Even if it seems that the air inside the house is very dry, and even humidifiers are specially purchased, it still contains a large amount of moisture vapor. Before the advent of energy-saving materials in construction, no one paid attention to this. Modern thermal insulation materials based on mineral wool were ineffective and lost most of their heat-retaining qualities due to gradual wetting. Therefore, special films have appeared on the market, some of which are mounted only outside and are wind- and moisture-proof, and the second are located from the inside, from the side of the room and prevent the penetration of steam. The article will focus on the correct vapor barrier at home..
A house without the use of vapor barrier can be in the event that it is insulated with foam, foam, or does not have an insulating layer at all, for example, a foam block and a brick.
- But to save on heating and to improve the heat-preserving characteristics of houses in modern construction, natural insulation made of cellulose (ecowool) or basalt wool is almost always used. But here we must remember about the constant moisture exchange that occurs in the living space..
- So, if the house is too humid, then water vapor will inevitably be absorbed by the walls and ceiling, and, conversely, with excessively dry air, this moisture will return to the rooms. From which it follows that if the insulation in the wall is not protected by a vapor barrier film, then moisture will accumulate in it, filling all the air cavities between the fibers of the mineral wool, thereby depriving it of all its thermal insulation characteristics.
Advice: the exception is the internal partitions in the house. One of the most important factors in which mineral-based insulation absorbs steam is the temperature difference that occurs at the outer walls. In this case, condensation accumulates inside, which is most dangerous for the material. But in the interior partitions there is no such effect, so they are not covered with a vapor barrier material..
- When the walls bordering the street are insulated with mineral wool from the outside;
- if the “cake” of the wall consists of several layers, one of which is a wadded insulation. In this case, the vapor barrier film is mounted from the inside. The most striking example of such a device is frame houses;
- when arranging ventilated facades. Mineral insulation should be closed from the outside with a waterproof film, and from the inside with a vapor barrier. The first will protect the thermal insulation from water and air currents, and the second from the side of the interior from steam. A good example is a wooden house sheathed with siding or wooden clapboard..
Vapor barrier films are produced in several types and, according to their purpose, are divided into wall and roofing films:
- roof vapor barrier. It is attached from the side of the living area, protecting the thermal insulation from rising vapors. This is an important stage, since moisture evaporation rises up with warm air and can get into the insulation. It threatens not only with heat loss, but also the formation of mold and mildew. It is needed only when arranging an exploited and heated attic. If the attic is cold, then the vapor barrier is not done, being limited to a windproof membrane under the roofing material itself, which protects it from condensation;
- vapor barrier of house walls. It should be carried out with special materials that, on the one hand, should not allow steam to pass to the insulation, and on the other hand, they should be freely taken out if moisture somehow got inside. This happens due to possible cracks or incorrectly made joints of rolled materials. It is better to choose special diffusion materials, instead of the usual plastic films or glassine;
- interfloor vapor barrier. It must also be done without fail, since condensation from rising vapors can accumulate $
- floor vapor barrier. It is necessary in rooms with high humidity or in houses where the floor is insulated with mineral wool. In this case, a waterproofing film is placed on the bottom side, and a vapor barrier is laid on top. They also equip a vapor barrier when concrete floor slabs are located directly above the ground.
If the question is whether a vapor barrier is needed in a wooden house, then it is necessary to rely again on the presence of insulation. If it is not there, and the wall of the house consists entirely of a bar or log, then it makes no sense to mount a vapor barrier film.
Until recently, glassine was the only vapor barrier material used in Russia. But with the development of technology, they gradually began to push off from him, preferring more durable and high-quality materials..
- Polyethylene films. They are best used to seal the ceiling in a living space. Most often, interfloor floors are insulated with mineral wool, since it has the best soundproofing properties. The polyethylene film will reliably protect it from the ingress of even a small amount of moisture. On sale you can find common materials, reinforced or with a foil layer.
- Polypropylene films. Best used for ceiling insulation in a residential attic. They are distinguished by increased resistance to mechanical damage and resistance to UV radiation. When arranging it, you can safely repair the roof without fear that moisture will seep inside the house..
- Membrane. This popular and frequently used type of vapor barrier is produced as a single or multi-layer roll material. These nonwoven materials can be one-sided or two-sided, their location and functional features will depend on this. The use of inexpensive double-sided non-woven membranes is considered optimal..
- Breathable films or breathable membranes. They completely exclude the possibility of water vapor penetration inside to the thermal insulation, but at the same time do not at all prevent their exit from the inside. They allow you to save on living space, since for their operation it is not required to equip the ventilation gap.
- Ordinary vapor barrier film. Its function is to create a vapor barrier from the inside of the walls and roof. It protects the heat-insulating material from the ingress of steam from the inside of the heated room..
- Reflex coated vapor barrier membrane. Capable of partially reflecting heat back into the room. This contributes to an increase in the thermal protection of the room and the roof up to 10%. Compared to standard counterparts, they have great vapor barrier characteristics, so it is advisable to use them in rooms with high humidity..
- Vapor barrier membrane with limited permeability. They have diffusional properties that allow steam to be removed from rooms that are used irregularly. For example, it can be a garden house that is actively used in summer, but can be heated only a few times in winter..
- Vapor barrier with variable vapor barrier properties. Ideal for renovation work as they can be mounted from the outside without removing the inner cladding.
This renowned company guarantees that its vapor barrier films will last for decades. There are 3 main types of these products on sale:
- vapor barrier film TechnoNicol. Used for interior work. A fairly versatile material that is suitable for insulating walls, ceilings and pitched roofs in the attic. The price of a roll is 1500 rubles;
- diffusion membrane films TechnoNicol, designed to isolate the under-roof insulation from the formation of condensation in it. It is a non-woven polymeric fabric and protection of both sides from polypropylene fabrics. Unlike conventional vapor barrier materials, this is a breathable film. The cost for a standard roll is about 3200 rubles;
- non-perforated vapor barrier film TechnoNicol. Narrowly targeted material for roof vapor barrier. Protects from both water and dust. For the greatest strength it has a reinforcement with a special mesh fabric. The approximate cost is 1200-1500 rubles / roll.
This is the rare case when a domestic company presents world-class high quality material at an affordable price..
- Izospan S. This is a two-layer film that protects the insulation from the inside of the room. It can also be used as a roofing film on non-insulated roofs. One side of it has a roughness, the role of which is to retain excess moisture and with its further evaporation. The second side is smooth, it is mounted on a heater.
- Izospan V. An analogue of the previous material, it is also chosen for the vapor barrier of the walls of a frame or wooden house from the inside.
- Izospan D. This is the most versatile vapor barrier film from the entire Izospan product line. It has an anti-condensation coating that can protect the mineral wool from both internal steam and external moisture and wind. Its strength is so high that it can be used as an independent roof covering for 3 months, even in winter. When installing it on the walls from the outside, it is allowed to postpone the arrangement of the finishing cladding for up to 6 months. Roll price 2500 rubles.
The technology of installing a vapor barrier implies its fastening from the inside of the house between the insulation and the crate, to which the facing material is mounted. If a modern membrane material is used, then it is placed with the smooth side close to the insulation. In this case, the vapor barrier will evenly distribute the streams of moist air, leading it to the ventilation system..
The method of fixing the vapor barrier depends on the purpose of the room in the house. In low-exploited or non-residential rooms, in which low humidity is allowed to use a one-sided method of arranging a ventilation gap. In all other cases, professionals advise to provide for bilateral ventilation, which is much more effective. Often, the manufacturer of the membrane on the packaging indicates the recommended installation method..
Stages of work
- If the house is not new, but repair work is being carried out, then first dismantle the entire cladding to the wooden frame of the wall. If possible, inspect insulation or wood for damage, if necessary, remove them.
- Walls and insulation must be thoroughly dried. It is advisable to carry out work in the warm season, since frost can form in winter, which, when closed with a vapor barrier, will eventually turn into a large amount of moisture.
- If the house is frame, then the membrane is rolled out along the length of the entire wall and cut off so that in the corners there is an overlap of 10-15 cm on the adjacent wall. Attach it in stages to each vertical board of the frame using a stapler. There should be no distortions, cracks or folds. Therefore, it is better to do the work together. The tension should be so strong that the insulation in the wall fits tightly without falling out of the wall.
- On top, again with an overlap, the next layer of vapor barrier is rolled out and attached in the same way. Then the joints are glued with tape. A frame made of strips is stuffed on top, which tightly presses the vapor barrier and at the same time serves as a frame for cladding. Represents a sosboy vertical slats, which are attached to self-tapping screws with a pitch of 60 cm (the distance corresponds to the width of the insulation and the frame of the walls of the house). In addition, the film is also fixed with strips around the perimeter of all door and window openings..
- If a vapor barrier is made of a house from a bar, then the frame is first stuffed to the walls under the insulation and it is tightly laid there. Further, all work is carried out in a similar way..
Most often it is done if the floor is made of wooden logs and insulated with mineral or basalt wool. To complete this work, two people will be required, it will be extremely difficult for one to do it..
- Before starting work, the ceiling must be disassembled and consist only of lags.
- Then, from below, that is, from the side of the living room, a vapor barrier is attached along the logs. This should be done along the longer side of the room to form as few joints as possible..
- The required length is measured and cut off on the floor and, with a prepared segment, is raised to the ceiling. Convenient when 2 masters are located on opposite sides of the room. This allows you to correctly position the vapor barrier and make sure that it does not warp during fastening..
- For the convenience of work, at first you can simply “grab” it in several places (but do it firmly). And after making sure of its correct location, already secure thoroughly.
- This is how the entire ceiling goes through, not forgetting about the overlaps and their gluing.
- From the bottom to the logs, it is attached with wooden slats, regardless of what the ceiling will be.
Advice: the work is quite painstaking and often happens when an accidental tear occurs in an already fixed area. In this case, a patch is cut out of the membrane with an allowance at the edges of 10-15 cm. It is inserted into the hole formed and glued along the edge with glue. This creates a fairly airtight layer. It is additionally glued on top with tape.
- After completing the fastening of the vapor barrier, from the side of the second floor, a heater is placed in the formed cells.
- Poor installation. At first glance, it seems that it is simply impossible to make a mistake when attaching a vapor barrier film. What could be easier than pulling it well, attaching it to the frame and gluing the joints. But it is precisely because of the apparent simplicity that some builders neglect accuracy during work. As a result, tears or folds are formed. But the worst mistake can be the wrong position of the membrane, or rather the wrong side, as a result of which it starts to work incorrectly. If all this was already covered with interior decoration, then the consequences of such work can be guessed only after a couple of seasons, when the thermal insulation layer starts to work worse..
- Installation of a vapor barrier film from the outside of the house. This gross mistake leads to the fact that steam, seeping from inside the house and passing through the insulation, rests against the vapor barrier and condenses on it. In a very short period, the insulation damp, without being able to ventilate. For external protection, it is necessary to use exclusively windproof films that are capable of letting excess moisture out..
- Lack of vapor barrier in a frame house. There are a number of materials that allow for the absence of a vapor barrier. It is polystyrene or extruded polystyrene foam. Most often it is made in houses from sandwich panels. But, in order to remove excess moisture from the house, in this case it is imperative to install a high-quality forced ventilation system. When insulating with ecowool or mineral wool, a vapor barrier must be present in all cases.
- Double vapor barrier. It happens when a vapor barrier layer is placed in rooms with high humidity, and a facing material with low vapor permeable properties, for example, plastic panels or tiles, is laid on top. It turns out that after passing through the grout seams or panel joints, steam enters between the vapor barrier and the tile, without the possibility of going outside. Therefore, for cladding in such rooms, it is recommended to make a crate on the wall that borders the street..
- Or simply abandon the vapor barrier in this place, but there will be a risk that, getting into the insulation, the steam will not have time to weather out through the windproof membrane from the outside. This is only valid for frame houses that are used as summer cottages..
Choosing a method for installing a vapor barrier. In total, there are 2 ways to use the vapor barrier. In the first case, the film is attached to the wall frame, and cladding material (drywall, lining, etc.) is mounted on top of the same load-bearing wall boards. In the second version, the film is similarly nailed to the wall frame, but under the wall cladding material, an additional frame is made of slats 2-3 cm thick.What is the more correct way to consider?
- The first option has the right to exist, but only if the materials of the highest quality are used for decoration. Otherwise, the repair will quickly become unusable, due to the lack of a ventilation gap. Or use this method when the building has an economic purpose and is not used all year round. But even here it is necessary to make ventilation wiring throughout the room..
- The second option with the arrangement of a ventilation fence is more acceptable for houses intended for permanent residence. This helps to eliminate the risk of excess moisture in the air..