Ventilated roof and its device. Features of the ventilated roof structure

Today, a wide variety of roof structures are becoming widespread, which differ not only in the complexity of the device, but also in the roofing cake, characteristics, and installation methods. Among such diverse types in a separate group is a ventilated roof, which is distinguished by excellent protection against swelling of the roofing carpet, wetting the cake, the appearance of mold, fungus.

Today, such a roof is considered one of the most optimal, its construction is economical, possibly directly on top of the old structure. At the same time, the ventilated roof allows you to completely dry the wet insulation, truss systems. In our article, we will consider the device of such a roof and its features that made them so popular in private construction and in the construction of apartment buildings, industrial, outbuildings. In addition, we will find out what options for such a roof exist, how exactly they differ from each other. Our experts will share the secrets of installation, which can be done by hand, without calling a team of professional builders.

Ventilated roof construction

Ventilated roofs, whose designs are quite simple, include such basic components necessary for ventilation, such as:

• ventilation of the space that is between the layers of waterproofing and insulation;
• ventilation between the waterproofing and the roofing itself, it covers all planes, even if the design is complex;
• direct ventilation under the roof itself, which is an element of the general ventilation system of the house.

It is the peculiarities of the location of the ventilation that distinguish such a roof from others, constant air inflows allow not only to effectively remove moisture to the outside, but also to control the temperature level. In this case, ventilation will greatly depend on whether the roof lathing system is properly arranged.

Scheme of ventilation of the roof of a non-residential attic.

The process of installing a ventilated roof has its own specifics. So, for ordinary outbuildings and garages, an uninsulated type of coating is excellent, which consists of the following elements:

• rafter system;
• crate;
• waterproofing;
• roofing material.

The film for waterproofing is attached to the rafters with slats, it does not allow moisture to get inside, extends the life of the roof. But such a design is cold, that is, a layer of heat insulator is completely absent in it. This is not suitable for private residential buildings; here it is necessary to arrange another roofing pie. In addition to the above layers, in this case, a slab insulation is required, an anti-condensate film that prevents condensation from forming on the roof elements. Such material consists of several layers:

• two layers of laminated film;
• moisture-absorbing non-woven material;
• polypropylene fabric.

In addition, the device of a ventilated roof assumes the presence of vents in the lower part of the cornice, ventilated skates.

Advantages of a ventilated roof

A ventilated roof differs from other structures in the following advantages that put it in the first place:

1. Installation of such a roof is possible even at sub-zero temperatures, the only exception is the presence of heavy rain, heavy snowfall, frost, which drops below minus twenty degrees Celsius.
2. During the reconstruction, the removal of the old roofing is minimal, including preparatory work; this makes it possible to save money and time for installation, the cost of the roof is much less.
3. During further operation, all elements of the roof are completely dried, including floor slabs, heat insulators, old roofing (if any). This allows you to completely remove the risk of rot, mold, fungus, which are very dangerous for the overall roof structure.
4. The old roof covering, which is located under the new ventilated structure, after drying, completely restores all its functions, that is, a kind of double roof is obtained.
5. The swelling of the roofing carpet is completely eliminated.
6. The resistance of the new coating increases, this roof is very resistant to frost, ultraviolet radiation, rotting, strong temperature changes, movements of ice and snow masses in winter, thermal expansion, and various mechanical damage.

How to properly design ventilation?

The design of such a structure always involves the thoroughness of the preparatory work. During the execution of the project, it is necessary to provide that:

• water from the surface always flowed down, that is, proper protection against its influence must be created;
• steam rushed up from the premises, that is, the presence of vapor protection is also required.

The device of such a roof is that rare case when the walls of the house should not breathe! Otherwise, the moisture that can linger in them will lead to delamination of the building material.

Ventilated roof options

Today, a variety of types of ventilated roofs are used, among which pitched and flat ones stand out. They can be used for a wide variety of buildings, the materials for them, however, are the same, only the design differs. Consider these two main design options, their differences, device diagrams, advantages.

flat roofs

Such flat roofs have been used since the early eighties, when it became possible to use heat-insulating materials with ventilation ducts to help remove excess moisture. Most often, such roofs were made for apartment buildings, where they were most effective.

The pie consisted of the following elements:

• concrete slab as a base for the roof;
• vapor barrier;
• a layer of mineral wool slab insulation, in the thickness of which was the end of the ventilation pipe, the so-called aerator, which removes excess moisture;
• cement-sand screed;
• bituminous waterproofing layer;
• polyurethane material;
• a layer of polyurethane mastic;
• roofing material.

A concrete parapet was erected on the sides, which was protected from the roofing pie with a layer of sprayed or bulk material. Today, this function is performed by polyurethane foam, which provides excellent insulation and sealing. All outlets of ventilation pipes and aerators are also insulated with this material. All flat roofs are considered cold, but still they continue to be popular due to their convenience and savings in building materials during installation.

pitched roofs

Pitched roofs differ from flat ones in that air flows enter through the lower overhangs and exit through the ridge, while all excess moisture that accumulates under the roof space in the insulation is removed with them. Ventilation in this case can be forced, for which roof fans are installed, the coating is recommended to be light, preferably having a wavy texture. The roof can be insulated and non-insulated, the roofing cake differs only in the presence or absence of a heat insulator layer. For residential buildings, it is necessary to have a heater, in this case, mineral wools in the form of plates are excellent, which are very easy to install, provide an insulated coating, and the absence of cold bridges.

Mounting

The ventilated roof is mounted in the following order:

1. Preparation of the base for work, including the elimination of cracks and potholes. This may be the usual laying of cement mortar, leveling the entire surface, or asphalting the slab. It must be remembered that the minimum slope of such a roof should be from two to three degrees!
2. Next comes the laying of a layer of vapor barrier film and insulation, in which strips and cracks are unacceptable. Most often, mineral wool or glass wool is used for this, which guarantee excellent quality and low installation costs.
3. Depending on the type of roof, further installation work may vary, but basically a waterproofing layer, a cement screed, is laid.
4. As a roof covering, rolled welded materials are used, which provide excellent quality. Laying is carried out using a gas burner, while the bitumen is melted, the material itself is firmly glued to the base. Lateral overlap should be from one millimeter to five.

When installing, do not forget to mark the outlets of the ventilation ducts, isolate them properly to ensure the normal functioning of the roof. Only in this case will it acquire its proper qualities.

Constant and high-quality air exchange under the roof is a guarantee of a long service life of both the roof itself and the entire building. The comfort of the people living in the house also depends on ventilation, since it plays a key role in shaping the microclimate.

Peculiarities

Soft roof ventilation is not an independent process. On the contrary, the presence or absence of ventilation in the premises directly affects the exchange of air in the roof. For effective removal of destructive moisture from residential premises through the roof, it is necessary to analyze the ventilation of all elements of the house as a holistic process.

If the roof configuration is complex, has many transitions, valleys, the exhaust air removal process must be divided into sections and the air flows in the roof should be organized separately.

As a result of good ventilation, the air in the space under the roof should be replaced approximately 2 times per hour.

The performance of a ventilated roof depends on the slope of the slopes. The steeper they are, the more intensive the ventilation process is.

And, on the contrary, in roofs with a slope of less than 20%, the ventilation of the under-roof space is unstable and is effective only under wind pressure.

A useful addition is the construction of auxiliary exhaust components (aerators) on the roof, which enhance the natural ventilation of the roof. They should be arranged on roofs of complex configuration, when ordinary funds are no longer enough.

Aerators are mounted near the ridge. In a two-layer welded-on roofing, the aerators are mounted on the bottom layer of the material.

The thermal characteristics of the insulation and the strength resource of roof structures directly depend on the presence of moisture in them. As a result, a ventilated roof and a room ventilation device are economically viable, even when forced air exchange is to be installed.

Pros and cons

The main purpose of the ventilation system is to ensure the passage of atmospheric air, which contributes to the extraction of heated air from under the roof covering. The exhaust air provides attic ventilation.

If under-roof ventilation is performed correctly, then such air flow passes naturally and there is no need to use additional mechanical equipment.

Aerators are available in different diameters and heights. Their size and number are selected depending on the area of ​​​​the roof of flexible tiles.

The presence of a ventilated space under the roof has the following advantages:

• consistently cool and dry condition of the attic;
• outside air from the attic is able to leave naturally;
• load-bearing components of the roof, coatings and thermal insulation layer are not exposed to high humidity;
• lack of conditions for the formation of mold and rot, prevention of damage to the finishing materials of the roof;
• reducing the cost of electricity.

Experts have found that when using soft coatings, the main disadvantage is the accumulation of excess moisture in the screed and thermal insulation.

The increased humidity of these layers of the roof provokes a number of negative consequences, such as:

• Bloating roofing, resulting from its heating in the summer due to the delamination of bitumen-polymer materials under the influence of high temperature.
• Increasing thermal conductivity causes moisture accumulated under the waterproofing material, which worsens the thermal properties. It has been theoretically proven that with an increase in moisture content by 1-2%, an increase in the heat-conducting properties of the material by 30-40% occurs. This leads to an increase in the cost of heating the object. Along with heat loss, oversaturation of roof layers with moisture can lead to the formation of mold.

• Destruction of the waterproofing layer and screeds are provoked by the penetration of moisture into the material. After the temperature of the surrounding atmosphere decreases, the moisture absorbed into the material crystallizes and its volume grows. This process entails the appearance of microcracks and the destruction of the screed. Similar negative processes occur in the waterproofing layer, destroying its integrity.

Varieties

Roof aerators come in a variety of designs and sizes. They are used to ventilate the space under the roof, eliminate condensation and remove moist air to the outside. Before purchasing an aerator, you need to understand the features of their design and types.

Point

In another way, these aerators are called roof-point valves. They are mounted on roofs in which there is no ridge - hipped and flat. The roof aerator itself is made of high-strength plastic, resistant to mechanical stress and exposure to sunlight (fading).

It has 4 parts in its structure: a flask, a protective umbrella for it, a tube and a filter mesh.

According to the configuration of the flask, they are divided into flat and bottle. Bottle roofs are installed on single-pitched and tent-type roofs, and flat ones are mounted on flat ones. Such aerators function productively if they are placed evenly throughout the roof. As a rule, one deflector is needed per 20 m2 of roof, but if possible, it is better to mount two.

Skate continuous

According to the name, they are installed on pitched roofs equipped with a ridge. They are a permanent outlet located at the very top of the ramp. The ridge aerator is implemented in the form of a square, equipped with through holes, which are called vents.

Airflows are point (made at a distance of 6-8 m from each other) and slotted (gap 5 cm). There is a protective grid from penetration inside a roof of insects. A similar device is mounted around the entire ridge and is attached to the roofing material. Its individual components form an integral system. The aerator perfectly retains moisture and lets air out, preventing it from stagnation in the attic.

How to choose?

On soft roofs, various deflectors are used, the choice of which depends on the type of roof.

When choosing an aerator, preference should be given to products that have certificates from a trusted manufacturer.

When buying, special attention should be paid to the completeness of the set and the absence of mechanical damage (scratches, chips, cracks and deformation).

When choosing aerators for a soft roof, it is necessary to build on the complexity of its structure, climate and the level of moisture saturation of the attic space. As a rule, one point aerator must be installed per 100-150 m2.

When mounting a ridge aerator, a different approach is used. A ventilation slot is constructed along the entire length of the joint, and air is supplied from under the overhangs, where a specialized air element (perforated tape) is placed on the slot.

For all types of aerators, a number of technical conditions are put forward, which they must comply with:

• withstand temperatures from -50? C to +100? C;
• resistance to chemicals that may be contained in sediments;
• corrosion resistance.

How to install?

Each type of aerator has a specific installation order.

Point devices are mounted on flat roofs and roofs with a slope angle of less than 12 degrees. They can also be used as an addition to ridge aerators.

Let us consider in more detail the installation technology of point aerators:

• We determine the location of the aerators. We apply the aerator with the base to the installation site and draw around the contour with a pencil. On the marked mark, we make holes with an electric jigsaw.

• We install the skirt (base) of the aerator over the finished hole and fix it with self-tapping screws or nails. For a stronger fixation, you can additionally use glue. In this case, we apply bituminous mastic to the inner segment of the skirt, glue it to the base and fix it with nails.
• We coat the top of the skirt with bituminous glue.
• We cover the skirt with soft tiles, cutting the shingles at the points of contact.
• We put an aerator mesh on top of the skirt, screw it with self-tapping screws. Then we install the cap (cover), snap it on and also screw it with self-tapping screws.

Installation of the remaining point aerators is carried out in the same order.

Installation of a ridge aerator is quite simple, it is installed along the entire length of a pitched ridge and its variety - a hip roof, the slope of which is from 12 to 45 degrees. There are two ways to install a ventilated soft roof ridge.

Installation technology:

• In the solid base, using a circular saw, we cut a ventilation groove. It can be single (at the highest point of the ridge) or consist of two parts (on the sides of the ridge). The total thickness of the ventilation gap should be 3-8 cm (depending on the aerator manufacturer's instructions). The ventilation groove should end 30 cm before the edge of the ridge on both sides, that is, the coating remains continuous.

• We cover the areas where the ventilation gap has not been cut with ridge tiles.
• We install an aerator. We fix each section of it with special roofing nails or screws screwed through the existing factory holes.
• We lay ridge tiles on top of the aerator profile. We overlap its petals, according to the standard mounting technology along the ribs. The only difference is the fasteners. In this case, we nail the tiles to the aerator with special roofing nails.

• We seal the places where the aerator meets the roof with a silicone-based sealant. Care must be taken not to form a cavity around the under-roof space ventilation device. Water and snow will linger in these recesses, which over time will certainly find a place to seep under the roof.

The second method involves fixing timber bars at the highest point of the roof slopes. It turns out a kind of crate for the ridge bar. From above, we nail plywood strips to the bars, forming a triangle. We form ventilation gaps between the bars, and cover the entire structure, as in the previous case, with shingles.

If the height difference on the roof is quite large and the total height of the structure is at least 7 meters, then instead of aerators, small box-shaped valves can be installed together with ridge ventilation.

Houses with tent or hip roof architecture do not have gables. But this is not a problem for the ventilation device. It is based on the same principles as for gable roofs, but at the same time, we must not forget that it is necessary to construct inlet gaps that ensure the passage of air around the entire perimeter of the roof. No matter how many slopes the hipped roof would have, each of them must be ventilated.

A great desire to forget about the device for ventilation of the space under the roof is given by a half-hip roof, since its inclined end elements have relatively small dimensions. The ventilation system here can be built according to the principle of ventilation on the main slopes of the roof.

It is a little more difficult to calculate the ventilation of the end slopes of the Dutch (hip) roof, since there is a window directly above them. This is an obstacle to the use of pipes, but, nevertheless, an aerator or gratings can be installed there.

In all the cases described, if the roofing is made of wood, then it should not be monolithic, since air must pass through its gaps into the space under the roof. But in parallel with the above installation rules, it is also necessary to make the correct calculation so that normal traction is formed under the roof. Otherwise, all this will not function.

Regardless of the method of the device, ventilation must guarantee:

• the passage of air vapor;
• protection of the space under the roof from precipitation and melting snow;
• moisture should not pass through the design of the ridge;
• ensuring the evaporation of excess liquid from the room.

When ventilating the under-roof space with your own hands, a number of important points should be taken into account.

• If you intend to get a stronger effect from the movement of air currents, then it is necessary to apply steam and hydrobarriers located under the crate. They are specialized meshes that allow air to pass through without difficulty, but prevent the passage of moisture and steam.
• To ensure ventilation under the roof of an ordinary pitched roof, a small number of vents placed in the lower and upper parts in equal numbers will suffice. If necessary, you can supplement the ventilation system with a fan for forced exhaust.

• If you are installing a fan in a building that is located in an area with higher than normal humidity, then the fan must be endowed with a higher motor power. The fans must be installed parallel to the roof structure. Inserting a device into a finished roof is more difficult and will cost significantly more.
• The combination works great on the roof- full ventilation of the ridge and auxiliary elements to enhance the air flow. If, for example, one of them is damaged in winter, the rest will remain in working order. The under-roof space will be one hundred percent protected from the accumulation of condensate.
• Also it is necessary to pay attention to the total component of all precipitation falling during the year. In areas with heavy snowfalls, it is necessary to raise the air ducts to a higher level, otherwise the snow drifts will block the low-mounted aerators.

• And the last - the desire to save money when installing roof ventilation can end badly, being a source of problems both with the roof covering and with structural elements. Proper organization of effective air exchange is a guarantee that the roof will last for decades without the need for repair, providing thorough protection for the entire structure and comfortable living conditions.

Arranging ventilation under the roof with your own hands for a roof of any kind is not so difficult, and such a design has a considerable amount of positive effects.

Roofing materials reliably protect the building from snow and rain, providing dryness and comfort in the interior. But the trick is that moisture attacks not only from the outside, but also from the inside. In the second case, it is possible to neutralize its negative impact only with the help of roof ventilation.

Why do you need roof ventilation?

There are two reasons to take care of the roof ventilation device:

1. Residential premises always contain a significant amount of water vapor, which is formed as a result of breathing and sweating of residents and pets, cooking, hygiene procedures and other processes associated with the use of water (laundry, cleaning, washing dishes, etc.).
2. Roofing, by definition, is vapor-tight, so it is not capable of escaping steam.

Without taking special measures, water vapor rising with warm air would condense on the inner surface of the cold roofing, followed by the occurrence of many negative processes:

To prevent all of the above phenomena, roof ventilation is arranged, which implies the presence of a blown gap and ventilation of the attic space.

The blown gap is called the ventilation gap. The movement of outside air in this gap will carry all the vapor penetrating the coating to the outside. Along the way, it performs two more functions:

The ventilation gap is arranged as follows:

• a waterproofing film is spread over the rafters;
• from above, along each rafter leg, a board with a thickness of about 30 mm is stuffed - a counter-lattice (it will fix the waterproofing film);
• a crate is stuffed on the counter-lattice across the rafters, and the roofing is laid on it.

Thus, the required gap is obtained between the waterproofing film and the roofing. Its height will be equal to the sum of the heights of the counter-lattice and the batten, which is approximately 50 mm.

To ensure the movement of outside air in the ventilation gap, as well as to remove moist air from the attic, various devices are used.

Roof ventilation elements

The main elements of the ventilation roofing system include:

1. Openings under the roof overhang, which are usually covered with so-called soffit gratings (protection from birds, insects and rodents), as well as along the ridge. These structural elements provide blowing through the roof gap due to wind and convection (having heated up under the roof, the air rushes up).

   Holes under the roof overhang are protected from rodents and birds with soffit gratings: they can be replaced with a filing with small gaps between the boards

2. Dormer windows. They are arranged in gables and serve to ventilate the attic space.

   The dormer window is one of the important elements of roof ventilation.

3. ventilation outlets. As well as aerators, they are pipe sections, but not intended for ventilation of the under-roof gap, but for connecting exhaust ducts of general house ventilation to them or for ventilation of the attic.

   An exhaust system can be connected to the ventilation outlet or used to ventilate the under-roof space

4. Aerators, also referred to as deflectors and weathervanes. They cut into the roofing at the ridge itself and serve to remove air from the under-roof space, that is, they perform the same function as the hole under the ridge. They are used in conditions where the thickness of the snow cover on the roof can exceed 2-3 cm (with small slopes), as a result of which the ventilation gap under the ridge would be muffled.

   The roof aerator is used to remove air from the under-roof space in cases where there is snow on the roof

Design features of aerators

There are two types of aerators available:

• point;
• linear or continuous (installed over the entire length of the slope or ridge).

In addition, they also differ in the place of installation - they are ridge and pitched.

The design of the aerator can be made in the form:

• fungus;
• tiles.

The aerator can be made of stainless steel, but today in most cases the material for such products is polypropylene. It is cheaper, and besides, plastic can be given any color. At the same time, it has sufficient strength to withstand the weight of a person, so that installation or repair work on the roof can be carried out without difficulty.

The aerator has a replaceable element - a penetration, the design of which is selected taking into account the type of roofing.

Aerators can be equipped with a roof passage device adapted to a specific type of coating

The product can be equipped with a fan - it is necessary to create forced draft in roofs with a small slope (convection is weak in them due to the small height difference) or with complex shapes, where natural draft is not enough to overcome the aerodynamic resistance of fractures.

To prevent the ingress of precipitation and insects, the aerator opening is protected by a filter. The diameter of the aerators varies from 63 to 110 mm.

Calculation of roof ventilation

The task of calculating ventilation is to determine the necessary parameters under which the volume of incoming air will be sufficient to effectively remove steam.

The height of the ventilation ducts above the roof is determined taking into account their proximity to the ridge or parapet:

Roof ventilation device

The ventilation system of the roof is arranged in accordance with the type of roof.

Mansard roof ventilation

The attic roof is insulated. The layout of the ventilation gap in such a roof depends on what material is used as waterproofing.

Roof with waterproofing from a polymeric vapor-proof film

If the insulation is covered with a conventional film that does not allow water or steam to pass through, ventilation gaps are arranged on both sides of it: from above - to the roofing and from below - between the film and the insulation. Due to the presence of a gap between the waterproofing and the insulation, the latter is prevented from getting wet if moisture condenses on the film.

The lower and upper ventilation gaps must communicate in the region of the ridge, so the waterproofing film is not brought to it by 5 cm.

In order not to accidentally lay the heat insulator plates close to the waterproofing barrier, it is recommended to drive limiting carnations into the rafters.

When using a simple waterproofing film, it is necessary to arrange ventilation gaps on both sides

Roofing with superdiffusion membrane as waterproofing

A superdiffusion membrane is a polymer film in which microscopic conical holes are made. The membrane passes steam only in one direction, so it is important to lay it on the right side. There is no need to make a gap under it - the insulation is laid close to the membrane.

The height of the ventilation gap in the attic roof depends on the angle of inclination of the slope and its length.

Table: ventilation gap height for different roof slopes (in cm)

Length stingray roofs, m	Roof pitch
	10°	15°	20°	25°	30°
5	5	5	5	5	5
10	8	6	5	5	5
15	10	8	6	5	5
20	10	10	8	6	5
25	10	10	10	8	6

Video: ventilated ridge device in a mansard roof

hip roof ventilation

The hip roof differs from the usual gable roof in the absence of gables, instead of which there are two triangular end slopes. The line of intersection of the end and longitudinal slopes is called the ridge. Roof ventilation is carried out according to the same principles as for a gable roof, while taking into account the following:

Installation of an aerator on different roof coverings

Requirements for the installation of ventilation elements depend on the type of roofing material.

Installation of an aerator on a metal tile

Installation of an aerator or ventilation outlet on a roof with a metal tile coating is carried out as follows:

1. On the roof, mark the installation sites of aerators. They should be no more than 60 cm from the ridge. The frequency of installation depends on the brand of the aerator and is indicated in its passport.
2. In the marked place, a template is applied to the coating (it is included in the kit), which must be circled with chalk or a marker.

   In order to outline the contours of the hole to be cut out, use the template that is included in the aerator kit.

3. The outlined section of the roofing is cut out. Alternatively, you can first drill a series of small diameter holes along the contour, and then cut the gaps between them. You can do this with scissors for metal or a jigsaw.

   A passage hole is cut along the drawn contour

4. The area adjacent to the resulting hole is cleaned of dirt and dust, and then treated with a degreasing compound.
5. A hole is cut in the casing (part of the aerator kit) with a diameter 20% smaller than the diameter of the element pipe. Thus, the casing will be put on the pipe with an interference fit, so the connection will be tight.
6. The pipe is inserted into the casing, after which the complete assembly of the aerator is carried out.
7. The edges of the hole in the cover, on which the skirt of the casing will be installed, are lubricated with a sealant for outdoor use.
8. The fungus is installed in place, while the casing is screwed to the roof with self-tapping screws.

   The aerator casing is fixed to the crate from the outside and from the inside

9. The pipe is brought to a vertical position according to the level and fixed. As a result, the deflector fixed on it should be at a height of at least 50 cm relative to the roof.

   The head of the aerator should rise above the ridge by 50 cm

10. It remains to check the correct fastening of all elements from the inside, that is, from the side of the attic. Found defects or distortions must be corrected.

Installation of an aerator on a roof made of soft tiles

Basically, the process of installing a fungus aerator on a soft tile roof looks the same as on a metal tile one. The differences are in some details. Here's what to do:

Features of mounting the aerator on corrugated board

To install an aerator on a corrugated roof, a wooden box is usually used. The installation process looks like this:

1. After marking at the place of installation of the aerator, a cross-section is made in the corrugated board.
2. The resulting triangular petals are bent down and nailed to the rafters and other wooden elements.
3. According to the size of the opening, a box is knocked together from the boards. Then it is inserted into the opening and screwed with self-tapping screws to the elements of the truss system.
4. A fungus aerator pipe is installed and fixed in the box, after which all the cracks are filled with sealant.

Ondulin roof aerators

Ondulin manufacturers produce all the elements necessary both for ventilation of the under-roof space and for organizing access to the roof of various ventilation ducts. Here is their list:

1. Aerators.
2. Ventilation outlets of the hood with insulation. Exhaust ventilation ducts from the kitchen are connected to such outlets (the hood above the stove can also be connected here) and the bathroom. The pipe has a diameter of 125 mm and is equipped inside with a special coating that counteracts the formation of grease and dirt deposits. From above, the outlet is equipped with a deflector that protects the internal cavity from precipitation and improves traction.

   Pipes for the ventilation outlet of bathrooms and kitchen hoods are painted in the main colors of ondulin

3. Sewer ventilation outlets without insulation. These outlets are connected to the sewer pipes of the sewer risers. Without communication with the atmosphere in the sewer, during a salvo descent of water, a decrease in pressure will be observed, which can lead to a breakdown of the siphons, followed by the penetration of unpleasant odors into the room. The diameter of the sewer outlet is 110 mm.
4. Ventilation sewer outlets with insulation. Such outlets differ from the previous version by the presence of a sheath made of polyurethane or another polymer (thickness is 25 mm), which helps to reduce heat loss and thereby minimizes the amount of condensation on the inner surface.

   The ventilation outlet for the sewer can have a protective sheath made of polymer material to reduce the amount of condensate that forms.

Corrugated pipes are usually used to connect ventilation outlets to the corresponding channels. The length of the outlet is 86 cm, and after installation, the length of the outer part, that is, the height of the outlet above the roof, is 48 cm.

Installation of ventilation outlets and aerators is carried out as follows:

There are situations when it is not possible to use a base sheet with a ready-made opening and a sealing element. Then the opening in the coating is cut out independently, and the gap between its edges and the removed pipe is sealed using the Enkryl waterproofing system, which is just designed to seal problematic joints. It is applied like this:

1. The area around the opening is treated with a degreasing compound.
2. Next, the first layer of Enkryl sealant is applied to it and to the pipe brought out into the opening with a brush.
3. The pipe or aerator is wrapped with a reinforcing fabric, such as viscose Polyflexvlies Roll. Here it is necessary to pause - the sealant must soak the fabric well.
4. The fabric wrap is covered with a second layer of Enkryl, which is also applied with a brush.

This method of sealing the passage through the roof is designed for 10 years. After this period, the waterproofing will need to be renewed.

To seal joints and crevices, instead of fabric and paste-like sealant, you can use Onduflash-Super adhesive tape.

Video: installation of ventilation on ondulin

Installation of ventilation elements on a seam roof

For the installation of roof ventilation elements on a seam roof (the coating is made of metal sheets), it is best to use a universal sealant for roof passages. It consists of a square aluminum flange on a silicone lining and a stepped pyramid attached to it made of the same silicone or special rubber, resistant to ultraviolet and other atmospheric influences. The size of the seal must be selected so that the inner diameter of the pyramid is approximately 20% smaller than the outer diameter of the aerator or ventilation outlet.

Installation is carried out as follows:

The aluminum flange of the universal seal is flexible and can be molded into any shape. Due to this, the element can be installed not only on flat roofs like seam, but also on wavy ones, such as ondulin, slate, corrugated board and metal tiles.

Roof vent installation

In the place where there is a ventilation outlet to the roof, a so-called passage unit is installed, the main task of which is to seal the gap between the pipe and the roofing. Nodes can be very different both structurally and externally. Basically, the following varieties are distinguished:

1. Equipped with a valve and not having one: the presence of a valve allows you to control the movement of air in the ventilation system. The passage nodes equipped with this element are installed mainly on the roofs of administrative and industrial buildings. Units without an adjustment valve do not provide for, but they are cheaper.
2. With and without insulation: the first in their design have a layer of mineral wool (this insulation is non-combustible) and are used in regions with a cold climate. The presence of thermal insulation prevents moisture condensation on the internal surfaces of the unit.
3. With manual (mechanical) and automatic control: in the first case, the damper is moved to one position or another by the user, pulling the cable attached to it. In the second, the damper is driven by a servomotor, which is controlled by an electronic controller. Such a system, with the help of appropriate sensors, can analyze the temperature and humidity in the room and, taking into account these indicators, regulate the throughput of the ventilation ducts.

The cross section of the node can be rectangular, round and oval. When choosing this element, the following microclimate parameters are taken into account:

• relative humidity;
• the content of dust and chemical contaminants in the air (gas content);
• temperature fluctuations in the room.

The ventilation outlet is installed in the same way as the aerator, with the only difference that it must be carried out not only through the roofing, but also through the waterproofing and vapor barrier films. To do this, proceed as follows:

Video: installation of a ventilation outlet to the roof

Installation of a ridge aerator

Ridge aerators can have a different design, but in most cases the installation is done like this:

1. The old coating is dismantled from the ridge zone (if the roof is new, this paragraph of the instruction should be skipped).
2. If a solid crate is laid under the coating, a line is drawn on it parallel to the ridge, 13 mm apart from it (on both slopes).
3. A cut is made along the drawn lines with a circular saw with an indent of 300 mm from the outer walls.

   A ventilation cut is made on both sides along the entire length of the roof, not reaching 30 cm to the gables

4. Two ridge shingles are attached to the edges of the roof.
5. Roof aerators are bent to the desired angle, depending on the angle of the roof.
6. Aerators are installed with an overlap in place. During installation, it must be taken into account that the covering and covered ends are structurally different. It is not necessary to seal the overlap points. The partitions available for the aerators must lie on the floor. If this rule is not observed, water may flow under the roof.
7. Aerators are fastened with nails, which must be driven into specially made holes. The sides in the process of driving nails must be alternated.

   The ridge aerator is fastened with nails through special holes

8. The last aerator is cut to length with a margin of 13 mm. Its edges are superimposed on the previous part.
9. The roofing is laid, which must be fixed with nails or self-tapping screws. It is necessary to drive or screw fasteners into a specially marked area on the ridge aerator. It is marked as such: “roofing fixation zone”.

   The ridge aerator is covered with roofing material, which is fastened through specially marked holes

10. The places where the ends of the chain of aerators adjoin the roof are sealed with a special mastic, which is usually supplied with the aerator. To do this, you need to prepare a mounting gun.

Video: installation of a ridge aerator

Under no circumstances should roof ventilation be neglected. There are no elements in the roof structure, except perhaps for films that would be immune to the negative effects of moisture, and in the absence of high-quality ventilation, it will certainly appear. Following the recommendations outlined in this article, you will ensure a long service life of the roof and a cozy microclimate not only in the attic, but also in other areas of the house.

• Constant daily fluctuations in temperature cause condensation to form. Most of all, its negative impact is experienced by the insulation. Having absorbed enough moisture, it practically ceases to perform its functions with all the ensuing consequences. Moreover, it should be noted that condensate is only one of the possible sources of moisture. But among the available roofing structures, there is one for which such problems simply do not exist. The device of the ventilated roof provides complete protection against swelling of the coating, the penetration of moisture under it and the formation of mold. These are not the only advantages of this type of construction.

  Advantages of a ventilated roof

  
  

  Design
  

  

  Such a design is not particularly complex. For the free circulation of air, a combination of three elements is necessary:

  • ventilation of the gap between the layers of hydro- and thermal insulation;
  • ventilation of the gap between the coating and the waterproofing material.
  • ventilation in the attic space is a component of the general house ventilation system.

  This ensures continuity of air circulation, which helps to maintain the temperature at about the same level and contributes to the rapid evaporation of moisture.

  Structurally ventilated roofing has several types, which primarily depend on the purpose of the building. For buildings such as utility rooms and garages, an uninsulated version is sufficient. Structurally, this

  • rafter system,
  • wooden crate,
  • waterproofing in the form of a polyethylene film, which is fixed to the rafters on the slats;
  • roofing.

  For heated buildings, a slab heat insulator and an anti-condensate film are added to the structure, which protects wood elements from condensate. A roofing cake usually consists of a sequence of such layers:

  • laminated film, laid in two layers;
  • non-woven material with a high degree of moisture absorption;
  • polypropylene fabric.

  An important element is the vents located on the cornice on the underside, and a ventilated ridge.

  When designing this type, the need for the presence of

  • natural drainage, in other words, the roof by its design should not interfere with the natural flow of water. This condition is especially relevant for flat roofs, since non-compliance with these rules leads to the accumulation of water on uneven areas of its surface;
  • venting steam through the roof.

  Types of ventilated roof

  The most popular are flat and pitched, differing in their design.

  flat
  

  With the advent of heaters equipped with ventilation ducts in the 80s of the twentieth century, it became possible to arrange ventilated ones. They were especially in demand in the construction of apartment buildings. Their design includes
  

  • Reinforced concrete floor slab, which simultaneously acts as the basis of the pie;
  • vapor barrier layer;
  • , and the head of the deflector must be located in the heat-insulating layer;
  • cement-sand screed;
  • bituminous;
  • a layer of polyurethane mastic;
  • flooring.

  To protect the roof structure, side parapets are built. They must be separated from the roofing cake. For this purpose, bulk or sprayed materials are used. Today, polyurethane foam is most often used in this capacity. PPU spraying gives a high degree of insulation and sealing. By the way, with the help of the same material, the abutments of the deflectors to the roof are processed.

  The device of a flat roof is quite economical and does not require much time. Some doubts are only caused by the level of thermal insulation and the insufficient resistance of the structure to external influences, which is why it is relatively. Although, admittedly, this does not affect its popularity in any way.

  pitched
  

  In this design, excellent air circulation is performed at a high level: it climbs through the lower overhangs and then penetrates into the under-roof space and exits through the ridge vents, preventing dampness from accumulating. And this, as you know, is the first enemy for the elements of the truss system made of wood and the components of the pie. In cases where it is impossible to provide full-fledged natural air circulation, they resort to a forced ventilation device through special roof fans. The pitched roof is cold or insulated. These options differ from each other by the presence or absence of a heat-insulating layer.

  One of the popular insulation used in the construction of pitched roofs is mineral wool. Among its advantages, one can note the ease and simplicity of installation and the absence of “bridges” of cold with well-conducted insulation.

  Mounting technology
  

  

  flat
  

  For a flat roof, the following types of work are sequentially performed.

  • Foundation preparation. Its surface is leveled, having previously repaired all existing defects: chips, cracks and potholes.

  The best option for preparing the base is the installation of a cement-sand mixture screed or asphalting of the floors, taking into account a slope of 2–3⁰.

  • Vapor barrier and thermal insulation. When laying these layers, it is important to perform it continuously, in a continuous array, without allowing any cracks or breaks.
  • Waterproofing and screed device.
  • Roof decking. Most often used in modern construction. Cloths of material are glued to the base, after melting a special layer. Laying is carried out with an overlap of 8-10 cm in the direction transverse to the slope.

  During installation, the outlets of the ventilation ducts must be clearly marked. All junctions are further isolated.

  Ventilation here, in particular, is organized through holes located along the edges of the roof. They must be covered with nets to protect against insects getting inside.

  pitched
  

  In the case of a pitched roof, the device manual is supplemented by the mandatory steps for arranging a ventilated eaves and a ridge hood. For the effective functioning of the ventilation gaps provided for when installing the roofing pie, it is necessary, on the one hand, to obtain an influx of air from the outside, and on the other hand, to ensure the exit of moist air from the upper ridge part. For this,

  • firstly, gaps or special holes are left on the underside of the eaves during sheathing, which are covered with a fine steel mesh - this is protection from birds and insects.

  One of the modern options for solving the problem of air intake is the installation of a continuous filing of the eaves with perforated panels, designed to ventilate the roof.

  • secondly, the skates must be of a special design - ventilated.

  

  If, for one reason or another, this possibility is not foreseen, then the air is taken out through the ventilated gaps left on the lower and upper parts of the roof by means of special fans.

  If corrugated sheets are used to cover the roof, no matter what they are - metal or not, the problem of binding the upper air with the atmosphere is solved automatically, even if you use a "flat" ridge - the air will escape through the gaps on the profile of the roofing material. In this case, it remains to ensure the operation of only the lower gap.

Constant ventilation of the insulated roof structure is a necessary condition for the long-term and reliable service of the entire building. The importance of ventilation cannot be overestimated - thanks to the convective air flow, excess moisture that has penetrated from a warm room is removed from the roof structure. In addition, the insulation and truss structure can gradually become saturated with atmospheric moisture in the summer or have residual moisture formed during the construction of the house.

In the absence or insufficient ventilation, all elements of the roof are moistened with condensate, especially dangerous consequences are the wetting of thermal insulation and wooden parts of the roof - rafters, Mauerlat, columns and crossbars.

The main negative results of inefficient roof ventilation include the following:

accumulation of moisture, leading to the formation of condensate on the rafters and substructure, and subsequently mold and fungus that destroy wooden elements (Fig. 1); corrosion of metal structures, destruction of brick and concrete parts; formation of ice on the roofing material and, as a result, damage to the roof and drainage system, penetration of melt water under the roofing during thaws; moistening of thermal insulation, leading to a sharp decrease in its thermal resistance and an increase in the cost of heating a home; overheating of the roofing material in the summer (this is especially detrimental to bituminous tiles) and the interior of the attic; increase in air conditioning costs.

Rice. 1. Installation error: freezing of condensate on the plywood base of the bituminous roof and roofing film, mold damage to the rafters

It is easiest to provide sufficient ventilation on cold (attic) roofs due to the large air volume and the absence of air circulation obstructions. The necessary air exchange is provided through openings on the eaves, ridge and ridge of the roof, as well as through the gable grilles. The main problems arise on mansard roofs, and they are solved depending on the design schemes of insulated roofs, which can be divided into ventilated (with two or one ventilation gap) and non-ventilated. The latter option has recently begun to be used in Europe, and there is simply no great experience in its application in Russia, so it is premature to dwell on it in detail.

Roofs with two ventilation gaps, traditionally used in the construction of attics since the middle of the last century, are well known to Russian roofers. The principle of ventilation is as follows (Fig. 2): external moisture that has penetrated under the roof is removed through the upper gap between the roof and waterproofing. It can be raindrops or snow blown by strong winds, melt water or atmospheric moisture that has fallen on the roof and waterproofing in the form of condensate. Structurally, the upper gap in most cases is provided by a 40-60 mm thick counter-lattice, which is mounted on top of the waterproofing and serves as the basis for a continuous flooring (roofing made of bituminous tiles or slate) or a step lathing of tiles, metal tiles and corrugated sheets. In addition, the counter-lattice reduces the risk of damage to the waterproofing during roofing. The lack of a counter-lattice between the under-roof waterproofing and the roofing material, or its insufficient height, almost always leads to the formation of condensate and other dangerous consequences for the roof and the entire building.

Rice. 2. Roof structure with two ventilated gaps

Through the lower ventilated gap between the waterproofing and the insulation, water vapor is removed, which penetrated into the roof from the interior of the attic through the vapor barrier. The reasons for transporting steam may be the low quality of the material or defects in the construction of the insulating layer - for example, the overlaps of the vapor barrier film rolls are not glued or the film adjoins walls, skylights, Mauerlats and other structural elements are leaky. A very wide range of materials can be used as under-roof waterproofing for a structure with two ventilated gaps: micro-perforated and anti-condensation films, rolled bitumen materials on continuous flooring and even some vapor barrier films. If installed correctly, such a scheme will work reliably for a long time, and the cost of waterproofing materials for its installation will be less than for modern structures with diffusion films.

However, the limited advantages of such a ventilation scheme are lost against the background of its fundamental disadvantages:

• increased heat loss due to the lack of wind protection and unimpeded heat transfer from the upper layers of fibrous insulation - the stronger the ventilation, the more energy is lost and, consequently, the homeowner's heating costs increase;
• the greatest risk of convective moisture transfer from a warm room to thermal insulation through any damage to the vapor barrier, since air moving along the lower ventilation gap provokes exfiltration of moisture-saturated air from the attic;
• humidifying the insulation in the summer with moisture contained in the atmospheric air (for example, at a temperature of 28 ° C and a relative humidity of 80%, the air can contain up to 24 g / m3 of moisture, which will certainly get into the thermal insulation);
• difficult to solve problems of insulation ventilation on roofs of complex shape and gentle slopes;
• open gaps in the under-roof waterproofing layer on ridges and ridges reduce the reliability of the roof from the penetration of external precipitation and force the use of ventilation rolls with dense meshes or non-woven fabric tapes - they protect against leaks well, but significantly worsen the ventilation of the roof structure;
• a gradual decrease in the characteristics of the insulation due to the mechanical entrainment of mineral wool fibers;

The fact that roofs with two ventilated gaps are used less and less in European countries (for example, in Germany this is no more than 3% of all new roofs) confirms the desire of investors, architects and roofers to reduce energy losses and increase the reliability of buildings. A design with only one ventilation gap between the roof and the insulation, protected by a diffusion (vapor-permeable) film, is devoid of the above disadvantages. Since the wind barrier, which also functions as a waterproofing layer, is laid with an overlap over the ridges and ridges, air elements and rolls with relatively large openings can be used - this will allow very efficient ventilation of the roof without the risk of leakage (Fig. 3).

Rice. 3. Roof structure with one ventilated gap

The area and cross-section of the ventilation ducts depend on the length of the cover (the length of the slopes), the angle of inclination and the complexity of the shape of the roof, as well as on the climatic features of the region. General recommendations are contained in the reference literature, so I will focus on only some recommendations for the conditions of the European part of Russia:

• practice confirms that the cross-sectional area of ​​​​the ventilated channel in any part of the roof should be 400–500 cm2 / m, which corresponds to a gap height of 4–5 cm;
• a strong increase in the height of the gap will not lead to increased ventilation. On the contrary, it can cause a significant reduction in air exchange under the roof due to the resulting turbulence and growing resistance to air flow;
• if the length of the coating exceeds 10 m, then it is recommended to use additional elements to enhance ventilation;
• ventilation openings on ridges, ridges, cornices and valleys must be protected from leaves, branches, birds and insects with the help of special ventilation elements offered by roofing system manufacturers;
• any narrowing of the ventilation ducts or structural obstacles can lead to poor ventilation and condensation;
• large air pockets in an insulated roof have significant inertia in terms of air exchange, which can also cause moisture condensation.
• the dust blown through the lower air gap is quite hygroscopic - it accumulates on the thermal insulation and can cause it to become moist.

Ridge and ridge (rib) For each roofing material, regular ridge ventilation elements are produced. The widest choice is offered by German tile manufacturers: these are ridge tiles with labyrinth air channels, ridge air elements and ventilation rolls (Fig. 4), which are successfully used in Russia for metal tiles as well. Roofs made of bituminous tiles are equipped with ridge strips made of metal or plastic, or a ventilated ridge is made from the main roofing material. The same is done with the installation of seam roofs. "Fillers for the ridge" of polyethylene foam metal tiles can reliably protect against external moisture, but they are not able to provide the necessary ventilation.

Rice. 4. Ventilation elements for the skate

The main errors in the installation of the roof ridge, which can lead to a decrease in ventilation or its complete blockage, are as follows: filling the ridge strip with mounting foam or sealing it with tapes. This is a common defect on roofs made of metal tiles and completely eliminates roof ventilation (Fig. 5); lack of air in the ridge part of the roofing film, if the roof structure is made with two ventilation gaps (Fig. 6). Very often, the problem of condensation is solved after the roofer cuts through the film on the ridge, leaving free air about 10 cm wide. Separate aerators installed along the ridge cannot always provide good ventilation of the roof, therefore it is recommended to use a fully ventilated ridge on all mansard roofs with any roofing material.

Rice. 5. Installation error: sealed ridge and ridge Rice. 6. Installation error: lack of air in the ridge part of the film

Eaves overhang When installing a cornice, it is necessary to ensure a sufficient area of ​​​​inlet openings for air, even despite the "opposition" of architects who are not enthusiastic about ventilation grilles, slats and spotlights. The options for filing the overhang may be different, but in any case, the air flow into the roof must be made in accordance with the calculation. Sometimes an obstacle to this can be external wall insulation or a “green facade” made of bindweed or other plants that can block the air. Sometimes the space under the roof is occupied by birds to build their nests, which can lead to poor ventilation and damage to the roofing film. But this can only happen due to neglect by roofers of ventilation elements (Fig. 8), which prevent the penetration of birds, or their improper installation.

Rice. 7. Ventilation options through the filing of the cornice overhang

Reliable protection of the air channels on the eaves are the ventilation tape covering the ends of the counter-lattice, as well as the overhang air element and the overhang grille. A drainage system can become a constructive protection against snow - it is recommended that the gutters be located directly under the roofing material (above the ventilation gap), so even if heavy ice or snowdrifts form, the gap will remain open for air flow. But low-lying gutters without a heating system do not protect the ventilation gap from snow and ice sliding off the slopes. The absence of a snow retention and snow stop system (snow stops evenly distributed over the roof) leads to snow sliding onto the eaves and blocking air access to the under-roof space.

Rice. 8. Installation error: ventilation problem due to birds

Endova (groove) The gutter can be attributed to the most complex roof assembly in terms of reliable roofing, ventilation and operation. A serious design error is the use of a scheme with two ventilation gaps on roofs of complex shape with long valleys and short eaves. In this case, it is extremely difficult to ensure ventilation of the insulation and rafters in those sections of the slopes that are adjacent to the valleys. Roofers are forced to make openings of sufficient area in the roofing film, and such openings must be in each span of rafters. Prefabricated parts can be used, such as the ventilation element of the BRAAS bottom protective film (fig. 9) or the SK TUOTE roof penetration seal. Other options are the implementation of special openings (Fig. 10) or the installation of a continuous ventilation duct along the valley (Fig. 11).		Rice. 11. Continuous ventilation channel along the valley

Measures such as drilling holes in the rafters are ineffective. Of course, it is also necessary to install aerators / ventilation tiles along the valley in the roofing material so that air can enter both the upper ventilation gap and the lower one (Fig. 12). However, such measures can only be relatively effective on roofs with large slopes (about 45° and above). On gentle slopes in the valleys, snow will accumulate, which will close the ventilation elements and will not allow effective ventilation of the roof structure. In such cases, forced ventilation may be required using inertial turbines, electric roof fans, or high nozzles that will not be covered with snow (fig. 13).

Rice. 12. Placement of aerators or ventilation tiles along the valley

The use of such elements can significantly increase the cost of the roofing kit, as a result of which the choice of the customer or his contractor in favor of cheap microperforated films will not be justified in terms of both roof reliability and financial costs at the time of construction and especially subsequent operation. On roofs of complex shape or with small angles of inclination, it is reasonable to use only modern diffusion films with high vapor permeability (Sd< 0,2 - 0,4 м) в схемах с одним вентиляционным зазором. Attachment to walls, windows and pipes Additional ventilation elements must be installed in cases where there are structural obstacles to the free movement of air flow. This usually happens when installing skylights (especially combined blocks that completely block ventilation along the slope), as well as when removing a chimney or chimney, ventilation shaft through the roof.		Rice. 13. Elements of forced ventilation for low roofs

Deterioration of ventilation can also be caused by insulation defects, when local heating of the structure due to increased heat loss leads to the fact that the heat flow prevents or even suppresses convective draft in the ventilation gap. Such problems are encountered, as a rule, on sloping roofs or with its complex geometry (Fig. 14). At the end of the article, I consider it necessary to once again focus the reader's attention on the fact that the reliability, durability and economy of the roof equally depend on all its constituent elements - the truss structure, insulation, hydro and vapor barrier, roofing system and ventilation. Errors in the construction or design of any element can lead to severe damage to the roof and the entire building.		Rice. 14. Installation error: lack of continuous ventilation of the ridge, no aerators on the valley