Pair of waterproofing film. Hydro-vapor barrier films for roofing. Polyethylene films and membranes

To preserve the heat-insulating properties of foundations, walls and roofs of buildings, they should be protected from steam saturation from inside the room, and also protected from moisture penetration from the outside. Even the most good insulation rather quickly loses its qualities under the influence of these factors. You can neutralize their action with the help of Isospan vapor barrier.

This is a multi-layer coating in rolls, made from a polymer film with various additives. One of the "pioneers" of production in Russia is Hexa LLC. For more than 10 years, major construction companies and small developers use Izospan brand films as a reliable vapor barrier.

Types and their application

The company produces 3 groups of film materials that differ in characteristics:

1. Windproof, waterproofing, vapor barrier membranes Izospan are used for sheathing outer side building. They protect walls, roofs, ceilings from wind, snow and moisture. At the same time, they remain permeable to water vapor, which avoids the accumulation of condensate under the skin. This group includes:

2. Hydro- and vapor barrier films - when sheathing the internal surfaces of building structures. Protect them from the penetration of steam and condensate from inside the room. This group includes such brands of Isospan:

3. Reflective hydro-heat-vapor barrier energy-saving films with a metallized coating. They are able to reflect up to 90% of infrared thermal radiation, and also protect the insulation, internal and external elements of building structures from wind and moisture. This group includes:

Parameters and cost

Technical characteristics of the vapor barrier Izospan different brands, as well as the average prices for them in Moscow are shown in the table:

Brand	Indicators					Price, rub/m2
	Tensile load, longitudinal / transverse, N / 5 s)	Water resistance, mm water column	Vapor permeability, g/m2/day	Density, g/m2	Combustibility/flammability*
BUT	190/139	330	3500	110	G3/V2	21–25
A-OZD	177/129	250	3500	110	G1/V1	38–41
AS	165/120	1000	1000	125	G4/V2	42–44
AM	125/95	1000	1550	90	G4/V2	28–31
AQ	355/–	1000	2100	185	G3/V2	45–47
AT	130/107	1000	22	70	G3/V1	15–20
With	197119	1000	18	90	G3/V2	21–26
D	1068/890	1000	3,7	105	G3/V2	20–24
DM	700/650	1000	7	105	G3/V2	24–28
RS	413/168	1000	7	84	G3/V1	19–23
RM	399/172	1000	7	100	G3/V1	18–23
FD	800/700	impenetrable	8	132	G3/V2	30-32
FS	300/330	impenetrable	10	92	G3/V2	23–25
Facebook	350/340	impenetrable	9	130	G3/V2	15–20
FX	176/207	impenetrable	10	139	G3/V2	58–62

*Combustibility group according to GOST 30244-94. Flammability according to GOST 30402-96.

The cheapest brand is B, the cost is 15-20 rubles / m2. The most expensive product based on polyethylene foam with a reflective FX coating will cost from 58 to 62. The price per m2 of Isospan AM is 28-31 rubles.

Advantages and disadvantages

The advantages of Izospan insulation include:

In terms of cost, the organization of vapor barrier of the roof with Izospan, as well as other elements of building structures, is cheaper by 20-30% than when using other domestic or imported analogues.

The disadvantages are few:

• Weak fire resistance. When working with films, open sources of fire should be avoided.
• Judging by the reviews, Izospan for hydro- and vapor barrier of brand A roofing, if handled carelessly, can tear or burst.

Selection Tips

Given the variety of types of membranes and films, a number of recommendations should be followed before buying them:

• For coverage outside walls or roofs are preferably multilayer membranes, so it is better to buy Izospan A, AM or AS.
• B, C and D are recommended for interior insulation.
• When arranging baths or saunas, it is advised to use grade F with a reflective coating.
• In addition, the instructions for using the Izospan film contain detailed instructions for using one or another variety. Careful acquaintance with the information presented will help to avoid annoying mistakes when choosing.

Installing a vapor barrier film

Working with hydro- and vapor barrier films produced by Geksa is not very difficult. Considering that the instructions for using the popular varieties of Isospan contain detailed guide for their styling, it can be done by hand. For this you will need:

• Reiki wooden 20-30 mm thick.
• Roulette.
• Construction stapler.
• Nails, hammer.
• Scotch.

Since the material is used for various building structures, consider the sequence of its installation on the roof. Scheme of the vapor barrier of the insulated roof with a film:

• The roll with the smooth side outward is rolled out horizontally in the direction from the bottom of the ramp to its upper part.
• With the help of rails, they are attached to the roof rafters. The overlap between the strips should be at least 10-15 cm.
• A crate is arranged over the rafters, providing a gap of 34 cm between the vapor barrier and the insulation (this necessary condition for Izospan A film; if grades AM or AS are used, this is not necessary, as they may come into contact with the surface of the main thermal insulation layer).
• Reflective insulation, such as FX, must be positioned with inside insulation, turning inside the room with a metallized side to reflect heat flows. Installation is carried out end-to-end, without an overlap of a cloth. A special adhesive tape is used for gluing the seams.

Proper use of new construction technologies improves operating parameters buildings. The vapor barrier film prevents the penetration of moisture into the depth of architectural structures. It prolongs their durability, provides protection against negative external influences. In order for such a barrier to perform its functions flawlessly, it is necessary to know the methods for selecting and using appropriate materials.

Air does not conduct heat well. This feature is used to improve the energy efficiency of buildings. In particular, mineral wool or other porous materials are used. They are installed in the construction of walls, floors and ceilings, under the roof.

Modern heaters have good consumer characteristics. But their beneficial features will be significantly reduced when moisture penetrates into the structure. To exclude such negative processes, vapor barrier films.

Such material is not intended for solving typical waterproofing problems. It prevents the penetration of water into the mold smallest particles, pair.

The simplest pattern is custom polyethylene film. With its help, you can solve the problem indicated above, but only partially:

• When the temperature outside changes, the dew point shifts and condensation inside building structures is not ruled out. An impenetrable barrier will become an obstacle to its removal in a natural way.
• Owners wooden houses they are valued for their unique micro-ventilation. It helps to maintain a healthy atmosphere in the premises without specialized equipment. In this case, complete sealing would also be redundant.
• Also useful in the bath good thermal insulation. But many polymers will break down at high temperatures. Films from them are not able to reflect infrared radiation and thereby improve performance characteristics the corresponding object.

The listed tasks are successfully solved with the help of various modifications of the materials of this group.

Application of insulation

To make the installation relatively simple, and in the process of future operation there are no problems, you should first take into account all the features of a particular project.

When placing insulation outside the building, it will come in handy good protection from the wind. Some polymers are degraded by direct ultraviolet radiation, so an appropriate outer skin must be provided. Universal vapor barrier film will withstand without damage big swings temperature.

Internal insulation creates conditions for the dew point to move towards the room. Therefore, its application is preceded by an accurate engineering calculation. Usually, the vapor barrier film is installed from the side of the warm area. But in this case, a more complex multilayer construction covering the mats from all sides.

A vapor barrier material is suitable that does not prevent moisture from escaping to the outside. Between it and the wall leave a small distance for ventilation. They provide free access to air. If necessary, special gratings are installed in the cladding.

Particular care must be taken with wooden structures. They themselves, and not just a special insulation, need reliable protection from moisture.

The figures show that in some cases a vapor barrier will be required at the joints between the insulation, the floor slab, the joists and the flooring. Ventilation ducts are also created in the floor structure.

Similarly, a hydro vapor barrier film is installed under the roof. Take into account the potentially greater possibility of water penetration from the outside. Also pay attention to the mode of operation. Maintaining high temperatures in winter attic rooms increase the likelihood of condensation.

Vapor barrier with foil is used in the bath. Here it helps to retain heat and high humidity (when using Russian technology or a hammam). It also prevents the penetration of water into the insulation and wooden parts. It is installed under the casing with a ventilation gap, a metallized layer towards the room.

In all of the above options, the installation of the vapor barrier film is carried out carefully. Thin materials overlapped by 15-20 cm with a stapler. The seams are closed with tape. If necessary, use a tape with a foil layer.

Varieties of materials

It is easier to understand different types and technologies of vapor barrier if you carefully study the current offers in the relevant market segment. In order for the study to be substantive, the products of the Akston brand will be further considered. This manufacturer produces a fairly wide range of materials.

The most democratic price vapor barrier membrane type "B". It consists of two layers with different surface quality. The side with increased roughness retains condensate on itself, which subsequently evaporates naturally. It is she who is directed when laying outside.

This mechanism of operation prevents the free movement of drops and the flow of moisture into other elements. building structure. With the use of one standard package weighing about one kilogram, you can close up to 15 square meters. area. Working with it quality material does not cause any significant problems.

Under the designation "C" is a hydro-vapor barrier. It can be used indoors and outdoors. In particular, such a film is often used to install ventilated facade structures. It is about 30% heavier than the previous version, but stronger.

The waterproofing modern vapor-permeable membrane "D" is reinforced with special structural inserts. Such products are used when installing a layer of insulation under the roof. Subject to right technology installation, they will not let water through even with significant violations in the layer of tiles or other topcoat.

All products in this category can be divided into the following groups:

• Protozoa inexpensive materials for vapor barrier of 1-2 layers. They are capable of performing only basic functions.
• Vapor barrier membranes with modified surface roughness. A typical example of such products is the “B” film of the Akston brand discussed above.
• "Active". This group includes products with microscopic holes. Such vapor barrier films allow air to pass through, therefore they are often used in combination with wooden house structures.
• Infrared-reflecting hydrovapor barrier has been discussed above. quality products of this category can significantly increase the efficiency heating appliances. They are more expensive, but their installation helps to save money during operation.
• An interesting variety of foil materials is a layer of several millimeters of foamed polymer. Good thermal insulation properties of this type of vapor barrier film are used to solve various practical problems.
• Vapor-permeable waterproofing ("Axton" "C") is more expensive. But it is stronger than other options, has good resistance to stress and mechanical influences different nature.

Film use

To understand how to choose the right products and for the exact application of vapor barriers, it is necessary to study in detail specific example with insulated pitched roof. For this option, a universal hydro- and vapor barrier is suitable. Installation of the appropriate film is performed smooth surface up.

To ensure that the condensate discharge is sufficiently active, two layers of ventilation are installed on both sides of the main insulation. The lower part of the system is used to accumulate and remove moisture that came along with warm air from the premises. The durable film prevents the penetration of rain and melt water.

Vapor barrier installation

Before proceeding with the installation of the product, it is necessary to find out one more question, which side to fix the vapor barrier. Above there were references to the need to observe a certain focus. Each manufacturer indicates the relevant data in official instructions. However, you can use the following generic information:

• If there is a rough surface, it is installed in the direction where moisture will condense. For example, it is mounted above the insulation under the roof, leaving a gap of several centimeters for ventilation.
• A film of several layers is directed with a smooth surface to mineral wool mats or other insulation.
• If foil is fixed on the material, it is installed towards the heat source.

Many products of this class are rolled up in a special way so that there is an outer layer on the outside. This speeds up styling and prevents errors at the same time.

Membrane protection together with thermal insulation can be installed under the roof according to the following algorithm:

1. Select and purchase appropriate materials, tools. For the production of work you will need:

• professional stapler (construction, furniture);
• adhesive tape one, - and double-sided;
• self-tapping screws;
• electric screwdriver;
• roulette;

2. Mineral wool mats are installed between the rafters. To them, self-tapping screws will strengthen the crate.

• The film is fixed on this frame with double sided tape. To completely close the entire area and work with complex areas, cut the corresponding blanks. Be sure to observe the recommended orientation of the outer layer.
• Parts of the edges are fixed using a professional stapler. The rows are laid with an overlap of about 20 cm, followed by sealing the cracks with one-sided tape.
• A solid roll is laid in the area of ​​\u200b\u200bthe ridge. There should be no seams here.
• Bars are installed on the membrane. They are attached with screws to the bottom of the crate. The height of these elements is chosen from 3 to 6 cm in order to form a sufficient ventilation space.
• From above, the roof is sequentially mounted in accordance with the technology of laying tiles, metal profiles, and other material. AT finish surface leave ventilation holes.

In order for the vapor permeability to turn out to be planned, the integrity of the created layer is checked. Small local repairs can be done using tape. Large holes are covered with a film cut to the desired size.

When choosing, it is necessary to study vapor barrier materials, taking into account a specific purpose. So, for example, more expensive films with reinforcement will not be needed in places where mechanical stress is excluded. A reflective foil layer is not needed where there is no intense infrared radiation. Excess functionality in some situations will be harmful. The final decision must be made on the basis of a careful study of the movement of air, moisture, and other important processes.

Additional protection of high-quality polystyrene foam boards is not needed. These materials have been successfully used for external insulation and foundation waterproofing. When equipped with locking joints, a layer of them does not allow water to pass through. But in the case of roof installation, a reliable vapor barrier film will be needed. It is installed separately, with a ventilation gap, to prevent moisture from penetrating the structure. wooden elements designs.

In the process of studying different materials you need to understand that they will be installed in the depths of the structures. When defects are formed, it will be difficult to eliminate the defects without large costs. emergency situations can quickly render the insulation unusable, which will also cause additional costs.

To prevent such problems, one must carefully choose a manufacturer that can provide reliable quality assurance.

Construction film video

The examples given explain the importance of complex analysis. The comparison should be made taking into account the prices of materials, the cost of their delivery and installation, the installation site, durability, and the features of the operation of the building. This approach will help reduce overall costs and prevent errors.

Tyvek waterproofing is nonwoven fabric manufactured by DuPont. It is used to protect heat insulating materials from the penetration of moisture, and also serves to effectively remove water vapor.

Ecoplast (material information) /

Roofing polymeric membrane based on high-quality plasticized polyvinyl chloride (PVC). Stabilized against UV radiation using the TRI-P® system. Contains flame retardants and special stabilizers. It has increased elasticity for easier styling at low temperatures.

Logicroof (material information) /

LOGICROOF PVC membranes are used for waterproofing single-layer roofing systems mechanically fastened and welded with hot air using automatic equipment. The membranes remain flexible low temperatures and apply in all climatic regions.

Planter (material information) /

PLANTER are one- and two-layer universal polymer membranes used in industrial, civil, transport and hydraulic engineering construction. Membranes are made by forming a single web of raw material from polyethylene high density(HDPE). The entire area of ​​the front surface of the membranes is made in the form of cone-shaped protrusions 8 mm high and attached to them (for certain grades) geotextile material.

Duke (material information) /

Domestic hydro- vapor barrier roofing films Duke from Sarov Polymers LLC. Provide the necessary humidity conditions in the under-roof space.

Until recently, it was practically unrealistic to provide absolute protection of the under-roof space from moisture penetration in roof structures of any type. Various steam and waterproofing materials have long been an integral part of any roofing project.

Euromet offers latest materials to provide vapor and waterproofing of the roof and facade, which are endowed with a number of new advantages and properties.

Waterproofing materials from Euromet:

• serve reliable protection roofs from penetration of steam from interior spaces. As a result, condensation does not form in the under-roof space;
• thanks to its increased strength able to protect building structures from impact external environment at the stage of installation of roofing;
• durable. Their service life is several times longer compared to traditional vapor and waterproofing roofing materials.
• they are not subject to decay, mold does not form on them, and pests are completely indifferent to them;
• absolutely safe for human and animal health;
• have low flammability and do not spread fire.

The steam and waterproofing materials we offer will ensure the necessary temperature and humidity conditions for the operation of the roof at any time of the year and almost completely eliminate the possibility of moisture getting into the under-roof space.

The function of an insulating material in construction is far from the last. Despite improved performance finishing materials, only reliable and durable insulators can save the house from heat loss and the harmful effects of moisture. At the same time, traditional heat insulators are gradually losing their relevance against the background of increasing requirements for performance buildings. Their place is occupied by a hydro-vapor barrier film, which also contains at its core, but does not allow it to become waterlogged. In essence, this is a multifunctional protective barrier with which you can protect the structure from cold and moisture.

What is waterproofing?

The concept of hydrovapor barrier is complicated by the functions of the material that can bear such a name. In the usual view, this is a membrane that is used to provide protection for a heat insulator. The most important thing is the phenomena and influences from which it protects. Depending on the field of application, it can be steam, moisture, cold, wind, etc. The composition of the hydro-vapor barrier film also differs - in this regard, profiled and flat membranes can be distinguished. The first are made of polyethylene in the form of sheets with round or square protrusions resembling spikes. Flat membranes are produced not only from polyethylene. Polyolefin and even polyvinyl chloride are also used in production. The result is a film whose thickness does not exceed 2 mm. Usually used in the arrangement of roofs and finishing materials flat film less than 1 mm thick, and thicker membranes are used to protect the foundation.

Characteristics of hydrovapor barrier

Technical data regarding the properties of hydrovapor barrier differ depending on the specific material. For example, it is worth considering the characteristics that the Izospan waterproofing film has. This is one of the most, according to reviews, popular materials on Russian market in this segment:

• Production material: 100% polypropylene.
• Tensile load transverse/longitudinal, N/5 cm: 107/130.
• Vapor permeability, δ: not less than 7.
• UV stability: period 3-4 months.
• Water resistance: water column not less than 1000 mm.
• The temperature range in which the use of the material is permissible: from -60 to + 80 ºC.

The use of material in roof insulation

Usually in the design, hydro vapor barriers act as a direct barrier against moisture, and also provide wind protection. This is exactly the case when insulators are presented with high requirements regarding strength and durability. As a rule, for the roof it is laid on a heater without a ventilation gap. This decision is due to economic feasibility in the form of reducing the cost of framing between a separate heat insulator and films with the effects of vapor and waterproofing can be used as subroofing layers in roof structures with different slopes, since fixation is provided over the rafters above the insulation. The resulting coating acts as an insulating element for load-bearing structure, protecting it from the penetration of under-roof condensate, as well as from wind, rain and snow.

Application in stud wall insulation

The installation of the main walls of the house structure also involves the provision of vapor and waterproofing. In this case, the film protects the material from atmospheric moisture, gusts of wind and powders. But there is, as evidenced by the reviews of the masters, another important function that should have waterproofing film for roofing and frame walls- this is the ability to remove vapors from a fibrous insulation material.

The installation of the film is carried out under the outer skin of the house on the outside of the heat insulator. It is desirable to mount it throughout the frame on top of the insulation in horizontal position. The joints are made with an overlap of 10 cm. The final fixation is performed with a stapler. It is important to consider that when performing further finishing, a ventilation gap of about 3-4 cm should be left. It is necessary to ensure moisture removal.

Waterproofing of interfloor ceilings

The material should be laid between the ceiling finish and its rough surface, as well as on the floor beams on top of the insulation. In this case, an increased gap of up to 20 cm is also made. To ensure the tightness of the barrier, the waterproofing film for the floor is additionally fastened special tape. Such material is also supplied by insulator manufacturers and serves as a connecting element.

It is important to note that if the rooms connected by an insulated interfloor overlap, have different temperature conditions, then it is necessary to select an insulating material with extended functionality. So, in addition to hydro and vapor barrier, it is necessary to provide for the ability of the barrier to reflect heat flows. For example, a hydro-vapor barrier film, which is planned to be laid in an attic or attic, should have similar qualities.

Waterproofing of internal walls

When providing insulation of frame walls from the inside, two tasks are performed: vapor barrier and an obstacle to the spread of unsafe particles of insulation throughout the living quarters. The membranes are fixed on both sides of the insulation on the supporting bases in the form of racks and beams. Also, if possible, a hydro-vapor barrier film can be attached to the surface of the rough finish. Installation is again done with a stapler or galvanized nails. But in this case, the overlap should be at least 15 cm. If further wall decoration with clapboard or plywood is planned, then the insulation can be fastened using vertical wooden slats that have undergone antiseptic treatment. Also, a 3-4 cm gap is maintained between the finish and the membrane.

How to choose the right waterproofing?

In choosing any, the importance of the design that is planned to be provided with this protection increases. That is, to begin with, threats to the place of application are determined, and then a hydrovapor barrier film is purchased. How to choose given material- the question is not easy, it should take into account several points. First you need to decide on the origin of the membrane itself. Usually it is polyethylene. It is advisable to choose a perforated film, as it is the most durable. With skillful installation, it can provide a durable and effective barrier to moisture and wind.

If tensile strength is not a fundamental criterion, then a flat hydrovapor barrier film may also be suitable. The price in this case will be low - a roll can be purchased for 1000-1200 rubles. If it is purchased with a metal layer, then you should be prepared to pay 2000-3000 rubles for it. But with its help, you can effectively provide not only functional insulation, but also durable.

Each person wants the living conditions in the house to be equally comfortable both in the summer heat and in the winter cold. But what is needed to create a favorable atmosphere in the house? Of course, in the conditions of harsh Russian winters, the main thing will be, perhaps, high-quality insulation, which will help save a considerable amount on heating.

As a heater of a floor, walls and overlappings it is usually applied mineral wool which is a good thermal insulator. However, mineral wool has at least one significant drawback - the ability to absorb moisture like a sponge, due to which it loses its ability to retain heat at times. To protect mineral wool from getting wet, materials such as hydro- and vapor barriers are used.

When arranging the roof, it is necessary to take into account the maximum possible temperature differences outside and inside the room, as well as precipitation in any form and winds up to hurricanes. After all, the roof of the house is in fact the boundary separating the air inside the room and outside. As we know from the laws of physics: the air that has more high temperature, will always rise up - to the ceiling. Therefore, insulation is laid under any roofing to keep the heat in the house. But in order for the insulation to serve longer and not lose its thermal insulation properties, it must be protected from moisture.

Of course, the roofing materials themselves protect the insulation well from direct ingress of moisture inside, but they are unlikely to save from the formation of condensate in the under-roof space - they are not so airtight as to prevent water vapor from passing through. In this case, high-quality waterproofing will come to the rescue, which will not let water vapor from environment into the heater.

It is worth noting the fact that many unfortunate builders neglect the waterproofing of the roofing insulation, buy cheap materials, or even completely replace waterproofing films with ordinary polyethylene from the garden or even vapor barrier, not finding any significant difference between them. Like, the film is also a film in Africa. Anyway.

As a result of such “minor” shortcomings, it turns out, for example, that after installation completed a year ago new roof water suddenly begins to flow from the roof of the attic, wet stains appear on the ceiling. The owners are confused. They begin to look for damage and leaks in the roofing, but without revealing any defects in it, they come to the age-old questions - who is to blame and what to do? And then the laws of physics begin to come to mind and clever thoughts come that the moisture in the air, it turns out, can theoretically condense inside the room itself, forming streaks on the ceiling ...

But why were there no signs of condensation on the ceiling before the repair? It can be assumed that waterproofing was laid under the insulation instead of vapor barrier, as a result, the properties of the porous insulation clogged with water vapor with all the ensuing consequences have already been lost. If no insulating films were used at all, then moisture will “walk” throughout the structure, damaging not only the thermal insulation, but also contributing to the destruction truss system and even interior decoration.

So what is the difference between waterproofing and vapor barrier?

There are so many different film insulating materials on sale now that, out of ignorance, you can easily confuse them. Special difficulties causes an initial misunderstanding of the differences between waterproofing and vapor barrier materials. The use of the concepts of "waterproofing" and "vapor barrier" as synonyms by "specialists" of pseudo-construction organizations and even sellers of some stores (this happens especially often in the provinces, where you can't find real craftsmen in the afternoon with fire) introduces even more confusion.

In order to avoid unpleasant surprises, such as the case with a “leaking” attic described above, you need to clearly understand the difference between vapor and hydroprotective films before starting the installation of a new roof and approach their choice consciously. Even if you are not going to insulate the roof with your own hands, then at least it is in your power and interests to control the progress of work and the correct selection of materials.

Before talking about the differences between hydro and vapor barriers as materials, you need to clearly understand the functions that they must perform.

What is waterproofing for?

The main function of the waterproofing film is to prevent the ingress of moisture from the street. “And why do we need it, especially on the roof, where the roof will not let any water inside? Extra costs and that's it, you say. And, perhaps, you will be right if you just need to replace the roof over the heated part of the room, for example, in an ordinary attic.

Roof waterproofing is necessary when laying a layer is supposed mineral wool insulation, which in the case of the attic is mandatory, since the roof can only hold back falling precipitation in the form of snow and rain, but will not provide protection against the penetration of water vapor after summer rain or fog. This steam, in the absence of an insulating layer, will go directly into the roofing insulation, which is mainly mineral wool, as a result of which all its air pores will be “clogged”, which will negatively affect thermal insulation properties. And this will be especially noticeable in winter period when moisture vapor crystallizes in the pores of the insulation material. Therefore, the heat-insulating layer must be protected from moisture from the outside. And the film waterproofing material will help us in this.

Why is vapor barrier needed?

Vapor barrier films, unlike waterproofing, are designed to be laid from below under a layer of roofing insulation to protect it from warm vapors seeping from the ceiling that are present in any room even with amazing ventilation, and all because we breathe, use steam irons or cooking, showering, watering flowers, etc. Thus, vapor protection in front of a layer of thermal insulation is a very necessary thing.

The main difference between waterproofing and vapor barrier is that modern waterproofing membranes are able to pass steam in one direction(at correct installation- out of the heater), while preventing the penetration of water from the outside.

Protecting the roof insulation from getting wet using a waterproofing membrane and vapor barrier

It should be noted that the vapor barrier layer, when viewed from inside the room, is always the last layer (before final finishing, of course). For example, if this is a floor above an unheated underground (basement), then the vapor barrier is not mounted along the ceiling (below), but from above, right under the finishing “clothes” of the floor. It's the same with walls.

Remember: water vapor always diffuses in the direction of colder air. And the first barrier on the way of steam to the insulation should be the vapor barrier! And that part of the steam that nevertheless seeps through it into the insulation layer must freely exit it through the vapor-permeable membrane and, being picked up by air flows, escape into the atmosphere.

External differences between vapor barrier and waterproofing

What is the difference between waterproofing and vapor barrier? This question can be answered by analyzing the structure of both materials.

Structure of vapor barrier films

Vapor barrier differs from waterproofing mainly in that both sides of it are completely waterproof. The vapor barrier should not allow steam or water to pass both outside (into the house) and inside the insulation. Conventional polyethylene can be attributed to a cheap version of such a film. However, it is not recommended to use it as a vapor barrier for a roofing “pie” due to the fact that under the roof, especially in summer, the film will get very hot, which will lead to its stretching and, possibly, damage. And since we cover the roof for more than one year, it is optimal to use a film of several layers with a polymer reinforcing frame, which prevents the film from stretching.

Installation of vapor barrier is carried out from the inside of the ravine

sheathing inner surface attic roof with a film covered with foil on one side will cost several more expensive to use different kind vapor barrier materials, however, in addition to creating a reliable vapor-tight barrier, it will also be possible to retain heat in the house. The installation of this film is carried out with a foil surface inside the room, which contributes to the reflection of infrared radiation from it, with which the main part of the heat from the dwelling disappears. Thus, the use of such a vapor barrier allows you to kill two birds with one stone, reducing heat loss through the roof of the house to a minimum, which in turn will allow you to save quite a lot on heating.

Before buying any film, be sure to make sure that it is a vapor barrier, as indicated by the inscription on the package.

Structure and types of waterproofing films

It may well seem to an amateur that if the vapor barrier is completely waterproof, then it may well serve as a replacement for the waterproofing layer. It can be assumed even out of ignorance that the vapor barrier better waterproofing which is fundamentally wrong.

Both vapor barrier and waterproof film materials serve a specific purpose, and if you substitute one for the other, this can lead to unpredictable consequences and additional monetary costs.

The main functions of waterproofing are as follows:

• protection against ingress of external moisture into the insulation layer;
• removal of accidentally trapped water vapor from the heater.

But how can steam suddenly appear in a heater? The thing is that not a single film in the world, it would seem, hermetically closing the insulation on both sides, does not have absolute vapor tightness. The proportion of water vapor, albeit insignificant, somehow penetrates through the film insulation from the ventilation gap and from the inside of the room into the insulation, which means that it is necessary to ensure that this moisture can escape to the outside. This purpose is served by waterproofing films, otherwise referred to as membranes.

waterproofing polymer films have a number of useful properties:

• resistance to ultraviolet radiation;
• resistance to temperature fluctuations;
• high strength properties.

However, this is all secondary. Most important property waterproofing film is porous structure of this material . The meaning of the idea is to enable that part of the water vapor, which somehow got into the insulation, to freely exit it into the under-roof space. This is precisely what contributes to the pores, which are very similar in shape to funnels, through the wide part of which steam exits the insulation. The narrow part of the pores, with proper installation, should be turned outward, which prevents the penetration of moisture into the pores in the form of a liquid from the atmosphere, since the volume of a water molecule is larger than that of vapor molecules. Using waterproofing membranes it is important not to confuse and put the film right side to the heater.

According to the type of porous structure, membrane films can be:

• diffusion;
• superdiffusion.

These structures differ from each other in the number of pores. In diffusion membranes, there are fewer pores, and, accordingly, the level of vapor removal is significantly lower. Such a vapor barrier cannot be placed directly on the insulation itself, therefore it is necessary to leave a ventilated gap not only between the roofing and waterproofing, but also between the film and the insulation. Otherwise contact pore diffusion membrane with the insulation material will lead to blockage of the "funnel" of the waterproofing with mineral wool and the loss of its functional properties.

Superdiffusion membranes are significantly superior in terms of vapor removal diffusion films, and it is not required to create a ventilation gap between the waterproofing and the insulation.

The organization of a ventilation gap between the roofing and the membrane is mandatory in any case, in order to allow water vapor to escape with the air flow into the atmosphere.

However, it is recommended to use membrane waterproofing films not with any type of roofing, but only with those that are resistant to the damaging effects of condensate accumulating from back side roofs. So, for example, in the case of roofing with metal tiles, it is necessary to use special anti-condensation films. Such waterproofing does not allow steam to escape from the insulation, but accumulates it through huge amount the smallest villi located on its back surface, from where moisture leaves with air flows through the ventilation gap.

Waterproofing is laid on top of the roof insulation

The choice of vapor barrier and waterproofing

When choosing the type of vapor and waterproofing, it is necessary first of all to take into account their characteristics. Consider, for example, what are the modifications of Izospan vapor barrier.

IZOSPAN "A" is a vapor-permeable film designed to protect walls, roofs and ventilated facades insulated from the outside from the effects of wind and moisture.

IMPORTANT! Such waterproofing materials should always be laid with a smooth, water-repellent surface on the outside, and a rough surface through which steam escapes from the insulation, inside. To facilitate the task of determining the sides, let's reveal one secret - the inscription on any film during installation should be at the top.

IZOSPAN "V" - has both hydro and vapor barrier properties. It is used for vapor waterproofing of roofs, installation is carried out from the inside. It can also be used for insulation of ceilings and walls, installation is carried out from the side of the thermal insulation facing the inside of the room.

IZOSPAN "C" - the most dense material used for waterproofing purposes.

IZOSPAN "D" is a universal, durable vapor-permeable waterproofing that can be mounted both on the outside and on the inside of the insulation.

IZOSPAN "FB" is a material intended exclusively for hydro- and vapor barriers for swimming pools, saunas and baths.

The whole process of insulation, vapor barrier and waterproofing of the roof is clearly shown in the video.

Video "How to insulate the attic roof"

Video "Heater. Waterproofing. Vapor barrier and insulation of the attic roof

Only competent use waterproofing and vapor barrier films can ensure the preservation of heat in the house and prevent the appearance of dampness and mold in the premises.