Everything you need to know about choosing a vapor barrier for cold and attic roofs. Choosing a material for vapor barrier in the attic - advantages and disadvantages Which vapor barrier film is better for the attic

The attic in the house has its advantages and disadvantages. Which? About it read here. As the voting results show ( see results here) a house with an attic attracts approximately 50% of readers.

Work on insulating the attic is carried out either from above before installing the roof covering, either from below, after the house is protected from precipitation.

The first option is from above, it is more convenient to install, and allows you to carry out work faster and with better quality.

With the second option - from below, you can postpone the work and costs of arranging the attic until later.

The designs of insulated roofs in both cases are somewhat different.

Insulating the attic from above

In this article, we will consider the use of steam-wind-moisture-proof membranes in the construction of an insulated roof of an attic floor using the example of a system of protective materials trademark Izospan. You can read about the materials of this system in the article “Vapor-wind-waterproof films and membranes”.

Installation of an insulated attic roof

1. Roof covering
2. Wind- and moisture-proof film Izospan AS, AM
3. Counterrail
4. Insulation
5. Vapor barrier Izospan B
6. Rafter
7. Interior decoration
8. Lathing

Scheme for protecting attic insulation from wind, moisture and condensation in Fig. 2

Wind and moisture protection of attic insulation

Fig.2. To protect the attic insulation from wind, moisture and condensation, a ventilated gap is arranged, and films and Izospan membranes are laid below and above.

Why protect insulation from wind?

Mineral wool insulation, which is usually used for roof insulation, has an open porous structure.

Air moving in the ventilated gap easily penetrates the insulation, blowing heat out of it. The effectiveness of thermal insulation due to air infiltration can be reduced by almost half.

In addition, air moving under the influence of wind in the gap tears off and carries away insulation particles. Weathering of the insulation occurs - over time, its density and thickness decrease, the insulation becomes a source of dust, which can penetrate into the house.

To prevent these processes, the insulation on the top side of the ventilated gap is covered with windproof, vapor-permeable material.

In addition, the wind-moisture-proof membrane (item 2 in Fig. 1) protects the insulation and load-bearing structural elements from under-roof condensation, snow and atmospheric moisture, which can be blown into the gaps of the roofing covering or penetrate into the joints of roofing sheets due to capillary suction.

The wind-waterproof membrane should not prevent steam from escaping from the insulation (vapor permeability of at least 750 g/m2 per day).

In the construction of an insulated roof, it is recommended to use vapor-permeable roofing membranes Izospan AM or Izospan AS as waterproofing and wind protection. Materials Izospan AM and Izospan AS laid directly on the insulation without a ventilation gap between them.

Izospan AM and Izospan AS are not intended for use as a main or temporary roofing covering for the period of installation.
Izospan AM and Izospan AS are laid with the white side facing the insulation.
When installing an insulated roof, Izospan AM (Izospan AS) is rolled out and cut directly on top of the insulation. Installation is carried out with horizontal panels overlapping, starting from the bottom of the roof. The overlap of panels at horizontal and vertical joints is at least 15 cm.

The stretched material can be further strengthened on the rafters with staples using a construction stapler.

On top of the material, wooden antiseptic counter-battens 4x5 cm are attached vertically along the rafters with nails or self-tapping screws. The place of the vertical overlap or the junction of two horizontal panels must be pressed against the rafters with a counter batten.

Lathing or continuous plank flooring is mounted along the counter-battens, depending on the type of roofing.

For weathering water vapor and roof condensation must be provided ventilation gap between the outer side of the Izospan AM (Izospan AS) material and the roofing to a counter-batten thickness of 4-5 cm.

In addition, to ensure ventilation of the under-roof space ventilation holes are provided in the lower part of the roof and in the ridge area for air circulation.

The material Izospan AM (Izospan AS) is fastened in a tense position so that water can roll freely over its surface. The bottom edge should provide a natural drainage of moisture from the surface of the membrane into the gutter.

Vapor barrier for attic insulation

The vapor barrier film (item 5 in Fig. 1) performs several functions at once:

1. Protects the insulation from penetration of water vapor from the attic room. From the article “Dew point, vapor barrier and air gap» you can find out why without a vapor barrier, insulation will accumulate moisture and collapse.
2. In addition, vapor barrier performs another function - it reduces the air permeability of the attic enclosing structures, thereby reducing heat loss.
3. The material protects the living space from the penetration of microfibers (dust) of the insulation.

Izospan B used as a vapor barrier in insulated roofs of exploited attics with various types of roofing.
When installing an insulated roof, the Izospan V vapor barrier is mounted on the inside of the insulation on the rafters or along the rough sheathing using a construction stapler or galvanized nails. Installation is carried out from bottom to top with horizontal panels overlapping with an overlap at horizontal and vertical joints of at least 15 cm.

When decorating a room with clapboard (plywood, decorative panels etc.) the vapor barrier is fixed along the frame with vertical antiseptic wooden slats 4x5 cm, and when finishing with plasterboard - galvanized profiles.

The material is installed with a tight fit with the smooth side to the insulation, with the rough side down. The interior decoration of the room is attached to a slatted frame or galvanized profiles with a ventilation gap of 4-5 cm.

To ensure the tightness of the vapor barrier, it is recommended to fasten the panels of Izospan B material together with Izospan KL or SL connecting tape. Places where Izospan materials meet wooden, concrete and other surfaces are glued with Izospan ML proff adhesive tape.

Instead of Izospan B, Izospan RS, Izospan C or Izospan DM can be used as a vapor barrier when installing an insulated roof. The installation diagram is similar.

Heat-reflecting vapor barrier for attic insulation

Can be used as a vapor barrier heat reflective vapor barrier: Izospan FS; Izospan FD And Izospan FX. The material is mounted on the inside of the insulation (on the rafters or along the rough sheathing using a construction stapler or galvanized nails) with the metallized surface facing the room.

There must be an air gap of 4-5 cm in front of the metallized surface of the membrane. Only in this case does it happen reflection heat flow, which increases thermal resistance coverings. Installation is carried out with horizontal panels overlapping, starting from the bottom of the roof. The overlap of material at horizontal and vertical joints is at least 15 cm (Izospan FX - end-to-end).

Vapor barrier sealing

The vapor barrier layer prevents the insulation from getting wet. In places with defective vapor barriers, the insulation becomes saturated with moisture in winter. These places begin to freeze, fungus and mold appear on the walls, and the insulation itself gradually deteriorates.

Careful sealing of the vapor barrier layer is a necessary condition for long and reliable service of thermal insulation and wooden roof parts. The same thing happens if water gets into the insulation from above. But developers, due to misunderstandings, often neglect the threat of moistening the insulation from below, from inside the room.

To wooden parts vapor barrier film secured with staples. TO metal profiles sheathing is glued to Double-sided tape. The vapor barrier film is laid with a 10 cm overlap. The film should not be stretched too much, since the film changes its size when the temperature changes.

The joints of the film are taped with tape made from a material with a similar coefficient of thermal expansion. The junction of the film to the walls is more reliable press with planks and apply sealant underneath them to the wall, since on rough surfaces adhesive tapes They don't hold up well.

It is more reliable to make film joints over a hard surface, where, in addition to gluing, the joints can be pressed with spacers, sheathing bars, secured with staples, etc. Passages through the vapor barrier of chimneys and ventilation pipes are also carefully sealed. Don't neglect sealing plumbing piping and electrical wiring.

Choosing insulation for the attic

To insulate the attic, it is recommended to choose fireproof mineral wool insulation. In summer the roof can heat up to 60 degrees C, and in winter through thin layer wet insulation can lose up to 25% of the heat. Therefore, it is so important to lay a sufficient layer of insulation and prevent it from getting wet.

Modern energy saving standards recommend providing a heat transfer resistance of 4-5 m2*K/W for the attic roof. In order to obtain the economically justified heat transfer resistance required by the standards, it is necessary to lay a layer of mineral wool insulation 20 - 25 cm thick.
How to calculate the thickness of attic insulation find out here.

The height of the roof rafters, as a rule, does not exceed 15-18 cm. Additional layers of thermal insulation are placed between the bars of the internal sheathing, or bars of the required height are nailed to the rafters from below.

Soundproofing the attic

In addition to good thermal protection, the outer fencing of the attic must provide sufficient sound insulation of the attic rooms from airborne noise. People sleeping in the attic should not be awakened by the impact of raindrops or hail on the metal roof covering.

Therefore, the external fencing of the attic is subject to fairly stringent sound insulation requirements.

In accordance with current standards, the airborne noise insulation index of the external enclosure of the attic - Rw, must be at least 45 dB. The same mineral wool insulation is used as sound insulation and against airborne noise as for thermal insulation.

To achieve this indicator in the external enclosures of the attic The thickness of mineral wool sound insulation must be at least 250 mm. If the thickness is less, then the sound insulation will not meet the standards. Thus, the thickness of the mineral wool thermal and sound insulation of the attic is selected based on two conditions: thermal insulation and sound insulation. The thickness is the greater of the two indicated.

Insulating the attic when working from the inside

Features of the attic insulation design when performing work from the inside, under the installed roofing, are clearly visible in the figure below (to zoom in, press the Ctrl and + keys simultaneously):

If the ceiling of the upper floor in the house is made according to wooden beams, then the floors and partitions in the attic should have light weight and provide the necessary sound insulation. In this case, it is best to make a floating floor with a dry screed from gypsum fiber sheets (GVLV) or other boards, and also install soundproofing frame partitions. Just such an option is shown in the figure.

Note, frame partition should cut through the attic sheathing as far as possible, and the base of the partition should rest on the subfloor. This design will prevent sound transmission to the adjacent room bypassing the partition, through the finished floor covering and attic cladding.

If special measures are not taken, then soundproofing of attic rooms with frame external walls, partitions, floors and ceilings will be insufficient.

If the ceiling of the upper floor in a house with an attic is made of reinforced concrete slabs or prefabricated monolithic from light blocks, then on such a floor it is more profitable to lay partitions from brick, as well as from light gypsum or concrete building blocks.

Watch the video, which clearly shows the thermophysical processes in an insulated roof and the basic installation rules. While watching the film, remember the need for wind protection with mineral wool insulation.

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Bituminous shingles. Mogtazh, laying of soft roofing

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Heating diagram with solid fuel boiler and heat accumulator.

When constructing an insulated attic roof, a vapor barrier must be used. The absence of this layer in the roofing pie leads to wetting of the insulation and premature destruction rafter system.

Vapor barrier for mansard roof protects insulation and load-bearing materials wooden structures roofs from saturation with moist vapors that appear as a result of human activity. This reduces the risk of fungus and mold appearing in the under-roof space.

Do not confuse vapor barriers with superdiffusion membranes. The latter are laid on top of the insulation and play the role of waterproofing, but at the same time retain the ability to “breathe” and remove moisture from the surface of the insulation.

Materials for roof vapor barrier are represented by several types of films:

Single layer films made of polyethylene or polypropylene. They are characterized by low strength; if handled carelessly, the film can easily be torn.

Multilayer films- have higher strength and service life, and can be additionally reinforced with a reinforcing layer.

Reflective films with a reflective layer of foil - allows you to retain heat in the room and will become great solution when installing a roof over a sauna, swimming pool or bathroom.

Read also: how to properly insulate the roof of a house.

1. If financial capabilities allow, choose Delta Reflex or AirGuard Reflective films.
   Delta DAWI GP is a little simpler and cheaper.
2. AirGuard Sd5 - suitable for houses with non-permanent residence. Has limited vapor permeability to remove residual moisture from the room.
3. Jutafol are Czech films from the Juta company. Lots of good reviews from builders, excellent choice in terms of price-quality ratio.
4. Ondutis and Izospan are an economical option.

Rules for installing vapor barrier film

The vapor barrier film is laid on top of the insulation from the attic side and fixed using a construction stapler. The joints of the canvases are glued mounting tape to ensure tightness.

When working with the material, you should consider the following tips:

The sheets can be laid in any direction if there is a rough insulation file. When installing directly on the rafters, it is better to place the sheets horizontally.

The minimum overlap of one canvas on another should be 10 cm. The joints and abutments must be carefully taped.

When working with window openings It is worth providing for a deformation reserve (fold). Near windows it is important to pay attention Special attention sealing joints and protecting the material from sunlight.

After fixing the vapor barrier, perform wooden sheathing 25 mm slats. It is needed for attaching the rough sheathing and creating a ventilation gap. When finishing the ceiling and walls of the attic with plasterboard, a special metal profile is used instead of bars.

Competent and high-quality execution Vapor barrier work on the attic will extend the life of the roof and save the owner of the house from costly repairs.

The roof structure is complex system. It consists of several layers dissimilar materials, each of which performs its own unique function.

To ensure comprehensive protection of the building from the influence environment high-quality implementation of all installation work, as well as the correct choice of basic and insulating materials. This whole process is briefly called roof insulation.

The standard composition of the roofing cake includes:

• Internal finishing layer;
• Lathing design;
• Vapor barrier material;
• Counter-breach;
• Thermal insulation (not used for a cold attic);
• Waterproofing layer (read about chimney waterproofing here);
• Ventilation shafts or gaps;
• Roofing covering.

Why do you need a roof vapor barrier?

Why do you need a roof vapor barrier? Vapor barrier layer protects the roof from the penetration of water vapor into the thermal insulation. The fact is that insulating materials for the most part have porous structure, since the air contained in them performs the function heat insulator. On contact with a colder environment, steam turns into condensate, which lingers in the voids.

This may result in loss of functionality heat-insulating material, as well as the occurrence of decomposition and rotting processes in summer. In winter, freezing water expands, thereby destroying the connections between cellular elements.

The main characteristic of vapor barrier material is vapor permeability, depending on the density of the material. The values ​​of this indicator can be found in the passport of the packaged building material.

Release form of vapor barrier films - roll. Vapor barrier can be made from various materials. Some of them have additional positive properties that increase operating efficiency interior spaces building. Installing a vapor barrier on a roof is not as difficult as it seems at first glance, but it requires a careful approach and accuracy.

Types of vapor barrier

Single layer polyethylene films

Made from low-density polyethylene, which provides an increased degree of steam penetration. This material often has defects due to the ingress of foreign particles during manufacturing. Most cheap look insulating material.

Polyethylene films with reinforcement

Compared to single-layer polyethylene, reinforced vapor barrier has little greater thickness, since it includes a reinforcing frame. It consists of polymer twisted threads located in mutually perpendicular directions. The mesh is attached to the polyethylene base by warm pressing.

This technique does not affect waterproofing and mechanical properties material, but maybe reduce the degree of vapor barrier.

Anti-condensation film

Made from two layers: smooth and fleecy. The smooth layer is attached to the insulated surface. The fleecy layer is created from cellulose fibers. When steam hits such a surface, it clings to the fibrous structure, thereby preventing moisture from flowing onto the underlying structures of pitched roofs. Excess water is removed along with the air through the ventilated space.

Polymers with foil layer

They are made of penofol or foamed polypropylene, coated with a thin layer of metal. Due to the reflective properties of metal surfaces, such a vapor barrier provides an additional function heat loss protection.

Membranes (film for roof vapor barrier)

Membrane vapor barrier materials are divided into five main classes:

• Type A. Has increased resistance to moisture and wind. It is laid between the roofing and the heat-insulating layer. Manufacturing technology: spunbond. This vapor barrier does not allow moisture to flow through the cracks of the roofing material, as well as from the condensation that forms. The absence of a laminating layer allows the use of such membranes in roofing structures with a slope more than 35 degrees. To remove excess moisture, it is necessary to install ventilation holes from a double sheathing located between the membrane and the insulation.
• Type AM. Unlike Type A has a multilayer structure. It is placed between the insulation and the roof to provide adequate protection from negative atmospheric influences. The most common is three-layer construction, consisting of two layers of spunbond with a diffuse film located between them. It acts as a waterproofing agent, as it allows steam to pass through but retains water. Laying is done directly on the heat-insulating layer, which reduces labor costs for creating a ventilation gap.
• Type B. Double layer material. Consists of a layer of vapor barrier film and spunbond. It is used to protect insulation from internal building vapors. Applicable only in insulated roof structures.
• Type C. Manufactured similarly to type B membranes. It is more durable and thick layer spunbond, which provides better protection of the insulation from moisture. Used in insulated and non-insulated, pitched and flat roofs.
• Type D. Consists of polypropylene fabric, protected on one side by a laminating polymer coating. The structure of the material allows it withstand significant mechanical stress. This dictates its installation between the insulation and the attic floor screed, as well as in non-insulated roofing structures.

Which side is the vapor barrier for the roof laid on?

The principle of installation of vapor barrier materials depends on which side the layer responsible for repelling water vapor is located:

We have figured out which side to lay the vapor barrier on the roof, now we will look in detail at how to properly lay the vapor barrier on the roof.

Vapor barrier for the roof: how to install it correctly using special technology

Laying a vapor barrier on the roof is carried out as follows:

Laying can be done vertically and horizontally. In the second option, installation of roof vapor barrier is carried out starting from ridge part roofs. Each subsequent stripe is superimposed on the previous layer with an overlap, the size of which should not be more than 10 cm.

CAREFULLY!

When joining elements, mandatory seam sealing, providing optimal protection from moisture getting into the gap between them. Most often, sizing is done with single- or double-sided adhesive tape or tape. On roofs with a slope of up to 3 degrees additional fixation using wooden planks.

1. The vapor barrier is attached to the wooden rafter elements using galvanized nails or a staple gun.
2. When installing films and membranes near roof hatches, you need to use a special vapor barrier apron, which is included as standard.
3. At the junctions with ventilation pipes, film and membrane structures are folded down, wrapped around the pipe and tightly fixed with construction tape.
4. After laying the vapor barrier layer, it is necessary to nail down wooden blocks. The rules for laying vapor barrier on the roof dictate the following rule - the pitch between the sheathing bars should be 500 mm. In this case, a ventilation gap is formed, and additional fastening of the vapor barrier layer is carried out. Now you know how to lay a vapor barrier on a roof, you can move on to the issue of waterproofing.
5. If the vapor barrier for the roof was damaged, then small cuts or holes can be seal with special tape for vapor barrier membranes.

Roofing pie diagram

Sealing joints with tape

Final vapor barrier option

NOTE!

A tightly stretched film is the key to a good vapor barrier.

Hydro and vapor barrier of the roof - what is the difference?

Waterproofing materials also serve as protection structural elements from moisture. However, unlike vapor barriers, they are not resistant to moisture-saturated air masses. That is, steam escaping from the premises will freely penetrate through the insulating layer. Therefore, when purchasing vapor barrier films and membranes, make sure that they are intended for the correct purpose. Read more about roof waterproofing here.

Useful video

And now we invite you to familiarize yourself with the video instructions on roof vapor barrier:

Conclusion

Vapor barrier is the lightest and thinnest layer of the roof. But neglect of its structure can nullify all material and physical efforts to create quality roof. So don't neglect it important element, it will significantly increase the service life of the entire building.

One of the most important tasks when constructing an attic is to protect it from the formation of condensation, which can lead to damage to the rafter system and thermal insulation material, as well as to increased costs for heating the house. Proper attic vapor barrier should be laid at the design stage. But if mistakes were made during the construction of the structure, then the volume of subsequent repair work, as well as measures to renovate the attic will be comparable only with a new stage of construction.

Mechanism of condensation formation

Before deciding which vapor barrier to choose for an attic roof, you need to understand the mechanism of formation and movement of water vapor. There are two principles of transfer and formation of condensate:

1. Diffusion is the movement of steam from an area of ​​high pressure to an area of ​​low pressure. In winter, such a transfer is carried out from a warm heated room towards the cold outside, where low partial pressure is observed. In the summer, the direction of flow changes, and steam from the warmer and more humid outdoor air is directed into the drier and cooler space of the attic. In the path of the diffusion flow there are attic roof structures (waterproofing, insulation, vapor barrier, finishing). It is the diffusion permeability of these materials that determines the amount of vapor that can penetrate due to diffusion. Since the layers of waterproofing and insulation practically do not resist the passage of steam, they can be ignored. In such a design, only the qualities of the vapor barrier material are important. This is why it is so important to choose a high-quality vapor barrier for your attic.

Important! The greater the difference in temperature and humidity between indoors and outdoors, the greater the diffusion flow.

1. Convective is the movement of air and steam flows through loose layers of coatings and thermal insulation materials. The intensity of this transfer is directly related to the strength of the wind and the dimensions of the cracks. In modern roof systems, the function of air protection is performed by layers of hydro- and vapor barrier. They can completely eliminate the possibility of convective moisture transfer.

IN real conditions During roof operation, both mechanisms of moisture penetration are present. In this case, the intensity of the diffusion process is directly related to the choice of good vapor barrier and pressure drop. In turn, the convective process completely depends on the quality of insulation work and the use of sealing tapes and mastics.

Attention! When comparing the degree of moistening of roof structures during the diffuse and convective process, we can say that the latter is much more dangerous, since it penetrates into the structure large quantity water vapor.

Consequences of dampening structures

Vapor barrier of an attic roof is an important component of the roofing pie design. If we choose a low-quality vapor barrier material or install it in violation of the technology, then home owners may face the following negative consequences of waterlogging of the thermal insulation material:

• The entire structure reduces heat transfer resistance. This leads to higher operating costs.
• Mold and moisture can damage roof support structures (both metal and wood).
• Due to increased air permeability of structures and dust ingress, the air quality in the house decreases. The favorable microclimate and comfort of living in attic spaces suffer significantly.

That is why, when arranging the roof structure and the roof itself, it is important not only to know which vapor barrier film is better, but also to install the material correctly. A particular danger from the point of view of poor-quality vapor barrier is represented by loose overlaps of vapor barrier material, poorly executed connections to walls and other structural components of the roof.

Important! the main task when arranging a roof - eliminating or minimizing the uncontrolled movement of air containing water vapor through roof structures.

Types of materials

Today we can choose not only high-quality vapor barrier materials, but also entire vapor barrier systems, which include special films, adhesive tapes and mastics, as well as ready-made technical solutions for roof installation. The choice of characteristics and type of vapor barrier material is directly related to design features attic space and its temperature and humidity conditions.

Below we provide a list of the most common vapor barrier systems with their pros and cons:

1. Single-layer polyethylene films. The advantages include high vapor diffusion resistance (more than 100 m) with a small material thickness (200 microns), the ability to control the quality of insulation due to the transparency of the material, as well as good elongation at break. Among the disadvantages is the low strength of the material in places of fixation with staples.
2. Polyethylene multilayer films with reinforcement. Pros: high strength and transparency. Disadvantages: low resistance to vapor diffusion due to the thinness of the interweaving of the reinforcing mesh fibers. It is worth noting that films weighing at least 200 g/m² are most often used.
3. Polymer films woven base with lamination in one layer. The advantages include high strength. The disadvantage is the lack of transparency, low diffusion resistance due to the presence of a continuous thin polymer layer, as well as low elongation at break.
4. Multilayer foil polyethylene film. The advantages include high density material and a relatively good coefficient of resistance to vapor diffusion, as well as additional heat retention in the room due to the reflexive layer. For a more airtight installation, self-adhesive tapes are used along the edges of the material. The only disadvantage is the lack of transparency.
5. Polymer-bitumen roll self-adhesive vapor barriers. They are quickly installed, since they are simply glued to a solid base of concrete or OSB on a layer of primer. Such products can be used on a vertical surface without additional gluing of overlaps.
6. OSB can be used as a vapor barrier, but this material is only suitable for places with normal humidity in buildings where wet finishing work is not used. Their scope of use is prefabricated and frame structures. Places of junctions and overlaps must be additionally taped. OSB is only suitable for roofs with simple geometry. Above wet areas It is necessary to lay a layer of film vapor barrier. This material is not suitable for use in houses made of timber and logs due to high shrinkage.
7. Adaptive polyamide vapor barrier has variable vapor permeability and is only suitable for renovation of places with normal humidity. It is not used in new construction.

As you can see, the abundance of vapor barrier systems allows you to reliably protect roof structures from condensation. However, the effectiveness of any material is directly related to the correct choice of it, taking into account the temperature and humidity conditions of the room and the roof structure, the use of accessories for better sealing of the layer, as well as the use of the right technical solutions.

When constructing an insulated attic roof, a vapor barrier must be used. The absence of this layer in the roofing pie leads to wetting of the insulation and premature destruction of the rafter system.

A vapor barrier for an attic roof protects the insulation and load-bearing wooden roof structures from saturation with moist vapors that appear as a result of human activity. This reduces the risk of fungus and mold appearing in the under-roof space.

Do not confuse vapor barriers with superdiffusion membranes. The latter are laid on top of the insulation and play the role of waterproofing, but at the same time retain the ability to “breathe” and remove moisture from the surface of the insulation.

Materials for roof vapor barrier are represented by several types of films:

Single layer films made of polyethylene or polypropylene. They are characterized by low strength; if handled carelessly, the film can easily be torn.

Multilayer films— have higher strength and service life, and can be additionally reinforced with a reinforcing layer.

Reflective films with a reflective layer of foil - allows you to retain heat in the room and will be an excellent solution when installing a roof over a sauna, swimming pool or bathroom.

1. If financial capabilities allow, choose Delta Reflex or AirGuard Reflective films.
   Delta DAWI GP is a little simpler and cheaper.
2. AirGuard Sd5 - suitable for houses with non-permanent residence. Has limited vapor permeability to remove residual moisture from the room.
3. Jutafol are Czech films from the Juta company. Lots of good reviews from builders, excellent choice in terms of price-quality ratio.
4. Ondutis is an economical option.

Rules for installing vapor barrier film

The vapor barrier film is laid on top of the insulation from the attic side and fixed using a construction stapler. The joints of the canvases are taped with mounting tape to ensure tightness.

When working with the material, you should consider the following tips:

The sheets can be laid in any direction if there is a rough insulation file. When installing directly on the rafters, it is better to place the sheets horizontally.

The minimum overlap of one canvas on another should be 10 cm. The joints and abutments must be carefully taped.

When working with window openings, it is worth considering a deformation margin (fold). Near windows, it is important to pay special attention to sealing the junction points and protecting the material from sunlight.

After fixing the vapor barrier, wooden sheathing is done with 25 mm slats. It is needed for attaching the rough sheathing and creating a ventilation gap. When finishing the ceiling and walls of the attic with plasterboard, a special metal profile is used instead of bars.

Competent and high-quality performance of attic vapor barrier work will extend the life of the roof and save the home owner from costly repairs.

Back in 1630, the architect Mansart proposed using the attic space for residential purposes. This is how the attic appeared - a comfortable room. And it will become even more comfortable if you insulate the attic from the inside. Collateral effective thermal insulation The rules are as follows: creation of a continuous insulation contour, provision of waterproofing and vapor barrier, arrangement.

Materials used

Not all insulators are suitable for do-it-yourself attic insulation. The best choice is slabs made of stone wool. They are fire resistant and vapor permeable, do not deform and almost do not absorb water. But builders try not to use polystyrene foam boards and fiberglass mats. The former cannot boast of fire resistance, the latter lose their thermal insulation properties over time.

Most often in in this case They use lightweight materials so as not to put a lot of stress on the main structures. Therefore, when making it, they prefer to use wood or a thin cold-formed metal profile.

During installation, you cannot take the product according to the exact cell size of the rafter system frame. If the insulator is calculated based on the size of the cell, it will not perform its functions: the material will “dry out” and small cavities will form through which the cold will seep.

When a slab of the selected insulation is taken with a reserve, it fits tightly into the space between the rafters and even after “drying out” the cotton wool fills the entire cavity.

We make thermal insulation of slopes

The roof under which the attic room, supported by the structure: sheathing and rafters, which are installed in increments of 600-1000 mm. Consequently, stone wool slabs are placed in spacers between the rafters. If the thickness of the insulation is greater than the cross-sectional height of the rafters, wooden beams treated with an antiseptic are attached to them using screws.

To remove moisture that has entered the under-roof space, an air gap is left between the roof and the insulator. If the roof is made of galvanized corrugated sheets, tiles or metal tiles, then the gap thickness should be 25 mm. If the roof is laid flat sheets(asbestos-cement, galvanized, soft bitumen shingles), a gap of at least 50 mm is required.

Builders also recommend taking care of a windproof layer vapor-permeable material. If we're talking about about building a house from scratch, windproof film is attached over the rafters wooden blocks. In the case where the attic is being landscaped on an existing attic, the wind barrier layer is attached to the rafters either with nails or wooden slats.

Vapor barrier

It is very important when starting to insulate the slopes, to properly do the attic vapor barrier with your own hands. This is necessary to ensure that water vapor does not penetrate from the living space into the under-roof space.

As a rule, the roof does not allow water vapor to pass through well, so condensation forms on the inside and on the sheathing due to temperature differences.

Over time this can lead to negative consequences: to the destruction of the frame of the structure, a decrease in the level of thermal insulation, and the appearance of smudges on the ceiling.

To prevent this from happening, the thermal insulation layer is additionally protected with a vapor barrier material (ordinary polyethylene film or a membrane specially designed for this purpose will do). It is laid on the inside of the slabs with an overlap of 150-200 mm, and then secured with wooden slats.

The vapor barrier material must be airtight. By the way, some thermal insulation materials have a special base made of foil. It allows you to protect the roof from condensation: during installation, you need to make sure that the insulation is placed with foil inside the room.

Finishing

It will be correct to finish the attic only after all procedures related to the thermal insulation of the slopes have been completed. The inside of the attic floor can be finished with plasterboard, plywood, clapboard or boards.

The finishing material is attached to bars or metal profiles. If the insulation is not equipped with a vapor barrier film, but with vapor barrier foil, the finishing material is fixed at a distance of 5 cm from the foil. This allows you to reduce heat loss.

It must be remembered that the outflow of heat in the attic occurs not only through the slopes, but also through the end walls (gables). Insulation of attic walls is carried out in two ways. The most effective is external (when the heat-insulating layer is located on outside pediment). This option is acceptable for houses built from timber, logs, bricks and foam concrete.

But external insulation is not always possible. Then the attic floor is insulated from the inside. In terms of technology, it is not much different from insulating a conventional frame wall:

• a windproof layer is installed on the frame beams, after which insulation is placed;
• if the frame is less thick than the insulating layer, then additional bars are installed;
• After the installation of the insulator is completed, the wall is covered with a vapor barrier.

Please ensure that the vapor barrier layer is not interrupted either at the gable or on the slopes. This can be achieved by fixing the panels of vapor barrier film overlapping.

Working with stone walls

For stone walls you will have to make a system from scratch. An alternative to the above insulation materials is the use of blocks made from alabaster chips. The best option is wood fiber boards, that is, fiberboard. Fiberboard has many advantages. So, one product with a thickness of 1.2 cm is similar to a 4.5 cm brick. In addition to heat-insulating properties, it is distinguished by sound-proofing properties. The slabs are treated with an antiseptic substance, so they are not susceptible to microorganisms or mold.

In general, fiberboard is a rather brittle, lightweight and soft-to-touch material. Outdoor area products has smooth surface, and the inner one is corrugated. The slabs do not react to sudden temperature changes, are quickly cut into pieces and do not deform under the influence of different loads. Wallpaper rolls are glued to the outer area of ​​the insulation, which will create home comfort on the floor.

The correct way to insulate gables with wood fiber boards is as follows:

• a slab measuring 250x122 cm rises to the desired area, after which it is strengthened from below with plank supports shaped like the letter “T”;
• the slab is nailed to wall surface. Length fastening elements– more than 3.5 cm.
• Under the heads of the nails, special plates measuring 1.5 * 1.5 cm made of thin aluminum - “duralumin” are placed.

Fastening is carried out in a checkerboard pattern and so that the caps are buried in the material, otherwise the surface will not be smooth and this will ruin the finish.

Working with the floor

When insulating the attic, it makes sense, in addition to the gables and ceiling, to insulate the floor surface. There are two popular methods. The first involves dismantling the old coating and then laying two layers of roofing felt. Following them are placed fibreboards of certain brands. We are talking about M-20 and Pt-100. At the end, the finished floor is laid again.

The second method is based on the use carpets special type. First, the baseboards are dismantled, and fiberboard is nailed on top. Carpet materials are glued to the slabs. Before gluing, it is necessary to keep the products unfolded in a dry place for 14 days - this is exactly the time needed for shrinking and leveling.

Another option for preserving heat is to place another layer of thermal insulation under the already installed layer. This is done as follows:

• on interior lining in the attic, a frame made of beams is installed, between which insulator slabs are placed (ideal stone wool). The height of the bars should be equal (or less) to the thickness of the insulation layer;
• the thermal insulation layer is protected by a vapor barrier material - it is attached to the frame bars.

Interior finishing

The inside of the attic can be finished with clapboard, plasterboard or plywood. It must be remembered that when using this particular technology, the thermal insulation of the attic is significantly reduced. effective area premises, as well as its height. The advantage is that you don’t have to dismantle the roof, so you can get to work not only in summer, but also in winter.

Insulating the attic also involves insulating the floor below it. There are times when, as optimal option A combined approach is suitable. It consists in insulating the ceiling on top of the existing thermal insulation. The inclined surfaces of the attic room are finished from the inside. In both cases, we must not forget about the thermal insulation of the gables.

So, insulating the attic from the inside is perhaps the only way to obtain a comfortable microclimate. In addition, correctly selected thermal insulation will allow you to pay less for heating even in very cold winters.

One of the most important tasks when constructing an attic is to protect it from the formation of condensation, which can lead to damage to the rafter system and thermal insulation material, as well as to increased costs for heating the house. Proper attic vapor barrier should be laid at the design stage. But if mistakes were made during the construction of the structure, then the volume of subsequent repair work, as well as measures to renovate the attic, will be comparable only to a new stage of construction.

Before deciding which vapor barrier to choose for an attic roof, you need to understand the mechanism of formation and movement of water vapor. There are two principles of transfer and formation of condensate:

1. Diffusion is the movement of steam from an area of ​​high pressure to an area of ​​low pressure. In winter, such a transfer is carried out from a warm heated room towards the cold outside, where low partial pressure is observed. In the summer, the direction of flow changes, and steam from the warmer and more humid outdoor air is directed into the drier and cooler space of the attic. In the path of the diffusion flow there are attic roof structures (waterproofing, insulation, vapor barrier, finishing). It is the diffusion permeability of these materials that determines the amount of vapor that can penetrate due to diffusion. Since the layers of waterproofing and insulation practically do not resist the passage of steam, they can be ignored. In such a design, only the qualities of the vapor barrier material are important. This is why it is so important to choose a high-quality vapor barrier for your attic.

Important! The greater the difference in temperature and humidity between indoors and outdoors, the greater the diffusion flow.

1. Convective is the movement of air and steam flows through loose layers of coatings and thermal insulation materials. The intensity of this transfer is directly related to the strength of the wind and the dimensions of the cracks. In modern roof systems, the function of air protection is performed by layers of hydro- and vapor barrier. They can completely eliminate the possibility of convective moisture transfer.

Under actual roof operating conditions, both mechanisms of moisture penetration are present. In this case, the intensity of the diffusion process is directly related to the choice of good vapor barrier and pressure drop. In turn, the convective process completely depends on the quality of insulation work and the use of sealing tapes and mastics.

Attention! When comparing the degree of humidification of roof structures during the diffuse and convective processes, we can say that the latter is much more dangerous, since a larger amount of water vapor penetrates into the structures.

Consequences of dampening structures

Vapor barrier of an attic roof is an important component of the roofing pie design. If we choose a low-quality vapor barrier material or install it in violation of the technology, then home owners may face the following negative consequences of waterlogging of the thermal insulation material:

• The entire structure reduces heat transfer resistance. This leads to higher operating costs.
• Mold and moisture can damage roof support structures (both metal and wood).
• Due to increased air permeability of structures and dust ingress, the air quality in the house decreases. The favorable microclimate and comfort of living in attic spaces suffer significantly.

That is why, when arranging the roof structure and the roof itself, it is important not only to know which vapor barrier film is better, but also to install the material correctly. A particular danger from the point of view of poor-quality vapor barrier is represented by loose overlaps of vapor barrier material, poorly executed connections to walls and other structural components of the roof.

Important! The main task when arranging a roof is to eliminate or minimize the uncontrolled movement of air containing water vapor through roof structures.

Types of materials

Today we can choose not only high-quality vapor barrier materials, but also entire vapor barrier systems, which include special films, adhesive tapes and mastics, as well as ready-made technical solutions for roof installation. The choice of characteristics and type of vapor barrier material is directly related to the design features of the attic space and its temperature and humidity conditions.

Below we provide a list of the most common vapor barrier systems with their pros and cons:

1. Single-layer polyethylene films. The advantages include high vapor diffusion resistance (more than 100 m) with a small material thickness (200 microns), the ability to control the quality of insulation due to the transparency of the material, as well as good elongation at break. Among the disadvantages is the low strength of the material in places of fixation with staples.
2. Polyethylene multilayer films with reinforcement. Pros: high strength and transparency. Disadvantages: low resistance to vapor diffusion due to the thinness of the interweaving of the reinforcing mesh fibers. It is worth noting that films weighing at least 200 g/m² are most often used.
3. Films made of polymers on a woven basis with lamination in one layer. The advantages include high strength. The disadvantage is the lack of transparency, low diffusion resistance due to the presence of a continuous thin polymer layer, as well as low elongation at break.
4. Multilayer foil polyethylene film. The advantages include the high density of the material and a relatively good coefficient of resistance to vapor diffusion, as well as additional heat retention in the room due to the reflexive layer. For a more airtight installation, self-adhesive tapes are used along the edges of the material. The only disadvantage is the lack of transparency.
5. Polymer-bitumen roll self-adhesive vapor barriers. They are quickly installed, since they are simply glued to a solid base of concrete or OSB on a layer of primer. Such products can be used on a vertical surface without additional gluing of overlaps.
6. OSB can be used as a vapor barrier, but this material is only suitable for places with normal humidity in buildings where wet finishing work is not used. Their scope of use is prefabricated and frame structures. Places of junctions and overlaps must be additionally taped. OSB is only suitable for roofs with simple geometry. A layer of film vapor barrier must be laid over wet rooms. This material is not suitable for use in houses made of timber and logs due to high shrinkage.
7. Adaptive polyamide vapor barrier has variable vapor permeability and is only suitable for renovation of places with normal humidity. It is not used in new construction.

As you can see, the abundance of vapor barrier systems allows you to reliably protect roof structures from condensation. However, the effectiveness of any material is directly related to the correct choice of it, taking into account the temperature and humidity conditions of the room and the roof structure, the use of accessories for better sealing of the layer, as well as the use of the right technical solutions.

Residential attic space called an attic. It should be warm and suitable for year-round residence, so the roof is insulated. Fiber insulation materials that are safe for humans are used as thermal insulation materials for residential premises. They have a number of advantages, but when wet they reduce their performance. This can happen due to roof leaks or condensation. In addition, over time, moisture causes materials to deteriorate, including interior decoration attic and to the appearance of mold. The article will discuss which waterproofing to choose for the attic.

The task of attic waterproofing is to protect the under-roof space and the room from moisture leakage due to rain or melting snow. Often moisture penetrates due to damage to the roof or due to a loose fit of the ridge and snow being blown under it.

Water getting on the insulation negatively affects its qualities, and with prolonged exposure leads to destruction. Traditionally, fiberglass treated with bitumen was used for this. But today modern materials have appeared that have best qualities. In addition, they are much more convenient to work with. First of all, we are talking about membrane films, which not only perform the function of waterproofing, but also prevent the formation of condensation, have the function of wind protection and vapor protection.

Vapor barrier and wind protection of attic roof

• Due to air movement and steam pressure, condensation occurs. This is especially true in winter, when there is much more vapor in a warm room than outside. As a result, diffusion occurs, in which steam penetrates into the under-roof space.
• When there is ventilation in the house, this leads to active air movement and increased pressure. Air and steam tend to escape through cracks or joints of materials.
• Finishing materials, which are most often used to clad walls and ceilings, are vapor permeable and do not prevent moisture from penetrating the roof structures. Therefore, it is advisable to protect the thermal insulation from the inside with polyethylene films, membranes or foil films.

• The film for waterproofing the attic from the inside is produced in wide rolls, which allows you to keep the number of joints to a minimum. A vapor barrier will only work if the fabric is absolutely intact, so all joints are made with an overlap, and the connections to the pipes are additionally glued.
• The recommended overlaps are 10 cm and should be on the frame element in order to secure them most firmly with a construction stapler or lath. Minimum film thickness 0.15 mm.
• If communications are planned to be carried out through the film, they must be tightly glued with reinforced tape.
• When is thermal insulation performed? pitched roof attic, it is important to protect the insulation from cooling from blown cold air or wind. Special tools do an excellent job of this function. slab insulation, which has the highest compressive strength. In terms of their vapor-permeable properties, they do not differ from other slabs, but they resist the wind in the best way. This insulation retains heat better and is an excellent soundproofing material. This is especially important if the roof is made of metal.

Tip: wind protection, vapor barrier and waterproofing of the attic are necessary when insulating it. Any roofing material on a pitched roof is not a continuous covering, so there is always a risk of moisture penetration from precipitation.

Materials for attic waterproofing

For waterproofing, films are used that are attached directly under the roofing material. These include:

• polypropylene films;
• non-woven membrane materials;
• polyethylene films that do an excellent job of hydro- and vapor barrier in the attic.

Often these materials are interchangeable. Thus, vapor barrier films are used as under-roof waterproofing, and waterproofing films are used as a vapor barrier from the inside of the room.

Advice: there is so-called simple waterproofing, but for the attic it is better to use a waterproofing material with an anti-condensation effect. It has an absorbent fleecy layer that functions to retain drops of water, thereby preventing it from reaching the insulation.

Polyethylene film for attic waterproofing

• Modern polyethylene films designed for waterproofing mansard roof, are reinforced with fabric or a special mesh. This material acquires high strength and does an excellent job of retaining moisture from the outside and steam from inside the room.

• There are two types:
  1. perforated. Its surface is covered with microholes. Which are able to retain moisture, but not steam. Therefore, its function is waterproofing;
  2. non-perforated. It has a monolithic fabric that copes well with vapor barrier.
• Regardless of the type used, a ventilation gap of 5 cm must be provided in the roof pie.
• In addition to traditional films, roll polyethylene with an aluminum layer is on sale. It can be made of foil or sprayed aluminum. This reflective layer allows you to additionally retain heat in the room.
• Foil polyethylene films from European manufacturers such as POLYCRAFT, JUTAFOL N AL, DELTA-REFLEX are of the best quality.
• Their moisture-proof properties are very high, so they are suitable for use in roofs of any design.

Polypropylene film for attic waterproofing

• Reinforced polypropylene films compare favorably with their polyethylene counterparts due to their much higher strength. They're not afraid ultraviolet rays and will reliably protect the attic space from precipitation.

• One side of this film has an anti-condensation coating. In this way, it protects the thermal insulation material from the formation of condensation. This coating is made from viscose fibers with cellulose. It is characterized by high moisture absorption and ability to retain it. According to experiments, the anti-condensation layer absorbs a large number of water and, holding it, does not form drops, which is guaranteed to protect the insulation and roof structures from getting wet.
• When the conditions that caused the condensation disappear, the air flow from the vent will quickly dry the material.
• When using such films, it is important not to mix up the sides; the glossy layer is placed on the outside, and the absorbent, rough layer is placed towards the insulation.

Anti-condensation films for attic waterproofing

• This is a type of waterproofing material, one side of which is rough. It absorbs moisture formed by condensation and retains it. When water accumulates, it does not form into droplets. And it is securely held by the material until air circulation in the ventilation gap between the film and the insulation brings it out.

• In addition, anti-condensation films have excellent moisture-resistant characteristics and will protect the ceiling from water leaks that could get through cracks in the roof.

Vapor barrier films for attic waterproofing

• It protects against small particles of water and steam. It only works if the fabric is solid, and if there is the slightest tear or gap at the joint, moisture will penetrate into the insulation.
• Not only the joints of the fabric are sealed, but all places where the vapor barrier film adjoins the walls and communications are sealed.
• When using a vapor barrier in the attic, between it and finishing material there should be a ventilation gap of 2-3 cm to prevent the formation of condensation on inside material.
• It also has 2 sides, the manufacturer indicates on the packaging how to position it correctly.

Diffusion membrane for attic waterproofing

• This is a modern breathable material that is completely vapor permeable, but at the same time protects the roof from precipitation, condensation and wind. Hence the second name - vapor-permeable wind-moisture-proof membrane.
• It's done non-woven method from synthetic fibers. Its main advantage is the saving of under-roof space, because the height of the ceilings of the attic floor is usually small. This is possible due to its characteristics and the ability to attach directly to the insulation, without installing a ventilation gap. You can use the resulting space differently - do additional layer thermal insulation.

• They are most often used not only in the construction of new houses with attic floor, but also when arranging a cold attic into a living space. In this case, there will be no need to reconstruct the rafter system.
• The initial cost of diffusion membranes differs slightly from the price of other vapor barrier materials. But during operation it will show maximum energy efficiency and allow you to save on heating.

How to choose waterproofing for the attic

The material used to waterproof the roof in the attic depends on several indicators.

• First of all, this is the angle of the roof. If the angle is sharp, then it is enough to install an under-roof windproof or vapor barrier membrane. A roof pie whose slopes are more gentle will already require a waterproofing anti-condensation film.
• When there are 2 ventilation gaps in the attic roof structure, simple waterproofing materials are used. And with a single ventilation circuit, preference is given to diffusion membranes.

• Since we are talking about waterproofing a residential heated attic, it is better to provide two layers of moisture-proof films. For example, with a conventional vapor barrier film and windproof membrane. Or with only one vapor barrier anti-condensation membrane, but with two ventilation circuits.

Advice: the best solution will be the design of insulation and waterproofing of an attic roof with 3 films. If we start from the living space, the pie looks like this: drywall, vapor barrier film, insulation, windproof film, ventilation gap, plastic film, ventilation gap and roofing material.

• The film should be stored in a dark, closed room. If it has already been mounted on the roof or walls, then it must be immediately covered with facing material. The membrane is destroyed quite quickly under the influence of ultraviolet radiation and wind. Indoors, non-woven vapor barrier should not be located near lamps or heaters. This also leads to the destruction of its structure.

How to waterproof an attic with your own hands

Since it is impossible to insulate an attic without waterproofing, this process must be considered in its entirety.

• The roofing material does not have heat-preserving qualities. Therefore, if we are talking specifically about a residential attic, then only environmentally friendly materials should be used. Most often this is mineral wool or glass wool. Both of these materials have high heat and sound insulation properties. This is especially important if the roof is made of metal. But all these qualities are reduced to zero when the insulation gets wet. Therefore, it is necessary to properly think through all the components of the design.
• If the house is new, then it is easier to carry out work from the bottom up, starting from the lower layers and ending with the roof. If the house has already been built, and the roof is insulated during operation, then there is no choice and the work proceeds in the opposite direction. Consider the option of working in a house under construction.

• A vapor barrier film is nailed onto the roof rafters from below with a tight tension using a construction stapler. To prevent the staples from tearing the material, it is pressed over the fastenings to each rafter with a strip, which is mounted on self-tapping screws (in the case of a wooden structure).
• In the resulting cells, the walls of which are rafters, and the bottom is a vapor barrier, thermal insulation material is laid in a checkerboard pattern with overlaps. With a thickness of 5 cm, 3 layers are made.
• The top is covered with windproof waterproofing. The top is also fixed with slats. Their thickness will provide the necessary ventilation gap. The width of the ventilated gap directly depends on the roof material. So, if you choose corrugated sheets, metal tiles or ondulin with a profile, then it is enough to leave 2.5 cm for air flow. For flat material, the ventilation circuit between the waterproofing material and the sheathing under the roof is provided at least 5 cm. Ventilation will be carried out from the eaves of the roof to its ridge.
• Practice shows that the best effect in protecting insulation under the roof can be achieved by using modern materials trusted manufacturers such as Izospan or Tyvek. Using regular polyethylene film gives worse results due to the formation of condensation, and the old way waterproofing with roofing felt, according to professionals, is unacceptable.

Advice: all seams and joints of films are taped with tape; this is the only way to guarantee that moisture will not penetrate inside.

DIY waterproofing

Do you need waterproofing in an unheated attic?

If the house is being built taking into account that in the future it is possible to convert the attic into an attic, then waterproofing will significantly speed up this process. But, if there is no such desire, is it necessary to install protection from moisture and wind under the roof without thermal insulation material?

• Even if there is absolute confidence in the quality of the roofing material, in its correct installation, which guarantees protection of roof structures from penetration of moisture from slanting rain or blowing snow, pull them onto the rafters waterproofing film still necessary. Since moisture penetrates not only from the outside, but also from the inside in the form of condensation. Water drops form on roofing and lead to its corrosion.
• For an unheated attic, you can use any type of waterproofing material: polyethylene film, diffusion membrane or anti-condensation film. Preference is given to anti-condensation materials, since they are cheaper than diffusion materials. And unlike polyethylene films, are able to hold condensation for a long time until it disappears naturally.
• Condensation forms especially often in cold attics when communications such as fireplace pipes, chimneys, etc. pass through them. Even if they are securely closed thermal insulation material, anyway, some of the heat will pass out, which will lead to a temperature difference and the formation of condensation.

• If you still plan to convert the attic into a warm attic in the future, then waterproofing should initially be carried out using diffusion materials.