Features of the vapor barrier of the bath. Laying technology for vapor barrier membranes

|| Water circulation in the pool bath || Features of the construction of premises for swimming pools || Construction of swimming pools || Heating, heating and ventilation of swimming pools || Ponds || Fountains and electrical equipment of reservoirs

As already noted, as a result high humidity air in the swimming pool with insufficient thermal insulation, moisture condenses on the inside of walls, ceilings and coatings. In addition, the content of vapor in the indoor air tends to become equal to the outdoor due to diffusion. If, along the path of steam movement, it encounters layers with low vapor permeability, then to prevent condensation, it is necessary to ensure heating of these layers, which is practically impossible. Therefore, one should strive to ensure that the vapor permeability of the layers grows from inner surface to the outside.

At the same time, a heat-insulating layer is laid on the outside, and a vapor barrier is laid on the inside. Regardless of this, building envelopes must always be airtight; the penetration of internal air through the building envelope means not only the loss of heat, but also the passage large quantities water vapor (10 thousand times more than with diffusion). The need for a vapor barrier layer is determined depending on the value of the indicator obtained by multiplying the thermal conductivity coefficient by the steam diffusion resistance coefficient. If the building element includes layers of various materials, then this indicator should decrease or remain equal in the direction from the inside out. Otherwise, a vapor barrier layer must be laid on the inside of the element. Thus, in the absence of a vapor barrier layer in the enclosing structures of the pools, it is necessary to carefully select the layers in order to outer surface had the maximum heat-insulating ability and the minimum resistance to diffusion. Building elements in which the layers are incorrectly selected or the vapor barrier is laid in the wrong place are prone to condensation; the design of such elements can be improved by ventilation. The vapor barrier layer is laid with inside building envelope (Fig. 33).

Rice. 33. :
a - without a vapor barrier; b - with a vapor barrier; 1 - outer wall

If unventilated heat-insulating screens (for example, acoustic cladding) are attached from above, then the thickness of the external heat-insulation should be calculated so that the heat-insulating capacity of the rest of the enclosing structure up to the vapor-tight layer does not exceed 18% of the total heat-insulating effect of the structure. Building elements with a vapor barrier are relatively simple to calculate; at correct location the vapor barrier layer functions reliably regardless of external influences. The disadvantage of the vapor barrier layer, especially in wall elements, is failure in places where fasteners are missed; a crack or gap of any width in the vapor barrier layer allows steam to pass through as a hole with a diameter of 15 cm. To protect the vapor barrier layer, a self-supporting cladding is used without anchoring to the base and a surface finish that does not require passage through the vapor barrier layer (painting, polymer plaster or adhesive lining). It is important to ensure that all materials used as a vapor barrier or vapor barrier layer adhere tightly to adjacent building elements. As is known, the vapor barrier coefficient of materials varies depending on their moisture content, therefore, to ensure reliability, the most unfavorable values ​​of diffusion resistance coefficients should be included in the calculation.

Implementation of each new technology in the field of construction provides an opportunity for a person to improve their own housing, which as a result becomes even more reliable, safe and comfortable. But for this it is also necessary in the process of building a house to strictly maintain the established standards and norms of construction.
The roof is one of the most important structural elements of a house that makes it comfortable to live in. Therefore, it is imperative to know the technology of laying a vapor barrier layer on the roof.

In this article

The need for a vapor barrier

The steam generated inside the room is mixed with warm air and, according to the laws of physics, rises. But, since the roof of the house prevents its further progress, it penetrates the thermal insulation layer, starting its destructive effect.

In winter, due to a sharp difference in internal and external temperatures, steam will be contained in the insulation material. As a result sub-zero temperatures the steam will first turn into frost, then into ice, respectively, the thermal insulation layer will freeze and stay in this state until the onset of heat, then it will thaw. As a rule, the consequences of such a process are the complete loss of protective properties by the insulating material, that is, unsuitability for its further operation.

In order to prevent the failure of the insulation after a year of operation, it is also necessary to lay a vapor barrier on the roof. The vapor barrier material will prevent the ingress of moisture into the insulation, respectively, significantly extend its operational period.

Materials used for arranging the vapor barrier layer

Previously, the only material used to protect the roof from moisture was glassine. Today, a wide variety of building materials are used to equip a vapor barrier layer on the roof.

• Plain low density polyethylene film. Due to its low density, experienced roofers do not recommend using it in private housing construction, as there are high risks of damage during installation and operation.
• Polyethylene film reinforced with polymer mesh. This is already a denser, stronger insulating material, which is most often used for arranging the roofs of agro-industrial enterprises. It is also not recommended as a roof vapor barrier in multi-apartment and private housing construction, since microscopic cracks form at the junction of polyethylene with reinforcing elements, through which steam can penetrate.
• Bag fabrics made from polypropylene yarns, which are subsequently laminated with molten low density polyethylene. Thickness vapor barrier material less than two times than that of a reinforced polyethylene film. Such a vapor barrier material is used for arranging cold roofs.
• Aluminum foil that has zero vapor permeability.
• Cardboard laminated on one side with polyethylene film.

Vapor barrier fabric of several protective layers used for roofs over rooms in which swimming pools, showers, laundries, etc.

Which side is the vapor barrier installed on?

• Standard vapor barrier film consists of two layers. At the same time, on the one hand, it has a rough surface that holds back drops of condensate, on the other, an absolutely smooth surface. It is the smooth side of the vapor barrier film that is adjacent to the insulation material, and the rough side is directed into the room.
• When using a foil film for vapor barrier, which is designed not only to protect the insulation, roofing, bases, but also to return thermal energy back to the room, it is laid with a reflective surface in the room.
• A vapor barrier membrane capable of passing air, protecting the bases, the roof from moisture penetration, provides the structure with the opportunity to "breathe". When using a double-sided vapor barrier membrane that has the same surfaces, it can be laid on either side. If a single-sided type membrane is used to equip the vapor barrier, then the wrong side of the material is indicated by the manufacturer.

When purchasing any type of vapor barrier material, be sure to read the instructions for its use provided by the manufacturer.

Basic rules for laying vapor barrier film

After finding out which side to the room or insulation you need to lay the vapor barrier material, you can proceed directly to its installation. In this case, the following rules must be observed:

• First- installation of thermal insulation, soundproofing material, then a vapor barrier film.
• Second- the film should be well stretched, there should be no sagging areas.
• Third- fastening of the vapor barrier material is carried out using ordinary adhesive tape (adhesive tape). You can also use nails with a wide hat (step - 30 cm) or a furniture stapler as fasteners, which will greatly facilitate the work and reduce the time it takes to complete. Film can be attached wooden slats, which are screwed with screws in increments of 30 cm.
• Fourth- individual sheets of vapor barrier film are overlapped up to 15 cm. In this case, it is necessary to make ventilation gaps up to 5 cm wide.
  This is general rules the use of vapor barrier material, but when laying it on different grounds, the roof has its own characteristics.

Roof vapor barrier

Providing moisture protection to the walls of the house is only 50% of the work, since the bulk of the evaporation is directed upwards. Also, the formation of condensate as a result of heavy precipitation cannot be avoided. As a rule, the main blow is taken by the roof of the house.

It is also necessary to understand that poor-quality vapor barrier installation on the roof will help reduce the temperature inside the house, adverse odors, dampness, mold, corrosion of metal structural elements, etc. Therefore, it is quite important to use high-quality vapor barrier material and install it correctly.

To protect the roof of the house, experienced roofers recommend using membrane-type vapor barrier materials that allow air to pass through and do not allow moisture to pass through. Membrane vapor barrier will also help remove excess moisture from insulation material. Double sided design membranes will work on both surfaces of the roofing.

Sequence of materials

When arranging the roof of a house, it is important that the materials of construction are in the following sequence:

1. Roofing
2. Control grille
3. crate
4. Waterproofing
5. rafters
6. insulation
7. vapor barrier
8. Roof filing

Vapor barrier is one of the important points in the construction of a house, as it protects the elements of the main structure of the house from mold, rot, rust and other negative impacts which help shorten their lifespan. As well as a well-laid layer of vapor barrier will provide the best in the house temperature regime for a comfortable stay.

Properly installed roof vapor barrier effectively retains heat in a residential building and provides a normal microclimate in it.

Each of us wants to live in a warm and cozy home. Your home will be like this only if you build it according to good project, not forgetting the need for proper installation of the roof and its reliable protection against ingress of external moisture into the premises. In addition, you should also remember about negative impact on the roof of the steam that forms in living and other rooms.

Physical laws say that the warm air in the house is saturated with water vapor. This mixture rises to ceiling surface and accumulates there, trying to find a way out of housing. Air tends to under the roof, where the temperature and humidity are low.

If on its way it meets a heat-insulating layer, which is additionally not protected by anything, a mixture of steam and heated air will begin to penetrate into the insulation, leading to its destruction.

Mixture of steam and heated air

When it gets colder outside, the steam on the outside of the heat insulator will turn into frost and then turn into a crust of ice. The formation of the latter will lead to freezing heat-insulating material. All its cracks will be filled with ice. With the advent of the warm season, the frozen steam will begin to melt and spread over the interior underlayment. As you understand, this will cause the insulation to lose its heat-insulating characteristics.

If you insulated the roof with polystyrene foam, it will last a couple of winters, after which it will become completely unusable. And mineral wool, often used for thermal insulation, will cease to fulfill its protective functions in a year. To avoid such serious problems allows the vapor barrier of the roof. You can easily create an additional barrier with your own hands, which will prevent condensate from entering the insulation. Such protection:

• guarantees non-rotting of wood structures;
• eliminates the risk of heat leakage from the dwelling;
• prevents the appearance of mold under the roof.

Thus, the vapor barrier ensures the removal of water vapor dangerous for the heat-insulating layer. She is considered a construction professional. obligatory element roof ventilation systems.

Previously, vapor barrier for the roof was made with roofing material. This material has performed well. The roofing felt is attached to the roof on rafters made of OSB-boards, or on a hard wooden flooring, under which without fail leave a small gap for good ventilation designs.

Such a vapor barrier is effective. But its cost due to the need to build a flooring is quite high. In addition, the arrangement of insulation using roofing material significantly increases labor and time costs. Therefore, modern experts call such vapor barrier on the roof yesterday.

At present, better and more environmentally friendly film materials are used much more often. Their installation does not require the installation of wood or slab flooring. And most importantly, their device is easily carried out with their own hands by any person, even those who are not very strong in building science.

Eco-friendly film materials for vapor barrier

Vapor barrier films have high tensile strength, as they are made of elastic components. Due to this, their do-it-yourself installation does not bring surprises - the films do not tear when fixed and with dowels. Also film products:

• maintain integrity when the roof structure receives any mechanical damage;
• are able to withstand severe loads that occur when the heat-insulating material loses its initial elasticity and slips onto the elements.

Films for vapor barrier are made of polypropylene and polyethylene. Polypropylene products are made from woven fabric which is laminated on both sides special technology. Due to this, the film becomes resistant to ultraviolet radiation.

Sometimes another layer is applied to polypropylene products - an antioxidant one. It is necessary to prevent condensation. Such a layer absorbs moisture coming from inside the house and retains it until the condensation conditions completely disappear. Installation of films with an antioxidant coating is carried out with a smooth surface up, and a rough surface (on which there is an additional layer) down.

Film with antioxidant coating

Film products made of polyethylene are less durable. They need to be additionally reinforced with a mesh (reinforcing) or a special fabric. Polyethylene films are non-perforated and perforated. Vapor barrier on the roof should be made of non-perforated products. Their perforated counterparts are designed for arranging roof waterproofing.

If you are planning to install insulating coating with your own hands on the roof of a pool or home bath, it is better to use films laminated with reflective aluminum foil. They have proved to be excellent as protectors from steam in humid and very hot rooms.

As you can see, there is no single answer to the question of which insulation is best for arranging roofs. For some objects, inexpensive polyethylene films can be used. But other rooms need a better and, of course, more expensive vapor barrier material with special properties.

In any case, you should remember that the vapor insulation you purchase must meet all the basic requirements for such products. If you mount not quality material, it will quickly fail, which will require its replacement. And it will not be easy to do this, because the vapor barrier is installed in hard to reach place. Getting under the roof structure is very difficult.

With your own hands, install films to protect the roof from steam, taking into account the following recommendations:

1. Cover sheets may be mounted horizontally and vertically.
2. The vapor barrier layer is laid from the inside of the object after the installation of the insulation is completed.
3. To the elements roof structure from wood, the vapor barrier is fixed with nails with a galvanized surface or special brackets.
4. In areas where ventilation pipes are laid through the roof, the film vapor barrier material is wrapped down and carefully wrapped around the pipe. After that, it is necessary to seal the film with adhesive one-sided tape.
5. If you are laying the material horizontally, the process starts from the top. The overlap of the canvases must be 10–12 cm. In this case, you will need to make high-quality sealing of the resulting seams with your own hands. For these purposes, two- or one-sided adhesive tape is suitable. If a double-sided product is used, it is attached inside the overlap. When a single-sided tape is used, its installation is carried out from the outside.
6. All joints, without exception, should be glued, achieving their complete tightness. Joint sections can be reinforced with strips (they are called pressure strips), which are required to be used with a low density of the heat insulator, as well as on roofs with a large (about 30 °) slope.
7. Installation of vapor barrier is carried out with a slight interference, even slight sagging of the material is not allowed.

Roof vapor barrier installation

In those areas where the vapor barrier is adjacent to various passages and openings (pipes, hatches, skylights, and so on), you need to put a special apron. You can use butyl double-sided tape instead. It should be placed around the perimeter of the frame of the structure that is interfering with you.

Another one important recommendation for home craftsmen who love to do everything with their own hands. After installing the film vapor barrier products, you need to lay between the heat insulator and the ceiling inner lining small wooden blocks that have previously undergone antiseptic treatment.

These elements create air layer between the vapor barrier and the casing and securely fix the heat-insulating coating. Their installation, among other things, makes it possible to mount any engineering communications in the resulting space. Note! When sheathing a room with drywall, it is better to use galvanized profiles instead of wooden bars.

Properly equipped thermal insulation will provide you with a pleasant and carefree life in your home!

September 29, 2016
Specialization: Capital construction works(laying the foundation, erecting walls, constructing the roof, etc.). Internal construction work (laying internal communications, rough and fine finishing). Hobbies: mobile communication, high technologies, computer equipment, programming.

A mandatory stage in the arrangement of the ceiling is the vapor barrier of the ceiling with breathable materials. Otherwise, water vapor generated as a result of human activity will moisten the insulation, which will lead to a deterioration in its technical characteristics and service life.

Today I will tell you what types of vapor barrier materials are used in construction and how to properly lay the one you have chosen. polymer membrane on the interfloor.

Materials used

I want to note right away that film and sheet materials for vapor barrier are on sale. However, I will not consider the latter within the framework of this article, since when using them you need to know how to properly make an installation and seal the seams between the elements.

More effective and easy to use, especially for beginners, are films, which will be discussed below.

Films for vapor barrier

All waterproof films that protect the insulation from moisture can be divided into two large varieties:

1. Waterproofing. They are used when erecting pitched roofs with inhomogeneous roofing materials (tiles, profiled sheets, slates, and so on) and insulating surfaces that can be affected by atmospheric moisture. Their main task is to protect the heat-insulating material from snow, raindrops and condensate. Another area of ​​application is the construction of facades with a ventilated gap.

1. Vapor barrier. They are used in cases where it is necessary to protect the insulation layer from water vapor generated as a result of human activity (cooking, washing clothes, washing, cleaning, and so on). Vapors rise to the ceiling due to convection transfer and diffuse into the ceiling, moistening the thermal insulation layer (and this should be avoided).

A few decades ago, domestic builders did not know about high-tech vapor barrier materials. The maximum that could be used was glassine, roofing material or plastic wrap (as for greenhouses). And many generally neglected this stage of work.

However, with the beginning of the construction boom and in connection with the widespread use attic floors increased requirements for the quality of buildings being built. Therefore, now the use of vapor barrier is mandatory, and every self-respecting heating specialist knows how to properly put the film he has chosen in an insulating cake.

I will tell you how to lay the membranes a little later, but before that I will describe their varieties. The fact is that the division into hydro and vapor barrier films is very arbitrary. Often, vapor barriers are used to protect against atmospheric moisture, and impermeable polymeric barriers are used as an obstacle to water vapor.

On sale you can find several types of films.

Polyethylene

Used for both hydro and vapor barrier. They usually have a reinforcing layer of reinforcing mesh or fabric, which increases the tensile strength of the material.

Polyethylene films, in turn, are divided into two types:

• perforated - the surface of these materials has micro-holes, due to which the film receives a greater degree of vapor permeability;
• non-perforated - fully sealed polymer membranes.

I will say right away that, in my opinion, the difference between these two varieties is small, since the vapor permeability coefficient of perforated films is too small to provide effective air infiltration. Therefore, when installing insulation with polyethylene membranes, it is always necessary to make a ventilation gap to remove condensed water vapor.

During the installation of vapor barrier membranes, including polyethylene, it is very important to lay the film so that it forms an airtight layer. To do this, you need to correctly connect the individual sheets of material between themselves and building structures. Connecting and sealing tapes come to the rescue.

On sale, in addition to conventional reinforced membranes, specialized materials are used, laminated with heat-reflecting aluminum foil. She reflects thermal energy generated by heating appliances, increasing the energy efficiency of the home.

When choosing a reflective film, you need to know which side to lay the vapor barrier on the ceiling. This should be done in such a way that the reinforcing layer is directed inside the living space.

Vapor barriers based on polyethylene films are not suitable for rooms with normal levels of humidity and temperature (living rooms). But they can be installed to protect the insulation layer on ceilings in kitchens, saunas, swimming pools, and so on.

Finally, I note that recent times more and more heating specialists are abandoning this type of vapor barrier in favor of more technologically advanced films.

Polypropylene

The advantages of this type of membranes are that they have much greater strength and are well tolerated. ultraviolet radiation. They can protect the ceiling of a house under construction.

Moreover, even if you do not have time to finish the roof, the membrane will temporarily protect the building from destructive external factors for at least 12 months.

The disadvantage of the polypropylene film is that when it is used to insulate the ceiling, a large amount of condensate forms on the surface of the material, which violates the humidity-temperature regime of the building. Therefore, products are now on sale that have a special layer of viscose fiber mixed with cellulose, which prevents condensation.

The bottom line is that this layer absorbs water and keeps it inside. Moreover, its water-absorbing properties are so great that drops do not form on the surface. After the humidity level inside the room decreases, the liquid from the viscose layer gradually evaporates under normal air exchange conditions.

Naturally, in this case it is also important to know which side to put the polypropylene vapor barrier on. The viscose-cellulose layer must be placed inside the room. And be sure to leave an air gap between the film and the decorative material.

In private construction, polypropylene membranes are widely used (both with and without a viscose layer) due to their high strength and affordable cost. However, recently they are increasingly losing their positions to the most effective vapor barrier materials.

Breathable membranes

These products appeared on the territory of Russia not so long ago, although they have been used abroad for 20 years. The essence of vapor-permeable membranes is that they reliably protect the heat-insulating layer from moistening with water, but at the same time do not interfere with the infiltration of water vapor. This effect is achieved due to the special membrane structure of synthetic fiber materials.

The wide distribution of breathable membranes is due to a change in SNiP number II-3-79. Regulatory authorities began to impose more stringent requirements for the vapor permeability of enclosing structures and polyethylene films could not cope with the tasks assigned to them.

A huge advantage of "breathing" films is a significant reduction in the thickness of the heat-insulating pie of the ceiling. Unlike other vapor barrier membranes, vapor-permeable material can be laid directly on the insulation without arranging a ventilation gap.

On sale there are two types of vapor-permeable films:

• one-sided application - it fits to the insulation of only one of the sides;
• double-sided application - here you do not need to figure out how to put the material correctly, since you do not need to choose a side.

The price of "breathing" membranes is somewhat higher than other types of vapor barrier described. However, the difference in cost is so minimal that it can be easily neglected, especially considering the cost of other building materials. Therefore, I see no reason to deny myself the purchase of such an effective film.

Types of vapor barrier materials

Modern domestic and foreign manufacturers vapor barrier films with various technical characteristics are produced. Their marking depends on the manufacturer. Before laying the film, it is necessary to determine the operational properties of its particular variety.

I will talk about the features of the product line using the example of Isospan vapor barrier. There are such types:

Type	Purpose
BUT	A vapor-permeable membrane for protecting building envelopes, including ceilings, from atmospheric moisture penetrating through the roofing material. It is used to remove moisture from the heat-insulating layer and protect mineral mats from fraying. Mounted from the outside.
A plus	Vapor permeable protective film to prevent wetting of the insulation as a result of ingress of atmospheric moisture. On the front side, the film has a smooth hydrophobic surface, and inside there is a special layer that prevents the formation of condensate. The membrane ensures the removal of water vapor from the heat-insulating layer of the ceiling, protects against condensate and increases the service life of the structural elements of the building.
AT	Impervious two-layer vapor barrier film. It is used on the inside of the ceiling to protect the enclosing structures from moisture. Also suitable for floor waterproofing.
With	Two-layer water-impermeable polymer film, dyed blue or black. It differs from other options in improved technical characteristics. Protects the insulation from moisture and building construction. Installed on the inside of the ceiling. Can be used to protect against dampness of flooring made of natural wood, laminate or cork.
D	Universal vapor permeable polypropylene film having a laminated layer on one side. It is characterized by high strength and is more often used for installation outside the walls of buildings and ceilings. Protects the insulation structural elements buildings from wind and water.
K	Two-layer fully impermeable film, used for comprehensive protection thermal insulation layer, ceilings, walls, rafters and other important elements buildings. Protects the interior from unproductive heat loss, littering with mineral insulation fibers, condensation of water vapor.

As an effective vapor barrier, in addition to those described above, you can use penofol - a foil insulation based on foamed polyethylene with a heat-reflecting layer of aluminum foil. However, this material does not apply to classic vapor barriers.

Adhesive tapes for vapor barrier installation

Any person who knows how to properly install a vapor barrier will tell you that this cannot be done without adhesive tapes sealing the joints of the moisture barrier. They paste over the places of joining of individual canvases (overlaps), as well as the places where the membranes adjoin the building envelope.

It is impossible to use ordinary adhesive tape for these purposes, since it peels off when moistened. You can achieve an ideal result only if you use such tapes (I will describe using the Izospan products as an example):

1. KL. Elastic tape based on spunbond - artificial nonwoven fabric obtained from the melt of the polymer raw material (polypropylene). It has an adhesive layer on both sides of a water-soluble polymer without the use of solvents. The minimum service life of this tape is 50 years. Used for gluing type A vapor barrier membranes.

1. KL Plus. Universal bilateral adhesive tape made of non-woven material, reinforced with a reinforcing layer. It is used for gluing canvases of the vapor barrier layer in order to create the most durable surface. It can be mounted and does not lose its operational properties at ambient temperatures from -60 to + 100 degrees Celsius. It can be used to bond vapor barrier membranes to porous and uneven surfaces of any material. Suitable for bonding all kinds of films.

1. ML Proff. Single-sided adhesive tape made of rayon, additionally reinforced with mesh fibers. The tape is used for gluing vapor barrier membranes to enclosing structures made of any materials - gypsum, plaster, wood, and so on. You can glue the vapor barrier film to pipes, window openings, and so on. The material is suitable for both indoor and outdoor use.

Laying technology for vapor barrier membranes

In this section, we will talk about how to lay the vapor barrier on the ceiling. Naturally, this process must be combined with the installation of heat-insulating material in the ceiling. In my case, we will talk about a wooden timber building, in which the ceiling is made along the support bearing logs. Therefore, it is very important to choose the type of vapor barrier when insulating the ceiling.

To insulate the ceiling wooden house with vapor barrier, it is necessary to perform several stages of work, which are indicated in the diagram below.

Now I'll tell you how to do it required list work at each stage.

The choice of vapor barrier, insulation and additional materials

To begin with, we will decide which materials are best suited for insulation (it also depends on which vapor barrier to choose for work). Considering that the work will be carried out in a wooden house, and this material belongs to the category of "breathable", insulate it better products with high vapor permeability.

I advise everyone to use mineral mats based on basalt fiber for this purpose. These products have a huge number of advantages.

Now let's decide which vapor barrier is best for the ceiling. wooden house. I do not want to limit you in the choice of products in terms of strength and other characteristics. I will only note that you need to buy vapor barrier materials with high vapor permeability. It is desirable that this indicator be not lower than the vapor permeability coefficient of mineral wool (0.56 mg / (m * h * Pa) and wood (0.32 mg / (m * h * Pa)).

Another thing, vapor barrier for a bath. In this case, it is necessary to take all measures so that the insulation layer does not get wet from the huge amount of steam generated inside the room. Therefore, you need to choose an impervious film with a foil heat-reflecting layer.

In the latter case, it is very important to know how to properly lay such a film, or rather, which side to attach the material to the insulation layer. But I will talk about this a little later.

So, everything is clear with insulation and vapor barrier. But you need to stock up on some more of the materials and tools, without which it is impossible to complete the installation:

1. Wooden boards 10 cm thick. They will be used for filing the ceiling from the inside of the room and hold the insulation between the beams.
2. Grooved floorboards. Suitable for flooring attic floor(with reverse side residential ceiling).
3. Screwdriver. Useful for fixing various trim parts.
4. Staple with staples. You will learn its purpose when you read about how to fix a vapor-permeable film on a ceiling.

Well, now you can go directly to work.

Ceiling preparation

Any specialist whom you ask how to properly fix the vapor barrier and insulation will say that work should begin with the preparation of the ceiling. To do this, I perform the following operations:

1. I am renovating ceiling beams. If the house has already been used, you need to check the integrity of the supporting elements of the shelf, clean them of dust and debris, and remove traces of mold and fungus. If defective areas are found, part of the beam (or all of it) must be replaced. Otherwise, it is impossible to guarantee any long service life of the insulation layer.

1. We treat the supporting elements of the ceiling with a fungicide and a fire retardant. To do this, you can use some kind of universal liquid such as Strazh-2 or "Fire Bioprotection". Such treatment will destroy the microorganisms living on the surface of the wood, and also increase fire safety ceiling covering.

1. I carry out the installation of engineering communications in the ceiling. This must be done before laying the insulation and installing waterproofing membranes. All electrical wires in a wooden house must be laid in metal or polyvinyl chloride fire retardant channels, and ventilation pipes insulate with polyethylene foam shells.

1. I make a box for the passage of a chimney through wooden ceiling. It is necessary to make sure that the heat from the pipe is not transferred to the ceiling. To do this, I recommend constructing a box from tin, which is fixed on the beams, and then covered with expanded clay or covered with mineral wool.

After such preparation, you can safely proceed to laying the vapor barrier membrane.

Ceiling vapor barrier

The very technology of installing a vapor barrier film will not cause you great difficulties. As a material, I propose to use the Isospan B membrane or similar, produced by another manufacturer.

Laying is done from the inside of the dwelling. The scheme is this:

1. I mount the first canvas on the floor beams. To do this, simply roll out a roll of film and attach it to the bottom of the beams with staples from a construction stapler. Wide-head nails can also be used. There are several points here:
   • The canvas must be fixed so that a slight overlap of the membrane forms on the walls of the dwelling. Otherwise, gaps will form there, through which water vapor will penetrate to the insulation and lead to its wetting.
   • If work is carried out in the hot season at high air temperatures, the film must be fixed not with an interference fit, but with a slight sag - about 2 cm per meter. This is necessary so that when the temperature (and, accordingly, the size of the canvas) decreases, the vapor barrier layer does not break due to strong tension.

1. I fix the second and subsequent vapor barrier sheets. You need to act in the same way as described above. The edges of the films should overlap each other at a distance of 10-15 cm to ensure greater tightness. For convenience, Izospan membranes have already been marked with appropriate markings, which you just need to follow.

1. I seal the seams of the vapor barrier layer. For this, various adhesive tapes are used, which I talked about in the corresponding section above. Pay attention to three points:
   • First, the seams between the canvases are sealed. To do this, bend the overlap, glue a strip of adhesive tape. After that, remove the protective anti-adhesive film from its surface and fix part of the second sheet. As a result, the adhesive tape will be inside, forming a completely sealed seam.
   • Then you need to seal the joints of the film with vertical enclosing structures (walls and partitions). Izospan tape will also help with this, which adheres well to both vapor barrier and other building materials. In this place, you need to leave a margin so that the film does not tear due to the displacement of the base.
   • After that, it remains only to paste over the box, which serves to pass the chimney through the wooden ceiling. Izospan trademark adhesive tape withstands surface temperatures up to +100 degrees, so it will not peel off during operation of the furnace or boiler. As a result, you should get a dense sealed surface, similar to that shown in the photo.

1. I sew up the ceiling from the inside with decorative material. Considering that I used a "breathable" membrane on which moisture does not condense, it is not necessary to equip the ventilation gap. Therefore, I will lay the lining directly on the vapor barrier, fixing the parts with clamps on the floor beams. The result will be the design shown in the photo.

Another thing is when you use a material with a reflective foil layer for vapor barrier. Then a gap is needed and decorative material attached as follows:

• brackets for a galvanized frame (the so-called “pawns”) are attached to the floor beams from the lower part directly through the layer of reflective vapor barrier;
• load-bearing profiles or wooden blocks of a suitable section are fixed on them (by the way, at this stage, you can additionally level the ceiling surface if the floor beams were installed unevenly);
• lining or sheet material (drywall, plywood, and so on) is attached to the rack-mounted supporting parts.

There must be a gap between the sheet material or lining and the vertical enclosing structure to remove moisture from the ceiling.

Insulation installation

I have already written more than once about the installation of insulation, in my case, mineral wool, and those who wish can find detailed information in one of my articles on this site.

Laying insulation boards on the outside of the ceiling (the vapor barrier membrane is clearly visible in the photo).

Therefore, here I will mention only a few features that are very important to remember:

1. The width of the insulation boards used should be 1-2 cm larger than the distance between support beams. Then thermal insulation material will become a surprise and not form cold bridges.
2. For arranging an insulating layer with a thickness of 100 mm, it is better to use plates with a thickness of 50 mm. They are laid in two rows with alternating layers to prevent the appearance of cold bridges in the transverse seams.
3. From above, the insulation must be protected from moisture with a waterproofing layer. I'll show you how to do it in the next section.

Ceiling waterproofing

To protect the heat-insulating layer from getting wet from the side of the attic (or attic), you need to use a reliable membrane that will not let water through if it flows through roofing. Installation is as follows:

1. I lay the film on top of the insulating material. It is necessary to make sure that the membrane is distributed freely over the surface, but does not form strong sagging. Otherwise, the air flow inside the ventilation gap will create an unpleasant rustling sound.
2. I fix the film on the beams. To do this, I use the same construction stapler with staples.
3. I seal the seams. This process is no different from the technology described above. Double-sided adhesive tape is used.
4. I mount the bars of the counter-lattice. For this wooden details with a section of 5 by 5 cm are fixed on the floor beams. Self-tapping screws are used, which are screwed directly through the waterproofing film.
5. I'm installing flooring. Attic or attic floor boards are attached to the bars. The result should be a cake similar to the one shown in the photo below.

Summary

Now you know how to choose a vapor barrier material suitable for the job and how to put the purchased film in the ceiling insulation cake. Therefore, an independent vapor barrier of the ceiling will not cause you any difficulties. You can leave your opinion about the information above in the comments.

It will not be superfluous to watch the video in this article, where the topic is depicted clearly.

September 29, 2016

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Water vapor is always present in a residential building. It actively rises up while washing dishes, drying and ironing clothes, wet cleaning, watering flowers, cooking and, especially, a hot shower. Even man himself is a constant source of it. And, although in modern houses most of steam is removed from the living space thanks to well-equipped ventilation, but still its tangible share remains. And this is where it causes a lot of problems.

Therefore, if this is your first time encountering the concept of vapor barrier, we advise you to carefully study this article, and not rely on the opinions of others. After all, unfortunately, quite often properties are attributed to vapor barriers that they do not even have in sight, or they approach the issue of installation completely wrong. But we will help you figure it out: what kind of vapor barrier to choose for the ceiling so that you never see stains, condensation, or signs of structural failure on it. All this is not difficult to understand, the main thing is to be patient!

If you're interested, this video tutorial does a good job of explaining why ceiling vapor barrier is so important, and what would happen without it:

When and what kind of ceiling vapor barrier is needed?

In itself, such protection is a whole range of measures that are necessary when steam can meet materials with high diffusion resistance in its path. And on what materials it is and what kind of room we are talking about ( home library or swimming pool), depends on how hard you need to protect the ceiling.

What happens between the two levels of rooms?

In simple terms, the process of equalizing humidity between two rooms on different height essentially resembles the process of temperature equalization. Warm air saturated with water vapor will always move from a warm room outward to a colder one, and at the same time pass through the ceiling and walls, which is called diffusion.

And this water vapor from the air in the process of such movement condenses and impregnates the walls with moisture. The covers themselves different materials pass this steam in different ways. Therefore, in the construction language, materials are divided into those with high or low diffusion resistance.

It's all about physics: the lower the density of the building material, the easier it is for vapor molecules to pass through it. For example, steam passes through plaster, red brick and wood quite easily. But silicate brick and concrete floors already has a high diffusion resistance.

Also, mineral wool, which is so popular today for insulating the ceiling, practically does not resist warm air and water vapor, but the foam plastic serves as an insurmountable obstacle for it. And in this case, the vapor barrier is installed either out of ignorance, or for the purpose of additional thermal insulation, which will never hurt. Especially if the vapor barrier is reflective, as here:

Well, if we are talking about the ceiling, which is located between two warm floors. In theory, inside these rooms there should be approximately the same temperature, and therefore vapor barrier may not really be needed. Then in such a cake only wind insulation is used, and for only one purpose: to isolate the living quarters from fine dust from the insulation. That is, in a word, there is no temperature difference - there will be no problems.

And a completely different picture if the upper room is not warm. According to the laws of physics, the internal air of a house can only hold a certain amount of steam. For example, at a temperature of 20 degrees, it will retain 17.3 g of water vapor, and this is already 100% relative humidity. But he can't take it anymore. In addition, if the air is completely saturated with water vapor, then with even a slight decrease in air temperature, the water will immediately turn into a liquid and fall out in the form of fog or condensate. But if the air is heated, it can take in even more steam.

In simple terms, the air becomes dense, increases and displaces excess vapor. And the steam will move from a warm room to a cold one, and the process itself is called diffusion. Steam always follows where the air temperature is lower, and this is the ceiling of a cold attic. Moreover, steam is always looking for easy ways for itself: cracks, leaks, material porosity, and so on.

If we take living room, then the temperature under the ceiling is always 2-4 degrees higher than near the floor, and therefore warm air from above will always retain more steam. That is why the diffusion of water vapor will occur unevenly: most of the vapor will escape through the ceiling, and a little through the top of the walls. And, squeezing out through the ceiling of a non-residential attic, the steam reaches the dew point - the very temperature on which it depends when the vapors turn into droplets of water. Unless, of course, a vapor barrier was not thought out in advance.

So vapor barrier is necessary then when the overlap is between an unheated and a heated room. For example, in the attic floor between the warm floor and the unheated under-roof space, as well as on the inside of the first floor of the ventilated underground:

Vapor permeability of insulation and floor structure

With the fact that the vapor barrier of the ceiling in a residential building is necessary, we have already decided. But how dense and how impenetrable? In fact, reinsurance is not needed here. And if you make a deaf vapor barrier above the living space, when you need a different view, then there is a risk of getting condensate as a result, although this issue could well be solved by controlled removal of steam through the ceiling. Therefore, the next point that you need to study for the correct choice of vapor barrier is such a characteristic roofing materials like vapor permeability.

Conventionally, all roofing insulation that is manufactured is divided into "wool" and "foam". The first group includes all heaters made of mineral and organic fibers: mineral wool, stone glass wool and the like. And foam materials include materials that are formed under factory conditions by hardening foam of various chemical composition. In fact, for the arrangement of the ceiling, the thermal conductivity of which materials is approximately the same is 0.04 W / m ° s.

But, in addition to thermal insulation properties, in all other respects they differ quite strongly. For example, all heaters that are made of fibers are vapor-permeable materials. Thanks to the intricately intertwined threads, closed pores do not form in them, and water vapor easily enters such a heater, as it easily leaves it:

In addition, in a number of modern cotton wool insulation, the fibers are also coated with a special water-repellent substance, and such insulation is called hydrophobized. The bottom line is that water vapor molecules can no longer penetrate the fiber, but only cling to its surface. And when a critical mass of such molecules is collected, they form a whole drop, and it rolls down under its own weight. Therefore, hydrophobized cotton wool insulation is also vapor permeable. Here, a big plus is that even with enough in large numbers a pair of such heat insulators almost do not get wet, and therefore do not lose their properties.

But foam materials, which are made by filling pores with air or inert gases, have a completely different level of vapor permeability. And such heaters can either pass water vapor or not, depending on the nature of their pores.

For example, polystyrene foam, which is made by extrusion and all its gas-filled balls are connected into a single whole, serves as an excellent vapor barrier, but polystyrene foam, which is also called non-extrusive polystyrene foam, just passes molecules of both air and water between its balls. Also vapor-permeable foil materials, one of the sides of which is covered with aluminum foil.

This is how the vapor permeability characteristic is calculated: the lower the coefficient, the less steam is able to penetrate into such a heater. Usually, the vapor permeability coefficient of the insulation is provided in the product data sheet, but please note: there is the concept of "vapor permeability coefficient", but there is a "steam resistance coefficient" and they are different.

How to organize a competent ceiling vapor barrier?

What is a ceiling vapor barrier? It is a material with a high ability to resist the penetration of water vapor. This layer consists of two important elements:

• canvas, which is a film or membrane,
• connecting tape, which is designed to ensure maximum tightness of all joints and overlaps.

A properly equipped ceiling vapor barrier should look like this:

On the laid and sealed vapor barrier arrange top coat, which often requires a framework. That's all the tricks!

How to choose a high-quality vapor barrier according to technical characteristics?

So, today there are many materials that have high resistance to vapor diffusion and low vapor permeability. For a long time, conventional polyethylene films have been very popular, which, in principle, do their job, but still do not please with high vapor permeability, low tear characteristics and fragility.

That is why modern manufacturers, following their policy of import substitution, produce quite interesting technological solutions, among which there are even metallized membranes. There are many such materials and it is worth studying their characteristics in order to understand: which the best vapor barrier for the ceiling of your house?

Let's list the most important characteristics for vapor barrier:

1. Vapor permeability– characteristics of films and membranes from 0 to 3000 mg per square meter per day. This indicator indicates how many grams of water in the form of steam can pass through each meter of film per day. And the lower the number, the better, of course. If the numbers show vapor permeability in hundreds or thousands of grams, then you have a vapor-permeable membrane in front of you, and you should put it not under the insulation, but on it.
2. Strength. This characteristic greatly affects how easy your installation work will be. Cheap vapor barrier films are quite easy to tear, they lose their integrity even during installation, when tools fall on them or when they are touched. On the other hand, a strong vapor barrier also tolerates temperature changes well.
3. Water column pressure. The vapor barrier film is designed to retain water. Basically, this indicator is important for a vapor-permeable membrane, which can literally get rain. For the ceiling, this, of course, is not critical, although attic leaks should never be ruled out.
4. UV resistant. This figure varies from a few days to a month. Surely you have watched how polyethylene, which has been on the street for a long time, becomes brittle and breaks. But high-quality material retains its strong performance for a long time. This is of value if your installation work involves keeping the vapor barrier film exposed on the ceiling for long periods of time without the inner cladding.

And, in order to understand and clarify whether you have chosen the right vapor barrier for the ceiling according to technical specifications carefully examine the pictograms shown on the packaging. And trust the brand that is known in the domestic market and is trusted. Among these brands are Izospan, Izover, TechnoNIKOL, Delfa and others.

Selecting the type of vapor barrier material for the ceiling

If everything is more or less clear with the need for a vapor barrier, then what kind of vapor barrier is better for the ceiling and what should be followed when choosing? Each of the vapor barrier materials offered by modern market, its benefits and features. For example, the same polyethylene films are the least resistant to low temperatures and exposure to oxygen, quickly become obsolete, but are affordable.

Therefore, the modern market also offers the consumer such vapor barrier materials:

• combined films;
• reinforced films with metallized layers;
• diffuse membranes of various properties.

These materials differ significantly from each other:

Vapor barriers: we create a reliable obstacle

For a vapor barrier of a conventional residential ceiling, a sufficiently reinforced or more affordable polyethylene film, which has maximum vapor permeability. Even glassine is suitable, just choose it then denser and thicker.

But more expensive membranes are strong reinforced materials that are covered with a foil or fleecy shell on one side. They have good tightness and even reflect heat loss (you probably know that heat always rises). Such membranes are indispensable for the vapor barrier of ceilings in rooms with increased level humidity, like kitchens, bathrooms, swimming pools.

Here is an example of a high-quality vapor barrier that will reliably protect mineral wool:

Limited vapor permeability: we control the condensate

But there is another type of membrane - with limited vapor permeability. Such insulation is created on the basis of non-woven polypropylene by thermal bonding of polymer fibers. And such a small vapor permeability allows you to evenly remove all unnecessary air humidity from the living room, but at the same time condensation will not form on the walls and ceiling.

Naturally, this option is only suitable if there is a non-residential attic above the room, which is great for country house and any other building where the residence is seasonal. Of course, in the case of wall vapor barrier and roof vapor barrier, such membranes are also used for insulated structures, but then forced ventilation is arranged there, and, as a rule, there is nothing of the kind in the ceiling.

Variable vapor permeability: smart approach

And, finally, films with variable vapor permeability are membranes that manage to change their properties! For example, in a completely dry room, such a barrier is vapor-tight, and when humidity increases, it becomes permeable and removes excess moisture from the premises. These today are mainly produced by Delta for ceiling vapor barrier.

And if the vapor barrier was not put at all?

Sometimes it also happens that the ceiling is already hemmed, but the vapor barrier was either forgotten or not known. Then do not panic and pay attention to what kind of material the ceiling is hemmed with. So, if this is drywall, then you are in luck: it absorbs moisture well. If chipboard, also do not worry, because. Chipboard itself is a dense material, and glue serves as its connecting element. Even the paint on the ceiling will be a good protection. And in general, when finishing with drywall, they usually use the simplest vapor barrier:

Selection of connecting tapes and adhesive for vapor barrier

A well-arranged vapor barrier is a continuous and continuous layer. Moreover, the usual construction tape for gluing overlaps and junctions is not suitable here - only a special vapor barrier. Each manufacturer offers its own options for connecting tapes for different tasks.

For example, some of them are designed exclusively for overlapping the canvas, while others are for adjoining films to smooth surfaces, and others are for connecting vapor barrier with a porous and rough surface. Moreover, it is extremely important to purchase connecting tapes from the same manufacturer as the vapor barrier itself in order to achieve 100% tightness of the layer.

There are also several types of these:

• special glue for the film;
• adhesive composition for connecting the membrane;
• construction tape;
• one-sided aluminum tape;

as well as double-sided adhesive tape to seal the individual sheets.

The subtleties of the correct installation of ceiling vapor barrier

And finally we'll give you a couple useful tips regarding the installation of the selected vapor barrier. The vapor barrier should always be laid with an overlap of 15-20 cm to ensure reliable protection from vapor penetration. All joints must be sealed with construction tape.

Under the attic floor, the vapor barrier should be pressed with wooden slats, and a crate should be mounted on top of them to create a gap between the ceiling sheathing and the attic floor. At the same time, ensure that future electrical cables and other engineering systems did not violate the integrity of the vapor barrier film. All electrical cables must be covered and battens are required.

In addition, ceiling lights should not be placed in such a gap, because. due to the slightest damage to the vapor barrier in such a space, condensate easily forms and drops of water will come into contact with electricity. And this is already fraught with considerable problems.

If everything is done carefully, even a fairly voluminous and multi-level structure can be easily fixed to the vapor barrier:

Be careful, and the result of the repair will only please the eye!