A vapor barrier layer is necessary when installing a roof. Films are presented in various options and allow you to make the roof structure more efficient, as well as reduce heat loss.

Functions and vapor barrier device

The roofing pie includes a rafter system, insulation, and external covering. A mandatory layer is also a vapor barrier, which is necessary to eliminate condensation formed as a result of the temperature difference between the roof and the outside. Moisture negatively affects the insulation and load-bearing elements of the roof, destroying them and contributing to the creation of an unfavorable atmosphere. Therefore, vapor barrier is necessary, because it performs the following functions:

Vapor barrier film is used to protect insulation from moisture. This layer of roofing pie is often confused with a waterproofing barrier, which is designed to protect the structure from moisture coming from the roof, that is, precipitation. It is impossible to install the same material in two layers, because you need to clearly know the properties of all the structures used.

The vapor barrier membrane is thin but durable

The film can be of high or low permeability. A specific option is selected depending on the required level of protection. For baths and saunas, the most effective films are used, and for an ordinary residential building any options are suitable.

Effect of vapor barrier materials for roofing

Materials for vapor barriers are varied, but they are always non-woven material of small thickness, since this indicator is not key when arranging the roof. The main role is played by the quality of the structure, because this determines its functionality and the level of moisture protection of the roof structure.

The vapor barrier is the first layer on the rafter system

Membranes or films have a two-layer structure. The fleecy layer is designed to absorb moisture and steam from inside the room, and the dense outer layer prevents moisture from affecting the insulation. This action is typical for membranes, but there are also single-layer films that are intended only to protect the heat insulator from moisture.

Vapor barrier film is used in both residential and non-residential premises

A high-quality roofing cake necessarily includes a layer of vapor barrier material. In the absence of such a component, moisture negatively affects the structural elements of the roof. For example, rafters, insulation, sheathing are subject to rotting and deformation. As a result, the roof loses strength and does not protect the building well from precipitation, temperature changes and other external factors.

Types of vapor barrier for roofing

Manufacturers produce several basic vapor barrier options, differing in properties, technical data, installation and operation features. All options are divided into two categories: films and membranes. The first material often has a single-layer structure and differs in that it only protects the insulation from moisture. Membranes are more functional, as they consist of two or more layers. They perform two main tasks: absorbing and evaporating moisture, as well as preventing the heat insulator from getting wet.

The inner layer of the membrane absorbs and evaporates moisture

When arranging the roof, the following materials are used:

Choosing a vapor barrier for the roof

The durability of the roof depends on the quality of all materials used to create the roofing pie. The vapor barrier fabric and its properties also play an important role and therefore the correct material should be selected. A comfortable atmosphere in the house depends on this, temperature regime under the roof, the integrity of the roof and the durability of the building. Therefore, when choosing a material, you should pay attention to the following features:

The cost of the material should not be suspiciously low. Before choosing, you should study the offers of several manufacturers, read the reviews and characteristics of the vapor barrier.

Features of materials

Each of the main types of vapor barrier is divided into several options, differing in properties and characteristics. Thus, polyethylene films can be reinforced or ordinary. The first option is more durable, but non-perforated polypropylene structures are optimal for roofing. If you choose perforated polypropylene film, you should take into account the level of humidity in the room. They are suitable for dry, warm attics.

Perforated films are lightweight but easy to install

Membranes are most in demand for roofing, but are expensive. Breathable or diffuse fabrics allow steam to pass through, are durable and practical to use. They can be one- or two-sided. The first option has one rough side for absorbing and evaporating moisture, and the other surface is dense and smooth, and is always mounted in the direction of the insulation. The double-sided version can be attached to either side of the heat insulator, since both surfaces of the material are the same, but perform the same functions as a one-sided sheet.

Manufacturers often designate different colors single-sided vapor barrier surfaces

Foil sheets are optimal for arranging the roof of a bathhouse or sauna. Other options cannot be used in these rooms, since when heated the materials emit harmful substances and may melt. Therefore, you need to choose a foil sheet that can withstand heating up to 120 °C. This vapor barrier is called reflective and reduces heat loss.

Review of manufacturers

Manufacturers produce many options for roofing products. One of the popular materials is “Izospan”, presented in several versions. The Gexa product line includes universal fabric, single-layer membrane, polyethylene film, non-woven fabric with a metallized layer and auxiliary materials.

Izospan membrane fabric is in demand for roof installations

The materials “Yutafol N”, “Yutafol D” and “Yutavek” are produced by the Czech manufacturer Juta. The range includes both polyethylene and polypropylene films, differing affordable price, good level protection and long service life.

The “Yutafol” canvas is lightweight and practical to use and install

Vapor barriers "Ondutis" are presented in variety. The Onduline product line includes superdiffusion, anti-condensation, and polymer film options. Vapor barrier for dachas has a simple structure and an affordable price, and the fabric for arranging the roof of a residential building is as reliable as possible and has high strength.

The best manufacturers

In the field of construction and roofing materials There are many vapor barrier manufacturers. The following brands stand out in particular:

These manufacturers are leading in the field of manufacturing quality materials for hydro- and vapor barrier, as well as complete roofing.

Installation of a vapor barrier for the roof

Installation of a vapor barrier structure can be carried out using several methods. Polypropylene and polyethylene films are attached with a construction stapler and staples to the system of wooden rafters of the pitched roof. If a membrane or foil sheet is used, then staples or small nails are driven through thin slats, pressing them against the sheet.

The joints of foil sheets are secured with metallized tape

The scope of work for attaching a vapor barrier may differ depending on the type of roof, but the general steps are as follows:

Installation features and SNiP

When attaching the film, clamping strips are often used, which prevent damage to the material and ensure a tighter fit to the rafters and insulation. And it is also worth considering that staples or nails must have an anti-corrosion coating that protects the fasteners from rust. The film can be fixed to a brick, concrete or other surface using polyurethane glue or synthetic rubber. The film should not be pulled too tightly, as this may damage it.

The film is easy to attach to staples and clamping strips

The construction of roofs and vapor barrier layers is carried out taking into account established norms and standards that ensure safety and high quality installation work. SNiP includes the following main points regarding the arrangement of a vapor barrier:

When installing a vapor barrier layer, the same basic rules are used as for waterproofing. The canvas is laid in one layer when fastened from inside the insulated attic. If installation is carried out outside and directly under the roofing material, then two layers of vapor barrier will be needed.

Video: features of vapor barrier installation

Installation mistakes and how to avoid them

Attaching the vapor barrier does not require the use of complex tools or special skills. In this case, inexperience can lead to certain mistakes that will cause damage to the structure as a whole. The most common situations when the following errors occur, which are easy to avoid:

All stages of installing a vapor barrier are simple, but require careful and careful actions. This avoids cracks and damage to the canvas.

The vapor barrier is a necessary component of the roofing pie, as it protects other layers from internal fumes. The right choice material and its careful installation greatly facilitate the further construction of the roof. Therefore, familiarization with vapor barrier options and methods of its installation require special attention.

When arranging a roof, several layers are required different materials. That is why this design is called a roofing pie. If you want your roof to serve you for a long time, you need to use materials for heat, hydro and vapor barrier.

Why do we need a vapor barrier, what is the point of protecting the roof from steam?

Waterproofing and vapor barrier layers consist of completely different materials.

Their differences are that waterproofing protects the house from moisture from above, and vapor barrier prevents vapors from entering the roof structure.

The need for vapor barrier is due to the fact that steam rises from below, from the living space, which enters the “roofing pie”. Thermal insulation material absorbs moist air, swells, becomes damp and becomes unusable. Wooden structures Roofs also begin to rot over time, fungus and mold form on them, which can lead to complete destruction of the roof.

Vapor barrier is also important for maintaining a favorable microclimate in the interior. If the steam rising from the living rooms does not leave the house, then the inside will always be humid and stuffy. Remember how you feel in a greenhouse - your home can turn into something like a greenhouse without a well-equipped vapor barrier layer.

In winter, a vapor barrier layer prevents ice from forming on the roof. On hot summer days it will help keep the house cool. However, it should be taken into account that for the vapor barrier to function properly, it is necessary to have a ventilated roof.

Do you need a vapor barrier under the corrugated roof of a cold roof?

Many people believe that installing a roofing pie in general and a vapor barrier in particular should only be done for warm roofs where the attic or attic will be located. But modern cold roofs made of corrugated sheets also need vapor barrier.

The fact is that the temperature inside the room, even if it is not heated, differs from the outside air temperature, so condensation on inside sheets of corrugated sheets will still accumulate.

The vapor barrier layer will protect against unwanted moisture from entering roofing structures that are susceptible to rotting and deterioration. They fasten the film with lathing, and only then install the roof from profiled sheets.

What materials to use

Roofing materials can be divided into hydro- and vapor barrier materials, and antioxidant ones are also distinguished. Basically, these are film materials based on polyethylene. IN lately A variety of building materials have appeared for all layers of the roofing pie. And if previously only glassine could be used for vapor barrier, now the choice in construction stores is very large. Glassine is practically not used; although it is cheaper, it is inferior in performance to modern analogues.

There are several main groups of modern vapor barriers:

1. Based on polyethylene. The film can be perforated or non-perforated, the latter is used for the waterproofing layer. The perforated material, despite the presence of holes in it, reliably protects against unwanted moisture. The holes are microscopic, so drops simply cannot leak through them. But steam passes through the perforation perfectly. Another option for polyethylene is foil film. It not only provides steam removal, but also retains heat. If you place it with the foil side down, it will reflect heat back into the house. When installing, it is advisable to reinforce any film with mesh.
2. Based on polypropylene. Compared to the first option, polypropylene film is much stronger. Due to the presence of a layer of special fabric, polypropylene film has antioxidant properties.
3. Membrane. It's comparative new material, which is ideal for roofing. The breathable properties of the membrane allow you to save on ventilation. The material does not allow moisture to pass through, but steam penetrates inside, settles on a special fabric layer and dries there. Membranes, or diffuse films, can be single- or double-sided. The method of laying them on the insulation depends on this.

When choosing a material for vapor barrier, you should pay attention to the following properties:

• High strength. Even with significant mechanical impact, the vapor barrier should not be damaged. For example, the material must withstand the weight of vapor and waterproofing if the integrity of the sheathing is damaged.
• Easy to install. This is especially true for those who perform installation work on your own. If the film breaks during the process, is difficult to lay and is inconvenient to unwind from a roll, then it is unlikely that you will be able to make a good vapor barrier.
• Good elasticity. This quality is important when fixing the film. When using fasteners, the film should not tear, but should stretch and tightly grip the screw.

How to install a vapor barrier on a roof. Step by step instructions

The vapor barrier layer is part of the roof, an important element of its arrangement. The first stage of installing a vapor barrier is preparation. The under-roof part should be thoroughly cleaned of dust and dirt; it is especially important to dry it thoroughly. Then you should lay the insulation, which always precedes the vapor barrier layer. The installation itself is carried out in several stages:

1. A roll with a vapor barrier film or membrane is unrolled directly at the installation site. If the roof is gable, installation begins from the bottom up, and then, after passing the ridge, goes down again. The film must be overlapped to prevent the appearance of cracks and gaps. Secure the material with tape around the perimeter and at the joints. (Read also: DIY installation of a gable roof rafter system)
2. Next, you need to more carefully secure the vapor barrier material under the roof. To do this, use nails or screws with wide heads. Another option is a construction stapler. If you have chosen good material, then it will not tear. The elastic film will close around the fastener. (How to choose the right self-tapping screw, read this article)
3. If you are installing a rough version of the roof, then before installing the vapor barrier layer, you should make a sheathing. You can use wooden or plastic slats for it, metal profile. The film is carefully stretched and attached to the sheathing using self-tapping screws or construction stapler.

When installing a vapor barrier layer, it is important to follow the manufacturer's recommendations. Many materials have special perforations, so it is important to lay them on the correct side.

If you are installing a roof for the first time or have never worked with modern vapor barrier materials, professional advice will help you avoid the most common mistakes.

• Regardless of what type of roof you are installing, installation of a vapor barrier is carried out only after laying the insulation.
• When installing overlapping film sheets, they must cover each other by at least 10 cm.
• It is imperative to glue the joints with adhesive tape/adhesive tape; moreover, it is better to use a wide tape, at least 10 cm wide. The best option– use of double-sided tape, which is glued inside the overlap. Stick it on first bottom layer film, then glue the top layer on top.
• When using nails or screws as fasteners, galvanized products are preferred. They are not subject to corrosion, which will extend the life of the vapor barrier.
• If there is a window or hatch in the roof, then it is necessary to use a special apron, which is sold complete with vapor barrier materials. If there is none, then the perimeter of the window or hatch should be covered with butyl tape.
• Also, when working with windows, you should leave a deformation margin around them. Over time, any house, even one built a long time ago, shrinks. This can damage the vapor barrier, which is why a fold of at least 20 cm is necessary.
• If installation is carried out near heating pipes or water pipes, then the vapor barrier material should be carefully wrapped around the pipe and sealed tightly.

The main rule when installing a vapor barrier is to ensure tightness. If the tightness is broken, then the effectiveness of the vapor barrier layer will be minimal.

The main errors in installing roof vapor barriers are noted in the video

Thus, a vapor barrier device is necessary condition for long-term operation of the roof of the house. it is necessary both for a warm roof with an attic or attic, and for a cold one.

During the process of washing, cooking, and cleaning indoors, steam is generated, which rises upward in accordance with the laws of convection. Having passed through all layers of roofing materials, it cools and turns into condensation, which settles on the thermal insulation, as a result of which it gets wet and loses its effectiveness, as well as on the rafter system, contributing to its rapid rotting. To prevent this from happening, a roof vapor barrier is installed.

Why do you need a roof vapor barrier? This question is asked by many owners before building a roof. Often people simply do not understand the purpose of this material and want to save money by completely abandoning vapor barriers, but in vain. It ensures effective ventilation of the roof both in summer and winter, while protecting the roof from excess moisture escaping from the room.

In the summer, the correct design will save you from the heat, because hot air, when rising upward, will freely escape through the ventilated hole, taking with it the moisture contained in the insulation, as well as heat from the hot roof. This is especially important if your home is equipped with any of. Therefore, when the question arises whether to install a vapor barrier or not, it is worth knowing that in its absence there is a risk of mold, accumulation of moisture in the rafters, freezing of the roof due to moisture entering from inside the house, as well as damage to the ceiling finish.

There are several types of vapor barrier films:

• Foil. This film is used in buildings with increased temperature requirements.
• Vapor barrier reinforced membrane.
• Polyethylene. The advantage is the low price, but durability and strength leave much to be desired.
• Universal vapor barrier film. The most commonly used material, perfectly compatible with all types of insulation.
• Non-reinforced vapor barrier membranes with a reflective aluminum layer.

Features of vapor barrier installation

Before you begin installation, you should pay attention to which side to lay the vapor barrier for the roof, since it has a one-way direction, namely, it allows steam to pass in only one direction, like a membrane. Fastening the film should ensure its maximum safety, for which the most suitable would be to use double-sided tape. Fasteners to wooden surfaces possible with construction staples or self-tapping screws with large heads.

Basic rules for installing vapor barrier film:

• Laying a vapor barrier on the roof should be done with the smooth side in relation to the insulation. If condensation forms, it will fall on the vapor barrier film from the rough side, which will not give it the opportunity to roll off, but will hold it on its surface until it dries completely.
• The vapor barrier must be laid with an overlap, and the joints must be covered with special adhesive tape.
• Due to the fact that steam has a high penetrating ability, during the installation of the roof, special attention must be paid to the places where the film adheres to pipes, rafters, and walls.
• Steam diffusion is much more intense with a sharp temperature difference, because steam moves from a heated room to a cold one, so when asking the question “Is vapor barrier necessary for a cold roof?”, the answer is obvious - it is absolutely necessary.

Instructions for installing vapor barrier on the roof

The installation of a roof vapor barrier is quite simple, so experience is not necessary to carry out such work. In case of ignorance of how to properly make a vapor barrier, or uncertainty in own strength, you can always turn to specialists for help. Below is a step-by-step sequence of doing the work yourself:

1. The vapor barrier film can be attached both horizontally and vertically. If selected horizontal installation, it should start from the bottom, gradually rising to the top of the rooftop.
2. Each subsequent strip is carefully laid on the previous one with an overlap of at least 10 cm. In this case, the seams must be carefully taped to avoid the appearance of gaps in the insulation, allowing steam to penetrate through it. When using double-sided adhesive tape, it will be convenient to apply it first to the bottom layer, then remove the protective coating and fix it with the top layer.
3. Fastening the film to the rafters is most conveniently done using a construction stapler. In case of nailing, you need to use galvanized ones, which do not rust. If the roof slope is less than 30 degrees, then it would not be superfluous to additionally strengthen the junction of the panels with planks.
4. If there are pipes in the roof, you should wrap them in film, first turning it down, and then carefully seal it with adhesive tape.

Before laying a vapor barrier on the roof, it is necessary to prepare and apply an antiseptic coating to the bars, which, upon completion of installation, will need to be used to secure the film, maintaining a distance of 0.5 m. This is necessary to form a ventilation corridor that promotes the rapid evaporation of emerging condensate.

Vapor barrier is not a material that is worth saving on, because it is what ensures the safety and long service life of the roof, thereby guaranteeing residents a pleasant and comfortable existence.

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, as a result of which its 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 various 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, when installing, they must be reinforced with light fabric or 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 a specific purpose, but there are also universal films.

This material is often used by professional builders and self-taught owners. Izospan is combined with any type of 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 home 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 chimney, you need to take into account the specifics of the irregularities to which the material will be attached.
7. Installing the film on a rough wall should be done using polyurethane glue or synthetic rubber.
8. Do not use polyurethane adhesive tapes as they may peel off the surface after a while.

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, today vapor barriers are used for TechnoNIKOL.

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