Those developers who have had to install the roof with their own hands know well that the roof has a complex structure. It consists of several layers. These layers are from various materials stacked in a strictly defined order, the result is a kind of puff roofing pie. The obligatory layer in this pie is the roof vapor barrier. It is needed to maintain the necessary thermal insulation conditions and to protect roof trusses from condensation and moisture.

Usually a vapor barrier is performed before installation roofing.

The absence of a vapor barrier can lead to the formation of mold on the wooden elements of the roof, and the rafters may begin to become moist. Without properly installed vapor barrier and waterproofing, external moisture in the form of snow and rain will penetrate into the space under the roof. This will cause the roof to freeze. Such consequences can and should be avoided by installing protective layers moisture and vapor barrier of the roof from a special film.

Materials for arranging vapor barrier

Modern vapor barrier materials are produced by industry in the form of thin films. They are sold in rolls. All films intended for use in construction are usually divided into the following types:

1. Polyethylene. They may vary in thickness. They are used in the construction of waterproofing structures and their vapor barriers.
2. Polypropylene. Films made from this material are often used when performing waterproofing work.
3. Diffusion. These are special breathable membranes. Used only for waterproofing equipment. Vapor barriers are not suitable for installation, although often these layers are installed simultaneously and complement each other with their physical and technical characteristics. Their main difference is that waterproofing is designed to protect the roof from moisture from the outside, and vapor barrier is designed to protect the roof from inside the building.

Vapor-proof materials protect the inside of the roof from the penetration of moisture vapor from the premises of the house. Moisture does not penetrate into the insulation, due to which the entire roof structure contributes to effective heat retention. Installation of vapor barriers is used on roofs of any type and with any roofing materials.

The vapor barrier is applied from below to the insulation layer. The film used is very different: polyethylene, roofing felt, glassine, foil material "Polycraft". Any of these materials must be laid with overlapping individual panels. The amount of overlap should be about 10 cm. The seams are additionally taped.

Roof vapor barrier protection: 1 – Roof covering; 2 – Izospan AS, AM; 3 – Counterrail; 4 – Insulation; 5 – Vapor barrier Izospan B; 6 – Rafter; 7 – Interior decoration; 8 – Lathing.

The vapor barrier film is secured to the rafters with staples using a construction stapler or thin slats. The foil film is laid in such a way that mirror side was directed towards the living quarters. All materials should be selected taking into account the climatic conditions of the area, roof structure, and type of roofing material.

The manufacturer of the vapor barrier film also matters. It is better to give preference to trusted brands and manufacturers. Experts recommend using “Delta” films made in Germany, “Tyvek” from Luxembourg and “Izospan” from Russia for vapor barrier.

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What is “Izospan”

Russian “Izospan” has a number of advantages over other materials:

1. The film has high tensile strength.
2. It meets all environmental requirements.
3. The film can withstand significant temperature increases.
4. The material is easy to cut and does not tear at the bends.
5. All positive properties persist for a long time.

Izospan is a durable, high-strength product, verified practice and time. There are quite a lot of varieties:

1. Izospan A is a film membrane that protects the structure from wind and moisture. Effectively removes water vapor and condensation from internal roof structures.
2. Izospan AS is a three-layer membrane for vapor barrier. Used to protect the roof from rain and snow, from wind and moisture from the insulation. Suitable for insulated roofing with any roofing materials.
3. Izospan B – two-layer vapor barrier film universal application. Used to protect the roof of buildings when insulating attics.
4. Izospan S is a two-layer film for installing hydro- and vapor barriers. Can be used without roof insulation.
5. Izospan D is a universal film for vapor barrier and foundations, interfloor ceilings.
6. Izospan SL is a tape for gluing and sealing joints of membranes with pipes, ventilation systems and other structures.
7. Izospan FL is a special metallized tape for sealing joints of vapor barrier film with various enclosing structures.

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Arrangement of vapor barrier

Without a vapor barrier layer, the roofing pie will not fully perform its functions. The insulation simply cannot do this if moisture gets into it. Water vapor can penetrate into the most microscopic cracks. Therefore, such places require the most careful treatment with insulating materials.

Installation of vapor barrier consists of several stages:

1. You need to print a roll of film and cut a piece of the required length.
2. Cut cloth smooth side applied to the rafters from the attic side. The film is attached to wooden structures with nails with large heads. This work can be done better and faster with a construction stapler.
3. There is no need to pull the film too tightly. The next panel is superimposed with an overlap of 10 cm on the previous one.
4. The seams are carefully taped.
5. On top of the film rafter legs Thin wooden strips are stuffed in, which will serve as lathing for finishing material. Between facing material and a vapor barrier film should form ventilation gap approximately 20-50 mm. The slats should be this thick. Electrical wiring can be placed in the same gap.
6. Finishing in progress decorative finishing. For this stage of work, you can use wooden and plastic lining, fiberboard, OSB, drywall and any other sheet material, which can later be painted, wallpapered, and finished to your taste.
7. Next, thermal insulation is performed and the remaining layers of the roofing cake are installed.

Some types of vapor barrier film come with instructions for use. Its content should not be ignored.

It seems to people ignorant of construction that installing a vapor barrier on the roof of a residential building is excessive caution and overinsurance, which only results in additional costs. However, every experienced roofing specialist will confirm that a correctly selected waterproofing film significantly increases the service life of the roofing covering, and also improves the microclimate in the attic or attic. In this article we will tell you how to choose your own hydro-vapor barrier for the roof, as well as how the process of laying the material on the rafter frame occurs.

Vapor barrier film – special material, which is necessarily included in the roofing pie, which has a pronounced vapor-blocking effect. According to the well-known law of convection, warmer and more humid air, abundantly released during human activity, rises up into the under-roof space, then it settles in the form of condensation on the roof rafter frame, leading to dampening of the insulation and rotting of the wooden structural elements. The vapor barrier film as part of the roof performs the following functions:

• Preservation of the performance qualities of the insulation. Installing a vapor barrier prevents the accumulation of condensation inside the thermal insulation material, which significantly reduces the effectiveness of insulation.
• Extending the service life of roofing coverings. Roofing materials are much better protected from moisture and corrosion from the outside. Installing a vapor barrier solves the problem of condensation affecting the lower surface of the roof covering.
• Protection wooden frame roofs from rotting. A properly installed vapor barrier film prevents the roof rafters from getting wet due to condensation, which results in wood rotting.

Note! Vapor blocking film “works” effectively only if it is correctly selected for climatic conditions, roof structure, and type of roofing material. An unsuitable vapor barrier will not only be of no benefit, but will also intensify the process of condensation.

Material requirements

The most primitive and cheap material for roof vapor barrier is glassine. But in modern realities installation of this outdated canvas is practically not carried out, since there are more effective and durable analogues. Current vapor barriers are made from high-strength polymers with improved performance characteristics. A properly selected vapor blocking film has the following qualities:

1. Wide temperature range. To do possible installation in any climatic conditions, the film must withstand high, low temperatures and even sudden changes. Optimal temperature range for products of this type, the interval between -70 and +100 degrees is considered.
2. High degree of vapor permeability. The lower this indicator is for the vapor barrier, the better. Previously installation was carried out polyethylene films with a vapor permeability of 13-20 g/m2, and now for roofing they use polypropylene analogues with a permeability of no more than 0.4 g/m2.
3. Long service life. Installing a vapor barrier whose service life does not exceed 10 years is impractical, since modern roofing materials last more than 20-25 years, and it is almost impossible to replace the film without disassembling the structure.
4. Elasticity. Vapor blocking film based on resistant polymers is highly elastic, which simplifies the installation of the material and also reduces the amount of damage during installation.

Important! Experienced craftsmen They believe that the main indicator of the quality of a vapor barrier is the high strength properties of the material. A properly installed vapor blocking sheet can even withstand the weight of snow, rain or melt water in the event of extensive damage to the roof.

Types of materials

Vapor-blocking film is a special material; it does not allow moisture-saturated, heated air to pass through, which leads to the formation of condensation, wetting of the insulation, and destruction of the roof frame. It is a thin, lightweight, but very durable and UV-resistant fabric based on thermoplastic polymers. There are the following types of materials for vapor barrier:

• Polyethylene. Polyethylene is a fairly thin, lightweight and at the same time cheap polymer that is used to make vapor-blocking membranes. However, the strength qualities of such a film are low, so it is reinforced with a special mesh or fabric. Installation of laminated polyethylene vapor barrier is carried out in saunas, baths and other rooms where it is necessary to retain heat.
• Propylene. Vapor blocking membranes based on propylene are characterized by increased strength, resistance to ultraviolet radiation, and low vapor permeability. They are a woven material with an anti-condensation layer.

Please note that the use of perforated materials to organize a vapor barrier for the roof is not allowed. It is important to choose the right vapor blocking membrane to protect roofs from negative influence condensate

Technology of use

Laying vapor barrier material is important technological operation, performed during the construction of the roof, the quality of which determines its reliability, service life and strength. Installation of vapor barrier is carried out from the inside attic room after ready rafter frame roofs in accordance with the following rules:

1. The vapor-blocking fabric can be laid along or across the rafter legs of the frame.
2. Be sure to start installation from the roof ridge, placing strips of material overlapping with an overlap of 10-15 cm.
3. The material will be fixed using construction staplers or galvanized nails.
4. The joints between the strips are hermetically connected using special adhesives s strips located along the edges of the canvas.
5. After installing the waterproofing, a glazing bead treated with an antiseptic is nailed along the rafters so that the sheathing does not touch the membrane.

Important! The vapor blocking film has two sides, which differ in the nature of the surface and properties. When installing, you need to place the canvas with the rough anti-condensation side down.

Video instruction

Installing and laying a roof is a necessary thing. Its main purpose is to prevent the formation and accumulation of moisture inside the roof.

If this happens, your roof will begin to rot and deteriorate from the inside, causing it to technical properties will quickly disappear. Below we will describe how to properly install a vapor barrier with your own hands.

The roofing pie consists of certain layers of different materials. It includes different quantities interlayers, but the key always remains vapor barrier, thermal insulation, etc.

Waterproofing layer provides protection to subsequent layers from penetration of moisture and dampness from the outside. This layer is a waterproof special material that is attached to, leaving a gap between the subsequent layer.

Insulation layer- These are, as a rule, thermal insulation materials, which are slabs with low thermal conductivity. They come from pressed, polyurethane foam or.

Water absorption also depends on the selected material, and this also significantly affects the choice of vapor barrier layer.

Several years ago, the main material for the vapor barrier layer was glassine. Currently, it is used only by particularly economical builders. And if we compare the performance indicators of glassine with quality modern materials, then the latter option is clearly more profitable.

Types of films

There are three types of vapor barrier films. They are classified depending on physical and technical parameters.

1. Polyethylene films.
2. Polypropylene films.
3. Diffuse film.

Polyethylene They are used not only for vapor barriers, but are also actively used for waterproofing layers.

These films are divided into:

• perforated,
• non-perforated.

But in any case, they must be reinforced during installation. light fabric or a mesh.

For the waterproofing layer, mainly perforated films are chosen, and non-perforated films are suitable for the vapor barrier layer.

Modern manufacturers offer several different modifications of isospan. Each specific version of this material is intended for specific purpose, but there are also universal films.

This material is often used professional builders and the owners are self-taught. Izospan is combined with any type roofing. And in addition to protecting the insulating layer from dampness and moisture, it does not allow the cake to crumble inside the house, as often happens with various building materials.

When purchasing isospan, be sure to check the characteristics and properties of the material you have chosen so as not to accidentally purchase the wrong modification.

Vapor barrier for flat roofing TechnoNIKOL

When purchasing a vapor barrier for a roof, pay attention to such material properties as water repellency and strength. The vapor barrier has these characteristics for flat roof TechnoNIKOL. This is a polyethylene film that protects the roofing pie from condensation indoors.

Roof vapor barrier film is used, as a rule, in warm roof vapor barrier systems. Thus, it is installed under the insulating layer on concrete floors.

Advantages of vapor barrier for TechnoNIKOL roofing:

• high strength and elasticity;
• excellent steam and water resistance;
• withstand mechanical loads;
• favorable price for vapor barrier for.

The flat roof vapor barrier film has dimensions of 3x30 m and is packaged in rolls.

Installation of roof vapor barrier

Below we provide a list of errors when installing and installing roof vapor barriers.

1. The junction points of the vapor barrier film are not sealed tightly. As a result, the insulation becomes damp, and rafter systems begin to rot.
2. Using narrow adhesive tape to seal film seams. When using tape with a width of 5 cm or less, it will simply come off.
3. There is no deformation reserve when working with windows. New house gives a certain shrinkage, so it is necessary to leave a margin of 20-30 mm.
4. The vapor barrier film around the windows is not protected from the inside. After a few months of use, the vapor barrier layer will be completely destroyed under the influence of sunlight.
5. A vapor barrier film envelops the wooden rafters. In this case, the rafter legs will begin to rot over time.
6. In places where the vapor barrier is adjacent to the walls of the house or a chimney, you need to take into account the specifics of the irregularities to which the material will be attached.
7. Installing the film to rough wall should be done using polyurethane glue or synthetic rubber.
8. Do not use polyurethane adhesive tapes, since after some time they can peel off from the surface.

The penetrating ability of water vapor is very high, which is why it is necessary to take a responsible approach to installing a vapor barrier layer. In addition to the popular isospan, vapor barriers are now used for TechnoNIKOL.

The basic rule when installing a roof vapor barrier– choose the right building materials and install them in a strictly defined sequence, then your roofing pie will serve you for decades.

Modern roofing materials are an almost absolute guarantee that moisture will not penetrate into the roof, regardless of external conditions. However, from inside the premises, the roofing pie is not protected from this in any way. First of all, the thermal insulation material is at risk, as it loses its performance characteristics when wet. As a result, the house becomes cold and damp. A properly installed vapor barrier will help prevent this process.

The need for vapor barrier

The warm air in the room is saturated with vapor and rises, trying to escape through any openings. But since the air temperature and humidity in the under-roof space are much lower, condensation forms, which can be localized on the insulation, which can lead to its destruction.

Vapor barrier material protects insulation from the destructive effects of moisture

A more severe situation is observed in the cold season. The steam escaping into the under-roof space stops, but first turns into frost, after which it forms an ice crust that will freeze absolutely any insulation in a short period of time.

To preserve the insulation, a vapor barrier is needed

With the onset of spring, the ice in all pores begins to melt and erode the interior finish. This becomes the reason that the insulation ceases to perform its functions, and mineral wool will become unusable after just a year of such use, while polystyrene foam will last a little longer.

Without a vapor barrier, the insulation will last much less

That is why a vapor barrier layer is required. His the main task- do not allow condensation to reach the insulation. This will warn:

• the appearance of mold;
• heat leakage from the premises of a private house;
• rotting of all wooden structures.

Materials used

There is a wide variety of modern building materials, which have vapor barrier properties. Conventionally, they are divided into three groups:

1. Polyethylene film. This type of material is universal because it can perform several functions at once. The film is covered with a special reinforced fabric. There are two types of this vapor barrier material: with and without perforation. But the holes are so small that they cannot be seen with the naked eye. For installation, it is necessary to use seals and connecting tapes, since the film is produced in rolls. The strips must be attached as tightly as possible, otherwise the functionality of the layer will be impaired. There are also polyethylene films with a foil layer that retains heat indoors.

   Vapor barrier polyethylene film reinforced with fabric

2. Polypropylene film. Used as a hydro- and vapor barrier material. On one side, the film is covered with an anti-condensation layer consisting of viscose-cellulose fiber. The principle of operation of this material is quite simple: condensate protruding from the side of the film that faces the insulation is absorbed into it and therefore does not fall on the insulation. Since the installation of the roof implies the presence of a ventilation gap, the moisture absorbed into the vapor barrier dries out.

   Polypropylene film has a smooth and rough side

3. "Breathable" film. The most modern vapor barrier material. Combines vapor and water resistance properties. The main advantage is that there is no need to arrange a ventilation gap, and this allows you to significantly save under-roof space. This membrane allows moisture to pass through itself, which subsequently settles on the rough layer of material, after which it is absorbed into it and dries. This allows the insulation to remain dry. Issued different types vapor barrier membrane, which can be single- or double-sided.

   Single-sided membranes conduct steam in only one direction; double-sided membranes can be laid on either side

For vapor barrier, it is better to use non-perforated film, since perforated film is more suitable for waterproofing.

Very important stage Arranging a roof vapor barrier can be considered not only the process of its installation, but also the choice. The quality of the roofing as a whole, as well as its service life, depends on this. When choosing, remember that the more weight the material has, the stronger it is. Typically it ranges from 60 to 270 g/m2. As for the vapor permeability parameter, you need to choose a material with a minimum value. The recommended parameter is less than 1 g/m2 per day.

How to properly install roof vapor barrier

Before installation, it is recommended to once again make sure that you have purchased exactly the vapor barrier material. You should also make sure that the vapor barrier you purchase is compatible with your roofing material. In this case, “Izospan B” is universal, which can be used regardless of the type of roofing pie.

Which side to put the vapor barrier on the roof

There are certain rules for laying vapor barrier material. Regardless of the type, the film has two surfaces: one smooth, the other rough. You need to lay it with the smooth side on top of the insulation. At the same time, carefully ensure that the material fits as tightly as possible; gaps are not allowed.

The smooth surface of the vapor barrier must be in contact with the insulation

When laying a vapor barrier membrane, it is necessary to provide a ventilation gap between the vapor barrier and the decorative roof sheathing. It should be at least 5 cm, and the type of roofing material in this case does not matter. A counter-lattice, which is mounted directly on the membrane, can provide this ventilation gap.

How to attach a vapor barrier to rafters

You need to attach the material to the rafters with inside insulation. For fastening, you can use different parts, for example, construction stapler or galvanized nails. Try to minimize the number of punctures in the material, as this may cause condensation to penetrate through these holes during the operation of the roof.

You can use a stapler or nails to attach the vapor barrier.

The option of attaching a vapor barrier material to the rough lining of the attic is also allowed.

The material can be laid horizontally or vertical stripes, rolling out the entire coating without tears. Additionally, it is necessary to process the joints, both vertical and horizontal. To do this, you need to lay the vapor barrier overlapping, the size of the overlap should be at least 15 cm. Next, seal the joints with a special tape, but you can only choose one that is designed to work with vapor barrier film.

All joints must be sealed with wide tape

It is also necessary to seal the joints of the material with wood or concrete base, even if a stapler or nails were used for fastening.

The vapor barrier film must be laid without sagging; it must be well stretched.

Video: rules for installing vapor barrier

Installation errors

Despite the fact that the process of installing a vapor barrier film is quite simple, sometimes mistakes cannot be avoided, but they are typical and can be prevented:

• loose connection of the film to the purlins, valley and ridge beams, this is especially true complex structures roofs;
• the use of a narrow connecting tape, because of this, the sealing of the seam may be broken during the operation of the roof;
• lack of deformation reserve when installing a roof with windows;
• absence internal protection vapor barrier film around skylights, because of which ultra-violet rays gain public access to this material and destroy it;
• the film bends around the rafter legs, which creates a gap through which moisture can pass and be absorbed into the insulation.

Video: consequences of improper vapor barrier

Steam is a substance that is quite difficult to block, so vapor barrier of the roof of a private house is a responsible mission. The safety of the roofing pie and wooden structures and the long service life of the roof can only be guaranteed by correct installation vapor-proof material.

Every person dreams of his home being cozy and warm. To achieve this goal, it is not enough to choose a suitable project; you must also ensure that everything construction works, including the installation of the roof, were carried out in strict accordance with technology. Everyone knows that roofing materials must protect the house from the penetration of external moisture. However, we should not forget about the destructive properties of steam, which is formed indoors during cooking, cleaning, washing, etc. In order for the house to have a normal microclimate and retain heat, a roof vapor barrier is required.

According to the laws of physics, impregnated with vapor warm air rises up and accumulates near the ceiling. It tends to go beyond the living space, into the under-roof part, where the humidity and temperature are lower. If there is unprotected thermal insulation in the way, the steam will penetrate into the insulation and begin to destroy it.

With the onset of winter, the following will happen: low temperature on outside thermal insulation will be stopped by steam, it will turn first into frost, and a little later into an ice crust that will freeze the insulation, filling all its cracks. With the onset of spring, the ice will melt and flow, eroding the interior finish. Thermal insulation material will lose its properties and become unusable. Mineral wool will deteriorate in one winter, polystyrene foam will last a little longer.

To avoid such consequences, it is necessary to install a vapor-tight barrier, the main task of which is to prevent condensate from entering the thermal insulation layer. This will protect the insulation from moisture, thereby preventing the formation of mold, heat loss from the room and rotting of wooden structures.

Vapor barrier is used both for pitched roofs, and for flat ones, regardless of the type of coating

What materials are used to protect against internal moisture?

For a long time, the main material for vapor barriers was glassine. Particularly economical builders even now use it. However, if we take into account modern requirements for strength, service life, environmental friendliness and insulation characteristics, this is yesterday.

IN Lately Film materials with a complex multilayer structure began to be used as vapor barriers. They have a wide temperature conditions applications and high vapor permeability. Thus, the vapor permeability of simple polyethylene is 13-20 g/m2 per day, and that of a more modern vapor barrier material is about 0.4 g/m2.

Film materials are elastic, tear-resistant and easy to use. This is very important because:

1. when fastening with dowels and self-tapping screws, the material does not tear, but tightly grips the fastening itself;
2. a durable film will maintain its integrity even if mechanical damage occurs in the roof structure;
3. the film must withstand the load that will fall on it if the insulation loses its elasticity and cannot stay on the rafters.

Vapor barrier films are of two types:

• polyethylene;
• polypropylene.

Film-type vapor barrier materials are produced in rolls, which greatly facilitates their installation.

Polyethylene films are not very strong, so they are reinforced with special fabric or reinforcing mesh. They can be perforated or non-perforated.

Important! For roof vapor barrier, non-perforated polyethylene films should be used; perforated ones are more suitable for waterproofing.

In addition to conventional reinforced polyethylene films, films laminated on one side with reflective aluminum foil are also available. The vapor barrier properties of such films are very high, so they are used primarily for vapor barrier in hot and humid rooms - saunas, baths, swimming pools, etc.

Polypropylene films are a woven material laminated on both sides with the finest polypropylene. They are characterized by higher strength and resistance to ultraviolet radiation. In addition, polypropylene films can have a special antioxidant layer that prevents the formation of condensation. It easily absorbs and retains all resulting moisture, and after condensation conditions disappear, it dries quickly due to ventilation. Obviously, the antioxidant film has a one-sided application - the antioxidant rough layer is down, and the smooth surface is up.

It is very important that the vapor barrier material is High Quality, because it is located at the very base of the roof structure and is difficult to access for repairs.

Three-layer polypropylene hydrophobic membrane

How to install vapor barrier

How a roof vapor barrier is performed + video and photos of installation can be found on the Internet. Let's take a closer look at how this process should work:

• Installation of vapor barrier should be carried out from inside the room after installing thermal insulation.
• Vertical and horizontal laying of canvases is allowed.
• Horizontal laying should start from the top. Each subsequent sheet is laid on top of the previous one with an overlap of at least 10 cm, with the seams necessarily sealed using single-sided or double-sided adhesive tape. Single-sided tape is glued on the outside of the overlap, and double-sided tape on the inside.
• If the installation is carried out along the rafter legs, and there is no rough filing of the insulation, then it is recommended to overlap the panels on wooden rafters.
• TO wooden elements construction, the vapor barrier material is secured with staples or galvanized nails.
• All joints must be tightly connected. It is advisable to reinforce the gluing areas with pressure strips. It is especially important to use such strips on roofs with a slope of up to 30 degrees and with low insulation density.
• In areas adjacent to skylights, hatches and other passages through the roof, it is necessary to use a vapor barrier apron included with them. If there is none, then double-sided butyl tape must be glued around the perimeter of the frame.
• In those places where they pass through the roof ventilation pipes, the film must be folded down, wrapped around the pipe and sealed tightly with one-sided adhesive tape.
• After laying the vapor barrier film, it is necessary to attach antiseptic-treated bars in increments of 500 mm so that the inner ceiling lining does not come into contact with the film. The bars perform several functions at once: they fix the thermal insulation layer and form air gap between internal lining and a vapor barrier. Various communications can be installed in the resulting space. When finishing a room with plasterboard, galvanized profiles should be used instead of bars.

Important! The vapor barrier film should be installed without sagging, with slight interference.

The vapor barrier film is laid along the lower plane of the rafters and fixed with staples or nails

Common installation errors

If the installation of vapor barrier on the roof is carried out without the help of professionals, then mistakes may be made:

• The most common vapor barrier defects are considered to be unsealed connections of the film to purlins, crossbars, ridge, valley and ridge beams. The more difficult truss structure and, accordingly, the shape of the roof, the more expensive and difficult the task of high-quality insulation becomes.
• To seal seams, you cannot use narrow (up to 50 mm) tapes. The width of the adhesive tape must be at least 100 mm.
• With vapor barrier window openings very often they forget to leave a deformation reserve of the film (a fold of 20-30 mm for the draft).
• If the plastic film around the roof windows is not protected interior decoration, then after a few months it will completely collapse under the influence of sunlight.
• The film should not be allowed to go around the rafters. In this case, moisture will enter the gap between the vapor barrier and the rafters, and when the “dew point” is reached, condensation will form on cold surfaces.
• In places where the vapor barrier adjoins internal walls, chimneys, shafts and other elements should take into account the nature of the surface to which the film will be attached. If the surface is rough ( Brick wall, unplaned wood), then the film can only be glued using special adhesives made from polyurethane or acrylic mixtures and synthetic rubber. Widely used butyl rubber and polyurethane adhesive tapes, as well as adhesive tapes, cannot be used, as there may be a loss of tightness due to poor adhesion.

To seal the joints of foiled polyethylene films, it is recommended to use aluminum-coated adhesive tapes

Water vapor has a very high penetrating ability, so installing a vapor barrier is a responsible process. Specialists who know all the subtleties and nuances will help you complete all the work efficiently. The main thing is to choose the right materials and do everything in the right sequence. Only a properly laid roofing pie will provide the residents of the house with a carefree and pleasant existence for a long time.