Roof ventilation device made of soft tiles. Soft roof ventilation - why it is necessary, main functions and elements Soft roof ventilation

Soft tiles are a popular roofing material that is suitable for roofs of any shape. Under the influence sun rays the surface of the shingles heats up and forms a monolithic coating that does not allow air and moisture to pass through.

This feature imposes certain requirements on the under-roof ventilation, which must provide constant air circulation.

Functional purpose

A change in air temperature, and with it the surface of the roof, leads to the formation of condensate on the truss system and inside.

High humidity leads to the formation of fungus and mold, which destroy wooden structures. removes moisture-saturated air vapor and equalizes the temperature in the roofing cake.

AT summer period it reduces heat soft tiles and roof space. In winter, it prevents the melting of the snow cover and the formation of ice and icicles.

Ventilation design

The operation of the ventilation system is based on natural convection, the air rises when heated.

Classic scheme - cold air enters the under-roof space through holes in the cornice overhang and exits through holes in the ridge or.

Eaves overhang device

When designing a ventilation system, for air access to the under-roof space, spotlights or a passage under the drip, which is closed with a plastic mesh, are used.

Soffits- this is special panels used for lining eaves overhang. There are two types: solid and perforated. Material: plastic, metal or aluminium. The perforated surface allows air to pass freely, while protecting the roof from debris, insects and small birds.

The counter-lattice is made from a bar 50 x 50 mm. Experts recommend mounting the timber at a small distance from each other so that air flows can move freely in the plane of the roof.

Why ventilation may be needed, not everyone knows, but if you ask a person who is far from construction why an attic is needed in the house, he will answer without hesitation that it is for warmth. Warmly, of course, means a good microclimate in a house or a city apartment. Of course, the city dweller will also note that attics contain some communications, for example, heating, but not every one of these rooms is used only for such technical purposes. By the way, it is on the example of city houses that you can see how many holes are in the attic. And these are not glazed windows, but through holes, so you can understand how strong drafts are walking under the roof of the house.

They are simply necessary there, because they carry away not so much heat from the house, but from excess moisture. And if there were no such ventilation in the attic, it would become useless. Then a reasonable question arises: how do they make attics in houses where people live, full-fledged heating works and windows can be closed hermetically in case of wind, cold and rain? Is it possible that a real "" is being created in these rooms? Not at all. More precisely, ideally, the attic should have the same microclimate as in the rest of the house, and only if the attic is insulated with gross errors, then the microclimate becomes much worse, and not only in the attic.

Even mansard roof must be ventilated, and this is achieved different methods. Their essence boils down to one thing: the under-roof space must be blown. And for this, a special gap is made between the actual roofing material and the rough roof. As a rule, the latter is a “multi-layered cake”, which uses at least two membrane materials, as well as insulating mats. The device of this "pie" is well known to every modern professional roofer.

But back to the roof space. Sometimes the roof area is so significant, and the configuration is so complex that it is impossible to ventilate all this space only due to gaps alone. Therefore, they outline such places in which special fans have to be mounted. Often, changes are made to the attic design itself related to the device. dormer windows or so-called roof bay windows. Remote windows are often made, but their arrangement is not directly connected with roof ventilation, and may even complicate it, since the roof surface becomes much more indented.

What causes poor roof ventilation?

It is never worth ignoring the roof ventilation device, because otherwise undesirable processes will occur, leading to the destruction of building structures. Let's imagine that heat comes from the house under the roof. On the other, outer side of the roof, it is cold. Then condensation will accumulate under the roof. It can be removed by constant ventilation. Even in those houses where communications are not provided for, completely flat rooms were made above the last floor. Their function was to ventilate the roof almost constantly. AT high-rise building under such a roof it was no longer as warm as directly in heated apartments, so condensate did not accumulate there so much, and it was easier to get rid of it by ventilation.

How can poor ventilation affect a soft roof? Also very negative. As a rule, these materials lie on a continuous crate or on concrete base. But excessive moisture coming from the inside can cause the roofing material to delaminate and exfoliate from the base. This will further lead to its depressurization, as a result of which the roof will begin to leak.

A roof covered with iron can rust over time, which will also weaken protective properties roofs, as in the first case. In addition, the shedding of hard roofing material from the roof is also a danger to all those who are below near the house.

And if in urban buildings hardly anyone decides to build a roof with a violation of its ventilation, then with private buildings everything is somewhat different, and there roofing masters often have to eliminate the mistakes made by non-professional builders.

How to ventilate the roof in a private house

There are several ways of under-roofing space in private buildings. It:

dormer windows in the attic, which are widely used for non-mansard roofs;
ventilation of the gable roof ridge, which will also help for the attic;
eaves type of ventilation;
installation of roof fans;
the use of piece elements with ventilation holes;
arrangement of skates of a special design;
ventilation gaps provided initially during installation or during the reconstruction of the roof.

It is clear that not every roofing material can implement a specific ventilation method. After all, roofs are made of different materials and their division only into hard and soft can be considered very approximate. For example, clay tiles and metal tiles, for all their external similarity - various materials, and if the first is an exclusively piece material, moreover, it is very fragile for certain types of impact, then the second can be attributed to the sheet type. In this regard, the metal tile is even closer to corrugated board. And if this material is not brittle, then it is subject to corrosion in those places where its protective coating has been broken.

By itself, a metal tile is such a material that is stuffed onto a crate, moreover, not always continuous. Installing a counter-lattice under it is an ideal way out if needed. warm attic. The counter-lattice not only raises the crate to a certain height in order to withstand the height of the ventilation gap, but also in order to fix the membrane on the rafter system. This membrane is a vapor barrier film with a special kind of holes that prevent moisture from entering the rafter system and, at the same time, release vapors from the attic room. Until these vapors become fog (from the point of view of physics, fog is a suspension of water droplets in the air, which we see as steam) and condensate, they are picked up by air and carried out from under the roof.

With this design of the roof, gaps appear at the cornices. Also, ridge vents are made on the same roofs to ensure constant traction, due to which effective ventilation occurs.

It is often possible to reclassify an attic into an attic if the room there is made all-weather. In this case, do not forget about the roof. But if it is so well laid that you don’t want to disassemble it, but at the same time it is not properly ventilated? There is a way out of the situation. As a rule, there is at least some gap in the crate, and our task is to make it ventilate. To make ventilation effective, you can put special pipes on the roof through which steam will be removed from the under-roof space. For this, it is better to use plastic pipes because they are not afraid of the weather. They need to be installed closer to the roof ridge, cutting holes in the metal tile for them. The number of pipes is calculated according to the area of \u200b\u200bthe roof - for 50–60 m 2, one at a time.

If the house is located in snowy areas, then you need to calculate the height of the pipes according to the maximum snow cap, and cover each pipe with a fungus so that precipitation does not get there.

Each pipe, when installed on the roof, must have a seal, because otherwise the metal tile may corrode at the cut site. The sealing element is made of silicone. You can also use specialized outlet elements for roofs under the pipe. They provide a hermetic connection of the pipe to the roof and facilitate the installation of the pipe in vertical position. These items contain a sealing circle that needs to be silicone grease to better perform their functions.

You should also pay attention to the tools with which the metal tile will be cut. If you take scissors for metal, they will not ruffle the coating of the sheet, but, on the contrary, will press it at the cut point to the base, as they work in compression. Using a hacksaw is a little worse. But even more damage can be done with an electric circular saw.

Working with such tools and devices will allow not to rebuild the roof, but to make it ventilated. If it still seems to you that a lot of moisture is collecting in the attic, then you can increase the number of pipes on the roof in the next summer season.

No less often than metal tiles, bituminous tiles are used in the construction of the roof of private houses. It is easy to mount, it makes little noise, besides it has a beautiful appearance than can argue with a metal tile. But the softness of the material leads to the fact that quite often under flexible tiles lay a solid crate, trying to provide additional strength. But at the same time they lose in the ability to ventilate the under-roof space. Therefore, when arranging such a roof, the crate must be done with gaps, even if they are small. After all, often during the construction of the attic, instead of the usual uninsulated attic, the roofing material is changed to a lighter one so as not to create additional loads on the walls and foundation (do not forget about the “pie” of insulation, which is very heavy). Therefore, rigid tiles can be removed from the roof and replaced with flexible tiles.

When arranging the truss system, it is necessary to maintain a distance from the roof to the insulation equal to at least 5 cm. At the top of the roof, aerators or ridge vents must be provided. Air intake into the ventilated space will be carried out from the lower edges of the slopes, and here a problem may arise: no matter how hard you try to keep this “air intake” free, birds can occupy it, blinding or building their nests there. You can protect yourself from this by installing a grid.

Because rafter system is done in insulated attics with a double crate, then you can make two ventilation circuits in it at once. One will pass directly under the roof, between it and the crate. The second "channel" will be located between the insulation, covered with a membrane, and the upper membrane, laid on top of the counter-lattice. At the same time, the type of the lowest membrane covering the insulation is a wind protection, and the type of the upper membrane is a vapor barrier. Approximately the same membrane is located under the heat insulator inside the attic room.

Above, we have repeatedly touched on the topic of a ventilated skate, but did not go into the details of this design. The horse can do it in several ways. Note that due to top position air enters it due to natural draft or due to convection. Since we need to remove warm air, saturated with steam, then, according to the laws of physics, it will rise exactly to the ridge if it is in the gap between the roof and the truss system, covered with wind protection.

In particular, air can enter the space under the roof from the side of the eaves. But through what it will be displayed depends on the design ridge ventilation. It can be implemented:

on pipes;
in the form of a continuous aerator;
with the help of deflectors;
with tiles for ventilation.

The use of tiles for ventilation is advisable on those roofs that have a large slope angle. This is a guarantee that the grate in such a tile will not clog. Deflectors are also effective where snow does not accumulate on the roof. The principle of their work is that they contribute to the creation of vacuum and additional traction under the roof.

But for snowy regions and at small angles of roof slopes, other methods have been invented, in particular - solid ridge. It makes the design of the roof interesting, and it all depends on the imagination of the architect: such a house acquires either something ancient Japanese in its style, or is associated with old Russian towers. The idea is that over the ridge, as it were, another roof is made with very short slopes, literally one or two rows of tiles. This roof is called an aerator. It is raised above the main slopes, and air escapes from under it through the resulting gap. The upper slopes are needed so that precipitation does not linger on the aerator. The same membrane serves as protection from birds, dust and slanting rain. Sometimes so-called fleecy membranes are used, on which the pile collects the smallest droplets, preventing them from turning into a continuous layer of moisture.

If even such a gap can become clogged with snow, then special deflectors with pipes are used. Even if there is a snow cap on the roof, the ventilation under the roof will still not stop. Pipes will work great and forced ventilation roofs. To do this, a low-noise fan can be built into each of them. A decision on forced ventilation can be made when a complete exchange of air under the roof is not ensured for half an hour. Fans will save you the hassle of installing additional pipes.

There are also deflectors of this design, which ventilate the attic room itself, removing steam from it immediately above the roof. These devices very well save the room itself, and especially in winter, when you will not often ventilate it. The attic undergoes the greatest load from warm air, because it is the highest room in the house. And if we protect its insulation with a vapor barrier membrane, which is “”, then we doom the attic itself to saturation with water condensate, which is not able to overcome this membrane.

The deflector with access from the attic to the roof has a small cross section, compared, say, with open window or even a window, so it can only be compared with a hood. Such a device will not allow vapors to remain in the attic and at the same time - to penetrate into the insulation and under the roof.

It should also be clarified what a multilayer "pie" of the attic is. So, it consists of several layers, which from the side of the roof will go like this:

roofing material;
crate;
counterlattice;
wind protection;
rafter system and insulation (can be laid between the rafters);
vapor barrier;
rough finish (drywall or plywood);
clean finish.

How to ventilate a shed roof

If the roof of the house is made with one slope, then it is very simple. One has only to make the correct gap between the roof and the truss system, as the thrust in the gap will arise by itself due to the height difference. If the gap is small for complete air exchange, then additional ventilation pipes, as it was done on a gable roof.

How to ventilate a hip and hip roof

With this architecture, the roofs do not have gables. But this is not an obstacle to the organization of ventilation. It is built on the same principle as gable roofs ah, but at the same time, one should not forget that it is necessary to make inlet gaps for air around the entire perimeter of the roof. No matter how many slopes there are on a hipped roof, each of them must be ventilated.

A big “temptation” to forget about the ventilation of the under-roof space is given by a half-hipped roof, because its inclined end elements are relatively small in size. Ventilation here can be built in the same way as on the main roof slopes.

It is somewhat more difficult to think over the ventilation of the end slopes of the Dutch roof, since a window is located directly above them. This is an obstacle to the use of pipes, but grates or an aerator can be placed there.

In all these cases, if a wooden filing of the roof is performed, it should not be continuous, since air must enter the under-roof space through its gaps.

But, in addition to the above installation rules, it is also important to do exact calculation so that normal draft is created under the roof. Otherwise, all this will not work.

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

Ventilation soft roof 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 atmospheric air, which contributes to the extraction outside of the heated from under the roofing. 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 produced different diameter 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 attic space 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 finishing materials roofing;
reducing the cost of electricity.

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

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

Bloating roof covering resulting from its heating in summer due to delamination 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 leads to 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 condensate and remove humid air out. Before purchasing an aerator, you need to understand the features of their design and types.

Point

In another way, these aerators are called roofing spot valves. They are mounted on roofs in which there is no ridge - hipped and flat. Myself roof aerator Made of high strength plastic, resistant to mechanical influences and exposure to sunlight (burnout).

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 skate. 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 complete 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 mounted ridge aerator a different approach is taken. 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.

To all types of aerators, a series of specifications which they must match:

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

How to install?

Each type of aerator has a specific installation order.

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

Let's take a closer look at the installation technology 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. By marking with electric jigsaw making holes.

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, on the inner segment of the skirt we apply bituminous mastic, glue to the base and fix 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.

The installation of the ridge aerator is quite simple, it is installed along the entire length of the ridge ridge and its varieties - 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:

On a solid basis through circular saw cut through the ventilation slot. 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 of its sections by means of special roofing nails or screws driven through existing factory holes.
We lay on top of the aerator profile ridge tiles. 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.

The comfort of the owners of private houses in many respects depends on the correctly chosen and laid roofing. If you have chosen Katepal flexible bituminous shingles for the roofing of your house, be aware that such a roof, like any other, must be constructed in compliance with all installation instructions for this roofing material and the laws of engineering. And one of the most milestones proper arrangement bituminous roofing is a well-designed and created ventilation system of the under-roof space.

Often, this element of the roof is left unattended during the construction of buildings, because the owners of houses spend crazy money on expensive and high-quality roofing, invest huge sums on arranging the roof or on repairing it, and decide to save on the ventilation system, not realizing how important it is. The advice of experts is ignored and the ventilation system is installed either in the most primitive form, or not installed at all. Such decisions are often made due to the fact that, in the unprofessional opinion of a simple layman, who is often not too deeply aware of the issues of operation shingles, and even more so in all the subtleties of arranging ventilation for it. Therefore, for such homeowners, the appearance of moisture in a new house or under a newly restored roof is often a big surprise, although in the absence of a proper ventilation system, this is a regularity.

Quite recently, in many houses, the roof was ventilated due to the presence of dormer attic windows, and in many old suburban buildings, all the functions of the ventilation system were generally performed by elementary cracks in the ceilings of the roof of the house. When installing bitumen roofing, such options are simply unacceptable, since the requirements for the construction of houses have increased significantly, and a bituminous roof with well-executed ventilation will last much longer without bringing unpleasant surprises.

So, what is the ventilation in a bituminous roof:

1. Through the ventilation ridge for shingles. In addition to ventilation, it gives the roof additional volume.

2. Through the roof aerator. aerator it ventilation outlet for bituminous tiles, used for ventilation of the under-roof space, at the rate of 1 aerator per 50 m2.

3. Through the passage elements. There are insulated and non-insulated. With fan and without fan. Insulated are usually placed in bathrooms and kitchens. Uninsulated are placed in unheated rooms

The consequences of the lack of a ventilation system for a bituminous roof

In the absence of a ventilation system under the bituminous roof, moisture can accumulate under the roofing, as a result of which the wooden part of the roof will begin to rot, the strength of the roof fasteners will significantly decrease, and this will lead to the fact that the rafter system will last less than the prescribed period.

Also, in the absence of ventilation, the insulation may get wet, and this will adversely affect the thermal insulation. This happens due to the fact that warm air, saturated with water vapor, which is present in every residential building, rises and accumulates under the roof. If the ventilation is properly arranged, air masses freely leave the under-roof space, then the roof structure remains safe and sound.

Air flow pattern

Modern ventilation system under a bituminous roof is based on the fact that warm air masses always tend to rise up. Due to the fact that air moves through all channels and space under the roof, the desired ventilation effect is achieved.

Between the insulation and the bituminous roofing, there must be air gap from 4 to 6 cm. Air should come from the bottom of the roof (cornice) and through upper part roofs. Air flow between eaves and vent hole must be unobstructed to allow cross-flow ventilation. That's why, ventilation duct or a shingle ridge should be provided under the entire base of the building.

Despite the hype around some roofing materials, the comfort and warmth in the house is affected not so much by them as by the competent installation of the roof. If the construction was carried out professionally, observing existing standards, then any coating will be a reliable barrier to the surprises of nature, whether it be cheap slate or expensive metal tiles, and the entire roof structure will save heat in the house and eliminate excess moisture. But the presence of condensate, high humidity"hints" that not everything is smooth with your roof. Well, to be more specific: roof ventilation was incorrectly created during installation (if it was created at all!).

And there are several reasons: either the roof was covered by non-professionals, or vapor barrier or waterproofing films were applied incorrectly, or the ventilation system was created without taking into account the type of roofing. There is only one result: you will have to disassemble the roofing pie and mount it again.

What layers should the roof ventilation system consist of?

Roof ventilation consists of three components, each with its own function:

Ventilation between roofing and waterproofing layer. Its task is to remove condensate from the roof, which forms on back side coatings.
Ventilation between waterproofing and insulation. It is needed so that the moisture that has entered the insulation from the air has the opportunity to leave the roof. If this layer is not created, the insulation can absorb water as a result of roof leaks or during the rainy season and cease to function as a heat insulator.
Ventilation of the internal roof space. This layer is responsible for the removal of vapors from the premises and prevents them from settling in the form of condensate on inside roofs.

In this roof, ventilation of the under-roof space is not thought out, so there is a lot of condensate on the coating

What laws of physics should be taken into account when installing ventilation

Steam and water will seep into the roofing cake from both sides. The ventilation system must either prevent this, or in case of contact, allow moisture to erode. In this case, it should be remembered: the steam does not go perpendicularly upwards, but slightly deviates to the side. The water does not go perpendicularly down, but also deviates slightly.

This deviation is just not always taken into account when forming a roofing pie, and allow the following errors mounting:

Underground ventilation. Errors in the installation of ventilation will lead to destruction roof structure

Errors in the use of vapor barrier and waterproofing films

Even if all the necessary air gaps are created in the roofing pie, ventilation will not be able to ventilate all the moisture if the waterproofing or vapor barrier films were not installed correctly. They are often confused due to their resemblance. But these films have different tasks, and, accordingly, an absolutely different structure.

Let's consider what problems will "fall" on the head of the owner, who confused the appointment insulating materials:

If you have laid a vapor barrier film instead of a waterproofing one. The vapor barrier film completely eliminates the ingress of moisture from both sides. If you lay it on top of the insulation, then the moisture that has got from the air into the heat-insulating material (and it will definitely get into it, especially in seasons of high humidity!) And it will remain in it, because it will not find a way out. As a result, every year the insulation will become more and more moistened, until, finally, it loses its properties completely, and the owners will face high heat losses.
If you have laid a waterproofing film instead of a vapor barrier. In waterproofing films (they are also called diffusion membranes) special properties: one side of them "breathes", and the other side is waterproof. They are laid under the roofing, turning the breathing side to the heat-insulating layer. At the same time, a ventilation outlet should remain between the layers. Then the moisture from the insulation will partially come out through the air gap, and the rest will seep through the funnel-shaped openings of the film under the roof and disappear. If through roofing if water accidentally gets in (as a result of leaks, through cracks, etc.), then it will settle on the film, but it will not be able to go deeper. And in the same way as the moisture from the insulation, it will go home.

If properly fastened waterproofing material on a skate, then the steam will not find a way out

During installation waterproofing film vice versa, i.e. On the “breathing side” of the insulation, water and moisture that have got in from the outside will calmly enter the insulation through the funnels, and they will not be able to get out of there. As a result, the entire design of the roofing pie loses its meaning.

Another option is when instead of vapor barrier film lay waterproofing. If you place it with funnels inside the house, then all the steam will instantly seep into the insulation, if vice versa, then the moisture from the insulation will return back to the under-roof space, although not much.

Errors in the ventilation system, created without taking into account the roofing material

Some owners unknowingly create not so much ventilation layers in the cake as they require a certain roofing. For example, metal tiles, euroslate are afraid of condensation on the back side, therefore, a ventilation gap is necessarily provided between them and the waterproofing layer. Those. stuffed not solid crate, and squared, leaving gaps for air circulation. If water enters from the outside under the roof, then with the help of this layer of ventilation it will be able to escape through the ridge.

The grate paired with the counter-lattice will create an air gap sufficient for the condensate to find an outlet to the outside

At the same time, anti-condensate films are used as waterproofing, which do not release vapor from the insulation under the roof, thereby relieving the roofing from additional condensate. But here is the second point: where will the moisture go from thermal insulation material if it is not released under the roof? To do this, create a second layer of ventilation, leaving an air "cushion" between the insulation and the anti-condensation film.

Do not lay as a waterproofing diffusion and super diffusion membranes, because they are designed to pass steam under the roof, and in such roofs this is fraught with corrosion of metal tiles.

Only a properly designed ventilated roof will retain heat and remove excess moisture from the house.

In a roofing pie, the waterproofing material is surrounded by a double ventilation gap

Soft tile roofs

And these roofs are not afraid of condensate, so they do not require a serious air gap between the coating and waterproofing. Under them, a continuous crate of plywood, boards, etc. is mounted. Wood materials themselves pass air well, therefore natural ventilation will work anyway.

The creation of an air gap between the waterproofing and the insulation will depend on which film you choose:

In soft roofs, anti-condensate films are not laid. Diffusion membranes are used here. But so that the funnels are not clogged with particles of insulation, an air gap must be left.
If you plan to lay a superdiffusion membrane, then it does not need an air gap. The level of moisture penetration is high and allows you to do without a ventilation layer. Such a membrane is laid directly on the heat-insulating material.

In this cake, the waterproofing layer is created using a superdiffusion membrane. It does not require a ventilation gap, but spreads directly on the insulation

Having created all the necessary ventilation gaps, it should be remembered that steam will tend upwards, and water downwards only when there is air movement. Do not forget to make a ventilated filing, and mount aerators on the upper edge of the roof or on the ridge. Otherwise, the roof will not be properly ventilated.

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