Polystroy and which side to lay. Vapor and waterproofing - hydro-vapor barrier... What films are placed and where in the roof or frame wall. Why do you need to install a vapor barrier inside and outside your home?
If, when insulating a building, you do not use a vapor barrier, then the insulation itself will last a very short period of time.
Moisture will begin to enter its layers and will carry out the process of destruction. This procedure very often occurs when it is cold outside, then large temperature differences occur inside and outside the room.
In order for the vapor barrier to be installed on the walls correctly, you should know its features, because not every side of the film can be used.
Purpose of vapor barrier
Vapor barrier will protect the house from condensation To date topical issue is saving money on paying for gas and electricity. Everything for the safety of money more people insulate their houses and apartments, and to protect the insulation itself from moisture and steam, vapor barrier materials should be used.
What exactly they are needed for can be found in the table:
| № | Highlights | Description |
|---|---|---|
| 1 | Vapor barrier preserves the building and the health of residents. | Thanks to protection from moisture, metal and wooden structures will serve long time, will not be subject to corrosion and rotting. In addition, using film will not prevent mold or mildew from appearing in the house. |
| 2 | If the house is insulated from the outside, then a vapor barrier may not be used. | In this case, a vapor barrier will need to be installed on the floor, ceiling or roof. |
| 3 | If insulation is carried out inside the building, the vapor barrier is laid on insulating materials. | In this case, the insulation can last a long time and will not collapse. |
| 4 | Vapor barrier can be installed inside and outside. | If you ignore installing a vapor barrier, then in addition to moisture, heat will escape from the house. |
Knowing the main tasks of a vapor barrier, we can safely say that its installation is a must in any home, but to carry out the work on your own, you will need to know the features, as well as carry out a number of preparatory measures.
In case insulation work are carried out from the street, then the protective material must also be laid outside the premises. If it happens inside the house, the film is also installed indoors.
Preparatory work
Use membrane films in wooden houses When preparing the protection of the house and insulation, you should start by choosing the vapor barrier itself, which will be used in the future. Today the choice is quite large, and films can be used not only for walls, but also for floors, ceilings, floors and other parts.
If the building is made of wood, then it is better to use films with membranes. If the base is brick or concrete, then other types of films are possible, among which are:
- Polyethylene. Most cheap option. Using such a vapor barrier will require constant ventilation.
- Polyethylene with aluminum. Used to reflect thermal energy.
- Reinforced polypropylene. Available in 1, 2 and 3 layers. The composition includes viscose and propylene. This material has one side smooth, the other fleecy.
- Diffuser membranes. Protect from moisture and release it outside. The film retains heat well and “breathes”.
Install insulation on walls impregnated with protective solutions Improper preparatory work will result in poor performance of the film itself. Preparation will depend on what the house is made of, namely the walls. If the house is just being built, and wood is used as the main material, then all elements must be impregnated with insecticides, mold, mildew and fire repellents. After impregnation, you can begin constructing and insulating the walls.
If the building is made of concrete, then there is no need to use impregnation. It will be enough to clean the surface from mold, mildew and dust. Next, the base will need to be checked for cracks and holes; if there are any, then putty them.
Vapor barrier films must be protected from contact with sun rays, since after 3 months under the sun the insulation will be unusable and its properties will be lost.
In general, installing a vapor barrier is simple and does not require any special skill. When the preparation is completed, you can begin to work, but you need to know that the film must be overlapped and additionally glued with tape.
This allows you to close access to air. Particular care must be taken to cover the areas adjacent to various openings. If a film with a foil layer is used, then the corresponding adhesive tape is also used.
Select adhesive tape according to the type of material After purchasing the film, you need to read the instructions, namely which side should be laid to the insulation, but in practice such information is not always available and to determine the front side you need to pay attention to the following factors:
On the wall, follow these instructions:
- The film is applied to the wall and fixed with a stapler.
- The next part is overlapped and also secured with staples. All parts of the vapor barrier should not be tensioned; the film should be laid loosely to leave room for ventilation.
- When the film is laid on the walls, all joints are covered with tape, which will provide maximum sealing.
During operation, tearing of the film is not allowed; if this happens, it is better to change the part or securely seal it with tape. The film itself must be dry before use. If you have to lay the film in winter period, then the heating should work in the house.
If the work is done correctly, then there will be no need to maintain the film, and the walls will serve for a long time without repair. The work of laying film on the floor and ceiling is somewhat different, but in general the essence remains the same. For more information on how to properly install a vapor barrier, watch this video:
During work, a certain supply of vapor barrier should be left near the openings. It is necessary if shrinkage or deformation of the house occurs. For reserve, a fold is made with dimensions of about 3 cm.
Read about the features in other articles on the site.
In order to properly carry out the work of laying a vapor barrier, you will need to study why such material is needed. Knowing the features and installation method, you can do the work yourself, in just one day.
The vapor barrier is laid according to the manufacturer's instructions, which must indicate which side it should be laid on. If there are no instructions, or there are no recommendations for choosing parties, you can follow general principles styling
Which side are they placed on? different types vapor barriers:
- Glassine. As a vapor barrier, it is laid on the inside of the insulation, with the black (bitumen-coated) surface facing the inside of the room.
- Single layer polyethylene films. They are attached from the inside to the insulation on either side, since they do not have additional properties, but perform only the function of a vapor barrier.
- Polyethylene films reinforced with a polymer mesh. They also do not have specific instructions for laying; they are convenient to lay as the roll unwinds.
- Two-layer films for vapor barrier (fluffy on one side and smooth on the other). They need to be laid with the pile facing out, close to the insulation with the smooth side.
- Foil vapor barrier. It is attached with the shiny side inside the room, as it is also a heat reflector.
You should not use superdiffusion membranes as a vapor barrier - their function is to remove steam from the insulation, and not to prevent its penetration.
Which side to lay the vapor barrier on the floor
You can lay a two-layer vapor barrier on the floor with the fleecy side on the floor beams. This option is suitable for brick houses with wooden floors so that the beams can “breathe”. If the film is attached to the ceiling under the beams, the wood may “rot”, which will lead to the formation of mold.
Which side to lay on the roof
By laying a foil vapor barrier on the inside of the roof with the shiny side facing the room, you can reduce the cost of heating the room. If you use glassine under the roof, you will have to lay it in several layers with the black side inward - due to its fairly high vapor permeability.
Which side to lay on the walls
Reinforced polyethylene films are attached inside to the walls with either side facing the insulation. They are preferable to ordinary polyethylene, as they are much stronger and, accordingly, easier to attach. No vapor barrier is used on the outside of the walls; instead, vapor-permeable wind insulation (waterproofing) is used.
will penetrate into layers of material and slowly destroy it. This property is especially important during the cold season, when the temperature difference between indoors and outdoors is significant.
For this reason, a volume of steam is formed in the house, which must leave it without obstacles. In order to correctly carry out the installation of materials that prevent the accumulation of moisture, you need to know which side to lay the vapor barrier.
During the preparatory work, it is necessary to make a choice of the one that will be used in the vapor barrier.
Today on the market of materials suitable for moisture protection are: various options, which are suitable for work on floor slabs, ceilings, under the roof, on walls or even on the floor:
- When installing vapor barriers on wooden structures: ceilings, walls or floors, it is preferable to use films with a membrane designed for such cases.
- For floors made of any material - mastics based on polymers and bitumen.
- For ceilings, various surfaces The universal “Izospan” is suitable for walls and floors; it is an excellent design against moisture and condensation accumulation.
- For concrete or wooden walls, foil, polystyrene foam, and mega-isol are suitable.
If the surfaces are not properly prepared, the vapor barrier will not be effective. The complex of preliminary work depends on the specific material from which the house is built, the walls, floor or ceiling are erected, as well as on whether it is planned to construct a new building or major repairs to a dilapidated one.
Surface preparation options depending on the material:
- If a wooden house is being built from scratch, then first you need to impregnate all parts with special insect repellents; this is important for the subfloor, ceiling and walls. It is also worth using impregnations against fungi, mold and fires. When this work is completed, you can do the vapor barrier.
- During major repairs They dismantle outdated floor coverings and all layers of insulation. All surfaces are cleaned, impregnated with products, and only then a layer of material is applied to protect them from moisture.
Concrete buildings do not require separate surface treatment with special substances; it is enough to clean the walls, floor or ceiling.
Vapor barrier helps prevent the formation of mold, mildew and rot in wooden buildings. does not require great skill, it is enough to properly prepare the surfaces and know a few nuances of the work.
We put a vapor barrier on the ceiling
During work, the question very often arises, which side should the vapor barrier be placed on the ceiling and how to lay it correctly? You will find the answer to this question in this article.
First, you need to determine where the front and back sides of the vapor barrier are. Typically, vapor barriers have a smooth side and a rough side. More uneven surface always faces the insulation layer, and is smooth on the outside.
If in doubt, you can take a small piece of material and cover the mug with it. hot water. Condensation will settle on the side that remains waterproof.
Instructions for installing vapor barrier on the ceiling
Before starting work on the vapor barrier of the ceiling, it is necessary to clean out all irregularities that do not exceed 5 mm, then clean it of dust and dirt, and then prime it and dry it.
Laying the material depends on its characteristics; most often, vapor barriers are installed in rooms precisely on inner surface ceiling or ceiling.
If the climate is such that in winter the temperature can drop to low levels, and the walls are not too thick, then it is recommended to install a vapor barrier inside and outside.
- The vapor barrier is usually attached to the surface using a stapler.
- Special attention should be paid to the corners; the material should slightly overlap the walls around the perimeter of the ceiling.
- The material must be whole; the use of several pieces is not allowed. It is important that the edge of the canvas overlaps the corner.
- When laying a vapor barrier film, its surface should be as stretched as possible. It is placed only after the insulation layer has already been laid.
- The film, which is laid between the ceiling beams, is secured using nails with a special wide head; a distance of about 30 cm must be maintained between them.
- The film sheets on the ceiling must be placed overlapping each other. The joints are hermetically sealed using tape.
Sometimes a vapor barrier is laid on the ceiling without a layer of insulation; in this case, the film can be attached using strips of plastic or wood, which are fixed to the ceiling with screws. The step between the slats should be small, and the attachment points themselves should be located at a distance of no more than 30 cm.
When insulation material is placed on top of a vapor barrier, there is no need to attach the vapor barrier layer separately. You can record everything at once.
Attaching various types of vapor barrier to the ceiling
Sheet vapor and thermal insulation requires a special approach during installation.
First, a special frame of profiles is installed.
It could be wooden blocks or special aluminum slats. The latter are much easier to work with, since they are designed for these purposes.
They have special grooves into which sheets are secured. To eliminate the gaps between the ceiling and, it is necessary to capture a small part of the wall.
There is a type of vapor barrier made from roofing felt; this type of work is called lining. This material is laid on the prepared floor surface. During pasting, heated bitumen or mastic is used, which is applied without missing areas.
If there are joints in the ceiling or corners, then it is necessary to introduce the material with a slight overlap and secure it with nails with large heads on a special rail. The edges of the material are folded under the insulation.
If a painted type of ceiling vapor barrier is used, then most often they use bitumen-kukersol mastic, varnish or hot bitumen. The varnish must be made on the basis of chlorinated rubber or polyvinyl chloride. A layer of mastic is applied using a special sprayer.
The varnish coating is applied twice, and you must wait until the first layer has dried before applying the second.
Features of laying vapor barrier to insulation
When carrying out work, it is very important to consider which side to lay the vapor barrier to the insulation. If you make a mistake at this stage, the thermal insulation will not be effective.
For all film-type materials, one rule applies: the film is placed in such a way that the smooth surface is on the insulation side, and the rough surface is on the inside.
This rule is suitable for protecting walls, ceilings and floors from moisture, but only if the material has a structure consisting of two layers. When working with a vapor barrier with an aluminum side, it is necessary to place the shiny surface inside and the rough surface against the wall.
When using polypropylene material, also rough side should be facing the room, and smooth towards the insulation. As a rule, high-quality vapor barriers have instructions and installation guide.
Installation of vapor barrier on the floor
Vapor barrier materials must be laid only on a prepared base. For this type of work optimal solution will use isospan. You will also need a construction stapler and adhesive tape, suitable for the following purposes:
- If the film is two-layer, then its first layer is laid directly on a wooden or concrete floor.
- The material should be laid with an overlap of approximately 5-10 cm on the walls, and secured with a special tape.
- In places where the film is glued together from two canvases, it is necessary to additionally fasten the layers with a stapler. When laying, the result should be a single canvas, without defects. It should completely cover the floor area.
- Any insulation material is placed on top of the vapor barrier: mineral wool, polystyrene foam, expanded polystyrene and others. After the layer of thermal insulation, it is necessary to put a second layer of material to protect against moisture.
- Vapor barrier is installed smooth surface to the insulation.
- In the first layer, the rough side faces towards the base of the floor, and in the second - towards the room.
- After the materials have been correctly laid, the main floor is installed.
When using a film with a foil side, it is laid end-to-end. To fasten the canvases, you need to use a special adhesive tape with an aluminum surface.
A layer with a metallic sheen is placed towards the room, then all the heat will be reflected from it and returned to.
Sometimes special rubber in a liquid state is used to vapor barrier the floor. The subfloor is prepared in advance; its surface must be dried and cleaned of dirt.
Then the mastic is applied using brushes or a roller. After time, the impregnation dries and forms a dense film that completely matches the texture of the floor.
Types of vapor barrier
An important stage in carrying out thermal insulation work is right choice material.
Not so long ago, the most popular way to protect against moisture was to use glassine or roofing felt.
Today the market is saturated with offers, and technological progress has gone far ahead - you can buy combined materials, which are distinguished by reliability and durability:
- The film is an excellent vapor barrier and prevents condensation from forming on the walls, roof and insulation itself.
- Film with layer aluminum foil. Metal surface has the ability to reflect heat and has excellent vapor barrier properties. This type of material makes sense to use in wet areas: baths, swimming pools, saunas and baths.
- Film with a membrane - has a limited ability to transmit steam. Depending on its condition, it can change its properties. As the humidity level increases, the film begins to allow steam to pass through; in a dry state, this property is much lower.
- Mastic based on bitumen - allows air to pass through and retains moisture.
Vapor barrier materials can also be produced in sheets and rolls. Depending on this, the installation technology differs.
When using the material in rolls, they should be rolled out in the direction from bottom to top. The fabric is secured using wooden slats or profiles in the horizontal direction.
The hole for ventilation is left in the gap between the vapor barrier layer and the finishing inside; its size must be at least 4 cm. The fastening must be strong.
The vapor barrier in sheets is mounted in a pre-prepared profile frame, and then the material is installed into it from the bottom up.
Features of vapor barrier
Vapor barrier materials are necessary for normal circulation of moisture in the room. A special membrane in the film prevents the insulation from accumulating moisture. Therefore, it is very important to observe several conditions when laying the layer:
- If a membrane with wind and waterproofing properties is used, it must be in close contact with the insulation. If there are gaps, the material will cool to a temperature that will be lower than that of the steam being released. Then membrane film may become covered with a thin layer of ice and cease to be effective.
- It is necessary to provide a gap for steam removal of at least 40-50 mm. But the size may vary depending on climatic conditions. It is especially important to maintain a balance for large roofs or with an obtuse slope angle, in which air circulation is worse.
- The amount of steam passing through the system should be kept to a minimum.
Vapor barrier has one important function - it prevents moisture from entering the insulation layer. But that’s not all, when silicate or polystyrene foam materials are used in houses to retain heat, the membrane will serve as a barrier to individual fibers entering the house and volatile substances which can be harmful to health.
Air does not escape through cracks and gaps in structures, and the house remains at a pleasant temperature.
Recommendations for proper installation of vapor barrier materials
Planning work on installing a vapor barrier begins with identifying the most critical areas where special attention is needed. Laying material that protects against moisture is needed where the surface becomes the boundary between warm and cold air.
Most often such places are basements, ceilings, roofs, attics, attics and walls. Wooden structures require special attention when performing vapor barrier work:
- The layer protecting against moisture must be laid with the smooth side facing the insulating materials, in this case there will be no influx of steam, rot or fungus will not begin to form, and heat will not be lost. This is especially important for wooden buildings.
- If the walls are insulated from the outside, then the vapor barrier is placed outside the room. At indoor installation For thermal materials, a layer of film that protects from moisture should also be located on this side.
- The most common mistake is a loose fit of the film to the insulation.
- When gluing the seams of vapor barrier sheets, it is necessary to use wide tape of at least 10 cm.
- When work is carried out in places window openings, then they often forget to leave a small supply of film, which is needed in case of deformation or shrinkage. This should be a fold measuring 2-3 cm.
- The film must be protected from exposure to sunlight; in just one season, the exposed surface can become unusable.
- To connect the joints of the film to the foil surface, you need to use metallized tape.
On the one hand, vapor barrier work does not require great skills, but there are still a number of nuances that need to be taken into account. The main condition for proper installation of the film is to install it with the correct side facing the insulation. As a rule, it is not difficult to determine the reverse and face of a material. The video shows how to install Izospan:
Last time we dealt with species and , which is made from stone wool. Despite its ability to repel moisture, even this material needs protection. For this purpose, vapor barrier is used. Today we will tell you how to properly install vapor barriers in thermal insulation pies of walls, roofs and floors. For interfloor ceilings where both floors are heated, such films are not needed.
How to lay a vapor barrier when insulating walls
Both sides of the vapor barrier are equally impervious to moisture and steam.
Let's figure out how to properly install vapor barrier on walls. There are two insulation options:
- internal;
- external
Of course, it is preferable to install thermal insulation outside the room, but in this case a vapor barrier film is not required. The material used for insulation also matters. Film is needed only when it is necessary to protect thermal insulation from moisture and steam. To figure out how to properly lay a vapor barrier film, you need to understand the principle by which air circulates. He always moves from the zone high pressure(where the temperature is higher) to the zone low pressure(where the temperature is lower). It turns out that the air, along with moisture, tries to leave the warm room and end up outside.
Which side to lay the vapor barrier to the insulation does not matter, since it does not allow moisture to pass in any form in both directions. Those who ask such questions most likely confuse vapor barrier film with waterproofing (diffusion membrane).
Scheme of laying vapor barrier on the wall from the inside.
Therefore, on numerous forums, when asked which side to attach the vapor barrier to the insulation, supposedly experts answer that it is rough. Where is the rough surface of the vapor barrier? It is a completely smooth material on both sides. As it turns out, even the builders themselves confuse these concepts. In our previous article we clearly explained .
Another frequently asked question regarding how to properly install a vapor barrier is the need for a ventilated gap. Some film manufacturers write that a ventilation gap is not needed at all, but it’s still not worth making hasty conclusions. When installing an insulation pie for walls from the inside, a ventilation gap is needed between the film and the finish, but is not necessary (although it won’t hurt) between the film and the insulation. Here we are somewhat replacing the concept of a ventilation gap, since in the space between the film and the finishing (even more so the insulation) it is not always possible to achieve the necessary air circulation.
Let's leave these subtleties aside for now and call the buffer air zone between materials a ventilation gap. Layers of insulation cake for walls, starting from the inside:
- finishing;
- ventilation gap;
- vapor barrier;
- insulation;
- wall.
The ventilation gap will keep the finish dry, as a result there will be no mold on it and it will last as long as it should.
Laying a vapor barrier film on the roof
Layout of vapor barrier for roof insulation.
The question of how to properly lay a vapor barrier is especially relevant for roof insulation, since this is where the most mistakes are made, which subsequently bring many problems. Before explaining the layer diagram, remember what we said about the direction of air flow and the main function of the vapor barrier. Our main goal is to protect the insulation from steam, so the film should be laid on the side of the warm room. There is no need to think about which side to attach the vapor barrier; absolutely all construction films are wound into a roll so that when unrolled they lay correctly.
That is, you take a roll and apply it to work surface, gradually unwind and staple the film, everything is as simple as shelling pears. In the process of installing the film with a stapler, installing the counter-lattice and stuffing the trim, holes will appear in the vapor barrier in any case. Through these holes, steam will penetrate into the insulation, and the film itself does not protect 100%. Therefore, you cannot cover the thermal insulation with a vapor barrier on both sides; you need to give moisture the opportunity to escape. Between the insulation and the zone low temperature a membrane must be installed that releases steam but does not allow the material to get wet.
Now we’ll tell you how to properly attach a vapor barrier using an example. Let's consider roof insulation with mineral wool, layers from the inside:
- vapor barrier;
- mineral wool;
- diffusion membrane;
- counter-lattice, thanks to which a ventilation gap appears;
- roof finishing.
In addition to the ventilation gap between the membrane and the roof trim, it would also help to have a gap between the same membrane and the insulation (optional, but preferable).
The vapor barrier is laid stretched; it should not sag. At the joints there is an overlap of about 10 cm, the joints are taped.
You need either aluminum-coated construction tape or specialized double-sided tape for films, the latter is preferable. Correct styling vapor barriers:
- First, one tape is laid;
- double-sided tape is glued along the edge;
- protective is removed paper tape– sometimes the paper tears, small pieces may remain that must be removed;
- The next tape of film is laid on top.
Double-sided tape connects the films very tightly, so that later you can’t tear them apart from each other.
How to properly install a vapor barrier on the floor
Scheme for laying vapor barrier when insulating the floor along joists in wooden house.
Floor insulation is not much different from the roof, the only thing is that there is no finishing rough coating. Thermal insulation is laid between the joists wooden house. A subfloor is first laid underneath, which should not be solid, that is, there should be indentations between the narrow boards that are no less than their width. Thanks to these indentations, steam will have the opportunity to leave the insulation. Moisture enters the thermal insulation along with the air from the room, so the layers of floor insulation in a wooden house should be laid as follows:
- finishing floor;
- vapor barrier;
- insulation;
- wind protection or waterproofing.
A gap between the insulation and the vapor barrier is not required, but whether it is needed between the finished floor and the film is a controversial issue. Let's return to the moment when we talked about replacing the concept of a buffer air zone with a ventilated gap. Essentially, a ventilation gap is a space where constant air circulation occurs; if this does not exist, then it is just a buffer zone.
A ventilation gap in the classic design can be observed in the roof structure and When insulating walls from the inside, it is still possible to achieve circulation in the buffer air zone, but with the floor it is increasingly more difficult. We need to make holes in the floor, but there is no guarantee that air will circulate there the way we need and whether it will at all.
Therefore, many craftsmen refuse the ventilation gap between the finished floor and the vapor barrier, and the same applies to the walls. But if you look from the other side, a gap is still needed. Even if moisture condenses on the film, it will not be absorbed into the material in contact with it, and accordingly, it will not mold.
Correct installation of vapor barrier: results
To figure out how to properly install a vapor barrier, you need to know why it is needed and the principle of air circulation. The film is needed to protect the thermal insulation from moisture that is in the warm air. The circulation of air flows occurs in the direction from a warm room to a cold street. Accordingly, the vapor barrier must be laid from the side of the room, preferably leaving a gap between the film and the finish. How to determine the sides of a vapor barrier? It has two sides: this and that, and both are the same. The film does not allow vapor to pass through in both directions. Such questions are asked by those who do not understand the difference between a vapor barrier and a diffusion membrane (waterproofing).
When insulating a roof or room with a heat insulator (mineral wool, glass wool, loose polystyrene) capable of transmitting and accumulating moisture, it is necessary to install a vapor barrier layer. Moisture that gets into the thermal insulation significantly worsens its performance properties, increasing thermal conductivity. In addition, due to the humid environment, wooden structures with which the insulation comes into contact quickly begin to rot and collapse. At the stage of preparation for insulating a roof or house, it is important to figure out which side to lay the vapor barrier against the insulation - a violation of the technology will lead to steam from the room penetrating into the thermal insulation layer.
What kind of vapor protection is needed?
Types of vapor barrier materials
The primary issue is the choice of material that will protect the insulation from moisture. Classic roofing felt and glassine, which were used for water vapor barrier, have given way to modern polymer films with different performance parameters. Membranes used in construction are divided according to vapor permeability into completely impermeable films and partially permeable (diffusion) films.
Manufacturers offer the following types of vapor barrier membranes::
- polyethylene film (can be used to insulate a roof or floor, the barrier is vapor and waterproof);
- reinforced polyethylene film (higher strength);
- aluminum foil film (used for internal insulation, mounted with the reflective side facing the room - additionally helps to retain heat, primarily designed for use in saunas and baths);
- film with anti-condensation coating (prevents moisture condensation, intended for installation in structures with metal elements, prone to corrosion - corrugated sheets, metal tiles, etc., the film is mounted with the treated side facing the heat insulator).
Reinforced polyethylene film If, when insulating rooms in a house, a completely impermeable film is used to create a vapor barrier, it is necessary to provide effective ventilation of the rooms that can remove excess moisture outside.
Vapor barrier films with a porous structure differ in their ability to diffuse. Due to the pores in the barrier, moisture from the insulation leaves to the outside, due to which the heat insulator retains its operational properties, and those in contact with it metal structures do not rust, wooden ones do not rot. Among vapor-permeable membranes there are differences:
- Pseudo-diffusion. During the day, up to 300 g/m2 of vapor is passed through.
- Diffusion. The amount of evaporation passed per day ranges from 300 to 1000 g/m2.
- Superdiffusive. The evaporation rate exceeds 1000 g/m2.
The vapor barrier film of the first type is classified as effective protection from moisture and are used for internal insulation of structures (from the room side). If pseudo diffusion membrane mounted on top of a fiber insulator on external wall, the vapor barrier will retain moisture in the insulation. For facade insulation diffusion and superdiffusion membranes are suitable, which simultaneously serve as a wind barrier.
Superdiffusion membrane Principles for installing a vapor barrier
Laying vapor barrier - important stage works on insulation of structures fibrous materials, capable of accumulating moisture. The work is carried out as part of the repair or reconstruction of the house or at the stage of preparation for finishing new construction. You need to know how to properly fasten membrane sheets together to ensure a continuous layer that protects against moisture penetration, and how to attach the film to structures. Before laying the vapor barrier film, it is also necessary to determine which side it needs to be placed against the insulating material.
Preparatory stage
To insulate a block or wooden house or arrange a bathhouse, thermal insulation materials are used, which must be protected from moisture accumulation. For this purpose, on the walls inside the house, on the ceiling or floor, on inside roofing pie install material that does not allow evaporation to pass through. Or a diffusion membrane for facade insulation.
On preparatory stage you should choose a vapor barrier option taking into account the installation features and requirements for the characteristics of the film. Popular options include “” (and its analogue “Megaizol”) - a membrane material with high performance parameters. The manufacturer offers a line of membranes with various technical indicators, which allows you to choose a material depending on its purpose - vapor barrier for the roof, floors, wall structures made of wood or concrete.
Those who plan to build a bathhouse, not without reason, believe that foil film will reliably protect the mineral wool insulation from getting wet and help maintain high temperature indoors due to the reflection of thermal radiation. Along with the classic “insulation + vapor barrier” scheme, today ready-made non-combustible heat-insulating mats with a foil-coated vapor-proof surface are used.
Correctly attaching reflective vapor barrier Before laying a vapor barrier, it is necessary to properly prepare the surfaces of the structures. The preparation technology depends on the material from which the walls, floor, ceiling or roof are made. It also takes into account what kind of work is being carried out at the site - construction or repair:
- When building a wooden house, all wooden structural elements must be treated with compounds against rotting, pest damage and fire.
- During repair work First, dismantle the finish, clean the surfaces, and:
- wooden structures are treated with an antiseptic and fire retardant.
- Concrete and block structures are treated with an antiseptic if they are damp and there is a risk of mold, as well as in wet rooms.
Due to improper preparation of structures, walls, ceilings or rafter systems can become unusable over time or become a source of fungal spores that can trigger allergies, asthma attacks, and exacerbation of respiratory diseases.
How to install a vapor barrier on a ceiling
Installation of a vapor barrier layer on the ceiling is required when insulating flat or pitched roof in a house without an attic, with thermal insulation of the basement, as well as residential premises above which is located cold attic. The ceiling in the bathhouse is also insulated and vapor-insulated. Before installing a vapor barrier on a roof made of concrete slab, on reinforced concrete or wooden floor from the inside, the surface of the structure should be prepared.
The fabric made of film or pseudo-diffusion membrane must be solid so that there are no joints through which moisture can penetrate into the insulation. If width roll material not enough, the strips will have to be joined together. The recommended overlap of the canvases is from 10 to 20 cm, while the joints on both sides are carefully taped with reinforced construction tape.
Fastening vapor barrier membrane Canvases made of foil film are laid without overlap - end-to-end, and the seam is taped with aluminum tape.
If the roof base or ceiling is wooden structure, first you need to put a waterproofing membrane (solid sheet) and attach it to the base (you can use vapor barrier material).
Then, in the spaces between the floor joists or rafters, a heat insulator is placed in the form of mats or rolled material made of mineral (basalt) wool. After this, you can lay a vapor barrier on the ceiling. If the thickness of the heat insulator corresponds to the thickness of the logs, you should nail a counter-lattice made of slats to create a ventilation gap.
The vapor barrier should be placed on the ceiling in such a way that the fabric extends along the entire perimeter of the walls and that all corners are closed. The joints of the canvases should be on the floor joists - this will allow them to be securely fixed. To properly install a vapor barrier on the ceiling, monitor the tension of the canvas, it should not sag.
Ceiling installation We will also consider how to lay a vapor barrier on concrete floor. To insulate a ceiling from the inside or flat roof, made of a concrete slab, it is necessary to attach a waterproofing coating (vapor barrier film) to it using self-adhesive tape, and then install a sheathing made of bars or metal profiles.
The correct height of the sheathing should be selected taking into account the thickness of the insulation and the ventilation gap, the installation step should be 1-2 cm less than the width of the insulation, so that the mats made of insulating materials fit into the cells at odds. How to attach a vapor barrier to the sheathing will be described in detail below.
How to lay a vapor barrier on the floor
Installation of a vapor barrier membrane on the floor is similar in technology to how vapor barriers are installed for walls and ceilings. After preparing the base of a wooden floor when insulating along the joists, before laying the vapor barrier on the floor, a waterproofing carpet is installed, which should go around the joists. Then a heat insulator made of mineral wool. After which the vapor barrier is laid, it is important to know how to lay the film correctly.
The overlap of the sheets of rolled material should be at least 10 cm, with the joint taped on each side. The resulting canvas is secured in such a way that the overlaps lie on the floor joists, and along the entire perimeter the evenly stretched canvas extends 5-10 cm onto the walls.
Insulated floor with air gap Before laying a vapor barrier on a concrete floor, it is necessary to install a sheathing, between the elements of which the waterproofing and insulation will be placed. Further work is carried out according to the standard scheme.
Fastening principles
If they are insulated concrete structures or wooden walls, it is necessary to install a sheathing of bars. To the resulting sheathing, to the ceiling or rafter system It is convenient to attach the film using staples and a construction stapler. You can also secure the vapor barrier material with nails with wide heads or pads under the heads. It is advisable to use galvanized nails - they do not rust. Films and membranes are placed on concrete structures using a special connecting tape.
Overlap when installing vapor barrier In order to properly fasten the vapor barrier, the canvas should be carefully pulled, and the fasteners should be placed in small increments - no more than 30 cm. Installation rules require careful attention to the fastening of the canvas around the perimeter - it is spread and fixed so as to exclude the possibility of moisture penetrating into the insulation.
Before attaching the vapor barrier, make sure that the sheet is positioned with the correct side to the thermal insulation.
Which side to install the vapor barrier material
Let's consider which side of the film or membrane is laid to the insulation:
- polyethylene film (simple or reinforced) can be attached to either side - this does not affect the functionality of the barrier;
- the foil film is placed with the shiny side facing the room so that the barrier reflects heat;
- the anti-condensation film is attached with the treated side to the structures, the fabric side to the room;
- the membrane should be facing the smooth side thermal insulation material, and rough towards the room.
Rule for laying vapor barrier to insulation If the front side of the membrane looks similar to the back side, and it is difficult to determine how to properly lay the material, you can conduct an experiment. Cover the bowl of boiling water with a small piece of membrane - whichever side the condensation appears on is the side that is waterproof; it should be facing the insulation.
It is important to know which side to lay the vapor barrier against the insulation if the membrane is used to install a waterproofing barrier - front or back. Thermal insulation “pie” with internal insulation it is mounted in such a way that the smooth side of the membrane faces the insulation on both sides. That is, the rough layer of vapor barrier should be facing towards the room, and when installing a waterproofing carpet - towards the structure that is being insulated.
Installation features
It is important not only to install the vapor barrier correctly, but also to provide a ventilation gap between the vapor barrier layer and the cladding of the structure underneath. finishing, for which counter battens are placed along the sheathing. Moisture settling on the rough side of the laid vapor barrier sheets will evaporate naturally without damaging the finish.
Scheme of an insulated roof with ventilation gap If the vapor barrier is installed correctly, the insulation is reliably protected from moisture. Almost half of the problems associated with freezing and damage to structures are associated with defects in the installation of the vapor barrier.
