Vapor barrier between floors in a wooden house

The need for vapor barrier when insulating mineral wool

The construction of a residential building or its renovation is a long-term work, the result of which must be quality. Vapor barrier is a film that, together with other structural objects, interacts to stop the formation of condensation. Usually people carry it out during major renovations. Hydro-vapor barrier helps to increase the service life because it prevents moisture from penetrating into the insulated layer.

In winter, vapor barrier is especially important, since the temperature indoors and outdoors is significantly different - this leads to the formation of steam in the house, which must leave the room without any obstacles. Basements, attics, first floors, and interfloor partitions most need vapor insulation.

The walls don’t really need it if they are insulated from the outside. A sign of this may be that the surface does not allow air to pass through:

surface covered with non-porous coating;
a thick, continuous layer of waterproofing is applied;
wall made of bricks.

There are other situations where a vapor barrier is not necessary. From all this we can summarize that walls, floors and ceilings insulated with mineral wool do not necessarily need protection from condensation. Vapor barrier is necessary only in cases where there is constant contact of warm air flow with the surface in the room.

Hydro-vapor barrier is one of the most important factors when insulating a residential building with mineral wool. This fence will help you overcome the dampening of walls, floors or ceilings by condensation (the transition of a substance from a gaseous to a liquid state) when warm air comes into contact with the surface.

One of the main advantages of vapor barrier of a room is that it can be done independently, without having any specific abilities and skills. But what is mineral wool? This article will discuss this material, intended for insulating a room, and the reason for the need for vapor barrier outside and inside the room.

Is a vapor barrier necessary when insulating with mineral wool?

The need for vapor barrier when insulating mineral wool

The construction of a residential building or its renovation is a long-term work, the result of which must be quality. Vapor barrier is a film that, together with other structural objects, interacts to stop the formation of condensation. Usually people carry it out during major renovations. Hydro-vapor barrier helps to increase the service life because it prevents moisture from penetrating into the insulated layer.

The walls don’t really need it if they are insulated from the outside. A sign of this may be that the surface does not allow air to pass through:

surface covered with non-porous coating;
a thick, continuous layer of waterproofing is applied;
wall made of bricks.

There are other situations where a vapor barrier is not necessary. From all this we can summarize that walls, floors and ceilings insulated with mineral wool do not necessarily need protection from condensation. Vapor barrier is necessary only in cases where there is constant contact of warm air flow with the surface in the room.

Hydro-vapor barrier is one of the most important factors when insulating a residential building with mineral wool. This fence will help you overcome the dampening of walls, floors or ceilings by condensation (the transition of a substance from a gaseous to a liquid state) when warm air comes into contact with the surface.

One of the main advantages of vapor barrier of a room is that it can be done independently, without having any specific abilities and skills. But what is mineral wool? This article will discuss this material, intended for insulating a room, and the reason for the need for vapor barrier outside and inside the room.

Mineral wool and its properties

The main indicator that shows the quality of insulation is the thermal conductivity coefficient of the material. Mineral wool is a fibrous insulating material. For such insulation, the thermal insulation qualities depend on the specific water content in the material (moisture content).

When any liquid gets in, mineral wool absorbs it, pushing out the air. As the amount of humidity increases, the thermal insulation properties of mineral wool decrease. The main disadvantage is that the liquid that gets inside is difficult to remove from the material. Mineral wool can absorb 2/3 of its entire weight in liquid, but its performance deteriorates.

Mineral wool and its properties

The main indicator that shows the quality of insulation is the thermal conductivity coefficient of the material. Mineral wool is a fibrous insulating material. For such insulation materials, the thermal insulation qualities depend on the specific water content in the material (moisture content).

When any liquid gets in, mineral wool absorbs it, pushing out the air. As the amount of humidity increases, the thermal insulation properties of mineral wool decrease. The main disadvantage is that the liquid that gets inside is difficult to remove from the material. Mineral wool can absorb 2/3 of its entire weight in liquid, but its performance deteriorates.

Mineral wool

But despite the excessive accumulation of water, mineral wool has become widespread. In rooms where there is no constant contact with water, the use of this insulation is recommended.

Before insulating this material, it is important to cover the surface of these places with a special film that protects it from any moisture, but at the same time allows air flow to pass through:

brick, frame walls;
the outer side of the walls made of wood;
floors;
interfloor ceilings;
the upper element of the building (roof).

Mineral wool can be made from various raw materials: glass, stone, or slag. Today, mineral wool is very popular in construction, in particular for room insulation. In particular, walls and ceilings are insulated with it. Mineral wool is also used for insulating furnaces and pipelines that have a high temperature, since this material is non-flammable. Additionally, mineral wool has soundproofing properties.

Mineral wool may contain potential dangers to the human body. But in fact, it contains fibers that are good for health. It is best to use it in a place that is regularly ventilated, or use ecowool. Ecowool consists of environmentally friendly materials.

Vapor barrier

The thermal insulation “pie” must allow air to pass through so that the room “breathes”. Therefore, the hot air flow escapes very slowly through the insulation fibers. With proper installation of insulation, this ability should increase from room to street.

There should be a ventilation gap of two centimeters under the decorative finishing of the walls and ceiling. Mineral wool is attached between the supports.

First, it is necessary to lay a wind and waterproofing barrier that will protect against precipitation and powerful gusty winds.

Partitions between rooms and interfloor ceilings need to be insulated using a different method, because air and moisture can impregnate mineral wool or ecowool from different sides, therefore, to preserve thermal and technical properties, a vapor barrier is required on both sides. In this case, residual moisture passes through the ventilation gap, which is located under the facade.

There are situations when hydro-vapor barrier when insulating with mineral wool or ecowool is not required at all.

For both waterproofing and vapor barrier, it is important to carry out a number of preparatory work:

cleaning the coating from various dirt and dust;
priming. This is necessary to seal surface cracks;
drying the coating.

Vapor barrier of walls in the room

Vapor barrier for a bath: vapor barrier schemes for ceilings, walls and roofs

The construction market offers a huge selection of materials for vapor barrier of a bath structure. They are divided into several categories:

film;
kraft paper;
membrane;
foil;
coating

Polyethylene film is the most inexpensive and accessible roll material, with a width of 2.5 to 6 meters and a thickness of 10 to 200 microns. It is suitable for covering wall and ceiling surfaces due to its resistance to rot and high humidity.

https://www.youtube.com/watch?v=iz0CACHiams

The main disadvantage of the film is its relative fragility and ability to break down under prolonged exposure to high temperatures. For this reason, such a vapor barrier is best used for a waiting room or rest room.

Polypropylene films are a reliable and practical option that can withstand elevated temperatures and are resistant to cracking and damage. In addition, they do not lose their vapor barrier characteristics when exposed to hot air and ultraviolet radiation. Often, such material is used for the outer cladding of a wooden bathhouse structure.

Films are made on the basis of cellulose and viscose fibers and may have a rough matte surface. Thanks to their porous structure, they are able to retain excess moisture, protecting the thermal insulation layer.

Kraft paper

In rooms with low humidity, it is allowed to use special construction cardboard - kraft paper with a protective foil or lavsan coating.

Foil paper without a polyethylene layer is hygroscopic, so it should not be used for lining a steam room, but for a rest room or dressing room it is a good option.

Dacron paper is a more expensive and wear-resistant material that is designed to protect dry and wet areas.

In addition, the following types of kraft paper vapor barriers are available:

megaflex;
isolar;
Rufizol.

This is the most popular material for protecting the internal structure of a bathhouse from steam. A distinctive feature of the insulator is its two-layer design, in which one layer prevents the penetration of steam, and the second ensures natural air circulation.

Membrane materials come with one or several layers and can be used for bath rooms with high and high levels of humidity.

Foil vapor barrier for a bath includes a whole range of protective materials that are resistant to temperature changes and high humidity. The reflective (foil) side of the insulator provides reliable protection against the penetration of steam, infrared and ultraviolet radiation. There are main types of foil vapor barrier:

kraft paper covering;
covering made of kraft paper and lavsan;
fiberglass covering;
foil covering.

These are polymer-bitumen mixtures of an industrial standard, which are successfully used for vapor barrier of bathhouse buildings. When polymerized, rubber creates a durable, wear-resistant film that provides maximum protection from moisture and steam. In addition, it has high heat and sound insulation properties.

As a rule, liquid rubber is suitable for treating floors, as well as walls made of concrete and brick. The material consumption is as follows: for walls - 1.6 kg, for floors - up to 3 kg.

One of the most practical and reliable thermal insulation materials, which are special films based on polypropylene. They have different thicknesses and strengths, and are designed to effectively protect the insulation from the negative effects of moisture.

This material can be used for covering walls and ceilings in steam rooms and washing rooms.

The following grades of material are presented:

FS - polypropylene-based membrane with metal coating;
FX - polyethylene foam;
FB is a foil insulator based on kraft paper.

An integrated approach to insulation, waterproofing and vapor barrier will provide effective protection against moisture and prevent heat loss.

The installation technology involves the use of modern vapor barrier materials: film, foil and membrane.

Vapor barrier of baths and saunas is carried out in several stages:

Preparatory stage.
Installation of waterproofing.
Laying insulation.
Installation of vapor barrier.
Decorative covering of surfaces.

Ceiling

When exposed to excessive temperatures and humidity, the ceiling surface first of all needs to be carefully insulated and treated with protective vapor barrier materials.

Vapor barrier of the bathhouse ceiling is carried out in the following order:

The log ceiling is pre-sheathed with boards 6 cm thick. A 100-micron foil material or thick cardboard treated with drying oil is fixed on top of the sheathing.
Next, a softened clay layer is laid out and a vapor barrier is laid.
Insulating material is evenly applied to the vapor barrier layer. The bathhouse ceiling can be insulated with mineral or basalt wool up to 5 cm thick. It is recommended to choose ecological wool or expanded clay filler as seamless insulation.
A moisture-proof membrane or wooden flooring is fixed to the insulation. This will prevent possible moisture from entering the insulating layer.

Which vapor barrier should I choose for installation on walls in wet rooms of a bathhouse? As a rule, glassine, aluminum and polyethylene based films are used for this. These are the most accessible and inexpensive materials.

Vapor barrier of bath walls is carried out in the following order:

A wooden sheathing is installed on the load-bearing wall structures, the thickness of which is 2.5 cm greater than that of the heat-insulating layer.
The insulation is installed between the sheathing elements. For this you can use mineral wool or glass wool.
A vapor barrier is laid on the insulating layer. How to lay material to prevent heat loss and steam penetration? Installation is carried out from the far corner, the edges of the film are fixed with an overlap of 12 cm. A stapler and metal staples are used for fixation, the joints are sealed with tape.
It is important not to forget which side to lay the vapor barrier. The foil heat-reflecting base of the film is directed inside the room, and the foam base is directed towards the insulation.
A wooden sheathing is mounted on the vapor barrier layer to create a technological gap for natural ventilation.
A wooden lining is fixed to the sheathing.

How to make a vapor barrier for a floor? The installation technology depends on the design features of the bathhouse. As a rule, a steam room is equipped with a wooden flooring equipped with a drain hole, which can lead to significant heat loss.

The correct solution to the problem is a multi-layer floor with waterproofing, insulation and vapor barrier.

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Work on vapor barrier of wooden flooring is carried out as follows:

A thin layer of liquid waterproofing is applied to the wooden boards.
Basalt wool is mounted on top.
A vapor barrier material that is resistant to rot is placed on the insulating layer.
Next, a concrete screed of the base of the required thickness is carried out and a decorative flooring is laid - porcelain stoneware or tiles.
A wooden flooring is laid on the lined base for ease of use of the steam room.

Roof

In some cases, it is not enough to only perform a vapor barrier on wall and ceiling surfaces; in order to provide protection from high humidity, it is necessary to take care of the vapor barrier of the roof.

To do this, a special insulating membrane is installed in the attic in the wooden ceiling of the bathhouse, an insulating layer is placed on top, and waterproofing is placed on top of it. A counter-lattice is installed on the waterproofing layer, to which the selected roofing material is fixed.

Other premises

Whether it is worthwhile to perform a vapor barrier in other bath rooms, the owner of the building decides independently. If a wooden bathhouse is not insulated from the inside and outside, then vapor barrier can be eliminated - drying of the interior will be carried out thanks to the natural ventilation of the wood.

Brick, block and concrete buildings require the installation of vapor barriers. In this case, not only the insulation material must be dried, but also the entire structure of the bathhouse - walls, floors and ceilings.

Therefore, when installing a vapor barrier layer, additional waterproofing of surfaces is provided.

Do-it-yourself installation of vapor barrier materials is technically simple, but requires a responsible approach and attention. Only in this case is reliable and effective protection of the steam room from the destructive effects of moisture and hot steam ensured.

Our grandfathers widely used clay as a vapor barrier. It makes an excellent hydraulic lock. All natural, no chemicals. Simply mix oily clay with water and add wood shavings to this “porridge.” The shavings play the role of a connecting element. During drying, the clay cracks slightly.

Another ancient method: From the attic side, dry leaves are laid out on the ceiling. Sawdust is poured on top, and then dry soil is placed on top. This option has also been tested for decades and works well. But today natural materials are rarely used. The industry offers a very large selection of excellent vapor barriers.

Bath foil

Firstly, these are vapor barrier films. This should not be confused with heat-insulating membranes, which operate on the principle of a “breathing waterproofing material”. Vapor barrier films create a reliable vapor barrier, especially if reinforced and foil films are used. For example, you can use Ondutis R Thermo, Izospan, Penotherm or other similar material. The choice is very large.

Secondly, simple aluminum foil also works great as a vapor barrier. But it is difficult to use in terms of installation: tearing should not be allowed and the integrity of the material must be carefully monitored. All seams are carefully taped with special mounting tapes (foil tape). The work is meticulous, but a simple furniture stapler will help you get the job done quickly.

Foil tape

Thirdly, ordinary cellophane can do a good job as a vapor barrier. However, I rarely use it in this area. Ruberoid or glassine also perfectly retains moisture, but it is not suitable for vapor barrier of a bathhouse ceiling. During high temperatures, harmful volatile substances are released, and this is not at all good for health.

Types of vapor barrier

Vapor barrier is divided into two types:

Rolled. Rolls are rolled out from the bottom of the item to the top. Next, they are secured with slats made of wood in a horizontal position. The gap for ventilation is located between the inner lining and the steam protective layer. This hole should be about five centimeters. After the procedure, check that everything is securely fastened.
Leafy. To work with sheet material, you should first install a profile frame. Sheets must be mounted into this frame. Self-tapping screws or nails will help you secure the sheets. The joint areas must be covered with polyvinyl chloride (PVC film). The vapor barrier layer sheet is placed with the inner area towards the place that you want to insulate.

Rules for attaching a vapor barrier layer

The reliability of fastening depends on screws or nails. Regardless of the location of the room, hydro-vapor barrier is established by general principles.

For the integrity of the vapor barrier coating, it is important to apply the layer in a continuous layer to avoid any holes or cracks. It is advisable to fasten the sheet with a furniture stapler. With the help of this construction tool, the vapor barrier film is attached closely to the surface of the insulated walls and a certain ceiling.

The vapor barrier layer is laid by overlapping individual rolls or sheets (depending on the types of vapor barrier) by 10-12 centimeters. In places with door and window openings, the sheets must be glued; this can be done using adhesive tape specially designed for this situation. But there is no need to stretch the vapor barrier film, otherwise due to sudden changes in air temperature, it will not be able to maintain its integrity. It is attached with a margin of three centimeters.

Hydro-vapor barrier of a ceiling insulated with mineral wool or ecowool is also carried out with overlapping rolls or sheets. To protect the ceiling from steam and moisture, the interior and exterior of the room must be covered with waterproofing vapor barrier layers.

The outer part of the building should consist of three layers:

paraisolating;
thermal insulation;
repeated vapor barrier.

Thanks to this, the service life is increased and the likelihood of condensation in your room is eliminated.

Floors made of reinforced concrete especially require protection from steam and moisture. Otherwise, sudden changes in air temperature will lead to the appearance of steam, which can cause fungus or mold to appear on the ceiling.

Vapor barrier is an important element that will bring comfort and coziness to your home. Typically, a vapor barrier is installed together with waterproofing and thermal insulation. When working with the material yourself, you should follow several rules and nuances. The choice is yours. This article could answer the question: is a vapor barrier necessary when insulating with mineral wool?

What is mineral wool?

Rock melts (basalts, dolomites) are used as raw materials for production. Sometimes industrial slags are added. The molten mass is formed into fibers, which are then pressed into slabs or rolls.

The strength of the final products is determined by the degree of compression during pressing and the binders, which use phenol-formaldehyde or urea resins.

The greater the force applied at the molding stage and the higher the concentration of binders, the more dense and rigid the material is.

Density, depending on the release form, can fluctuate within a very significant range:

Rolls – 20-50 kg/m3;
Mats –50-80 kg/m3;
Lightweight slabs – 80-120 kg/m3;
Medium hardness slabs – 120-200 kg/m3;
Rigid slabs – over 200 kg/m3.

Features of ceiling vapor barrier

Regardless of whether a Russian bathhouse is equipped with a steam room equipped with a wood-burning stove, or a sauna with a firebox using electric heating elements, a high level of humidity and heat will be constantly maintained in the room. To effectively retain heat over a long period of time, such rooms are equipped with thermal insulation.

However, there are also some nuances here. The need to equip a vapor barrier layer in a bathhouse appears in a situation where mineral wool is used. In a dry state, this structure is endowed with increased thermal insulation properties, which will significantly decrease when wet. When using foam plastic or penoplex, a vapor barrier layer is not equipped.

There are several main types of suitable vapor barrier materials available for sale when equipping a bathhouse:

Film. This is the simplest type of vapor barrier layer, which is a dense canvas of white or blue colors. Depending on the brand, the material may be smooth or slightly rough. More expensive models use reinforcement that can look like a cage;
Membranes are non-woven materials that provide sufficiently high-quality protection of insulation from condensation and steam;
Foil. This is the most optimal vapor barrier material for bathhouse equipment, since it retains thermal energy quite effectively due to its coating.

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Properties and application features of the material

The main property that determines the effectiveness of a particular insulation is the thermal conductivity coefficient.

It characterizes the heat loss occurring through a layer of material 1 m thick in an area of 1 m2 for 1 hour with a temperature difference on opposite surfaces of 10 ° C.

For various forms of mineral wool, this figure is 0.03 – 0.045 W/(m*K).

A distinctive feature of fiber insulation is the dependence of their thermal insulation properties on moisture content.

When wet, droplets of water envelop the fibers and gradually penetrate into the volumetric structure, gradually displacing air from there.

An increase in the amount of water inside, between the fibers, leads to a sharp drop in thermal insulation characteristics. The situation is further aggravated by the fact that water that gets inside is extremely difficult to remove outside.

The insulation can absorb up to 70% of its mass in water. Naturally, under these conditions, the efficiency of its work will tend to zero.

Despite the criticality of getting wet, the scope of application of mineral wool is extremely wide. When building a house, its use is possible almost everywhere where direct contact with water is excluded:

Hollow walls (frame and brick, made using well masonry technology);
External surface of wooden or brick walls;
Internal partitions;
Floors;
Interfloor ceilings;
Roof.

When is a vapor barrier necessary?

It is definitely enough to simply formulate the condition of whether a vapor barrier is needed. When insulating with mineral wool, protection from water vapor will be needed when there is a possibility of contact with air coming from the room.

To ensure effective operation, each layer of the thermal insulation “pie” must allow air to pass through to one degree or another. In the direction from room to street, this ability should increase.

Thus, warm air from the room very slowly seeps between the fibers, displacing cold air from there.

There is a small ventilation gap of 1-2 cm under the internal decorative lining. The insulation is installed inside the structure between the supports.

These can be vertical frame posts, floor joists or rafters. A wind-waterproofing barrier is installed on the outside (external) side, protecting from the effects of precipitation and strong direct wind.

Vapor barrier for a bath: vapor barrier schemes for ceilings, walls and roofs

What does it look like

Foil vapor barrier is the best choice for a steam room

If this is a regular vapor barrier, it is a milky, white, blue film. There are them “checkered” with reinforcing fibers, and there are homogeneous ones. They feel dense to the touch and can have surfaces of different textures - smooth and rough. There are vapor barrier membranes. They are nonlinear - they have a corrugated surface or with spiked protrusions.

Especially for baths and saunas, vapor barriers with a heat-reflecting coating are produced: it can be made of foil or metallized lavsan.

What is it for?

High humidity and temperature in the steam room of a Russian bath require a special approach. It is important to protect the heat-insulating layer from moisture. Why protect him? The fact is that basalt wool is most often used for thermal insulation of premises. In a dry state, it has good heat-insulating qualities, is made from natural materials, and tolerates high temperatures well.

From moisture coming from the room. The humidity in the Russian steam room is very high, the air is oversaturated with moisture, so the steam tends to flow into other rooms and outside (through the heat insulator). And we need to avoid this.
From moisture formed due to temperature changes in the steam room and in the attic and on the street (and on the interfloor ceiling and on the walls). It condenses even before steam begins to be supplied, during the heating of the air in the steam room.

Laying rules

In order for such material to fulfill its tasks, it is necessary:

ensure the best possible tightness of seams and joints;
make sure there is a ventilation gap between the foil and the finish.

To ensure normal vapor barrier in a bathhouse, you need to install it not only on the walls and ceiling, but also on the roof. To do this, a vapor barrier membrane is laid on a wooden frame in the attic, and insulation and waterproofing are placed on top. And already on it the counter-lattice is installed, followed by fastening of the roofing material.

In the article above, we looked in detail at how to make a vapor barrier in a bathhouse. You need to clearly understand the difference between vapor barrier and waterproofing, understand their characteristics, so that after all the work is completed, unforeseen nuances do not arise. If everything is done correctly, the finished bath will last a very long time.

Insulation scheme without the use of vapor barrier

Sometimes doubts about whether a vapor barrier is needed when insulating with mineral wool are quite justified. A characteristic feature for such situations will be the presence of airtight layers:

Interior or exterior non-porous finish;
Continuous sealed layer of waterproofing;
Brick wall;
Facade plaster;
Decorative facing brick.

Another situation where mineral wool does not require additional protection is well brickwork. During the construction of the wall, internal cavities are formed, which are subsequently densely filled with thermal insulation material.

Video instruction:

Based on a brief review, we can conclude that protecting mineral wool from the effects of water vapor is not always a mandatory operation.

It is necessary only in cases where there is possible contact between warm, humid air in a living room and insulation fibers.

Ceiling vapor barrier Izospan

The goal of this process is to protect the building material used for the ceiling from moisture. Air humidity in rooms varies, but it is present everywhere, even in those rooms where the air seems dry. And steam accumulates in the ceiling area, so mold appears first there and on the side walls at the corners of the ceiling. High indoor humidity contributes to the premature destruction of building materials and increases the likelihood of wood being destroyed by beetles and other woody insects that require moisture to survive.

Which Izospan is suitable for the ceiling

There are types of Izospan that include several characteristics at the same time, and there are those that have only the main technical characteristics necessary for vapor barrier: moisture impermeability, elimination of condensation.

Izospan B is best suited for ceilings; it is used to protect insulation materials located on the inside. If we are talking about vapor barrier of the attic ceiling from the outside, then use Izospan A, for the ceiling of an unheated basement - Izospan D.

What is mineral wool?

Rock melts (basalts, dolomites) are used as raw materials for production. Sometimes industrial slags are added. The molten mass is formed into fibers, which are then pressed into slabs or rolls.

The strength of the final products is determined by the degree of compression during pressing and the binders, which use phenol-formaldehyde or urea resins.

The greater the force applied at the molding stage and the higher the concentration of binders, the more dense and rigid the material is.

Density, depending on the release form, can fluctuate within a very significant range:

Rolls – 20-50 kg/m3;
Mats –50-80 kg/m3;
Lightweight slabs – 80-120 kg/m3;
Medium hardness slabs – 120-200 kg/m3;
Rigid slabs – over 200 kg/m3.

Properties and application features of the material

The main property that determines the effectiveness of a particular insulation is the thermal conductivity coefficient.

It characterizes the heat loss occurring through a layer of material 1 m thick in an area of 1 m2 for 1 hour with a temperature difference on opposite surfaces of 10 ° C.

For various forms of mineral wool, this figure is 0.03 – 0.045 W/(m*K).

A distinctive feature of fiber insulation is the dependence of their thermal insulation properties on moisture content.

When wet, droplets of water envelop the fibers and gradually penetrate into the volumetric structure, gradually displacing air from there.

The insulation can absorb up to 70% of its mass in water. Naturally, under these conditions, the efficiency of its work will tend to zero.

Hollow walls (frame and brick, made using well masonry technology);
External surface of wooden or brick walls;
Internal partitions;
Floors;
Interfloor ceilings;
Roof.

When is a vapor barrier necessary?

Thus, warm air from the room very slowly seeps between the fibers, displacing cold air from there.

There is a small ventilation gap of 1-2 cm under the internal decorative lining. The insulation is installed inside the structure between the supports.

This scheme is valid when constructing frame walls, floors, attic roofs, and the ceiling of a residential floor in the presence of a cold attic above.

Internal partitions and ceilings between living spaces require a slightly different approach. In this case, humid air can penetrate the mineral wool from any side. To maintain the thermal characteristics of the structure, a vapor barrier is installed on both sides.

Another case when protection from internal moisture is necessary is external insulation of wooden log houses made of timber or logs. A vapor barrier is installed between the wall and the insulation slabs.

Excess moisture is removed through a ventilation gap left under the outer decorative facade.

Methods of vapor barrier of a bathhouse ceiling

Next, you need to consider the process of installing a vapor barrier and recommendations from professionals on how to properly equip the ceiling. First you need to take into account the type of roof, more specifically, the absence or presence of an attic space. In a situation where an attic or attic is installed in such rooms, the ceiling will be much worse at transmitting air filled with moisture, but this does not mean that there is no need to install a vapor barrier layer.

Often, similar materials are used to insulate a room with an attic, but it is advisable to treat the board on the roof side with a clay mixture. Determining the most effective vapor barrier material for a bathhouse is not so easy.

Be sure to familiarize yourself with the most effective methods:

Boards with a minimum thickness of 2 cm are laid on the wooden ceiling. A vapor barrier layer made of foil or cardboard treated with drying oil is mounted on the board.
After this, the cracks between the boards are covered with clay-sand mortar.
Then insulation made of expanded clay, ordinary mineral wool or polypropylene is applied.
The boardwalk rests on top of the insulation.

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Second way:

The board is placed on square beams.
To make the surface sufficiently moisture resistant, you need to pre-treat the boards with a drying oil solution.
On the upper side, boards are laid on the ceiling beams, the gaps between which are also processed.
Then the board surface is covered with a vapor barrier layer.
As thermal insulation, a little sand is poured onto the vapor barrier. Today there are many other higher quality materials for providing thermal insulation that can also be used.

For expanded clay or mineral wool, polyethylene film is suitable as a vapor barrier material. One of the most significant steps before installing a vapor barrier for the ceiling in a bathhouse is antiseptic treatment. This procedure allows you to get rid of possible difficulties associated with dampness in the future.

Insulation scheme without the use of vapor barrier

Sometimes doubts about whether a vapor barrier is needed when insulating with mineral wool are quite justified. A characteristic feature for such situations will be the presence of airtight layers:

Interior or exterior non-porous finish;
Continuous sealed layer of waterproofing;
Brick wall;
Facade plaster;
Decorative facing brick.

Video instruction:

Based on a brief review, we can conclude that protecting mineral wool from the effects of water vapor is not always a mandatory operation.

It is necessary only in cases where there is possible contact between warm, humid air in a living room and insulation fibers.

Waterproofing the basement

For waterproofing the basement floor on the residential side, moisture and windproof films Ondutis A100 and Ondutis A120 are used:

- a subfloor is placed on the lower surface of the floor beams;

— Ondutis moisture and windproof film is laid on the subfloor between the joists with the logos facing outwards. The edges of the panel are placed on the logs and secured with a construction stapler;

— the joints of the panels are sealed with Ondutis ML mounting tape, the overlap width at the joints is 20 cm.

On the living room side, insulation is laid on top of the moisture-windproof film between the joists. The height of the gap between the insulation and the upper edge of the log is 3-5 cm.

In the case of waterproofing on the basement side, the Ondutis SA115 superdiffusion membrane is used:

— the membrane is mounted on top of the subfloor with the logos facing out, the panels are laid with an overlap of 15 cm. The overlap width at the joints is 20 cm. The overlaps of the panels are sealed with Ondutis ML mounting tape, the junctions with the walls of the basement are glued with Ondutis BL mounting tape.

The insulation, as in the previous case, is installed on the side of the living room.