The principle of vapor barrier in insulating attic floors. Attic technology. Is there a need for an air gap at the membrane?

Attic spaces, the frame of which is presented in the form of wooden trusses, are correctly called “cold”. These objects are not particularly durable compared to reinforced concrete structures, but they have their advantages.

Basically they come down to the great possibilities of using thermal insulation materials. A classic attic floor on wooden beams is equipped with insulation using ordinary carpentry tools, unlike reinforced concrete, where special equipment is required.

Insulation of the attic floor, in addition to insulation, requires the installation of proper vapor barriers and exhaust hoods that prevent the formation of mold and mildew. And if you correctly follow the technology when installing insulating material, then air exchange will be guaranteed.

The design of the attic directly depends on the parameters of the building and the purposes intended for the use of this room. The under-roof space plays the role of a kind of air gap separating warm heated rooms from the cold roof.

In this case, the floor in the attic performs two tasks:

Isolating. In the attic of a house, the air temperature is almost no different from the street temperature. In this case, the floors have an insulating function, thereby preventing the penetration of cold air into the living spaces.

Carrier. In most cases, the ceiling on wooden beams between the attic space and the upper floor of the house, like the walls, has a load-bearing function. In this regard, it must be reliable and durable, since people move along it, utensils are stored or any equipment is placed.

Therefore, in order to know the permissible load on the attic floors, it is necessary to make a calculation. Then, based on their results, draw up a project that will show how to properly insulate the attic floor of a building.

Selection of material for insulation

The technique for insulating an attic is simple, since the material is laid directly on the floor, in the gap between the rafters and wooden floor beams. If you plan to use the attic space as an attic, then you also need to insulate the roof.

To insulate the floor between the beams in the attic, several types of insulation are used:

• Mineral wool.
• Foam plastic.
• Expanded polystyrene.
• Sawdust.
• Expanded clay.
• Foam.

Let's take a closer look at each insulating product.

Mineral wool insulation

In order to save heat, the material must be placed between steam and waterproofing films. Vapor barrier protects against moist air masses that form in living spaces near the ceiling, especially at the junction with the walls. The second layer protects the wool from water entering from the roof through microcracks and holes in the roof.

The attic space of a house is insulated most often from the floor rather than from the ceiling of the lower floor. For this purpose, mineral wool is a reliable, inexpensive insulating material with high compression, allowing it to cover the surface of not only the floor, but also beams of various shapes. This insulation is sold in rolls or slabs of different thicknesses.

At the same time, it has the following advantages:

• Budget cost.
• Easy to install.
• Rodents do not grow in such insulation.
• High fire safety of the material.
• Ability to isolate any uneven surface.

At the same time, when working with mineral wool, it is necessary to take protective measures: wear thick clothing, work in goggles and protective gloves, and it is also advisable to use a respirator.

Foam plastic

Insulating an attic space with polystyrene foam is a good option for converting it into an attic, suitable for year-round use. This material has low thermal conductivity, as it is produced in the form of foamed air granules pressed into slabs.

During installation, the foam must be cut so that the plates fit tightly between the attic floors. Any gaps and cracks become “bridges” for the penetration of cold, and thereby significantly worsen the quality of insulation.

In this case, it is necessary to maintain a distance between the foam plastic board and the waterproofing film of at least 2-3 cm. It is recommended to use it as insulation with a thickness of 70 mm, and in regions with a harsh climate - 100 mm.

Attention! When installing a vapor barrier film, you need to pay attention to the fact that it faces the insulation with the required layer, according to the instructions. Otherwise, the opposite effect will be produced: all the steam will be directed towards the insulating material.

Extruded polystyrene foam

When insulating the ceiling of a living space over the attic floors, for many builders this material is considered the best option. This insulation does not cause any difficulties during installation; it can be laid under any beam ceiling.

It also saves space, since you can get by with two to three times less thickness than using the same mineral wool. Extruded polystyrene foam comes in different types, as it is produced by different manufacturers. To insulate attic floors, the density of such material should be about 32-34 kg/m, and its thickness should be from 40 to 100 mm.

Manufacturers also produce shaped elements from expanded polystyrene, which are used to lay out complex fragments in the attic ceiling. It is convenient to install this insulation in two layers: the first layer is laid between the attic floors, and the second layer is applied end-to-end along the bottom row, covering the wooden beams as well.

The main disadvantage of such insulation is that it is flammable. To reduce the fire hazard, you can lay mineral wool with expanded polystyrene, or add antipyrine.

Expanded clay

Expanded clay for the attic of a house is a traditional method of thermal insulation technical floor. This material is poured between wooden floors with a layer thickness of at least 150 mm. This mass is universal remedy, capable of insulating floor structures, and can also be used as thermal insulation in conjunction with other bulk materials.

Attention! Expanded clay is a fairly lightweight insulation material, but when a thick layer is applied, the load-bearing surface of the ceiling will bear a large load.

Thermal insulation is best carried out at the construction stage of the building, since it is easy to waterproof the ceilings of the rooms under the attic and provide for an exhaust hood.

To do this, cover the ceiling with a vapor barrier film to protect the expanded clay layer from getting wet. It is not recommended to pour it directly onto the floorboards for another reason: during operation and operation of the room, a lot of dust is released, which penetrates into the living rooms.

Sawdust

Sawdust is a product of lumber processing in the woodworking industry. This is the most cheap insulation for attic floors, since you can buy sawdust at any sawmill for free. Thus, sawdust is still an option as a reliable heat insulator in attic spaces.

Note! Sawdust is of organic origin, therefore, it is completely harmless to human health. Since ancient times in Rus', sawdust mixed with clay has been used as insulation in attics.

Sawdust has the following advantages:

1. Low cost of thermal insulation. Probably, the popularity of such insulation lies precisely because of this factor: its cost is almost equal to the cost during transportation.
2. Safety for human health. Wood shavings and sawdust do not cause skin irritation, allergies, or poisoning, which cannot be said with complete confidence about modern insulation materials.
3. Low thermal conductivity coefficient. Unlike wood, chips have a porous structure, so they have low heat conductivity.
4. Easy installation. To form a heat-insulating layer in the attic floors, no special skills are required. You just need to mix sawdust with clay or lime, and then pour it into the space between the attic floors.

The only significant drawback is the fire hazard of the material, despite the mixture with other non-flammable substances.

Foam

IN lately For insulation of attic floors, two types of insulating materials have become popular: blown-in wool and ecowool. The latter material consists of 80% cellulose fibers made from waste paper, and 20% from additives, which are fire-fighting and antiseptic components.

This material has low thermal conductivity, it is very light, and looks like regular polyurethane foam. Both types of insulation are usually sprayed onto the boards between wooden beams, but sometimes ecowool is used in granules in a crumbly state. In this case, this mixture, as an option, is simply poured between the floor beams and compacted.

Vapor barrier

The vapor barrier film protects wooden beam ceilings from moisture formed in the air of residential premises. In addition, it protects floors from the appearance of mold and mildew in the insulating material.

Regardless of how the attic floor is made, the vapor barrier for the floor should form a continuous carpet that does not allow condensation to penetrate. Particular attention should be paid at the joints with walls, where there is a high probability of condensation penetration. To do this, the covering film is overlapped and its edges are glued together with tape.

Insulation technology

For correct application insulation, follow the step-by-step instructions:

Step #1. Carry out an inspection and, if defects are found, eliminate them. Treat boards and timber with antiseptics and fungicides.

Step #2. Lay out vapor barrier material and seal all gaps with mounting tape.

Step #3. Lay (pour) insulation into the openings of wooden floors on the floor.

Step #4. Pay special attention to the joints between slabs of insulating material. If necessary, apply additional insulation.

Step #5. Lay with an overlap waterproofing film, fasten the joints with mounting tape.

Step #6. Separately install insulation on the ventilation duct, chimney pipes in the form basalt wool, perlite, and it is advisable to install a special corrugation on top.

Installation of wooden attic beams

The attic ceilings are designed to separate the living rooms from the under-roof space. They do not allow cold air to pass through, so the main task is their thermal insulation. Various equipment is also often installed in the attic.

In this regard, another important task is to create solid foundation, capable of withstanding this load. Thus, the safety of people, their comfortable living, and also the durability of the structure depend on the high-quality arrangement of wooden floors.

Attic flooring on wooden beams - standards, requirements

According to the requirements of SNiP 31-02, attic floors must withstand thermal, statistical, acoustic and fire conditions. In addition, they must be energy-saving, therefore, reliable thermal insulation must be installed on the floors.

When installing an attic floor on wooden beams, you must strictly adhere to all sanitary and hygienic requirements. When erecting a frame, it is necessary to construct the structure, and then insulate the attic floor. At the same time, the same temperature must be maintained between the lower part of the attic and the living room. The difference in indicators in degrees according to the standards is allowed no more than 4˚С.

For structural elements of the attic, dry, seasoned timber with a cross-section of 100×150 or 200×250 mm should be used, while the humidity in it is allowed to be no more than 20-30%. The distance between the load-bearing beams depends on the load, but usually it is taken at intervals of 3 to 6 meters. In addition to bearing load, wooden floors require a maximum safety margin.

It must be borne in mind that the minimum load on such load-bearing beams is 100 kg/sq. m. And the period of trouble-free operation of wooden floors according to the standards is 60 years. It is due to the fact that the wood is susceptible to damage from fungus and insects, as well as a change in the strength of the beams under the influence of possible condensation.

Read more about regulatory requirements on attic floors, watch the video:

The joints between the rafter beams and the wall, as well as the load-bearing ceiling beams, should be especially protected with insulating material. If all these conditions are met, the house will serve you faithfully for a long time.

Ceiling vapor barrier in houses with a cold attic is considered the most important construction stage. Vapor barrier components, do not allow moisture to pass through, do not allow condensation to occur on support structures, protect the insulation from the appearance of microorganisms and mold. The installation of this system protects building materials from destructive processes that lead to the gradual destruction of structures. In this material we will analyze in detail how to properly install insulation and moisture and wind protection on the attic floor.

The role of moisture insulation in residential buildings cannot be overestimated. IN everyday life the air in the rooms is constantly saturated with water vapor. This is moisture from cooking, running showers, evaporation from the human body and from his breathing. All this air with tiny suspended particles of water does not disappear without a trace. It is absorbed into the partitions and insulation of the walls and ceilings of the house, which leads to a deterioration in the properties of the materials from which they are made.

Known fact: Fungi and mold feel great and actively multiply in warmth and moisture. Such a microclimate is formed in a room with high humidity, and it is destructive for any building materials.

In most of the territory of our country it prevails cold climate, so almost all the time the temperature in houses has to be maintained at a high temperature. Warm, moist indoor air moves, according to the laws of physics, into the environment. But on the way he encounters construction ceilings: the ceiling and the roof. To prevent evaporating moisture from being retained and deposited on structures, they must be protected in a special way.

If the vapor barrier was initially installed correctly, the process of moving air into the external environment will not cause any damage to the structure. But if the technology has been violated, excess moisture in the house threatens it with rapid cooling, especially in winter time, as well as dampness in the rooms. The result may be a need for major renovation the entire structure.

Why do a vapor barrier in the attic?

Myself cold attic consists of a roof with two slopes, which is sheathed on the outside with roofing material, as well as a ceiling with insulation that separates the attic from the living rooms. Attic space equipment is required ventilation windows- they prevent moisture condensation.

The attic floor is also the ceiling of the room below. When it's cold outside, the temperature in the attic also drops, but indoors it remains the same. Because of this difference, the top of the attic floor is cold and the bottom is warm. This is how condensation appears. To prevent moisture from entering the ceiling, it is covered with a special protective moisture-proof material.

A vapor barrier is installed on any floor base. During construction, floors are insulated with fiberglass (glass wool), special mats (for example, isover slabs) or loose thermal insulation. All structural elements must be insulated (only ventilation holes are retained). This material does not skip warm air, keeping it indoors. Thanks to this, you can reduce heating and save on heating costs.

How to protect the attic floor from moisture

Thermal insulation in its structure is a multi-layer cake. One of its layers is a vapor barrier film, which should prevent moisture from penetrating into the structure of the structure.

To protect the insulation from fumes, a vapor barrier film is installed in front of the insulation layer (from the side of the living rooms). The vapor permeability of the film should exceed that of thermal insulation - this will allow you to quickly remove moisture that has entered the insulation through the protection.

There are 2 reasons for vapor deposition on floor structures. The first is as a result of the release of household fumes and their diffusion through the ceiling. The second is the occurrence of dew due to the difference in temperature inside the room and the unheated attic.

A vapor barrier is installed on the ceiling if it is expected that the attic will be unheated. The rest of the space is not subject to insulation, because... it is uninhabited. But the protection of slopes and rafters is necessary, these are:

• waterproofing - to eliminate external influences from the street.
• natural ventilation - from condensation that appears due to the difference in temperature outside and in the house. According to standards total area everyone ventilation holes must be at least 1/300 of the floor area or roof projection (horizontally). If ventilation is arranged correctly, in winter the difference in temperature in the attic and outside will be no more than 5-6 degrees.

Rules for installing vapor barriers and ventilation for cold roofs

There is no need to install a cold attic vapor barrier on the roof slopes. Films made of polyethylene and polypropylene, as well as roofing felt and glassine are not suitable for waterproofing a cold roof. These materials retain steam-saturated air, which leads to dampness and condensation. inside films.

A cold roof made of corrugated sheets can be ventilated through the ridge: thanks to the counter-lattice, the air passes through the roof covering through eaves overhang out.

In a cold attic, there must be properly positioned dormer windows for proper ventilation of the space. If the attic is very large, then the system is supplemented with forced exhaust.

The ventilation system is a mandatory addition to the vapor barrier

Possibility of insulating a cold attic in the future

If cold roof it is supposed to be insulated and converted into a room for living; when creating waterproofing, you need to take not a perforated film, but a special membrane. The reason is that it is impossible to attach insulation to the film without a gap - if this is done, it will allow moisture to pass through. To prevent this from happening, you need to leave a small gap (5 cm).

This does not happen with membranes; they can be placed on insulation without any problems, and they also reduce the thickness by up to 10 cm roofing pie. The downside is the high price.

The rebuilt roof does not require vapor barrier, because... moisture will not accumulate in the insulation, but will quietly escape into the atmosphere through the membrane or film.

Features of creating a vapor barrier

When creating a vapor barrier for attic floors, you need to select materials with minimal vapor permeability (evaporation volume per unit area - mg/m2). This indicator is indicated on all building materials.

Preference is given to materials with parameters of zero or slightly more, but always less than those of thermal insulation.

Wood is an excellent conductor of moisture, but its accumulation in this material can lead to its rotting and deformation. This feature taken into account in the manufacture of building materials from wood. But when building a house, you must not forget about the vapor barrier of such elements and choose components with minimal evaporation rates to protect them.

The general procedure for laying vapor barrier is as follows:

• first materials with minimal vapor permeability;
• then, as this indicator increases, all the rest.

And when insulating the attic along the beams in wooden floor(as seen from the room):

Vapor barrier- glassine, membrane, film. Placed on floors during construction. And during repairs, it is fixed with slats to the room ceiling.

Thermal insulation layer. Placed between beams; sometimes - on the floors. For a cold attic, waterproofing and wind protection (from wind) are not provided ceiling protects the roof).

Waterproofing layer- membrane or polyethylene; laid only if the attic space is planned to be inhabited. Placed under decking or flooring. If the attic is uninhabited, waterproofing is done on the roof slopes to protect it from rain and snow.

The process of installing vapor barriers on floor beams in the attic

Important! When laying a vapor barrier over wooden beams, you need to form a continuous carpet that completely covers all structural elements. Additionally, it is necessary to provide an overlap on the walls or roof and prevent contact of the insulation with the wooden elements of the ceiling.

We must not forget about the need to create a system of ladders that allows for the repair and maintenance of the roof (for example, to prevent caking of the insulation, which impairs its functions). They are placed on logs - when using thermal insulation in rolls or tiles. Or they put it on posts - if the thermal insulation is bulk.

Protective vapor barrier material must be laid correctly: freely, with an overlap (in accordance with the instructions) on the walls and covering all structural elements of the attic - beams, compartments, cells, corners, ceiling from the inside (during repairs to improve insulation). Therefore, you need to cut out the material with a reserve. If necessary, strips of material can be glued together with reinforced tape, and foil insulators with similar tape (it is advisable to make joints on joists). The film must be secured with thin slats for better fixation and protection from damage.

Important rule: sagging or deformation of pieces of vapor barrier is not allowed; At the same time, they must lie freely so that they do not tear due to temperature changes.

Place the material after preliminary preparation: when using wood in a structure, insulation is laid, and then a ceiling vapor barrier. If the height of the logs and the thickness of the insulation coincide, a counter-lattice is installed. The vapor barrier for wooden ceilings under the attic must be continuous so as not to allow moisture to pass through.

An air gap between the insulation is required

When using concrete in floors or on a flat roof, first install the waterproofing and then the sheathing (its height should ensure free ventilation, and the installation step should be a few centimeters narrower than the heat insulator).

Video: example of laying a vapor barrier for a cold attic roof

Which vapor barrier to choose. Pros and cons of different materials

Choosing the right one vapor barrier material is very important, since the effectiveness of the thermal insulation cake depends on it, and on its combination with insulation.

IN ancient times This role was played by clay mixed with soil and plants (peat, shavings, sawdust, leaves, etc.). It protected the floors from temperature changes.

Modern steam and heat insulators make installation procedures faster and easier. But, according to professionals, they are often inferior in quality to old materials.

For reference. Vapor permeability as a characteristic of a material indicates how many grams of water in the form of steam can pass through each square meter films. If this amount is expressed in tens of grams, then such material is called vapor barrier. The lower this indicator, the less steam will pass to the insulation.

Types of modern vapor barrier

Glassine - an inexpensive option (70 mg/m2 per day) for domestic buildings with a stable humidity level. Plus - it perfectly prevents the passage of moisture, and minus - low air conductivity.

Polypropylene or polyethylene films (often reinforced; 3−5 mg/m2 per day). This material tolerates temperature fluctuations well; resistant to physical impact and ultraviolet radiation. Ideal for wooden structures. Polyethylene is suitable for warm regions of the country: when low temperatures it quickly loses its properties. The disadvantage of polyethylene is that it tears easily, so it is difficult to install.

Polyethylene film is the simplest type of film vapor barrier

Polypropylene film is stronger than polyethylene; can be produced with the addition of viscose and cellulose, which makes it stronger and more hygroscopic. The downside is that when installing it, good ventilation of the room is required, otherwise the water accumulating on the insulator will not be able to evaporate.

Polypropylene film - more practical look vapor barrier for attic

Membranes with a foil shell (0.04−2.55 mg/m2 per day) - an option for houses with high humidity and frequent temperature changes (baths, swimming pools, etc.). Withstand high temperatures and prevent the passage of steam well.

Membrane is the most modern type of vapor barrier

Types of membranes:

• Kraft paper:
  • foil - easy to install, but not resistant to microorganisms; poor hygroscopic properties.
  • with lavsan coating - very high temperatures (ideal for saunas and baths), but does not tolerate the effects of cleaning chemicals.
• Fiberglass with a foil shell is considered the best of materials; minus - high cost.

Anti-condensation diffusion membranes (3−15 mg/m2 per day) - a new product in vapor barrier; installation is possible on any side of the thermal insulation layer. The material is double-sided: the rough side is placed towards the flowing air steam, the smooth side does not allow water inside.

All membrane vapor barriers are capable of passing moist air in only one direction, which ensures rapid outflow of water and good air exchange throughout the entire room. When installing membranes, good ventilation is also required.

Liquid vapor barrier materials - varnishes and mastics And. After application, they form a film that retains water but allows air to pass through. Plus - it practically eliminates the possibility of mold or mildew. The downside is that not all products, due to their composition, can be used in residential buildings.

Liquid hydro-vapor barrier

Modern new coatings - an analogue of varnishes and mastics, having properties similar to them; used for vapor barrier of the ceiling on the side of a cold attic or flat roof.

Table. Comparative characteristics popular brands of vapor barriers

Material	Weight, g/m2	Vapor permeability in 24 hours, g/m2	Longitudinal/transverse strength, N/5 cm
Glassine	240	79,2	-
Polyethylene film 0.16 mm thick	120	3,2	-
Isorok Foyle VB	90	5,5	150/110
Izospan B	70	0,14	128/104
Icopan, Monaflex classic	110	0,22	285/260
Icopal, Elephant Skin	200	0,2	460/410
Nicobar 85	85	0,8	300/200
Ondutis P70	105	0,7	375/275
Tyvek	100	4,9	550/450
Utah, Utahfol N96 Silver UV	96	0,98	600/450
Utah Standard	118	1,1	230/300

Types of vapor barriers

For correct installation vapor barrier, you need to correctly determine its type:

Type A— passes steam coming from the room through itself, allowing it to evaporate on the other side, but does not allow moisture to penetrate from the street (rain, snow). Installed on a sloping roof.

Type B- a classic vapor barrier that does not allow condensation. It is important to mount the side with the film to the insulation, and the rough surface to the outside. Minus - only suitable for insulated roofs.

Type C- dense, thick membranes, very strong and durable. Installation rules are similar to type B. Can be used as an addition to non-insulated or flat roofs.

Type D— polypropylene fabric; one of the sides is laminated. Has high performance mechanical impact; wide range of applications, especially for places with high humidity.

Rules for laying vapor barrier

If both sides of the material are the same, then it does not matter how you lay the material. But if the parties are different, you must adhere to the following rules.

Distinguishing the sides of a vapor barrier

Usually an indication of the outer and inner sides of the material is in the instructions. If it is missing, but you need to follow the rule, then the side that is lighter in color is placed next to the insulation.

The roll insulation is wound up by the manufacturer so that it can simply be unrolled and laid without turning it over.

If the surfaces of the vapor barrier are different, the smooth side is considered internal (placed against the insulation), and the rough side is considered external.

Different sides of films

How to attach?

Strengthen the material using a stapler, nails with a large head or a counter lath.

How to determine membrane leak?

The material will indicate how wide the overlap should be (8-20 cm). The width of the overlap depends on the installation location:

• on the roof horizontally from bottom to top - 15 cm;
• in the ridge - 18 cm;
• in the valley - 25 cm;
• on other elements - 10−5 cm.

The membranes must be inflated during installation

Is there a need for an air gap at the membrane?

It is always necessary to create an air gap (5 cm) near the membrane - it is necessary for ventilation. In the case of diffusion material, the gap is left outside, and the film is laid on the insulation.

Do joints need to be treated?

Places where pieces of vapor barrier are connected to each other, as well as their connections to window and doorways, you definitely need to glue them with special tapes on a self-adhesive basis (they can also be used to repair torn insulation). Scotch tape is not suitable for this type of work.

Video: how to properly vapor barrier an attic floor

Review of the main vapor barrier manufacturers

There are several popular vapor barrier manufacturers on the market:

1. The Ursa Pure One company surpasses all other companies in quality (according to the Test Purchase program).
2. The manufacturer Technonikol does not lag behind the leader either in quality or in the use of the latest technological developments. This is a domestic company that produces a very high quality product.
3. Ecolife products are good for both industrial and residential construction, but are not suitable for creating temporary roofing.

Not included in the top three:

• Polish company "Fakro" - the company's products are distinguished by the fact that they can withstand very low temperatures.
• "Ondutis" - low prices, excellent connecting tapes, rolled materials.
• Tyvek products provide ideal wind protection.
• German DELTA - steam and wind protection.

Video: how to distinguish a vapor barrier film from a waterproofing film

Let's sum it up

As you can see, the vapor barrier device for the attic floor is very important stage in building a house. Both the functioning of building structures and the health and well-being of residents depend on correctly selected materials and high-quality installation. We hope that this material will help you understand the issues of vapor barrier in the attic ceiling.

Any processes that take place inside a house or living space affect the strength, durability and integrity of all layers of building structures. For example, due to the destructive effects of moisture, load-bearing wooden elements rot, and the effectiveness of thermal insulation decreases. To protect against moisture coming from external environment and premises, vapor and waterproofing of building structures is performed. We'll talk about insulating the ceiling surface. Moreover, protection from moisture is needed not only when there is a risk of flooding in an apartment building, vapor barrier of the ceiling in a cold attic in private building designed to protect structures and increase the efficiency of insulation.

Why is ceiling vapor barrier done?

The main purpose of the vapor barrier layer is protection against moisture condensing in building structures due to temperature changes. This is usually observed in a private house with an unheated attic. But vapor barrier of the ceiling in a warm attic is also important, because it protects the insulation from the penetration of moist air from rooms with high humidity.

The second function of vapor barrier membranes is to ventilate the insulation. Compared to a dense waterproofing layer, vapor barrier allows air to circulate in building structures and remove moisture that condenses in the insulation. This protection is especially important when using wooden floor structures.

Vapor barrier functions:

1. Protection of wooden floor elements from deformation, damage by rot and mold and subsequent destruction.
2. Vapor barrier extends the service life of building structures and insulation.
3. Vapor insulation is part of the insulation system for ceiling surfaces.
4. The fire safety of ceiling structures is increased.
5. If there is a living room above a room with humid processes, then the layer allows you to maintain a favorable microclimate in it.

There are several types of vapor barrier materials, differing in their characteristics and scope of use. What kind of vapor barrier on the attic ceiling will be used depends on the purpose of the room and the presence or absence of heating in the attic space.

Types of vapor barrier materials and areas of application

All vapor barriers according to their operating principle are divided into:

1. Standard materials that are attached to the inside of the ceiling.
2. Also on sale are insulators with a reflective layer that protect against the penetration of water vapor and prevent heat loss by reflecting heat into the room.
3. In buildings for seasonal purposes, vapor barriers with controlled action are used. When the steam cycle is unstable, it is important that the material allows it to escape through the pores in the surface. This insulating material is laid above the insulation (closer to the top of the ceiling). Due to partial vapor permeability, the membrane does not allow moisture to remain in the insulation.
4. There are also insulators with variable vapor permeability. They are mounted above the insulation. Thanks to the special design of the pores, the material allows steam to effectively evaporate from the ceiling and insulation, but at the same time does not allow moisture condensing in an unheated attic to penetrate into building structures.

Also, all insulators are divided according to the type of material from which they are made. The ceiling vapor barrier scheme depends on the insulator used. Let's consider their features in detail.

Glassine

The material is made on the basis of thick cardboard and impregnated with bitumen. It is designed to protect building structures from moisture and water. It is attached to the ceiling on either side. The main advantage is considered low price, and the disadvantage is associated with a short service life.

Polypropylene films

The main advantage of polypropylene products is high mechanical strength and resistance to impact sun rays. The use of these films is justified when the insulating layer is exposed to ultraviolet radiation for a long time. This usually happens when there is a significant break in construction during the summer.

Polyethylene films

The film copes well with its tasks when installed in the ceiling between an unheated attic and a bathroom or kitchen. This material has the highest coefficient of resistance to vapor permeation. If the bathroom or kitchen is located under an unheated attic, then it is better to choose a film with a reflective layer.

Advice! To extend the service life of film vapor barrier, buy reinforced two-layer products. Even rodents cannot damage them.

Conventional membranes

Membranes can perform the functions of vapor and water insulators at the same time. Due to one-way permeability, membrane insulators allow steam to escape from the ceiling and prevent moisture from penetrating inside. The pores in the product have a certain configuration - they are narrow at the bottom and wide at the top. For the material to work effectively, it is important to install it right side– the narrow part of the pores is towards the insulation, and the wide part is towards the top of the ceiling.

Important! There are multilayer, single- and double-sided membranes on sale. They are equally effective, but double-sided products are more economical.

Breathable membranes

For efficient work With a regular membrane, it is important to lay it with a ventilation gap of 5 cm between it and thermal insulation material. Because of this, the thickness of the overlap increases. Breathable membranes do not have this disadvantage. They are mounted close to the insulation. This is due to the peculiarities of their action - they allow water vapor from the heat insulator to pass out, preventing it from becoming damp.

In what cases is ceiling waterproofing used?

The main purpose of the waterproofing layer in the ceiling:

1. Waterproofing the ceiling against leaks from above is important in apartment buildings. It is done in the bathroom and toilet. Its purpose is not only to protect the room from flooding and damage to furniture, but also to prevent the appearance of mold on the ceiling.
2. The coating increases the service life of finishing materials and protects building structures from damage by water.
3. Waterproofing the ceiling in a private house is designed to protect electrical wiring from getting wet and short circuiting.

Waterproofing of the ceiling surface is carried out in rooms with high humidity (bathrooms, kitchens, bathrooms), in basements, on balconies and loggias, and ground floors. In a private house, this layer will protect living quarters in case of a leaking roof.

Waterproofing materials and applications

In apartment buildings, ceilings are often waterproofed from the inside. Materials different in composition, principle of application and action are suitable for these purposes. Each of them is intended for certain type surfaces and has its pros and cons. The largest selection of products designed to protect against moisture concrete surfaces.

Pasting materials

This insulator is divided into two types:

1. Polymer products are made on the basis of atactic polypropylene and modified copolymers. This includes polyethylene and vinyl plastic.
2. Non-polymer waterproofing materials - roofing felt, roofing felt, fiberglass.

Installation of this waterproofing on the ceiling is quite labor-intensive, so it is not advisable to use these materials. There are adhesive insulators with a self-adhesive base and materials that are fused to the surface using a gas burner. The only place where this option for moisture protection is appropriate is a loggia and a glazed balcony.

Penetrating insulation

Penetrating ceiling waterproofing is the most effective method of protecting the ceiling surface from moisture. The resulting coating is durable. The mixture is applied to a damp ceiling, which causes the active ingredients to transform into insoluble crystals. They tightly fill all the pores and cracks on the ceiling surface. Suitable for use on concrete ceilings only. It has been proven that these products increase the strength of structures by 15-20 percent.

Important! The main advantage of penetrating waterproofing is its harmlessness and the fact that it does not interfere with air exchange of the treated surface.

Coating waterproofing

These compositions are divided into several types:

• bitumen-rubber (elastic);
• bitumen-polymer (elastic);
• cement-polymer (inelastic).

They are easy to apply and have a reasonable price. However, plaster must be applied above this waterproofing layer. The insulator is laid in several layers and is used to treat cracks, seams, floors, walls, ceilings in bathrooms, bathrooms, balconies or loggias.

Worth knowing! In terms of their composition, coating products can be two- and one-component. The latter are immediately ready for use, while the two-component ones require preliminary preparation.

Waterproofing by plastering

In addition to cement and sand, such plasters contain special additives and waterproof polymers. After hardening, they form a surface that protects against moisture penetration even under significant pressure. Waterproof plasters are suitable for treating brick and concrete surfaces. They are applied only to a dry base, without cracks.

Powder insulation

It is a mixture of resins, plasticizers and cement. A solution of plaster consistency is prepared by diluting it with water. After this, the mixture is simply applied to ceiling surface. This material is rarely used due to its low resistance to mechanical stress.

Painting compositions

This includes special paints, varnishes, emulsions based on rubber, bitumen, latex and other waterproof components. These mixtures are easy to apply, environmentally friendly, and economical in consumption. Their main disadvantage is their short service life. Suitable for different surfaces, including wooden ones.

Water repellents

These are universal ready-made compositions that are suitable for use on any surface. They have a water-repellent effect. Water repellents are divided according to the method of application. Some are applied by painting, while others are applied like plaster.

When ensuring insulation of a private house and insulation of the roof along the rafters, one must not forget that special attention should be given to a place like the attic.

Development of attic floor insulation with mineral wool

Warm air tends to rise to the top, and therefore temporarily unheated room heat can escape through the cold attic space. Therefore, the issue of insulating the attic must be resolved without delay.

1 Why do you need attic floor insulation?

Insulating a cold attic floor with stone or mineral wool is generally necessary in lightly used rooms that are properly equipped with special roof ventilation.

The attic, or rather its ceilings, serves as a kind of boundary between heat and cold. In such places, the attic floors are exposed to intense moisture due to the formation of condensation.

However, you can properly insulate the floors in the attic of a house with mineral wool with your own hands. The process of insulating the floor in the attic with mineral wool is the creation of a durable thermal insulation coating, which will have a low degree of thermal conductivity.

The technology itself for insulating mineral wool floors in the attic, as well as Energoflex thermal insulation for pipes, implies strict adherence to its stages and requirements.

The technology itself is quite simple and understandable. Good attic floor insulation using mineral wool helps close unwanted gaps.

To do this, the insulation must be laid tightly. In most cases, mineral wool is used to insulate the attic of a house.

The presented insulation is the most suitable for this type of work; it can also be used to insulate the floor surface in the living areas of the house.

Schematic insulation of the attic floor with mineral wool

By organizing good insulation with mineral wool, the most optimal temperature will be maintained in residential premises.

If the procedure is performed incorrectly, moisture rising from the floor of the house will lead to the formation of condensation.

It will accumulate on the ceiling and then seep through the ceilings. The resulting temperature difference in those areas where the attic floors adjoin the walls of the house initiates the formation of mold and microscopic fungi, which can be causative agents of allergic diseases.

1.1 Requirements for attic insulation

The process of insulating the attic floor and insulating the roof of the house with your own hands, or rather the level of its quality, has a direct impact not only on the size of heat loss, but also on the duration of the operational life of the entire truss structure and roof coverings.

The fact is that water vapor located inside the heated room diffuses to the attic of the house. In order for the insulation used to provide a high degree of calculated efficiency of the thermal insulation layer, it must always be dry.

Based on this, the insulation must be protected from excessive humidification by vapors of rising heated air using a special vapor-proof material.

If the attic space is well insulated, it will not only provide high-quality thermal insulation, but will also help increase the service life of the entire roofing structure.

If there is no vapor barrier, steam will penetrate through the unprotected attic floors and condense on the floor surfaces.

This will lead to moisture flowing onto the rafters, which, under its influence, will begin to slowly rot from the inside.

As a result, the likelihood of destruction of the entire roofing pie increases. The thermal insulation performance of the structure is also reduced due to the fact that the tightness of the vapor barrier layer has been compromised.

Before insulating the attic, you need to drain the layer and remove moisture from the entire attic space. To do this, ventilation should be done through windows. They may be:

In order to ensure maximum ventilation intensity, the total area of ​​all ventilation openings should be equal to 0.2-0.5% of the attic floors.

If all work is carried out correctly, then icicles will not form on the roof in winter. The process of insulating the attic space itself is carried out not from the living quarters, but from the attic floor.

This is the most convenient way to lay insulation, the choice of which depends on the technology used and design features buildings.

1.2 Features of insulation of beam floors

When implementing such an insulation scheme using mineral wool, heat is retained in the space between the beams. Their usual height is almost always enough for this, but if necessary, several bars are packed on top.

Insulating the ceiling with mineral wool from the attic side

The lower part of the ceiling is sewn up using molded material, as when insulating the attic of a private house. For this, lining or sheets of plasterboard can be used.

The subfloor covering is laid on top of the beams. It could be a tongue and groove board, plywood sheet or OSB board. Mineral wool is placed on a pre-prepared special vapor barrier layer.

An alternative to it can be an ordinary film made using polyethylene. If the vapor barrier material is foil-coated, then it is laid with the shiny surface down.

The intermediate distance between the beams is filled with mineral wool with the required thickness parameters. The surface of the beams must be equipped with an additional insulating layer.

This will lead to blocking the so-called cold bridges and will significantly reduce the overall level of heat loss. If high quality timber was used to create the beams, then the finishing material is spread directly onto their surface.

Mineral wool is placed between them as when insulating a roof using polyurethane foam, and the attic floor is laid on top. The use of this technology is especially important in houses that are made of logs or beams.

It is important to reliably protect mineral wool from the smallest drops of moisture, this is especially true if the roof has minor coating defects that cause leaks.

The layer of mineral wool must be reliably protected from the effects of wind from the eaves. For this purpose, mineral wool slabs with a high degree of density are used.

2 Why is mineral wool used to insulate an attic?

In most cases, when insulating attic floors, the consumer's choice falls on mineral wool. Its advantage is that its installation does not require special skills.

Mineral wool has excellent thermal insulation properties. Its structure consists of thin glassy fibers, the length of which ranges from 2 to 60 millimeters.

Insulating the attic with mineral wool

High sound insulation characteristics are ensured due to the presence of a large number of air pores.

These pores are located in the space between the fibers and can occupy 95% of the total volume of the insulation. Mineral wool is presented in three varieties; it can be basalt glass and stone.

Basalt wool is made using molten basalt rocks, to which binding elements are added.

This may be a carbonate type rock, which regulates the acidity level of the substance, which entails an increase in the service life of the insulation. Glass wool exhibits high heat-resistant properties and can withstand temperatures up to +450 degrees Celsius.

2.1 Technology for insulating attic floors with mineral wool

When carrying out work related to mineral wool, it is important to comply with all safety requirements and regulations.

This is due to the fact that in the process of cutting and laying such material, the air is filled with tiny particles that can enter the respiratory organs and thus cause harm to human health.

When carrying out installation, be sure to ensure the availability of funds personal protection. Goggles, a respirator and thick rubber gloves must be available.

The process of insulating attic floors begins with the selection of the necessary tools and additional materials. You can't do without:

The essence of insulation technology is that the insulation must be carefully laid in the space between the attic floors or beams.

To enhance the thermal insulation qualities, reliable vapor barrier protection should be used. Warm and moisture-saturated air will continuously rise from the living rooms and reach the top through the ceiling.

There, in the under-roof space, it will collide with a layer of insulation. Due to the fact that mineral wool is generally considered a vapor-proof material, it will absorb all the outgoing moisture inside itself.

If it is left without the necessary access to air and sunlight, it will gradually dry out and, ultimately, lose all its heat-insulating qualities.

The attic is cold interfloor covering 20 cm min of cotton wool

In order to avoid such destructive consequences, it is necessary to lay a vapor barrier material under a layer of mineral wool.

Before starting the main work, you will need to carefully calculate required quantity insulation.

The amount of cotton wool purchased depends on how many layers you plan to use when covering the attic space. In addition, the thermal insulation thickness parameter directly depends on the features climatic conditions in the region.

Insulating the ceiling of a cold attic with mineral wool

Insulating the ceiling of a cold attic with mineral wool - advantages. Features of insulation of cold attic floors with mineral wool.

Cold attic

The device of the so-called cold attic is used in a significant number of private pitched roofs residential buildings and baths. This is due to a number of advantages that are provided by such a constructive solution. The main advantage is that, despite the presence of the word “cold” in the name, such an unheated attic can significantly reduce the heat loss of the building.

The installation of a cold attic is the simplest solution from a technological point of view, especially when compared with the alternative warm option or building an attic. The air temperature of such a room, as a rule, is slightly higher (no more than 4 degrees) than the air temperature outside.

The composition of the structure under consideration includes the following elements (from top to bottom):

• roof covering;
• external attic walls;
• insulated ceiling between the attic and the living space underneath.

It should be noted that insulation of the ceiling of a cold attic with mineral wool or other heat-insulating material can be done both from above and below from the side of the living room, regardless of whether it is wooden or concrete.

The option under consideration has a number of advantages:

• reliability of waterproofing of the coating. It is achieved by reducing the number of superstructures protruding above the roof, which, as a rule, are its weakest points;
• ease of operation. The existing internal under-roof space makes it easy to inspect and maintain all floor and roof structures;
• overlap area is less than area pitched roof, the area of ​​possible heat loss is correspondingly reduced;
• availability of additional operational premises.

In order for the benefits of a cold attic design to be fully manifested, it is necessary to correctly and competently resolve several issues related to the insulation of the attic floor, as well as proper ventilation cold attic.

Organization of ventilation

The main purpose of ventilation in this case is as follows:

• removal of excess water vapor penetrating through the ceiling from below from the residential part of the building, in order to prevent the appearance of condensation and moistening of the insulation and roof truss system;
• creating an optimal microclimate.
• Ventilation occurs through two types of vents:
• cornices (the air passing through them is called supply air);
• ridge (exhaust air passes through them).

Their total area should be 0.2-0.33% of the roof covering area, in other words for a covering area of ​​1000 sq.m. The area of ​​the vents should vary from 2 to 3.33 sq.m. This calculation is carried out in accordance with SNiP standards, and it is quite simple to do. It applies equally to various roofing options covered with metal tiles, corrugated sheets or soft tiles.

The basic rule for the location of vents is as follows: the most efficient work ventilation system with the maximum distance between the inlet and outlet openings.

In most cases, a scheme is used with an approximately uniform arrangement of vents around the perimeter of the building under the overhangs and along the entire length of the roof ridge.

Additional ventilation is often performed through dormer windows installed on the gables or roof slopes, which help with enhanced ventilation. When installing them, they are guided by the rule of symmetry: in order to prevent the presence of unventilated areas, dormer windows should be located on opposite slopes.

Typically, dormer windows are made of three types:

They are installed in such a way that the lower part of the window is no more than 1 meter from the floor level, and the upper part is at least 1.75 meters higher from the floor level. Often, dormer windows are used as an exit to the roof for the purpose of inspecting the roof and the elements of the ventilation system and chimneys installed on it. Sometimes a special hatch is installed for this purpose.

In order to prevent birds from entering, the vents are equipped with protective nets or gratings, and blinds are installed on the dormer windows.

Thermal insulation options

The cold attic design can be used in buildings of any number of floors. One of mandatory conditions its normal operation is high-quality insulation ceilings It is performed in one of two ways:

• from the attic side;
• from the inside from the residential part of the building.

Thermal insulation from the attic

This option is considered the most effective. A wide variety of ceiling insulation for a cold attic can be used: mineral wool (the most commonly used option), polystyrene foam, expanded clay, etc.

Sequence of work stages:

• vapor barrier device (ordinary PVC film or modern materials, having much higher performance characteristics);
• laying mineral wool thermal insulation in two layers;
• creation of a protective coating from cement bonded particle boards.

This unit is one of many possible ones that fulfill the basic requirements for insulating the ceiling of a cold attic and allow you to obtain the following advantages:

• due to the presence of a vapor barrier, moisture does not enter the insulation;
• the DSP coating allows you to move freely without damaging the insulation;
• the design is quite reliable and durable (to further increase the service life, it is recommended to treat the surface of the DSP with antiseptics, which significantly reduce the likelihood of fungi or mold appearing).

It is imperative to additionally insulate the perimeter of the attic. It is carried out by laying a layer of mineral wool 0.75-1 meter wide and a layer thickness of 10 cm. This will reduce or completely avoid the risk of freezing in the upper floor rooms in the corners.

Thermal insulation from inside the living room

Installing a ceiling in a private house with a cold attic and insulation from the inside is done much less frequently, since the work is accompanied by a number of disadvantages:

• the ceiling level decreases;
• Carrying out thermal insulation work disrupts the finishing, if it has already been completed, and requires subsequent repairs;
• not all thermal insulation materials are useful and environmentally friendly, which leads either to an increase in the cost of work or to a decrease in living comfort. For this reason, the use of mineral wool is not recommended. In addition, it is always recommended to leave a ventilation gap between the thermal insulation material and the finishing material.

Thermal insulation from the inside is often carried out in parallel with the installation of suspended ceilings.

One of the most common methods of insulation from the inside is the option using extruded polystyrene foam (penoplex):

• First, the sheathing is installed, onto which the drywall will subsequently be attached. The thickness of the sheathing beam should be 2-3 mm greater than the thickness of the insulation, and the sheathing pitch should be 1-2 mm less than the width of the penoplex;
• after this, the insulation is secured between the sheathing bars with additional fastening with dowels to the ceiling;
• as finishing suspended ceiling plasterboard or suspended ceiling is attached.

There are many other possible ways to insulate a ceiling, but with all the differences in the technologies and materials used, the basic principles must correspond to those given above.

Conclusion

The installation of a cold attic, if the work is carried out competently and the technology requirements are met, is an effective and expedient design solution.

Insulation, ventilation and vapor barrier of the ceiling of a cold attic in a private house

How to properly insulate, ventilation and vapor barrier the ceiling of a cold attic in a private house and what is the best insulation to use?

Roof installation with a cold attic

Most pitched roofs in our country have a cold attic in their design. This name is due to the air temperature in the attic, which should not differ much from the air temperature outside the house. With this arrangement of the attic space, a sufficiently large buffer air zone is formed, which allows you to effectively regulate the temperature in the attic if it is properly arranged.

Cold attic design

When building the roof of a house, many people think about making a cold attic or attic underneath it? The easiest way to organize a roof is with a cold attic space. Construction of an attic will cost several times more and require more labor.. Although, it is undeniable that the attic will significantly expand the living space.

Cold attic roofs have the following main components in their pie::

1. roofing;
2. attic external walls (applicable for gable roofs with pediments);
3. insulated ceiling between the living space and the attic.

Ventilation is provided by eaves and ridge vents. The air passing through the eaves openings is called supply air, and the air leaving through the ridge is called exhaust air. Additionally, ventilation can be done through dormer windows on the gables or roof slopes. The windows are equipped with louvered grilles to allow the ventilation intensity to be adjusted.

Dormer windows are located on opposite slopes of the roof so that there are no unventilated areas.

Dormer windows can be rectangular, triangular and semicircular in shape. Their lower part should be at a height of no more than 0.8-1.0 m from the floor of the attic, and upper part no lower than 1.75 m from the floor in the attic. They can also serve as an exit to the roof of the house to inspect the roof, ventilation and chimney elements.

Steam and thermal insulation of a cold attic

For a roof with a cold attic, it is most important to minimize heat loss through the attic floor. For both wooden and reinforced concrete floors Vapor barrier is mandatory. It is laid on the ceiling itself and protects the insulation from vapors that can condense in the heat insulator after passing through the ceiling of the living room. Slab and bulk materials can be used as insulation. The ceiling pie consists of a vapor barrier, floor beams and insulation.

Often used in ceiling coverings the following types heat insulators:

• expanded polystyrene and foam boards;
• mineral wool slabs or mats;
• expanded clay granules;
• fuel or granulated slag;
• sawdust with lime or clay;
• pumice.

The thickness of the required insulation layer is selected depending on the calculated winter temperature using the table below.

Winter temperatures are calculated according to SNiP 2.01.01-82 (building climatology and geophysics) or selected by regions of the Russian Federation from the corresponding climate maps.

The insulation is placed between the joists or ceiling beams, and the top is made boardwalk for attic passages. Joists are usually 50 mm thick, and decking boards are 25-35 mm thick.

For ventilated attic spaces Soft or semi-hard heat-insulating materials are considered the most optimal.

Attic waterproofing device

Waterproofing roofs with a cold attic, according to many experts, controversial issue. Some say that waterproofing must be present under the roofing material, while others categorically recommend that it be abandoned. Here, a lot depends on the type of roofing material and the angle of inclination of the roof slopes.

Metal roofs are most susceptible to corrosion, which occurs due to possible small leaks or condensation. Therefore, we once again draw your attention to the fact that ventilation plays one of the main roles in the fight against condensation formed.

For flat metal roofs, experts recommend installing superdiffusion membranes. It will prevent moisture from entering the outside of the roof when snow or rain blows in. No matter how well the roof is laid, there is always the possibility of minimal leaks. That is why, by paying a little extra, you will receive additional protection from moisture getting on the insulation in the ceiling of a cold attic.

Possible leaks or condensation entering hydrophobic insulation materials significantly reduce their thermal insulation properties.

If, for example, slate is used as a roofing material, then waterproofing can be abandoned. There is also corrugated sheeting with an anti-condensation coating on the market, which can hold up to 1 liter of water per 1 m2. For our part, we recommend always using waterproofing membranes, because this is the cheapest and easiest additional way to protect your roof from possible leaks.

When installing waterproofing membranes, a counter-lattice is used. It serves as a fixing strip and, due to its height, provides the necessary clearance for ventilation of the under-roof space. The installation of lathing in a cold attic is no different from insulated roofs. The dimensions of the sheathing and its pitch determine the type of roofing being installed.

Cold attic temperature

To prevent ice and icicles from forming on the roof, it is necessary to maintain the correct temperature and humidity conditions in the attic. If the thickness of the thermal insulation material is insufficient, significant heat losses through the ceiling. Warm air, heating the roof covering, causes snow to melt and ice dams to form. By choosing the right insulation layer, this can be avoided.

You can evaluate the effectiveness of a heat insulator by measuring the temperature of the top layer of insulation. Electronic thermometer immersed in insulation by 10-20 mm.

As you can see, the design of a cold attic pie is not particularly complex in design. Main task– ensure the required ventilation intensity and thickness of the thermal insulation layer in the ceiling.

Cold attic: ceiling pie, device, ceiling vapor barrier and waterproofing

Construction and design of a cold attic pie. Vapor barrier for ceilings and waterproofing in a cold attic. Optimal temperature for the attic.

Vapor barrier for ceilings in wooden floors: technological rules for installation

In order to reduce heat loss through building structures, they are equipped with a layer of thermal insulation. Almost all types of insulation need to be protected from the penetration of atmospheric water from the outside and household fumes from the inside. The construction of a vapor barrier cannot be neglected, because this component of the insulation system plays no less a role than waterproofing. It is especially important to know how a vapor barrier is constructed for a ceiling in a wooden floor, since materials that are extremely sensitive to excess water are used in its construction.

The role of vapor barrier in construction

Building structures from the inside are constantly exposed to steam flows released during mandatory operations. household work, breathing of household members, taking hygiene procedures, etc. The penetration of water suspended in the air into the systems that enclose and insulate a house negatively affects their technical and operational properties.

On surfaces moistened with steam, colonies of fungi settle at a brisk pace, rendering almost all types of building materials unusable with amazing speed. Wooden elements rot and collapse. Wet insulation loses about half of its insulating qualities, because... The water contained in it significantly increases thermal conductivity.

Warm air, saturated with water suspended in it, always rushes to where the pressure and moisture content are lower. In our northern latitudes, for most of the year, the temperature and humidity parameters inside buildings are significantly higher than outside them. This feature explains the direction of movement of vapor-containing air masses moving from indoors to the external environment.

The predominant volume of evaporation, according to its own physical nature, is directed upward to “exit” into the atmosphere through the enclosing systems. The most active air flows that include steam “attack” the ceiling, the upper segment of the walls and roof structure. It is they who need to be strongly protected from the penetration of water in the air.

The process of air masses flowing into areas with lower pressure and water saturation is called diffusion. There is nothing particularly scary about it if no mistakes were made during the construction of building structures. Humid air simply will not penetrate the thickness of the insulating pie or move outside without causing damage to the structure.

However, if there were violations during the construction of a house with insulation systems technological rules, water will begin to linger in the enclosing structures. At best, the result will be increased heat loss, a feeling of eternal cold and dampness. In the worst case, destruction or damage to structures is coming, dictating mandatory major repairs.

Steam protection of attic floors

The function of the vapor barrier film in a thermal insulation cake is to prevent water suspended in the air from penetrating into building structures. This means that it is the vapor barrier that must stop evaporation, so as not to let it pass at all, or to reduce it to minimum values something that managed to get through it.

We have already found out that in our regions, steam, along with the air flow, most often moves from buildings to the outside. Only in the summer heat is reverse current possible. The vapor barrier layer should be the first in the path of moist air. Consequently, it is laid on the side of the used premises before thermal insulation.

The installation of a vapor barrier along the ceiling is carried out if the attic is not intended to be heated. In this case, there is no point in insulating the attic space at all, because... it will not be used at all or will be used as a cold warehouse.

True, it is still necessary to protect the materials of the sheathing of the slopes and rafter frame. Waterproofing is installed against external influences, and a ventilation system is installed against the formation of condensation occurring due to the difference in temperatures inside and outside the structure.

According to the requirements of building regulations, in winter, the temperature within a cold attic should not exceed that outside by more than 5 - 6º C. The rules outlined in SP 17.13330.2011 state that in order to equalize the temperature and humidity parameters inside and outside the attic, it is necessary to arrange a natural type of ventilation.

This means that it is necessary to provide the roof structure with vents, dormer windows, aerators, etc. The total area of ​​ventilation openings, regardless of their type and purpose, should be on average 1/300 of the floor area or horizontal projection of the roof. The described measure is quite sufficient to maintain the temperature and humidity balance specified by building regulations.

Specifics of the vapor barrier device

Materials with the lowest vapor permeability are used as vapor barrier protection for the attic floor. This characteristic indicates the ability to conduct evaporation in a certain volume per unit area, indicated in mg/m² per day. All building materials have it to a greater or lesser extent.

Despite the ability of wood to freely allow evaporation to pass through, excess exposure to moisture is undesirable. Natural organic matter is unstable in linear dimensions; when moistened, it expands. Naturally, this property is usually taken into account by designers, but excessive movements of the elements of wooden structures do not benefit them, and moreover, they often lead to rotting.

For the normal operation of a ceiling located under a cold attic, it is necessary to correctly arrange the components according to their ability to pass humidified air. The first thing you should do is place the component with minimal possibility conduct steam, then with vapor permeability greater than the previous one.

Therefore, for a steam protection device, materials with the ability to transmit steam close to zero or equal to fractions of one are mainly selected. Note that it can be several dozen, but must be less than that of thermal insulation. Even taking into account the fact that wood has quite high ability conduct steam, the material for the protection device against it should not allow more than several tens of mg/m² of vapor to pass through per day.

The diagram of an insulated wooden floor, when viewed from the side of the premises being equipped, should look like this:

• Vapor barrier. A layer made of glassine, diffusion membrane, polypropylene or plastic film. During construction it is laid on top of the ceiling. When performing repairs, it is installed on the ceiling from the side of the rooms, glued or secured with slats.
• Thermal insulation. A layer made of backfill, roll or slab types of insulation. Most often it fills the space between floor beams, less often it is laid on top of the floor on a rough flooring or screed. If the attic is not intended to be used, then the thermal insulation is installed without waterproofing and wind protection.
• Waterproofing. A layer made of a diffusion membrane or perforated polyethylene. Installed only in the case of attic use, placed under the flooring or floor covering.

If you do not plan to use the attic, then there is no need to install waterproofing on top of the insulating layer. It is transferred to the slopes, where it performs the work of protecting the entire roofing system from atmospheric water. The insulation layer over the ceiling also does not require wind protection, because The enclosing structure itself protects from heat blowing out of its thickness.

To service the roofing system, ladders are installed within the unused attic. They are laid directly on the joists if slab or roll material is used. The drains are installed on legs if the insulation was formed by filling with expanded clay. Insulation materials laid loosely in the attic must be periodically “loosened” so that caking does not reduce the insulating properties.

Technological subtleties of laying a vapor barrier

The vapor barrier layer under the insulation is laid in the form of a pallet with peculiar sides extending onto the walls. Those. so that this barrier is not only between the ceiling and the thermal insulation, but also between the insulation and the parts of the walls in contact with it. Each beam or wall of the panels must be covered with protective material.

Laying of vapor barrier material on the ceiling is carried out:

• With a bend around each beam. The material “without tension” is laid in longitudinal strips perpendicular to the beams with a recess into the space between the beams. The opening of the vapor barrier is carried out taking this circumstance into account. If the length of one strip is not enough, the panels are glued together.
• With wrapping from the inside of each compartment of the box-panel floor. The material is cut into pieces corresponding to the size of the shield and the height of its walls.
• With laying on top of the rough flooring or with fastening from the inside to the ceiling, if insulation is carried out in order to increase the insulating properties of the structure during the period of repair.

Regardless of the floor plan, vapor barrier for the ceiling under the attic in wooden house should form a continuous carpet that does not allow water to pass through or conducts it in a minimal volume. For this cloth roll material laid with the overlap specified by the manufacturer, the size of which is indicated in the instructions, and glued together with one- or double-sided tape.

The vapor barrier material should be rolled out over the ceiling as it was wound by the manufacturer. There is no need to turn over or rewind anything. In order not to confuse the sides of the installation, the manufacturer designates the side in contact with the ceiling.

How to choose suitable material

It is important not only to install the vapor barrier correctly, but also to choose the most suitable material for its installation. Tandem vapor barrier - the insulation must work perfectly, preventing the possibility of the thermal insulation cake getting wet.

The most ancient version of the steam protection device is fatty clay, which was used to treat the ceiling from below or above. Paired with clay, a dry soil-vegetative layer was used to prevent the penetration of hot air in hot weather and cold air in cold weather. Instead of soil, fine peat, shavings, sawdust, dry leaves and similar materials can be used.

Instead of outdated insulating varieties, materials specially designed to protect against steam and heat loss are now used. Their installation is much easier and significantly faster. However, in terms of insulating properties they are inferior to old proven methods.

For the installation of vapor barrier protection for attic floors, the following are now used:

• Glassine. Budget option with a vapor permeability of about 70 mg/m² per day. It is used mainly in domestic buildings that do not require an increase in humidity levels above standard values.
• Films made of polypropylene and polyethylene. Vapor permeability is measured in units, approximately 3 – 5 mg/m² per day. Most of these are reinforced materials that are resistant to temperature changes, mechanical stress and UV radiation. Suitable for arranging wooden floors under backfill insulation.
• Vapor barrier membranes with foil shell. Vapor permeability averages 0.04 – 2.55 mg/m². They are used for arranging rooms with high humidity and unstable temperature conditions: saunas, steam rooms, Russian baths, swimming pools, combined bathrooms.
• Anti-condensation diffusion membranes. Their ability to transmit steam varies over a wide range from 3 to 15 or several tens of mg/m². This newest varieties universal purpose. In a used attic floor, thermal insulation can be installed on the bottom and top sides.

Anti-condensation varieties are available in the form of double-sided polymer membranes. On one side, which should be facing the steam, they are rough, which prevents the formation of dew. The opposite side is smooth, it prevents the penetration of moisture from the outside.

Vapor barrier for a ceiling in a wooden floor: vapor barrier in a wooden house

How to install a vapor barrier for a ceiling in a wooden ceiling, rules for choosing and using a vapor barrier film in the insulated structure of a wooden house.

The device of the so-called cold attic is used in a significant number of pitched roofs of private residential buildings and bathhouses. This is due to a number of advantages that are provided by such a constructive solution. The main advantage is that, despite the presence of the word “cold” in the name, such an unheated attic can significantly reduce the heat loss of the building.

Description

The installation of a cold attic is the simplest solution from a technological point of view, especially when compared with the alternative warm option or the construction of an attic. The air temperature of such a room, as a rule, is slightly higher (no more than 4 degrees) than the air temperature outside.

The composition of the structure under consideration includes the following elements (from top to bottom):

• roofing;
• external attic walls;
• insulated ceiling between the attic and the living space underneath.

It should be noted that insulation of the ceiling of a cold attic with mineral wool or other heat-insulating material can be done both from above and below from the side of the living room, regardless of whether it is wooden or concrete.

The option under consideration has a number of advantages:

• reliability of waterproofing of the coating. It is achieved by reducing the number of superstructures protruding above the roof, which, as a rule, are its weakest points;
• ease of operation. The existing internal under-roof space makes it easy to inspect and maintain all floor and roof structures;
• the overlap area is smaller than the area of ​​the pitched roof, which reduces the area of ​​possible heat loss;
• availability of additional operational premises.

In order for the benefits of a cold attic design to be fully realized, it is necessary to correctly and competently resolve several issues related to the insulation of the attic floor, as well as proper ventilation of the cold attic.

Organization of ventilation

The main purpose of ventilation in this case is as follows:

• removal of excess water vapor penetrating through the ceiling from below from the residential part of the building, in order to prevent the appearance of condensation and moistening of the insulation and roof truss system;
• creating an optimal microclimate.
• Ventilation occurs through two types of vents:
• cornices (the air passing through them is called supply air);
• ridge (exhaust air passes through them).

Their total area should be 0.2-0.33% of the roof covering area, in other words for a covering area of ​​1000 sq.m. The area of ​​the vents should vary from 2 to 3.33 sq.m. This calculation is carried out in accordance with SNiP standards, and it is quite simple to do. It applies equally to various roofing options covered with metal tiles, corrugated sheets or soft tiles.

The basic rule for the location of vents is as follows: the ventilation system operates most efficiently when the inlet and outlet openings are as far apart as possible.

In most cases, a scheme is used with an approximately uniform arrangement of vents around the perimeter of the building under the overhangs and along the entire length of the roof ridge.

Additional ventilation is often performed through dormer windows installed on the gables or roof slopes, which help with enhanced ventilation. When installing them, they are guided by the rule of symmetry: in order to prevent the presence of unventilated areas, dormer windows should be located on opposite slopes.

Typically, dormer windows are made of three types:

• rectangular;
• triangular;
• semicircular.

They are installed in such a way that the lower part of the window is no more than 1 meter from the floor level, and the upper part is at least 1.75 meters higher from the floor level. Often, dormer windows are used as an exit to the roof for the purpose of inspecting the roof and the elements of the ventilation system and chimneys installed on it. Sometimes a special hatch is installed for this purpose.

In order to prevent birds from entering, the vents are equipped with protective nets or gratings, and blinds are installed on the dormer windows.

Thermal insulation options

The cold attic design can be used in buildings of any number of floors. One of the prerequisites for its normal operation is high-quality insulation of the floor. It is performed in one of two ways:

• from the attic side;
• from the inside from the residential part of the building.

Thermal insulation from the attic

This option is considered the most effective. A wide variety of ceiling insulation for a cold attic can be used: mineral wool (the most commonly used option), polystyrene foam, expanded clay, etc.

Sequence of work stages:

• vapor barrier device (ordinary PVC film or modern materials with much higher performance characteristics can act as a vapor barrier material);
• laying mineral wool thermal insulation in two layers;
• creation of a protective coating from cement bonded particle boards.

This unit is one of many possible ones that fulfill the basic requirements for insulating the ceiling of a cold attic and allow you to obtain the following advantages:

• due to the presence of a vapor barrier, moisture does not enter the insulation;
• the DSP coating allows you to move freely without damaging the insulation;
• the design is quite reliable and durable (to further increase the service life, it is recommended to treat the surface of the DSP with antiseptics, which significantly reduce the likelihood of fungi or mold appearing).

It is imperative to additionally insulate the perimeter of the attic. It is carried out by laying a layer of mineral wool 0.75-1 meter wide and a layer thickness of 10 cm. This will reduce or completely avoid the risk of freezing in the upper floor rooms in the corners.

Thermal insulation from inside the living room

Installing a ceiling in a private house with a cold attic and insulation from the inside is done much less frequently, since the work is accompanied by a number of disadvantages:

• the ceiling level decreases;
• Carrying out thermal insulation work disrupts the finishing, if it has already been completed, and requires subsequent repairs;
• not all thermal insulation materials are useful and environmentally friendly, which leads either to an increase in the cost of work or to a decrease in living comfort. For this reason, the use of mineral wool is not recommended. In addition, it is always recommended to leave a ventilation gap between the thermal insulation material and the finishing material.

Thermal insulation from the inside is often carried out in parallel with the installation of suspended ceilings.

One of the most common methods of insulation from the inside is the option using extruded polystyrene foam (penoplex):

• First, the sheathing is installed, onto which the drywall will subsequently be attached. The thickness of the sheathing beam should be 2-3 mm greater than the thickness of the insulation, and the sheathing pitch should be 1-2 mm less than the width of the penoplex;
• after this, the insulation is secured between the sheathing bars with additional fastening with dowels to the ceiling;
• plasterboard or suspended ceiling is attached as the final finishing of the suspended ceiling.

There are many other possible ways to insulate a ceiling, but with all the differences in the technologies and materials used, the basic principles must correspond to those given above.

Conclusion

The installation of a cold attic, if the work is carried out competently and the technology requirements are met, is an effective and expedient design solution.