The reliability, service life of the roof, as well as its efficiency are determined by the constituent elements of the structure, be it layers roofing pie, covering or supporting structure. Any of the design errors or violation of technology is fraught with deformation of the roof and the entire structure.
One can only welcome the attention that developers pay to heat, waterproofing and wind protection. Unfortunately, at the same time, they quite often do not attach due importance to such an important element as ventilation of the under-roof space.
It would seem that what is so necessary about it? At first glance, especially from the point of view of the common man in the street, nothing. Indeed, it is difficult to imagine that moisture can form under the roof of a dry house that has just been built or renovated. In addition, there was a time when roof ventilation was carried out practically at the expense of. Yes and in suburban construction Until recently, there was no particular need for this, since, unlike modern sealed houses, air circulated freely through the cracks in the roofing pie and its walls.
In accordance with the laws of physics, warm air rises up into the attic or attic and concentrates at the very top of the structure - under the roof. Thus, on cold winter days, snow that has settled on warm areas of the roof melts. As a result, the following processes occur:
When the thermometer drops below zero, problems begin on the inside - due to the difference between the outside and inside temperatures, the moisture contained in the air condenses on the cold surface. The resulting moisture flows into the roofing pie, reinforcing structures, as well as beam floors. Alternating freeze-thaw cycles gradually destroy them, reduce the effectiveness of thermal insulation, and create a favorable environment for the formation of fungal mold.
Lack of ventilation of the under-roof space of metal tiles causes corrosion of the roof. First of all, areas where the factory coating was damaged during installation or operation begin to corrode.
The summer period is also associated with negative phenomena, for example, overheating of the roof, which, coupled with UV radiation, shortens the service life of the roof, and the use of the attic space becomes problematic.
The traditional use of a dormer window for air ventilation is generally ineffective. As for the ventilation of the attic under-roof space, such a solution is generally not applicable here.
The consequences of insufficient ventilation can appear quite early after about 5-6 months in the form of unsightly streaks and stains appearing on the interior of the finish.
Attention!
As metal structures corrode and wooden structures rot, the question of premature repair or complete replacement roofs.
Modern ventilation is organized on the basis of the following provisions:
It is aimed at performing the following tasks:
With a cold roof
This is the simplest case of solving the problem, since it allows large volumes of air to move freely. Vents located under the eaves, under the ridge strip, in the gables allow air masses to circulate due to natural convection:
Of course, in this way it is impossible to completely level out the temperature difference between the roof surface from the outside and inside, however, it is usually not enough for condensation to form on the inside of the attic.
As a rule, the number of vents located at the top and bottom of the slope of pitched roofs of a simple configuration is the same. The only condition under which normal air circulation is ensured is that the total area of the vents should be about 0.33% or ⅟300 of the area of the slope.
For a warm roof
Ventilation is a little more complicated. In such a structure, air cannot circulate freely, since it is almost entirely occupied by attic spaces.
Air circulation in the residential attic, located in the under-roof space, is ensured by a convective flow directed from the eaves towards the ridge. In order for it to pass this path unhindered, additional space is created in the roofing pie between the layers of heat and waterproofing using counter-lattice and sheathing. The gap must be at least 5 cm high.
Then a ventilated circuit is formed in the space under the roof, that is, they provide air flow, as well as its exit with vapor:
Attention!
It is important to ensure continuity of the circuit in order to exclude the formation of “stagnant zones”, places where condensate may accumulate.
The roofing materials market offers developers special elements that increase the efficiency of the system. Some of them increase the intensity of the air flow, others form the entrance/exit for it. They are called aerators or aeroelements.
It’s not even worth talking about the need for roof ventilation. Everyone knows this. But this article will discuss how to make it effective, durable, and also install it yourself, using advanced engineering practices.
The importance of the roof is difficult to overestimate. Therefore, erecting a building, experienced builders they arrange the roof with special care, providing it with reliable insulation, insulation and a ventilation system.
During the operation of the house, steam is generated indoors, which, according to the laws of physics, rises into the under-roof space. And if there is no properly adjusted roof ventilation, then steam settles on the roof structures, rendering them unusable and destroying them. load-bearing elements building.
A roof without ventilation is dangerous. Increased humidity will lead to the formation of mold and mildew on the walls, wetting of the insulation, and therefore deterioration of thermal conductivity and freezing of the house. A well-established roof ventilation system will help to avoid this, which will remove condensation outside and prevent it from ruining the entire structure.
In order to extend the life of the roof, it is equipped with a high-quality ventilation system
Home ventilation can be spot or continuous, natural or forced. The most common sources of air circulation include:
Sufficient for small or medium roofs natural ventilation. Forced ventilation elements are installed on large roofs, where natural air exchange in the under-roof space is insufficient.
The assembly of ventilation components (including labor) is no more than 2–5% of the cost of the roof itself, which is much less than what will be required to repair the roof, individual sections of the house, or even the entire building as a whole, if the ventilation system is not installed or installed on “maybe, I suppose, somehow.”
The main tasks assigned to the elements of the ventilation system:
The ventilation system of the building consists of various elements, performing one common task: to ensure normal temperature regime roof and under-roof space
The ventilation tape covers all the cracks in the roof, while ensuring sufficient air exchange and protecting the under-roof space from debris, invasion of birds and other small animals.
Ventilation tape TOP ROLL S 240 mm ensures good air circulation and protection of the under-roof space
Depending on the purpose there are:
Advantages of using roofing tape:
Ridge roofing tape protects the roof ridge from precipitation and snow getting under the roof. Along with this, it removes steam from the roofing pie, preventing wetting and rotting of the rafter system and covering material.
Good ventilation tape famous manufacturers, as a rule, is treated with special compounds against UV radiation, which ensures additional protection roof joints from destructive solar radiation. The ridge strip is laid along the edge of the roof, and the ridge is mounted on top of it. Work is carried out at air temperatures from +5 °C.
The ridge ventilation tape is placed under the metal plate of the ridge
Eaves perforated tape is used to cover eaves overhangs. It not only protects the under-roof space from rodents, birds, insects, dirt and creates free air exchange, but also increases the strength of some roofing components.
PVC ventilation strip reinforces the eaves structure
For pitched roofs, in addition to proper air exchange, protection from insects is also an important task. Hornets, wasps and small birds populate the under-roof space, build nests, thereby creating not only a noise effect and unsanitary conditions, but also interfering with the natural ventilation of the roof. To combat such a scourge, a ventilation mosquito net with cells measuring 2–3 mm is designed.
Stainless steel mesh is considered the best, as it is the most durable and strong. It is resistant to corrosion, does not spoil the exterior of the house, and has a much longer service life than analogues. The only downside is the high price compared to other types of mesh.
Stainless steel ventilation mesh for roof ventilation is considered the most durable and strong
It is undesirable to use steel mesh, as they corrode due to condensation leaks, rot and rust. In order to save money, it is better to use a painting mesh with small cells as a budget option. Its advantage is its low cost and ease of installation - the mesh is laid overlapping and stapled to wooden parts roofs. However, the painting mesh is not very strong and therefore short-lived.
Fiberglass paint mesh does not have sufficient strength and is easily torn and pecked by birds, so it is best used as a temporary option.
Pass-through elements (penetrations) are an integral part of ventilation pipes. They are designed to seal roof openings. As a rule, they are not included in the delivery package, but are selected separately for each type of roof.
Penetrations are varied in shape, size, color, which is determined primarily by the manufacturer, and secondly by the roofing covering (soft roofing, corrugated sheeting, metal tiles). But they are all easy to install. They are installed both at the construction stages and on a finished roof.
Penetrations are used to seal the joints between ventilation pipes and roofing.
Only with precisely selected passage parts corresponding to the covering material can we talk about the durability of the ventilation system, the absence of leaks in the tie-in areas and the ability of the roofing components to withstand all climatic loads.
Roofing accessories such as aerators are designed for more effective ventilation of soft roofs. These are elements of forced ventilation that reduce pressure under the roof and increase draft, which ensures the necessary air flow.
Aerator for roof ventilation soft tiles reduces pressure in the under-roof space, which ensures good ventilation of attic spaces
Aerators are selected depending on the roof area, observing the following rules:
Ventilation accessories also include an overhang ridge, which has a frequent row of teeth that protect the eaves gap and the adjacent under-roof space, as well as roof fans. They are indispensable on flat roofs with insufficient natural convection and on pitched roofs when it is not possible to arrange natural ventilation.
The overhang ridge is mounted directly under the final row of groove tiles using self-tapping screws
Any ventilation duct is led to the roof of the house and forms a so-called passage unit (PU) at the exit points in the form of a pipe inserted either into the roof itself through the outlet or into reinforced concrete glasses.
Each element of the ventilation system requires a sealed unit to pass through the roof
Industrial ventilation passage units are manufactured in accordance with GOST 15150 and are:
Depending on the type of roofing and the design features of the roof and air vent, they differ in shape:
Along with typical elements, non-standard units are often manufactured, designed for ventilation systems that are original in structure and assembly. However, all of them must meet the requirements defined by GOST:
The passage units for chimney ducts are arranged in strict compliance with fire safety regulations.
Many people wonder whether a ventilation gap is needed and, if so, why. Is it possible not to do it, since there is already a gap between the covering and the sheathing.
But is it really necessary to have a ventilation gap on the roof? Let's try to figure it out. Ventilation of the under-roof room consists of three gaps: the eaves, through which air flows, the gap between the roof and the insulation (the membrane does not count) and the gap at the highest point of the roof (ridge or abutment).
Their goal is to ensure good air circulation under the roof and prevent the insulation from getting wet. And if you neglect the gap on the roof, the consequences will be very disastrous - you will have to dismantle the roofing pie and change the insulation. And this is the least of all troubles.
To keep the house warm in winter and cool in summer, ventilation on the roof must be arranged according to all the rules.
Additionally, hard surfaces typically require repainting every 10 to 20 years. But if there is no gap, the resulting condensation will spoil the flooring sheets from the inside. And while painting them on top is quite simple, it is impossible to do this from the inside without dismantling the entire roofing pie and replacing the sheets completely.
So the answer to all questions is obvious - make gaps. Allow the roof to breathe to avoid problems that are initially unnoticeable but snowball. In addition, the gap on the roof must be sufficient to ensure the operation of the entire chain.
If you block the roof ridge, that is, do not create a gap, there will be no benefit from the gap between the insulation and the roof, as well as the eaves clearance.
A metal roof is beautiful, modern, durable and reliable, but it has one big drawback - limited air exchange, i.e. it does not allow air to pass through well. To ensure normal circulation, ventilation is installed according to the following algorithm:
Ventilation of a soft roof faces the following tasks:
With properly organized ventilation, cold air flows enter the under-roof space at the overhangs and exit through the ridge or aerators.
The arrows indicate the direction of air flow in the under-roof space with proper ventilation
Ventilation of soft roofs can be single- or double-circuit. But for it to be sufficient, a number of conditions must be met:
If the roof is not new, and the soft roof is being repaired, then look for places with the greatest swelling, and install aerators there.
Ventilation hip roofs can be conditionally divided into two groups - ventilation of a cold attic and an insulated attic.
Arranging ventilation for a cold attic space will not present any difficulties. Due to the large volume of the attic, there are practically no barriers to normal air circulation. Air exchange occurs through the eaves overhang, ridge and ridge. Dormer windows covered with bars and located on opposite sides of the roof provide a draft.
Natural air circulation occurs through the ventilation gap in the roof and dormer windows
When it is necessary to increase ventilation, aerators are installed along the passage of the valleys. But they make sense if the slope angle is more than 45°. Otherwise, in difficult areas in winter, due to snow accumulation, the operation of aerators will be ineffective.
For small slopes, it is better to do forced ventilation using roof fans, inertial turbines or nozzles of sufficient height so that they are not covered with snow.
It is advisable to plan the ventilation of the attic during construction, since its arrangement is more labor-intensive than the ventilation equipment for a cold attic space. There is no free air circulation here, which is why the space for air exchange is created by the sheathing installed between the insulation and the flooring.
Air circulation in the insulated room occurs due to the ventilation gap in the roofing pie
In addition, a gap of at least 2–3 cm between the hydro- and thermal insulation is required. If the depth of the rafters does not allow required clearance, then they are built up using boards.
But this method of air exchange is quite difficult to implement on roofs of complex shapes with many kinks and junctions. Therefore, roofers advise installing diffusion membranes (vapor-permeable) directly on the insulation, which allow moisture to pass through only in one direction.
A seam roof, like all other types of roofs, requires normal air circulation in the under-roof space. And this is ensured with the help of a gap between the coating and thermal insulation layer at least 50 mm, for which a sheathing is assembled from timber 50x40 or 50x50 mm. In addition, for greater reliability, the insulation is protected with a vapor barrier film.
To remove moisture from the ventilation gap on the roof, install a ventilation outlet for a seam roof at a distance from the ridge of no more than 0.6 m.
The ventilation outlet for seam and soft roofs is used to remove moisture from the ventilation gap
A seam roof laid in accordance with all the rules and well ventilated will last about 25 years without major repairs.
To equip the ventilation of pitched roofs you need:
It is not difficult to arrange ventilation with your own hands. General scheme one is to provide gaps under the eaves overhangs, protect them with tape or mesh, and create a gap between the sheathing and the insulation.
Further work depends on the roof slope. When the slopes have a slope of 10–45°, the exhaust gap is located in the ridge and is covered with a ridge aerator with a protective filter made of polyurethane foam. One such aerator, about 60 cm long, ventilates 25 m² of attic space.
If the structure of the roof does not provide for a ridge or the slope of the slopes is from 5 to 12°, then it is necessary to increase the number of supply holes at the bottom of the roof, and install aerators in the upper zone at a distance of 0.5–0.8 m from the roof itself. high place roofs.
With this arrangement, the aerator ventilates 5 m² of the attic space, but if the building is located in a well-ventilated area, then it throughput increases to 25 m².
The size of the ventilated gap depends on the slope of the slopes - the lower the roof slope, the greater the height of the gap. The type of thermal insulation material does not affect the size of the gap, but the type of roofing is very important. Under a hard covering (metal tiles, corrugated sheeting), you can use a counter lath for lathing a small section of 25x50 mm, since this is not a continuous covering, but has its own gaps and joints, through which air also circulates. Although experts do not advise experimenting and, for greater reliability and strength, recommend using 50x50 mm bars for all coatings, i.e., making the optimal gap height 50 mm.
Any home heating system, with the exception of electric, requires access to the roof. chimneys for the release of combustion products into the atmosphere. Let's look at how to remove a chimney through corrugated sheeting.
When calculating the height ventilation shafts take into account:
Requirements and standards according to SNiP:
If there are other outlets nearby ventilation ducts, the height should exceed the others by 20 cm.
Ventilation aerators are special devices for ventilating the under-roof space and removing moisture and water vapor to the outside. They are used on flat roofs, preventing swelling of the covering roll material due to temperature changes, and on pitched roofs for efficient ventilation and condensation removal.
Vanes (aerators) are produced in different sizes and designs. They are considered the most effective elements of ventilation systems. On a flat roof, they are installed evenly over the entire surface at the joints of the slabs. On pitched structures they are placed closer to the ridge (0.6 m from it) or in places where valleys pass (on complex roofs).
On pitched roofs, aerators are installed closer to the ridge or in places where the roof breaks.
The manufacturing material is AISI 316 stainless steel or durable polypropylene, thanks to which they can withstand a wide temperature range from -40 to + 90 °C.
With double layer coating roll materials aerators are installed in the bottom layer:
In single-layer flooring, aerators are installed on the screed, making a hole up to the vapor barrier. The coating is laid on the skirt of the aerator, hot mastic and a patch are applied on top, covering the skirt and extending about 15 cm onto the coating. The aerator is then secured with self-tapping screws, and the joint is treated with sealant.
The installation of ventilation outlets on roofs made of metal tiles and corrugated sheets is the same and is associated with damage to the roofing covering, so it must be carried out especially carefully so as not to have to change damaged sheets of covering material.
When installing ventilation elements, you must use proprietary fasteners, which are included in the kit.
Considering that today many people install the roof of their home on their own, let’s look at the most common mistakes when installing ventilation systems.
The basic rule when designing ventilation systems is that the more proportional and shorter the ventilation is, the more efficiently and with less noise it will work.
When setting up ventilation, sometimes it becomes difficult to select components. Let's look at the most popular manufacturers whose products deserve attention.
WirPlast equipment is used for various purposes - installation of room ventilation or fan outlets (sewage system), as a kitchen hood, for installing antennas or constituent elements solar panels.
Advantages:
WirPlast ventilation equipment is different high quality, which is confirmed by a ten-year guarantee for all products
TechnoNIKOL ventilation systems are available in two variations:
Advantages:
Vilpe products are developed by the Finnish company SK Tuote Oy. Excellent as forced ventilation systems installed both during the construction stages and during renovation.
Advantages:
Vilpe roof ventilation is made from impact-resistant polypropylene and can withstand large temperature changes
The success and demand for Kronoplast products is due to the fact that the company produces almost all parts for the ventilation of a private home - under-roof ventilation, kitchen outlets, vacuum cleaner outlets, sewer risers, etc.
The main feature of this product is 100% impermeability of all exits on the roof, without which full ventilation is impossible. Roofing elements are available for any coating in six basic colors.
Installation roof ventilation- an important and necessary process that requires attention and responsibility. It is not difficult to do it yourself, observing the mandatory rules and regulations. Only in this case the roof of the house will never “cry”. Good luck to you.
Under-roof ventilation
The roof of any home needs to breathe. With properly equipped ventilation, the service life of the roof increases significantly. It is necessary to make an important caveat - we are talking about classic attic, when an insulated living space is located under the roof and the space of the house is used as efficiently as possible, rather than a cold attic.
In almost any roof structure, humidity is always high. This happens for two reasons:
High humidity in the roof space affects wooden roof structures, insulation, and, as a result, the entire roof as a whole. Wetting the insulation reduces it thermal insulation characteristics several times, and wooden structures are subject to rotting, mold and fungus, which significantly reduces the service life of the roof and can negatively affect the health of the residents of the house.
Ventilation
When the roofing pie is installed correctly, the vapor barrier prevents the penetration of water vapor from the room, and the diffusion membrane closes the insulation from the outside, preventing water from passing through from above and allowing water vapor to escape from the insulation to the outside.
1. Wooden rafter system. 2. TECHNONICOL vapor barrier film. 3. Slabs from stone wool TECHNOLITE EXTRA. 4. TECHNONICOL Optima superdiffusion membrane. 5. Counter beam for creating ventilation ducts. 6. Sparse sheathing. 7. Wooden flooring (OSP-3; FSF). 8. Underlay carpet ANDEREP PROF. 9. Multilayer tiles TECHNONICOL SHINGLAS. 10. Step lathing for insulation.11. Attic filing
It is precisely in order to remove these water vapors from the space between diffusion membrane and wooden flooring made of OSB-3 or FSF (see figure), to protect the roof structure and insulation, ventilation of the under-roof space is needed. It is necessary to ensure air access at the eaves overhangs and air outlet at the ridge parts of the roof. And if the first does not present any difficulties, then releasing air where it is necessary to ensure complete tightness of the roof covering is not so easy. It is to solve these issues that the elements of under-roof ventilation are used.
Ventilation
Thanks to under-roof ventilation, cold air can enter from below and exit from above. At this moment, air movement occurs throughout the entire under-roof space.
Ventilation removes residual steam from the premises of the building, stabilizes the temperature over the entire roof area, preventing the formation of condensation on the inside of the roof and the appearance of ice and icicles, and on a sunny day reduces the temperature in the premises when the roof covering is heated from sun rays.
Ventilation
It is known that where there is excessive humidity, mold appears very quickly, which is dangerous to human health due to the mycotoxins it releases. Mold spores move freely through the air and enter the human body through breathing. Exposure to mold can cause breathing problems, allergies, or asthma. The mucous membranes become easily inflamed after exposure to mold, which can subsequently lead to sinusitis, bronchitis and even pneumonia.
The most the best way To prevent the growth of bacteria and mold in the roof, and subsequently throughout the house, is to keep the building structures dry and properly organize the ventilation system.
There is no need to skimp on quality ventilation. Its cost relative to the cost of the entire roof is unlikely to take more than a few percent. But repairing a roof due to its incorrect or poor-quality structure will cost much more.
For proper ventilation installation, everything must be correctly calculated and installed, otherwise improperly equipped under-roof ventilation or its complete absence will lead to fungus and mold attack of the building’s load-bearing structures, starting with the rafter system.
At first glance, it seems that it is difficult to understand the huge number of elements intended for the installation of under-roof ventilation; it is not clear what is for what. And is it necessary to install them all at all? But that's not true. Modern under-roof ventilation systems are so easy to install that anyone can handle them.
One of the optimal ventilation solutions now is plastic under-roof ventilation from TECHNONICOL. It allows the roof to “breathe” freely.
TECHNONICOL Corporation has developed the following elements for the installation of an under-roof ventilation system, adapting it to the climatic conditions of Russia:
Let's look at the elements of under-roof ventilation in more detail.
Used for ventilation roofing structures and attic spaces, to remove excess moisture from the under-roof space and serves as the main element of ventilation. For the aerator to work correctly, it is necessary to first organize an air flow through the eaves overhang, as well as a channel through which air will flow to the aerator and organize a cut in a solid base 5-8 cm wide at the installation site of the element.
The aerator is installed on the roof ridge from flexible tiles, is fixed mechanically. Covered with ridge-eaves tiles. Two or more elements are connected at the ends into a lock. The ventilated area of the under-roof space is 25 m2.
designed to ventilate the sewer system of summer houses and to remove all odors and vapors generated during cooking. It is installed on the roof and connected directly to the sewer riser using pipes and couplings. Characteristics: Outlet D 110 mm, Pipe H 500 mm.
Ventilation outlet D110
It is also used to provide ventilation for the sewer system, but is recommended for installation in houses with year-round accommodation. An insulated ventilation outlet is installed on the roof and, using a system of pipes and couplings, is connected directly to the sewer riser, which ensures the removal of odors. The insulated ventilation outlet is made of innovative materials that are not subject to icing even during prolonged frosts. (characteristics: pipe D 125 mm, external pipe D 160 mm, pipe H 500 mm and 700 mm).
Insulated ventilation outlet, D125/160 (H 500 / H 700)
It is used to remove excess moisture from the under-roof space of flexible tile roofs with a missing roof ridge or when ridge ventilation is not sufficient. The pressure difference created by the aero element sets air flows in motion, thus helping to remove moisture evaporating from the insulation from the under-roof space. The recommended installation location for the aero element is 0.5–0.8 m from the roof ridge, while air flow is ensured on the overhangs. One aerator provides ventilation of 10 m2 of roofing, provided that the height of the ventilated under-roof space is 5 cm.
Consumption: 1 aero element ~ per 10 m2. Size: Outlet D 110 mm.
Each of the elements has its own functionality in the under-roof ventilation device.
No one modern house today cannot do without under-roof ventilation devices.
High-quality under-roof ventilation, if properly installed, will ensure a long service life of the roof and the entire building as a whole and will allow significant savings on energy consumption.
The strength, reliability and durability of a roof are determined by many different components. And builders try to take all these components into account in order to prevent fatal mistakes.
But such a component as ventilation of the under-roof space, as practice shows, is sometimes given insufficient attention. Meanwhile, not only the service life of the building, but also the comfort for those who live in it depends on how thoroughly the under-roof space is protected from moisture.
But, even understanding the importance of this element of home improvement, many non-specialists, deciding to build on their own, do not always know what exactly and how should be ventilated.
But when moisture appears in a constructed building from nowhere, it may be too late to redo anything. Therefore, it makes sense to specifically consider some of the features of this problem.
Some non-professionals mistakenly believe that the “cooler” the brand of roofing, the louder the name of its manufacturer and the higher its price, the less moisture it allows to pass through. But the reputation of any product, including building materials of the highest standard, cannot ignore the laws of nature.
Regardless of how high-quality the roofing material that was laid on the roof is, and how well its installation was carried out, in conditions of low ambient temperatures the inside Water condensation may form. Leaks may occur during strong winds or rain. It cannot be excluded that water may enter the under-roof space through the gaps in the holes in the places where the roof is attached to the roof sheathing.
If ventilation is not provided at all or is poorly designed, the load-bearing rafters, attic structures made of bricks and the thermal insulation layer will be affected.
The negative impact of moisture begins with the formation of drops of condensation, then mold and mildew appear, which begin to corrode any material. As a result, if urgent measures are not taken, wooden, stone and metal structures will steadily collapse, shortening the life of the entire building.
To avoid this, a well-thought-out ventilation system is needed, and its creation should be started at the planning stage of the roofing. At the same time, it should not only eliminate the possibility of condensation, but also facilitate the removal of vapors from the interior of the building, and also serve as a kind of thermal insulation layer that prevents both hypothermia of the under-roof space and its overheating as a result of intense exposure to sunlight.
Summarizing all the options for such ventilation, we can distinguish two main types - natural and forced.
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Natural ventilation device
Natural ventilation involves creating conditions for the occurrence of convective flow (due to the natural temperature difference between heated and cooled air masses). To do this, it is necessary to design a small under-roof space between the lower waterproofing layer and top layer roofs - the actual roofing material.
The gap between these surfaces is created by installing a uniform roof frame made of sheathing and counter-lattice. The dimensions of the wooden blanks for this frame must be selected in such a way that a free space of at least 5 cm thick is created under the roof.
In addition, in order to avoid the occurrence of stagnant zones that are dead-end for air flow (condensation can accumulate here), complete freedom of air passage under the roof and continuity of the ventilation gap (ventilated circuit) should be ensured. Only such a circuit will ensure maximum ventilation.
Ridge unit of the attic floor of the roof with an aerator and soft roofing.
However, the constant influx fresh air and its circulation through the ventilated circuit are impossible without the creation of special ventilation holes(outlet). It is necessary to provide at least two types of technological openings - lower (eaves) and upper (ridge). The first ones are done in the area of the eaves overhang or along the ridge of the roof, the second ones - in the area of the upper junction of the roof slopes.
In accordance with the laws of air flow, the air under the roof is constantly heated and rises to the ridge vents, exiting through them to the outside. Colder air flows from the street into the space thus rarefied by gravity through the eaves vents. Thanks to this constant movement, condensation does not form on the roof and in the rooms under the roof (attic, attic).
Meanwhile, in winter, ridge vents can become clogged with fallen snow, which can cause convective ventilation of the under-roof space to be disrupted. To eliminate this danger, which primarily concerns buildings with slightly sloped roofs, special pipes can be installed. With a height greater than the thickness of the expected snow cover, they guarantee continuous ventilation.
The great advantage of the natural type of ventilation is its very wide applicability in construction. It provides effective ventilation of the gap under the roof of almost any roof configuration of any complexity.
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Creation of forced ventilation
The development of construction technologies and new approaches to architecture, which involve the construction of buildings with flat roofs, have forced specialists to develop options for forced ventilation of the under-roof layer. As you might guess, in such roofs it is almost impossible to create a convective air flow based on the independent movement of air from bottom to top when heated.
Therefore, in structures with flat roofs, forced ventilation is often used. This method They are also used in cases where for some reason it turns out to be too difficult to make a sufficient number of vents intended for natural ventilation.
Forced air flow is ensured by including a roofing electric fan in the ventilation circuit. It is installed in the upper (ridge) vent. When turned on, this device draws heated air out from under the roofing layer.
It is worth noting that this method has its advantages and disadvantages. In particular, thanks to the presence of a fan in the upper vent there is no need for large quantities ventilation holes. At the same time, this device requires a separate power supply, which creates certain risks in terms of fire safety.
Another option for forced air draft is the installation of special deflectors in the ventilated circuit, which, due to the cross-section of their design, enhance the natural air flow, as well as ventilation turbines. Moreover, in their lower part, these devices pass through the lower waterproofing layer roofs. Air is pumped into the under-roof space from warm attic or attic.
Or the rafter system itself. Here, any design errors, technology violations or incorrect combination of basic elements can lead to deformations of the roof, as well as the entire building. Realizing this, many homeowners invest heavily in roofing, choosing the highest quality materials.
However, today it is quite common for one of the essential elements roofing system - ventilation of the under-roof space - future owners country houses don't attach much importance. This happens because, despite all the importance proper ventilation roofing, its necessity is not so obvious at first glance. For example, without being a specialist, it is quite difficult to figure out what needs to be ventilated and why, and where moisture can even appear in a dry house under a roof made of such high-quality materials. Considering the fact that more than one generation has grown up in houses where there was no roof ventilation system at all, attempts to save on its installation become quite understandable. However, this myth should be dispelled.
Cold (attic) roofs They are premises not intended for living, and therefore not insulated, since this is not necessary. Such attics were common a few years ago and were the easiest to organize sufficient ventilation. The large air volume of the under-roof space of such roofs, as well as the absence of barriers to air circulation, contributed to the necessary air exchange of the entire under-roof space through the openings on the eaves, ridge and ridge of the roof, as well as through the gable grilles. That is why additional ventilation elements in in this case there was no need to worry: the service life of the truss structure in such attics already reached more than 100 years. The fact is that the wood used for rafters, under conditions of constant air exchange and air circulation, in such attics only became stronger over the years.
Insulated (attic) roofs- a completely different option for organizing the under-roof space. Moreover, today it is one of the most popular. In this case, empty attics are converted into usable spaces by insulating and waterproofing them, solving the problem of increasing additional living space without large material costs. However, it is in such roofs that ensuring ventilation of the under-roof space becomes much more difficult, and most importantly, much more important. Why?
Let's consider the design of an insulated roof. As a rule, it consists of materials installed in a certain order (we go FROM the room):
The builder’s task is to organize the meeting of warm and cold air in such a way that it occurs without consequences for the structure of the house. And for this, it is necessary to create a strong air flow that will ensure such ventilation of the space between the waterproofing and the roofing material so that condensation either does not have time to form or quickly erodes from the inner surface of the roofing material. 
The space between the waterproofing and the roofing material is called the under-roof space or ventilated gap.
IN winter period Warm air, which has not cooled in the ventilated under-roof space, begins to heat the roofing material, which ultimately leads to the melting of snow on the roof and the formation of icicles and ice on the roofing material. All this can cause damage to the roof and drainage system. In summer, such processes can lead to overheating of the roofing material (especially bitumen roofs) and the interior of the attic.
It should be noted that insufficient performance of the ventilated gap can make itself felt within six months, when unsightly stains and stains begin to appear on the interior finishing as a result of condensation. Rotting wood or corrosion of steel rafters can ultimately result in premature repairs or even complete replacement of the entire roofing system.
Next, you need to turn the under-roof space into a ventilated gap (also called a ventilated circuit). For this we organize:
A logical question arises: how can we ensure the inflow and outflow of air from the under-roof space and how can we make the ventilated circuit continuous? Especially for this purpose, there are special elements on the roofing materials market that either enhance air flow or create an inlet or outlet for air. Such elements are called: aerators or aeroelements. There are two types of aerators: for organizing point ventilation and continuous.
Type I - point aerators- installed pointwise on individual sections of the roof or ridge. There are two types of point aerators: pitched and ridge.
Pitched aerators they take their name from the place of their installation, that is, on the slope. They are mounted where increased air flow is necessary: on structurally complex or long slopes. For example, the valley and ridges of the roof usually require increased air flow (if the roof is made of natural tiles, special ventilation elements are installed on both sides, 2 pieces per linear meter of the ridge and valley). Restoration of air flow is also required in places where the ventilated circuit is interrupted (for example, if a roof window is installed or a “lantern” is made in the roof). In this case, aerators are installed before and after the break. The number of aerators depends on the area and design of a particular roof.
Ridge aerators installed on the ridge of the roof in the same way as pitched ones, to create and enhance air flow.
For example, KTV aerators from the Finnish company SK TUOTE (VilpeVent series). One such roof outlet is capable of ventilating a space of 50 sq.m. Made in the form of small tiles, aerators have an aesthetic shape and are almost invisible on the roof. All aerators are equipped with passage elements for each type of roof, be it profiled, metal tile or seam metal, soft bitumen or natural tile roofing. Aerators are made from anti-corrosion, impact-resistant polypropylene in a wide variety of colors, sizes and shapes, which allows not to disturb the design of the roof.
Type II - continuous aerators- those that provide continuous ventilation along the entire length of the ridge. These ventilation elements are covered from above with roofing material, which makes them completely invisible on the roof. The body of such aerators itself is made of anti-corrosion plastic, which can withstand the weight of a person (which is extremely important during installation). Continuous aerators have built-in filters that prevent insects, snow or rain from entering the structure, even during hurricane winds. Among these devices, we can highlight the Ridge Master system of the American company Mid America, as well as various aeroelements that are installed under natural ridge tiles.
Aeroelements– this term is mainly used to designate accessories for natural tiles (ceramic or cement-sand). Aeroelements provide continuous ventilation, i.e. entrance or exit along the entire length of the cornice, ridge or ridge.
The aero element for arranging the eaves overhang is made of plastic and is practically invisible. In addition to the function of ensuring air flow on the eaves, such an element plays the role of a “filter” against the penetration of birds into the under-roof space. Aeroelements for the ridge and ridge are made of plastic, aluminum, lead or copper. These elements also act as a seal, i.e. provide optimal connection between:
As for installation, it can be carried out on your own, but construction must be carried out by specialists - only they will be able to not only calculate the required number and location of ventilation elements, but also organize installation according to all the rules, without disturbing the structure of the roofing system.
In conclusion, I would like to say that if your project involves a roof with a rather complex geometry, with big amount valleys, junctions or roof windows, it will be necessary to take care of proper organization under-roof space. The cost of all these systems, together with their installation, will be only a few percent of the cost of the entire roof, which is tens of times less than the cost of repairs that may soon be required if they are neglected.
