case, installation is performed as follows:
- Cleaning the subfloor from debris;
- Laying a vapor barrier film on the subfloor;
- Installation of foam plastic;
- Laying waterproofing, plywood and flooring.
The foam should have a thickness of 10 centimeters. The density can be any. However, it should be taken into account that as this parameter increases, the thermal insulation characteristics and mechanical strength of the material.
Polystyrene foam has poor sound insulation. And if the attic room will be used as a living room, then it is necessary to provide a soundproofing layer. It is mounted under the decorative cladding of the attic.
Instead of polystyrene foam, you can also use polystyrene boards. This material offers the same benefits as polystyrene foam, but is also more durable and resistant to rodent damage. It should be noted that the cost of polystyrene is higher than polystyrene foam.
You can reduce your home heating costs not only by using energy-efficient equipment, but also by using high-quality insulation. We talked about how to properly insulate a roof.
In this case, the installation of insulation should be carried out on absolutely all building structures, including the roof.
An acceptable result can only be achieved correct choosing and following the technology of its application.
Various polymeric raw materials can be used to produce polystyrene foam, incl. polystyrene, from which expanded polystyrene is made.
However, the difference in manufacturing technologies of these materials leads to different physical properties finished product.
So, polystyrene foam is more durable. This is achieved by the fact that, unlike the latter, in polystyrene foam the foam granules of the initial raw materials only sinter with each other during cooling.
In expanded polystyrene, the raw material is foamed not simply by treatment with hot steam, but by extrusion - melting and mixing with foaming reagents. The result is material with much smaller cell size than in foam plastic.
In addition, polystyrene foam is actually monolithic material with a large number of sealed cells filled with carbon dioxide.
The main differences between polystyrene foam and expanded polystyrene follow from the difference in production technologies:
- foam is less dense;
- unlike foam plastic, expanded polystyrene does not absorb moisture;
- mechanical the strength of polystyrene foam is much higher.
Accordingly, roof insulation with polystyrene foam is practiced in those places where ordinary polystyrene foam is of little use. As an alternative to expanded polystyrene, you can insulate the roof.
Types of expanded polystyrene
The classification of expanded polystyrene foams is based on their manufacturing technology.
Advantages and disadvantages of the material
Among the most significant advantages expanded polystyrene include the following:
- low thermal conductivity;
- light weight, simplifying installation even on roofs of complex configurations;
- hardness;
- frost resistance;
- resistance to moisture;
- durability.
At the same time, the material also has some flaws:
- actively supports combustion, with the exception of fireproof samples;
- It is quite difficult to perfectly join sheets of material, which leads to the appearance of bridges of cold;
easily damaged by rodents; - destroyed by vapors active chemicals;
- ages quickly and crumbles under ultraviolet light.
However, if we exclude the influence of destructive factors, then polystyrene foam is one of the most suitable for roof insulation. suitable materials. If you decide to abandon polystyrene foam, we recommend that you pay attention to.
How to choose high-quality polystyrene foam?
In order not to make a mistake with the choice of insulation, it is advisable to pay attention to the following points before purchasing:
- the material must be non-flammable type;
- You should not rely only on the numbers in the labeling. It gives a rounded value for the weight of a cubic meter of material. It is necessary to clarify specific numbers from the technical specifications;
- extruded polystyrene foam, which is most suitable for roof insulation, has a density of about 40 kg per 1 cubic meter;
- when trying to break off a piece of material, small polyhedra should be visible on the cut, and not large balls;
- you just have to choose famous manufacturers guaranteeing the quality of their products.
NOTE!
Use material with a density less than 17 kg per 1 cubic meter. as a roofing material it is extremely undesirable. It has excessively high porosity and will accumulate moisture.
How to choose the optimal insulation thickness?
The choice of the thickness of polystyrene foam for roof insulation is influenced by several factors.
Firstly, roof type: flat or sloped.
Secondly, the presence insulated attic.
Third, climatic conditions.
Practice shows that for middle zone the most optimal is thickness of expanded polystyrene 100 mm. This thickness can be achieved several layers of material, laying them with overlapping and waterproofing the seams.
Roof insulation with polystyrene foam: technology and practical advice
The sequence of actions for insulating flat pitched roofs varies significantly. If flat roofs insulated from the outside, That pitched sheathed from the attic. If you are planning to insulate your attic roof, be sure to read.
External insulation of a flat roof:
- a layer is applied to the cleaned reinforced concrete base of the flat roof bitumen-polymer waterproofing . These can be either various mastics or weld-on rolled materials;
- if necessary, a slope-forming layer of fine gravel, slag, expanded clay, etc. is poured;
- fits vapor barrier fabric. The joints of the overlapping sheets are sealed with tape. Vapor barrier is necessary here for the reason that there may be microcracks in the floor slabs of a flat roof, and there may be leaky seams between them. Without a vapor barrier from the inside, moisture from warm rooms will penetrate under the insulation and accumulate there;
- as possible closer to each other sheets of expanded polystyrene are laid out;
- layer is laid fiberglass for mechanical protection of insulation. Can be used instead of canvas sheets flat slate or other materials capable of bearing significant loads;
- sheets are laid overlapping waterproofing material;
- mounted roof covering.
Scheme of a flat roof roofing pie
When using polystyrene foam for insulation of pitched roofs from the inside, the installation technology will be slightly different:
- the entire inner part of the roof, along with rafters and sheathing, is laid. The canvases are placed with overlap, the joints are sealed with sealing tape;
- Insulation sheets cut to size are attached. To fix them, you can use either glue or specialized fasteners (nails with very large heads);
- all joints between sheets and rafters are treated with foam adhesive for polystyrene foam;
- If necessary, further layers of insulation are applied. Each layer is sealed separately;
- . The vapor barrier film will prevent the penetration of moisture from warm air attic space inside the insulating pie. To ensure waterproofing, the joints of the canvases are glued with construction tape.
- the resulting structure is sewn up with sheet finishing materials (moisture-resistant plasterboard, multi-layer plywood, fiberboard, etc.);
- finishing is installed.
Finishing roof insulation work
The insulation is laid in several layers to create the required thickness
For interior decoration it makes sense to use materials with low thermal conductivity(wooden lining, imitation timber, etc.). This will help improve the quality of the insulation performed. If you are planning, we recommend that you familiarize yourself with the nuances of insulation.
Not allowed to use sealants, chemically incompatible with this insulating material.
As you can see, insulating a roof with polystyrene foam is not as complicated a process as it seems at first glance. With proper preparation, even a beginner in construction can install insulation.
Useful video
We bring to your attention video instructions for self-insulation polystyrene roofs:
Conclusion
Roof insulation with polystyrene foam profitable both in terms of the achieved effect and in terms of the cost-effectiveness of the entire event. Consumables They're not too expensive, but self-execution of all work provides even greater savings.
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The roof not only protects the house from rain, snow and cold, but also preserves existing heat Houses. It has been established that 20% of the heat escapes through the ceiling of the building. Therefore, it is very important to insulate the roof. Market building materials has sufficient products that are used for thermal insulation of any type of roof. The most popular option is roof insulation with foam plastic.
Today on the building materials market you can see a large assortment of polystyrene boards of different thicknesses and densities. Our article will help you choose the most optimal floor or attic space, and will tell you how to insulate a roof with foam plastic.
Advantages of polystyrene foam for insulation
Polystyrene foam (expanded polystyrene foam) is a lightweight white material that consists of 98% air bubbles enclosed in polystyrene shells.
Advantages of polystyrene foam compared to other insulation materials:
- has a low weight, which allows it not to be reinforced bearing structures;
- does not pose an environmental hazard, because it is used for the manufacture of packaging products in the food industry, as well as in the production of toys for children;
- low thermal conductivity coefficient, due to the large amount of air in its composition;
- has excellent sound insulation;
- has a long service life;
- does not lose its heat-insulating properties even when used in a humid environment;
- does not promote the growth of bacteria and does not cause allergies;
- the material is not afraid of temperature changes;
- foam plastic for roof insulation in a fire does not flare up like wood, but only melts;
- lightweight material for installation, can be processed with any tools.
How to insulate a roof with foam plastic
Using polystyrene foam you can. However, experts recommend using mineral wool or glass wool for these purposes. Because the stability of shape under the conditions of the rafter system is better for these materials. At the joints of the polystyrene foam, the roof is insulated with foam (spray foam is used). However, over time, so-called cold bridges may form at the joints of the material.
Insulation of the attic floor
The first step is to clean the floor from old backfill and debris. Then steam and waterproofing should be done. After preparatory work it is necessary to lay out foam plastic slabs on the ceiling. The joints formed as a result of the layout should be treated with polyurethane foam, insulating the roof with foam. It is worth noting that in places where the roof meets the walls, be sure to leave a gap of 3-5 mm for ventilation.
If desired, you can lay a layer of roofing felt on top of the foam or make cement-sand screed with reinforcement. This is due to the purpose of the attic space. If you want to turn the attic into a living space, then you should lay a coating on top of the insulation that can withstand the weight of people, furniture, necessary plumbing or other equipment (parquet, laminate, boards).
What density should foam have?
Before insulating the roof with foam, you need to make sure whether the attic floor can withstand the expected loads, with the addition of living space.
- polystyrene foam with a density of 15 kg/m3 (PSB15), thickness 50-100mm - for pitched and attic roofs, ceilings
- polystyrene foam with a density of 25 kg/m3 (PSB-25), thickness 50-100 mm - for walls
- polystyrene foam (PSB35) or extruded polystyrene foam - for flat roofs, floors and attic floors with mechanical loads
Roof insulation
To wooden structures condensation has not formed, it is necessary to lay a vapor barrier membrane. This should happen during the installation of the rafter system before using foam plastic. If the insulation process occurs in parallel with the construction of the roof, then it is necessary to fill the rafters with sheathing from below, which will serve as a support for foam boards. The slabs are installed tightly between the rafters. Then they are covered from above with waterproofing material.
It can be ordinary roofing felt or new materials based on foamed polyethylene. The process of attaching to the rafters waterproofing film or roofing felt is carried out with a construction stapler. But we should not forget that waterproofing material there is no need to tighten it, but on the contrary, it should sag slightly.
About the dangers of polystyrene foam as insulation
Many developers often ask the question: is polystyrene foam harmful because of its toxic fumes, and is it possible to insulate the roof with polystyrene foam? It is also noted that polystyrene foam, which is used for insulation of residential premises (PSB), is self-extinguishing (that is, it does not support combustion). Its flammability class belongs to category G1 (fireproof material).
Roof insulation with foam plastic, detailed video instructions:
If you choose polystyrene foam for roof insulation, be sure to check the thickness of the insulating layer for your region. When making calculations, you should keep in mind both the roofing material used and the climate zone. General rule: do not use insulation materials with a thickness of less than 100 mm (read: " ").
If two layers of foam are higher than the size of the rafters, then you will have to build them up. Because it is not advisable to nail the frame for plasterboard boards in the future. In addition, attaching foam sheets will be problematic. In the following articles you will learn how to insulate a roof with foam insulation.
In a person’s mind, a house is, first of all, a “roof over one’s head” that protects its inhabitants from snow, rain and wind. However, it is important not only to keep out the cold and bad weather outside, but also to retain the heat inside, which is produced by heat-generating devices. According to thermal imaging studies, 20-30% occurs through the roof surface. total heat loss. Therefore, when building a house in northern and temperate latitudes, thermal insulation of slopes is mandatory. IN Lately professional builders insulate roofs with foam plastic, the effectiveness of which we will discuss in this article.
Foam plastic is a foamed mass of polystyrene foam, in the smallest bubbles of which air is “preserved.” Due to the fact that the gas content in this material reaches 97-98%, it has low thermal conductivity, light weight and practically does not burn.
Polystyrene foam used for roof insulation is produced in the form of slabs different sizes and thickness. The density of polystyrene foam is only 15-25 grams per 1 square meter, denser grades are used for installation on floors and ceilings, where they are subject to significant load. This type of insulation has the following advantages:
- A light weight. Perhaps the most important advantage of polystyrene foam is the light weight of this material. One square meter of insulation based on polystyrene foam is only 15-25 grams, which allows you to insulate the roof with polystyrene foam without reinforcement rafter frame and lathing.
- Low thermal conductivity. A 10 cm layer of foam plastic corresponds to the thermal insulation properties of double brickwork or a 20 cm wooden wall.
- Easy to install. Working with expanded polystyrene; the installation technology of this insulation involves the use of the most simple tools, available in the arsenal of any master.
- Vapor and waterproof. When using polystyrene foam for roof insulation, you do not have to worry that the thermal insulation properties of the material will decrease upon contact with water. Almost zero hygroscopicity and vapor permeability make this insulation the best option for thermal insulation of slopes.
- Fire resistance. Foam production technology High Quality involves the addition of fire retardants, substances that lead to self-extinguishing of the material. Therefore, such insulation is considered safe and non-flammable.
- Durability. The service life of polystyrene foam is more than 50 years. This material is not susceptible to decomposition, rotting and the action of fungal or mold microorganisms.
Note! based on expanded polystyrene have low resistance to mechanical damage. In addition, they are destroyed when some varnishes or paints come into contact with the surface of the material. Rodents are not averse to profiting from polystyrene foam, so it requires special protection.
Varieties
Expanded polystyrene is a type of synthetic polymer or plastic that is widely used in manufacturing. Several types of roof insulation are produced from it. Depending on the production method, there are 2 main types thermal insulation materials based on it:
- Regular foam.
Conventional polystyrene foam is produced by foaming polystyrene foam under the influence of air or carbon dioxide. This is a lightweight, inexpensive, non-flammable insulation with excellent thermal insulation qualities.
The weakness of conventional foam plastic is the fragility of the boards; this material is extremely susceptible to pinpoint impacts that can damage the sheet. It has low strength, higher thermal conductivity and permeability, and is also cheaper. To insulate the roof, foamed polystyrene foam with a sheet thickness of 100-200 mm is used.
To produce this insulation, the extrusion method is used. First, polystyrene foam granules are mixed with a foaming agent under the influence of high pressure and temperature, and then extruded through an extruder.
The result of these actions is a denser, solid insulation with a closed fine-cell structure. It has higher mechanical strength, does not allow water and steam to pass through, and also has improved thermal insulation characteristics.
Extruded polystyrene foam for roofing is more expensive than usual, however, more is used for insulation. thin sheets. Experienced roofers believe that it is better suited for thermal insulation work.
Important! Although polystyrene foam is a non-hygroscopic and vapor-proof material, roof insulation is carried out using a waterproofing and vapor barrier membrane. The membrane that protects the insulation from steam penetration is fixed on the inside of the roof, and the membrane that protects from moisture is fixed on the street side. This measure, in conjunction with exhaust ventilation will help extend the life of the roof rafter frame.
Installation technology
Despite the high performance characteristics of the insulation, the main component of effective thermal insulation is high-quality installation in compliance with all technological nuances working with expanded polystyrene.
Installation errors can even create big problems than lack of insulation, for example, to rotting rafters, dampness or mold. Roof insulation with foam plastic is performed before laying the roofing material on the rafters in the following order:
- WITH bottom side rafters on brackets construction stapler secure strips of vapor barrier membrane. The membrane is cut into sheets of the required size and fixed across the rafters so that it sag slightly and there is an overlap of 10-15 cm between the strips. The joints are glued with adhesive tape or construction tape.
- From the attic side, perpendicular to the rafters, guide bars made of wood or metal are attached on top of the vapor barrier, which will support the insulation. The thickness of the guides should provide a ventilation gap between the thermal insulation and the wall cladding.
- Foam boards are inserted between the rafter legs and glued using special glue. The material is cut so that there are fewer joining seams.
- The joints between the slabs and the junction of the insulation with the rafter legs are sealed using polyurethane foam.
- Strips are fixed over the rafters waterproofing membrane, overlapping one sheet over another to avoid leakage at the joints.
- The waterproofing is secured with counter battens, the sheathing is installed and the roofing material is laid.
I advise professional roofers: if you are insulating a residential attic roof with polystyrene foam, consider installing fiber soundproofing material, especially if as roofing metal tiles or corrugated sheets are used. Expanded polystyrene has low noise-reducing ability, so the roof increases sounds during rain.
Video instruction