Wall vapor barrier

Beyond simply choosing the right heating system, there are many other factors to take into account in order to maintain comfortable and energy-efficient homes. Insulation is an important factor that contributes to both lowering energy costs and preserving a comfortable indoor environment. But in the world of insulation, there’s one element in particular that frequently goes overlooked but is vital to maintaining its efficacy: the wall vapor barrier.

Imagine that you have spent time and money insulating the walls of your house to keep heat from escaping during the summer and entering during the winter. All of that work, though, might be jeopardized in the absence of a suitable vapor barrier. Now, describe a vapor barrier in detail. In essence, it’s an additional layer of material—typically composed of foil or plastic—installed on the wall’s warm side insulation. Its main purpose is to keep moisture out of the walls, which can cause problems like rotting wood, the growth of mold, and reduced insulation efficiency.

It is crucial to comprehend the behavior of moisture in our homes in order to appreciate the significance of a vapor barrier. Warm air within the home carries moisture vapor in the winter. This heated, humid air has the ability to condense into liquid water when it comes into contact with any of the walls’ cooler surfaces, including the insulation or the wall itself. In the absence of a vapor barrier to prevent it, the moisture may seep into the insulation and cause a variety of issues in the future.

What occurs, then, if moisture seeps into the walls? It’s not very pretty, though. Because they grow best in damp conditions, mold and mildew can seriously endanger the health of residents and harm the structure of the house. Moisture can also weaken the insulation material itself, which will eventually reduce its effectiveness and raise your energy costs because your heating and cooling systems will have to work harder to make up for it.

Applying a layer of plastic and calling it a day is not the only step in installing a wall vapor barrier. It necessitates giving careful thought to elements like local building codes, building materials, and climate. For example, to stop warm indoor air from condensing within the walls in colder climates, a vapor barrier is usually installed on the interior side of the insulation. To stop moisture from entering the walls from the outside, the barrier might, however, be positioned on the outside in warmer climates.

Vapor barrier for walls

We have previously discussed various materials used as roof vapor barriers. We’ll explain which vapor barrier wall is better for use outdoors and which is better for use indoors today. Also consider the methods of application of roll and liquid materials made of bitumen. A range of materials can be used to provide vapor barrier, not just the well-known polypropylene films that are sometimes mistaken for diffusion (or waterproofing) membranes. These are two entirely distinct materials with essentially different modes of operation.

Why do you need a vapor barrier for walls

Vapor barrier for walls is installed within the wall.

The primary purpose of the wall vapor barrier inside the room is to shield the insulation from moisture, which this material cannot withstand in any way. There are, however, some exceptions, such as when the building envelope’s foundation material needs to be protected. We are referring to a sauna room made of concrete, brick, or wood. Moisture has the potential to harm all of these materials:

  • wood – mold and rot;
  • Bricks and concrete – lose their rigidity and crumble.

Why is a vapor barrier necessary when insulating walls? Certain insulators lose their capacity to stop heat loss when moisture penetrates their structure. They also have a propensity to absorb moisture like a sponge.

Materials that, even when damp, retain heat in the space and are not highly absorbent are still protected by a vapor barrier.

First, the material’s ability to retain heat insulation is limited by its moisture content, which rises with increased moisture content. That is, there will eventually come a time when the insulation will no longer function.

Second, the moist material will undoubtedly become home to a harmful microflora in the form of fungus. A layer of mold will grow on the insulation, extending beyond the boundaries of the thermal insulation pie. The fungus is very hard to get rid of, and its spores are dangerous to people. Only if one of the following materials—which don’t absorb moisture—is utilized as insulation does vapor barrier become unnecessary:

When regular foam plastic is exposed to moisture for an extended period of time, it crumbles. Without an additional vapor barrier, the foam plastic displays itself flawlessly when the indoor air humidity is within normal bounds.

A certificate of temperature measurement in the apartment is required if the house is cold and you wish to achieve a recalculation of kommunalka (sample form attached).

Humidity increases lead to the growth of mold. Here are some instructions on lowering the room’s humidity.

Types, manufacturers, characteristics

Isospan: excellent quality at a fair cost.

In order to choose the right vapor barrier for walls, you must first ascertain the extent of its application. For various operating conditions, different materials are used:

  • for the walls of the basement, foundation or swimming pool – bitumen (liquid or in rolls), liquid rubber;
  • for wooden and masonry above-ground walls for internal insulation – polypropylene films, foil insulator.

Both domestic and international manufacturers produce the polypropylene used to make vapor barrier walls. The most well-known brands are Izovek, Utafol, Spanlite, Technohaut, and Izospan. It should be recognized that the film does not provide 100% protection. For instance, Izospan has a vapor permeability of 7 mg/m*h*Pa, which is not a significant amount but still evident. The most popular brands of foil insulators are Tepofol, Isover, and Penofol.

Every polypropylene film has fiberglass reinforcement. There are two ways to reinforce something:

  • The grid is pressed into the still unstiffened polypropylene;
  • fiberglass fabric is laminated with polymer on both sides.

It is possible to produce a stronger material using the second method. The tensile strength of all vapor barrier types for walls must meet strict specifications. Polyethylene foam backing is optional for foil insulation. preferred substance on a polyethylene foam damping cushion with a closed cell structure.

Although there are numerous ways to measure the air humidity in an apartment, a hygrometer will provide the most accurate reading.

Everything you need to know about panel house end wall insulation can be found here.

Arrangement of vapor barrier walls on the exterior and interior side

Let’s first discuss how to apply vapor barriers to walls, from the inside or the outside. It goes without saying that film is also installed inside in frame homes and other situations where the walls are insulated from the interior. Read "Self-insulation of the frame house’s walls" as well. In the case of the basement or foundation, external vapor barriers are required for the walls. Pools are unique because their walls are better shielded from the outside and inside using the same technique as a basement floor.

The insulation is placed on top of the basement floor’s vapor barrier, which is installed from the exterior.

In order to address the techniques for correctly installing a vapor barrier on walls, let’s begin with a more basic one: coating concrete structures submerged in the ground with a protective layer. The work surface is first given a thorough external cleaning. In the event that liquid rubber is your choice, professional assistance is required. The intricacy of creating liquid rubber for vapor barrier walls lies in the requirement for specialized tools.

The material is composed of two components that are mixed in a split second before coming into contact with the treated surface because mixing causes nearly instantaneous polymerization. Only a twin-flare cannon, which sprays liquids under pressure, makes this feasible.

The way the bituminous materials are arranged in the basement walls’ vapor barrier:

  • the wall is lubricated with mastic – this is an adhesion layer (roughly speaking, primer);
  • then glued or patched bituminous roll materials in two layers, the joints should not coincide.

Every task can be completed on your own. It is possible to apply bituminous mastic to the work surface in multiple layers without using any roll materials at all. Modern materials have replaced the antiquated practice of using resin and roofing felt.

Plan for frame houses’ vapor barrier walls.

Work is only done from the inside of above-ground structures because they are shielded from the moisture in the center of the space. The vapor barrier is not used when installing an external insulation or ventilated facade using the wet facade method.

How to properly install a vapor barrier inside walls:

  • In any case, a batten is required;
  • between the purlins you can lay insulation;
  • film or foamed polystyrene is attached to the purlins – if reflective insulation is used, the shiny side should look inward;
  • The joints must be glued – everything must be airtight;
  • need a counter-batten – for polypropylene films is desirable, for foam foams – necessarily;
  • Finish is attached to the counter battens.

When installing a vapor barrier, an extra air gap is never unnecessary, but its absence can lead to a lot of problems, particularly in a restroom. If there is no gap, moisture that condenses on the vapor barrier will be absorbed into the trim. This significantly shortens the latter’s service life.

Here is a quick rundown of how to attach the vapor barrier to the wall:

  • for the basement floor – bituminous materials or liquid rubber are applied on the outside;
  • for ground constructions – foils or foam foil are laid on the inside of the battens. The shiny side (if there is one) looks inward, there should be a gap between the vapor barrier and the finish;
  • double (outside and inside) protection with liquid materials is preferable for a swimming pool.

The primary goal is to protect construction materials and insulation by forming a monolithic layer that prevents moisture from passing through in either direction.

How to choose and install a vapor barrier on the room’s walls correctly. Prior to fixing, it’s important to ascertain the various uses for which various film kinds are required.

In the world of home heating and insulation, the wall vapor barrier plays a crucial role in maintaining a comfortable and healthy indoor environment. Acting as a shield between the interior and exterior walls, this barrier helps to prevent moisture from penetrating into the structure of your home. By blocking moisture, it not only safeguards against potential damage to the walls but also helps to prevent the growth of mold and mildew, which can pose serious health risks. Proper installation of a vapor barrier can also contribute to improved energy efficiency by reducing heat loss and preventing drafts. However, it"s essential to strike a balance, as improper installation or use of the wrong type of barrier can trap moisture inside the walls, leading to problems like rot and decay. Understanding the importance of a wall vapor barrier and ensuring its correct installation can significantly enhance the effectiveness of your home"s insulation and heating systems, ultimately creating a more comfortable and durable living space for you and your family.

Vapor barrier walls with their own hands

A high-quality vapor barrier for the walls should be installed with special attention during the building process because moisture can lead to the growth of mold and fungus, which can ultimately destroy the building.

Wetness may arise from condensation at the heat-cold interface or from a breach in wall insulation technology. For this reason, adequate ventilation is required to remove moisture from the air. Sadly, this approach is illogical in the winter because the room will be excessively cold (though brick and wood houses may be an exception). In every other situation, a vapor barrier is necessary.

Why do you need a vapor barrier for walls?

Breathable wall insulation materials have the potential to create a moisture condenser effect. Insulation materials absorb moisture, becoming soaked and losing more of their properties as a result. In these areas, plaster cracks, wallpaper starts to peel, and mold starts to grow.

Quality vapor barriers must also be provided by ventilated facades and multilayer walls. A year-round ventilation system is also something that should be planned ahead of time as it is necessary to establish the ideal microclimate in the space.

A substance that can allow moisture to remain on the exterior while still allowing air to pass through all of it is used in the vapor barrier process (thanks to microscopic pores). This vapor barrier system helps to totally remove any moisture from the space when combined with a high-quality ventilation system.

Materials for vapor barrier

There are various categories of vapor barrier materials:

  • Polyethylene film, the thickness of which is 0.1 millimeters. One of the most budget-friendly means of vapor barrier, not without its disadvantages. As a result of the use of this material, the advancement of air is reduced to nothing, because of which the walls cease to "breathe". Some people advise to perforate the film, which is fundamentally wrong, because in such cases it completely ceases to fulfill its function;

  • special parisoling mastics. The material, which is applied before the final finishing, perfectly allows air to pass through, but at the same time does not allow steam to penetrate inside;
  • membrane film – one of the latest solutions in construction, fully coping with its task. Air passes through in the right volume, vapor is not allowed, thanks to which the insulation is fully protected.
  • Vapor barrier for the walls of a frame house

    Approximately 75% of the walls in a frame house are made up of insulation, which highlights the importance of ensuring high-quality vapor barrier housing of this kind. In addition to negating the benefits of insulation entirely, a weak vapor barrier may eventually lead to the collapse of the building.

    A frame house’s wall pie should consist of:

    • exterior cladding of the house;
    • waterproofing and windproofing;
    • layer of insulation with a width of about 150 millimeters, which is placed between the frame posts;
    • framework;
    • vapor barrier membrane;
    • interior finishing.

    Vapor barrier layers should be firmly attached to the frame risers and strapping using a construction stapler. After that, tape needs to be used to completely seal the joints.

    It is advised to adhere to the following guidelines when repairing the vapor barrier film to maximize its effectiveness:

    • To ensure quality ventilation of the walls and optimal microclimate, the membrane is installed only on the inner side of the thermal insulation layer;
    • vapor barrier should not be attached on both sides, as the outer layer acts as a protection against moisture, but not from steam. In turn, the vapor barrier and the inner side of the moisture barrier film should allow air to pass through, thereby providing ventilation, drying and airing of the insulation layer.

    Vapor barrier of the walls of a wooden house

    The building material that is most negatively impacted by moisture is wood. The only exceptions are when homes are built using cylinder or glued beams. This kind of bar already goes through all the necessary steps at the manufacturing location (it is dried and shaped into a distinct, geometric shape), which gives it a high level of tightness and creates a natural moisture barrier.

    The wood used to build houses typically takes a very long time to dry. The most obvious deformations to the wood occur during the period of complete drying, which can last up to five years, particularly in the first year. Among them are:

    • gradual shrinkage of the walls;
    • Cracks appearing in the walls;
    • changing the size of the logs;
    • gradual change in the shape of the logs.

    Defects of all kinds always develop in tandem with this natural process. Installing a thermal insulation system—which comes in internal and external varieties—can address this issue.

    Vapor barrier on the wall: instructions

    Vapor barrier insulating a wooden house’s walls from the exterior

    The wall pie construction for exterior thermal insulation of a wooden house is as follows:

    • to start with, a vapor barrier layer is laid on the log, which must be placed overlapping, with edges overlapping each other by about 2 centimeters. Joints should be carefully sealed with self-adhesive tape, and the foil should be sealed with metal tape;
    • then the frame is laid, which is traditionally made of timber. On this layer the insulation is fixed, which is carefully protected with waterproofing material;
    • Finally, the final finishing must be carried out.

    There are various ways to attach a vapor barrier, depending on the kind of log being used.

    • if a round log is used, the vapor barrier layer is fixed on the tree itself with a simple construction stapler. Ventilation gaps are not required in such cases;
    • In turn, ventilation gaps are needed in those situations, if rectangular and square logs are used. To do this, the laths, the width of which is about 2.5 centimeters, and the step between them – about 1 meter, should be piled on the wood. After that, the vapor barrier layer is laid and fixed.

    Interior walls of a wooden house acting as vapor barriers

    The following steps will be taken in order to complete the internal insulation of the house’s walls:

    • to ensure quality ventilation will require a purlin, the width of which is up to 5 centimeters;
    • a layer of waterproofing film is attached to the purlins. The gap formed between the film and the wall will provide quality ventilation;
    • on the waterproofing film attached metal profiles, on which then laid a layer of insulation;
    • Then comes the turn of the vapor barrier film, which must be attached in overlap. After that, it is required to carefully seal the joints;
    • The final finishing is carried out at the end.

    A vapor barrier is a must for a wooden house because the material is highly permeable to moisture. All that needs to be done to extend the walls’ and the building’s service life is to incorporate a vapor barrier layer into the wall structure.

    Features of vapor barrier walls of a wooden house

    • Wooden houses are exposed to the negative effects of vapor and condensation much more than houses made of other building materials (e.g., brick);
    • as mentioned above, the walls of the house, the construction of which used logs, begin to shrink during the first five years of operation. As the timbers change size, the grooves begin to deteriorate. As a result of the fact that it is problematic to get to the grooves, the possibility of carrying out the interior finishing of the house is lost. In this case, it is necessary either to carry out vapor barrier elements of the structure of the building in advance, or wait for its final shrinkage;
    • The vapor barrier material should have the same contour as the floor of the basement and attic;

    Vapor barrier walls ought to be a required step in the building process, regardless of the purpose or type of structure being constructed. If this step is neglected, issues like mold and fungus may arise, which could eventually cause the house to collapse.

    Walls of vapor barriers using their own hands Quality vapor barrier walls should be installed with particular attention during home construction because the moisture can lead to the growth of mold and

    Vapor barrier walls of a brick house

    A vapor barrier is an essential component of any brick home’s construction that shields the insulation and walls from the damaging effects of moisture. With this type of insulation, you can prevent the growth of numerous minor issues like mold, fungus, and other issues. It is important to note that no extra effort is needed when laying the corresponding materials. The primary focus is on properly prepping the house’s walls. The decision of which building materials to use for the project will also need to be made in conjunction with this.

    Vapor barrier elements are typically rolled from bottom to top rather than just bolted to a horizontal surface. Material sheets are arranged horizontally rather than vertically. The galvanizing and wooden strips are used to help fasten them.

    Instead of introducing

    These are the vapor barrier materials that are currently available for insulating brick homes’ walls:

    • – ordinary polyethylene film;
    • – Pergamin, tol and other vapor barrier materials based on bitumen;
    • – aluminum foil;
    • – liquid rubber;
    • – Isospan, megaisol and others;
    • – polyurethane foam.

    The traditional polyethylene film is still used as the vapor barrier. Because the material is prone to damage when laid, there are specific requirements for its use. Recall that in order for this element to hold together with the steam and air, its base must be perforated. In this case, it probably won’t be able to create the ideal microclimate from within the room.

    Perforating the vapor barrier membrane on its own is permitted. You will need a special roller for these purposes, with hammered nails or sharp spikes on the working surface.

    The membrane insulation material differs from regular film in that it is composed of multiple layers, each of which serves a distinct purpose.

    Using a construction stapler or hand-applied galvanized nails, insulation is secured. It is advised that the bottom edge of the vapor barrier be placed below the base line of the previously drawn markings to stop moisture from penetrating into the walls and into the interior of the house. Material sheets must always be placed overlapping, with at least a 50 mm overlap from the previous layer. Experts also use vapor barrier tape or specific water-repellent adhesive tape to seal them. There should be no gaps and all seams securely glued.

    It should not be assumed that the insulation and house walls provide complete prevention of vapor intrusion. The most common components are membranes, which can still allow some air to pass through. Should this not happen, a greenhouse effect will arise from within the space, with far more dire consequences than just the insulation and house’s brick walls getting wet. Moisture no longer affects the main components from the inside because it is qualitatively isolated from the air flows that pass by. The moisture flow via the exhaust ventilation is ensured when a specific type of thermal insulation with an internal "fur coat" is used.

    Experts as components of the vapor barrier are increasingly selecting the standard mastic. Once it has cured and taken on its functional properties, it can perfectly hold onto moisture while letting enough air flow through in large enough quantities. Typically, a home’s brick walls are treated prior to the structure’s ultimate completion.

    "Brane D Super" multilayer vapor barrier for anticondensate;

    Α. Ventilation-hydroinsulation reinforced Izospan RS;

    Izospan FX reflective thermal-hydro-vapor insulation;

    Γ. Tyvek Solid is a high vapor permeability single-layer waterproof material.

    Features of vapor barrier walls of brick from the inside

    Expensive elite brick baths require vapor barriers that are of a high caliber and are challenging to install. These kinds of buildings have an extremely intricate vapor barrier. Furthermore, modern large houses with multiple walls-partitions dividing the space into multiple zones may require a vapor barrier. Typically, sound-absorbing materials that are sensitive to moisture, like fiberglass or mineral wool, are used to treat them. The aforementioned elements will quickly lose their advantageous characteristics and form if this is not stopped. This is the reason that a vapor barrier is also placed on top. Common wooden laths that have been treated with an antiseptic substance can be used to install it.

    Treatment for partition walls is always bidirectional. There should be at least 30mm of overlap between the joints. The fact that they shouldn’t line up on either side and shouldn’t be more than 500 mm apart is another crucial detail. Using foil with another layer of foil is the best solution. It is best to face the shiny side outward.

    When siding is added to the house’s brick walls, the vapor barrier needs to be considered from the beginning of construction. And foil foil will be a great option in this situation. A wooden frame is covered in insulation, and the joints are sealed with tape that can withstand moisture.

    How the vapor barrier is carried out brick walls of the house?

    There are various methods for vapor barrier, and each has advantages, features, and particulars of its own.

    With diffusion membranes that are no thicker than 1 mm and polyethylene films, protecting walls from the inside can be accomplished fairly easily. Therefore, it makes sense to reduce the amount of steam that enters the insulation from the space. Furthermore, there will be an increase in thermal resistance, adding to the construction’s durability. Remember that the interior vapor barrier surfaces of the brick house’s walls should form a single contour, accounting for the attic and basement spaces as well.

    It is common practice to use specialized foil-based material with heat-reflecting qualities. It is simple to attach to any surface using adhesive or hardware. Verify that the reflective side is in the proper position. Its orientation ought to be inside the rooms.

    The first step is to identify the working area. Determine the surface area that will be covered by the vapor barrier and multiply the result by 0.1-0.15 (adding 10-15% of the total area is required). For the purposes of illustration, we’ll assume that mineral wool will be used to insulate the building from heat. Mineral wool needs to be shielded from steam on the inside of the room and from condensation on the wall side.

    Our experts advise selecting one of the composite foil reflective materials, such as alufom, penotherm, or penofol, to act as a vapor barrier.

    Prepare the surface for applying the vapor barrier after choosing the material. The insulator can be easily damaged by sharp protrusions, so it is important to carefully inspect the wall’s surface because these materials are incredibly weak. Eliminate everything that could lessen insulation’s effectiveness and make sure it’s dust- and dirt-free.

    Next, secure the waterproofing to the thermal insulation’s cold side. We will assume that the brick wall was protected from moisture using an expensive and high-quality injection technique of microcement, acrylate, or methacrylate gels since the topic of this article is not waterproofing.

    After that, mineral wool boards are positioned between the laths to serve as insulation.

    The vapor barrier will then be installed over the insulation and fastened with battens. In order to create a vapor barrier, the canvases should fit together tightly and the joints should be sealed with metallized adhesive tape.

    By the end of the day, for instance, if you were working on building a bathhouse, wagoning.

    When it is impossible to do without vapor barrier brick walls of the house from the inside?

    In the following circumstances, protecting surfaces is crucial:

    • 1. Internal insulation has been applied to the walls. Most often it is minwool, as it provides a breathable effect. A significant disadvantage of this method is the high hygroscopicity of the material, which leads to its destruction. The only solution is to lay a vapor barrier.
    • 2. When it is necessary to maintain the desired microclimate in the space. Additional wall protection will help create a reliable, effective and efficient barrier to moisture and the necessary ventilation.
    • 3. When a strong wind barrier is required, especially in buildings with a ventilated facade. As a result, it is realistic to reduce the load on the main insulation and provide a "breathable effect". It is worth remembering to make a ventilation gap, through which excess moisture will be removed.


    To sum up, we will state that every vapor barrier device needs to be able to seal the joints between insulation materials in a dependable and efficient manner. The primary goal of utilizing the right parts is to shield the insulation from moisture’s effects, as moisture is naturally eliminated in a very slow and ineffective manner. If you ignore this issue, your home’s interior brick walls’ thermal protection will eventually deteriorate and lose its beneficial properties. This could take several years.

    A brick home’s vapor barrier will prolong the insulation’s useful life, preserve the ideal microclimate within the space, and save money.

    Advantages 1. Prevents moisture from entering walls and causing damage. 2. Helps regulate indoor humidity levels. 3. Improves overall energy efficiency of the home.
    Disadvantages 1. Improper installation can lead to trapped moisture and mold growth. 2. Can be punctured or damaged during construction, compromising effectiveness. 3. May require professional installation for best results.

    One essential step to guaranteeing your home’s longevity and energy efficiency is installing a vapor barrier on your walls. A vapor barrier helps guard against mold, mildew, and structural damage from water infiltration by keeping moisture from penetrating into your walls. This protects your investment in your property and enhances the quality of the air indoors.

    To maximize its effectiveness, the vapor barrier must be installed correctly. Careful consideration of elements like local building codes, building materials, and climate is necessary for proper installation. To guarantee that the vapor barrier is installed precisely and effectively, seeking advice from an expert or adhering to manufacturer instructions is recommended.

    Even though vapor barriers have many advantages, it’s important to understand that they are only one part of a complete insulation strategy. A vapor barrier can be used in conjunction with sufficient ventilation, air sealing, insulation, and other building materials to further improve your home’s energy efficiency and comfort. Regular monitoring and maintenance are also necessary to guarantee long-term performance and quickly address any problems.

    In summary, a vapor barrier is essential for both enhancing energy efficiency and shielding your house from moisture-related damage. Homeowners can improve their living environment and raise the value of their property at the same time by realizing the importance of it and making sure it is installed correctly. Long-term advantages for your house and your finances can be achieved by making an investment in high-quality materials and expert advice.

    Video on the topic

    Building a frame house correctly #1. How to install vapor barrier alone?

    Insulation of frame walls, taping of vapor barrier. Some useful installation tips.

    Fixing the vapor barrier to the wall | Securely fixing the vapor barrier

    How to protect the house from wind and moisture? / Vapor barrier of a frame house: construction technology


    Vapor barrier for the walls of a frame house in Finland .


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    Sergey Ivanov

    I like to help people create comfort and comfort in their homes. I share my experience and knowledge in articles so that you can make the right choice of a heating and insulation system for your home.

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