Despite the hype around some roofing materials, the comfort and warmth in the house is influenced not so much by them as by competent installation of the roof. If the construction was carried out professionally, observing existing standards, then any coating will be a reliable barrier to nature’s surprises, be it cheap slate or expensive metal tiles, and the entire roofing structure will save heat in the house and eliminate excess moisture. But the presence of condensation, high humidity“hints” that not everything is going smoothly with your roof. Well, to be more specific: during installation, the roof ventilation was created incorrectly (if it was created at all!).
And there are several reasons: either the roof was laid 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 reinstall it.
What layers should a roof ventilation system be made of?
Roof ventilation consists of three components, each with its own function:
- Ventilation between the roofing and the waterproofing layer. Its task is to remove condensation from the roof that forms on the back side of the covering.
- Ventilation between waterproofing and insulation. It is needed so that 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 under-roof space. This layer is responsible for removing vapors from the premises and does not allow them to settle as condensation on inside roofs.
In this roof, the ventilation of the under-roof space is not thought out, so there is a lot of condensation on the roof
What laws of physics should be taken into account when installing ventilation?
Steam and water will seep into the roofing pie from both sides. The ventilation system should either prevent this from happening, or, if it gets in, allow the moisture to evaporate. It should be remembered: the steam does not flow perpendicularly upward, but slightly deviating to the side. The water does not go perpendicularly down, but also deviates slightly.
This deviation is not always taken into account when forming a roofing pie, and the following installation errors are made:
Ventilation of the under-roof space. Errors in ventilation installation will lead to destruction of the roof structure
Mistakes in using vapor barrier and waterproofing films
Even when created in roofing pie all necessary air gaps, ventilation will not be able to ventilate all the moisture if waterproofing or vapor barrier films were installed incorrectly. They are often confused due to their external similarity. But these films have different tasks, and, accordingly, a completely different structure.
Let's consider what problems will fall on the head of the owner who has mixed up the purpose insulating materials:
- If you laid a vapor barrier film instead of a waterproofing film. 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 gets from the air into the heat-insulating material (and it will definitely get in, especially during seasons of high humidity!) 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 it finally loses its properties completely, and the owners will be faced with high heat losses.
- If you laid a waterproofing film instead of a vapor barrier. Waterproofing films (also called diffusion membranes) have special properties: one side “breathes”, and the other is waterproof. They are laid under the roofing, turning the breathable side towards the heat-insulating layer. In this case, there should be a ventilation vent between the layers. Then the moisture from the insulation will partially escape through the air gap, and the rest will seep through the funnel-shaped holes of the film under the roof and evaporate. If after roof covering If water accidentally gets in (as a result of leaks, through cracks, etc.), it will settle on the film and will not be able to penetrate deeper. And in the same way as moisture from the insulation, it will go home.
If secured correctly waterproofing material on a skate, then the steam will not find a way out
When installing a waterproofing film, it is the other way around, i.e. on the “breathing side” of the insulation, water and moisture entering from the outside will easily enter the insulation through the funnels, and will no longer be able to get out. As a result, the entire design of the roofing pie loses its meaning.
Another option is when instead 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 on the contrary, then the moisture from the insulation will return back into the under-roof space, although not much.
Errors in a ventilation system created without taking into account roofing material
Some owners, out of ignorance, create not as many ventilation layers in the pie as a certain roofing requires. For example, metal tiles and euro slate are afraid of condensation on the back side, so a ventilation gap must be provided between them and the waterproofing layer. Those. They fill not a solid sheathing, but a lumber one, leaving gaps for air to circulate. If water gets under the roof from the outside, then with the help of this layer of ventilation it will be able to evaporate through the ridge.
The grille paired with the counter-lattice will create an air gap sufficient for condensation to find its way out
At the same time, anti-condensation films are used as waterproofing, which do not release vapors from the insulation under the roof, thereby relieving the roof covering from additional condensate. But here is the second point: where will the moisture go from thermal insulation material, if she 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.
You cannot lay diffusion and superdiffusion membranes as waterproofing, because they are designed to allow steam to pass under the roof, and in such roofs this can lead to corrosion of the metal tiles.
Only a properly created ventilated roof will retain heat and remove excess moisture from the house.
In the roof pie, the waterproofing material is surrounded by a double ventilation gap
Soft tile roofs
And these roofs are not afraid of condensation, so they do not require a serious air gap between the coating and the waterproofing. A continuous sheathing of plywood, boards, etc. is installed under them. Wooden materials themselves allow air to pass through well, so natural ventilation will work in any case.
Creating an air gap between the waterproofing and insulation will depend on which film you choose:
- Anti-condensation films are not installed on soft roofs. Diffusion membranes are used here. But to prevent the funnels from becoming clogged with insulation particles, 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 passage 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. She doesn't demand ventilation gap, but spreads directly onto the insulation
Having created all the necessary ventilation gaps, it should be remembered that steam will tend upward and water downwards only when there is air movement. Don’t forget to make a ventilated underlayment and install aerators on the upper edge of the roof or on the ridge. Otherwise, the roof will not be properly ventilated.
When building a house, it is imperative to consider high-quality roof ventilation. This is one of the main tasks of designing and constructing a durable home. Without a good ventilation system, the entire roof structure will very quickly become unusable. Everyone will suffer first from moisture. wooden elements, which will already reduce the degree of safety and comfort of the building. Then the roofing material will begin to deteriorate. Let's take a closer look at the issues of ventilating the roof of the house and natural ventilation of the roof.
Where does moisture come from in the roofing “pie”?
The roof of a residential building is a complex system consisting of wooden frame, roofing, as well as layers of waterproofing, vapor barrier, thermal insulation. In general, a high-quality roof is a sealed package. But moisture still gets onto the wooden elements and insulation. The fact is that air containing water vapor penetrates inside the roofing pie. When the temperature changes, steam settles in the form of condensate on the surfaces of the inner layers.
Even through the most reliable vapor barrier made of steam and waterproofing, some air still penetrates inside the “pie”. In addition, air can enter through "breathable" wall materials such as porous blocks, wood or cellular concrete. Therefore, condensation cannot be avoided. This phenomenon is especially pronounced during precipitation or fog, when the concentration of moisture in the air increases noticeably.
Purpose of roof ventilation
Ventilation system roofing system performs several important functions at the same time, thanks to which the comfort of living in the house is increased and the service life of the roof is extended.
The main function of ventilation is removal of vapors from the under-roof space, which rise from residential premises. During ventilation, circulating air prevents moisture from accumulating on inner surface roofing pie, from where it can penetrate into the roof.
Movement air masses in the roof provides not only weathering excess moisture, but also uniform temperature distribution. As a result, all elements of the “pie” warm up quite well during heating season. Therefore, a roof with good ventilation is less likely to become overgrown with icicles, which create additional stress on the roofing.
IN summer period ventilation is necessary for roof cooling. This is especially important for houses with soft roofing, which gets very hot and can melt and slide even with a high slope.
Natural and forced ventilation
For their long and uninterrupted operation, both types of ventilation systems require careful calculations, which will show which one is better to use in terms of efficiency and economy. When making calculations, specialists must take into account the features of these systems.
Natural ventilation
It is carried out due to the convective flow, which arises as a result of the interaction of warm and cold air masses. For such ventilation to work, you need to assemble a roofing pie with a gap (at least 5 cm) between the bottom waterproofing layer and the roofing layer.
Effective natural roof ventilation is possible with proper design and competent work of builders. It is not easy to create conditions for it. It is necessary to carefully calculate the system of lathing and counter-lattice, and ensure the continuity of the ventilated circuit. But the most important thing is to provide ventilation vents. There should be at least two of them in the ridge area and the same number in the cornice area.
The air in the under-roof space heats up and naturally rises upward, where it is forced out through the ridge vents. Fresh air enters through the eaves openings. Thanks to this process, condensation does not settle on the roof surface.
If the slope of the slopes is small, in winter period ridge vents may be clogged with snow. To prevent this, you need to install special pipes along the ridge that will rise above the snow level.
Forced ventilation
Since for the organization artificial ventilation required optional equipment, then with technical point view is more difficult option. There are rare exceptions when designing forced ventilation is easier than calculating natural ventilation, but these are still exceptions that prove the rule.
It became widespread as a result of the fact that, firstly, low and completely flat roofs came into fashion, in which it is simply impossible to create natural ventilation. Secondly, new ones have appeared construction technologies, allowing to automate and improve the maintenance of cottages.
Compulsory systems are installed not only in houses with flat roof, but also in houses that, for one reason or another, cannot be provided with roof vents. Recently, more and more often, solid cottages with standard roofs are equipped with forced ventilation, since it is more reliable than natural ventilation.
Forced ventilation can be carried out by installing a fan in the ridge vent. To do this, you need to stretch a wire into the upper part of the roof. The second option is installation special devices, increasing the intensity of air movement.
On our website you can get acquainted with the most popular from construction companies, presented at the exhibition of houses “Low-Rise Country”.
Methods for arranging ventilation
Ventilation can be provided for the roof different ways. The choice of arrangement option depends on architectural solution designer.
Aerators
Installing roof aerators is the most common option. The aerator is a piece made from a small piece of pipe with a flat base for installation on the surface and an umbrella that covers the upper hole of the pipe from precipitation. A protective filter is placed inside.
Aerators can be installed in various ways. The location of these devices depends on the type of roof and the degree of humidity in the region. Typically, aerators are located near the ridge. You can install them point by point. Experts believe that the most effective is to install a continuous aerator gutter stretched along the entire edge of the roof. It is advisable to install this type of ventilation simultaneously with the installation of the ventilation system of the entire building.
The advantage of aerators is that they do not interfere with the design of the house. In addition, when using them, the roofing covering does not have to be sealed, that is, it can be laid without the use of special tape and foam.
On our website you can find contacts of construction companies that offer roof repair services. You can communicate directly with representatives by visiting the “Low-Rise Country” exhibition of houses.
Ventilated cornice
The use of a ventilated eaves provides air access to the under-roof space. As a result, the roof is well ventilated, and everything works better ventilation diagram building. The eaves for roof ventilation can be arranged in different ways:
usage spotlights for roofing;
installation ventilation grilles ;
installation of special eaves over eaves elements with vents.
Insulation materials are not laid in the places where the eaves ventilation channels are installed. To protect them from precipitation, elements are used drainage system and snow guards.
Dormer window
Ventilation using a dormer window is also a fairly common option. Ventilating the roof of a house using this method, among other things, improves the aesthetics of the facades. Windows can be different in shape, and it is important at the design stage to think about the type of windows that will correspond to the overall style of the building.
Dormer windows are roof elements that are quite expensive to construct. But they have their undeniable advantages - high efficiency both ventilation system and aesthetic appearance.
Ventilation of roofs made of metal tiles and corrugated sheets
These are the most common roofing materials in our country. They are very convenient in terms of application technology and price. They are manufactured using the same technology and differ primarily in shape. Corrugated sheeting looks less impressive, but at the same time has stiffening ribs along its entire length.
In the process of installing a metal tile or corrugated roof, difficulties arise with ventilation. The fact is that these materials are absolutely vapor-tight and thermally conductive. They heat up and cool down quickly, causing a lot of condensation to accumulate on the inside. But these materials also make it possible to create high-quality roof ventilation - roof ventilation, which extends the service life of the entire building.
Manufacturers of metal tiles and corrugated sheets produce special additional elements, with the help of which they arrange ventilation passages. The main thing is to entrust the installation of the roof to specialists who will think over a good ventilation system. Since these materials do not retain heat very well, when using them, additional layers of hydro and thermal insulation are provided. Moreover, these themselves roofing material They must be protected from moisture with special care. Due to these features, roofs made of metal tiles and corrugated sheets are often equipped with forced ventilation.
Ventilation of soft roofing
Soft roofing under influence high temperatures may swell and melt. Therefore, it is so important for it to have ventilation that will not only remove moisture from the roofing pie, but also cool the roof during the summer heat. Typically, roof ventilation, the roof of which is made of bitumen tiles, is equipped with the help of aerators (vents).
Video description
Roof ventilation using valves (aerators)
Attic roof ventilation
Ventilation system mansard roof performs additional function– regulation temperature regime in the upper level rooms of the house. It is designed more carefully than roof ventilation above the attic. On the other hand, it is easier to protect the attic roofing pie from moisture, since attic spaces, unlike attics, are heated and well ventilated.
To remove condensation from the attic roofing pie in most cases forced ventilation no roof required. But between the waterproofing and thermal insulation layers, space must be provided for the unhindered passage of air.
Video description
How to properly ventilate an attic roof
If the attic is converted into an attic
A simple attic can be converted into an attic to expand the living space. In this case, the roof is usually re-roofed. Insulation and roofing materials are replaced with higher quality ones. More efficient ventilation of the roofing pie is being installed. However, if the roof was originally laid very well, you can improve it a little without disassembling it.
Any roof has at least a very small gap in the sheathing. It needs to be turned into a ventilation duct. This is achieved by installing special pipes in the roof plane through which the steam will ventilate. Closer to the ridge of the roof, holes are made with the calculation of 1 pipe per 50 sq. meters of roofing. Each such element must be protected from precipitation. As a result of installing a pipe vent system, ventilation on the roof will become more intense.
Video description
How attic roof without a ventilation gap, turn into an attic
Stages of work
The process of arranging a ventilation system for any roof consists of several main stages. The first step is to provide for the presence of ventilation elements in the roofing system design. After this, during the construction of the roof, roofing strips are made ventilation ducts and holes. In case of forced ventilation, special ventilation equipment is installed. On last stage ventilation holes provide protection from precipitation and dirt.
Conclusion
The roof of a private house must be well ventilated, otherwise the elements of the roofing pie will be negatively affected by condensation. They will quickly lose their original technical characteristics, and there will be a need for replacement. In addition, without high-quality roof ventilation, the rooms of the house will be damp, and heating will require more energy consumption. Therefore, it is very important to correctly design and correctly construct a roof with effective system ventilation, taking into account the type of roof structure, type of roofing material, climatic conditions of the region and other important factors.
The worst enemy with which every homeowner wages fierce battles is moisture. Water is a condition of prosperity both for us and for microorganisms and fungi, whose destructive action leads to the appearance of rot or mold. It is capable of penetrating both from the outside in the form atmospheric precipitation, and from the inside in the form of vapor condensate, which are products of human activity. To extend the life of a private house with a heated attic, roof ventilation is necessary, which will become the first echelon in the fight against dampness.
When creating a roofing pie for a house with a heated attic, experienced builders follow the principles of absolute tightness, that is, they place the materials in several layers, and even overlap each other. This system guarantees protection against moisture penetration and heat retention indoors. However, it also becomes a big obstacle to hood. Forced ventilation of the roof of a private house, installed in accordance with the requirements of SNiP, solves the following problems:
Note! According to building regulations and the requirements of SNiP, an attic is legally recognized as residential only if it is equipped with a forced ventilation system, and the total area of the ventilation vents is at least 1/300 of the roof surface area.
Roof ventilation equipment
Forced roof ventilation obeys a simple physical law - the principle of convection. Thanks to it, lighter, warmer air rises, making room for cold air. atmospheric air with more mass. To ensure exhaust in accordance with the requirements of SNiP, the following is required:
The ventilation equipment for heated and unheated attic roofs is significantly different. For a non-residential attic, it is enough to leave two dormer windows and a cornice vent. A residential attic requires more a complex system from roof deflectors, ridge aerator, eaves vents. Required amount ventilation holes, recommended by SNiP, calculated based on the roof surface area, 1-2 pcs. for 25 sq. m.
Roof deflectors
In order for the heated air to escape from attic room, and excess moisture evaporates from the roofing pie; roof deflectors are installed on the roof slopes. They consist of the following elements:
- Frame. The body of most aerators resembles a bottle consisting of two parts. The lower part of the body is mounted into the roofing pie at the stage of its laying, and the upper part is put on after completion of the work. The case diameter usually varies between 30-50 mm.
- Protective filter. A mesh or sponge filter is located inside the aerator housing. It is necessary to protect it from debris getting inside the ventilation and prevent blockages.
- Protective umbrella. An umbrella is placed on the head of the housing pipe to protect the aerator from moisture penetration during precipitation.
- Flange. A silicone or rubber apron that ensures the tightness of the seam between the deflector and the roofing pie. Experienced craftsmen note that more than 90% of leaks through the roof of a new house occur due to careless installation and insufficient waterproofing of roof ventilation elements.
Roof deflectors are placed at a height of 50 cm from the ridge, that is, on the top of the roof, so that it is easier for warm air to escape outside. The average cost of a high-quality deflector is 260-300 rubles. Please note that the minimum number of these ventilation elements even for a roof with an area of less than 25 square meters. m, 2 pieces.
Rules for placing ventilation elements
To ventilation system roof worked correctly, forcing air to circulate inside the attic space, you must follow a few simple rules:
It is better to calculate and determine the complete set of roof ventilation before starting roofing works to avoid mistakes and alterations that spoil the aesthetic appearance of the house. It’s good if you select all the elements from the range of one manufacturer that optimally complement each other.
A well-equipped roof ventilation protects the roof from premature destruction, makes the microclimate inside residential premises pleasant for humans and rationally distributes heat. Its installation is relatively inexpensive, especially when you consider how much money it will save by increasing the service life of the attic roof and interior decoration.
Video instruction
Not everyone knows why ventilation may be needed, but if you ask a person who is far from construction why an attic is needed in a house, he will answer without hesitation that it is for warmth. Warmth, of course, means a good microclimate in a house or city apartment. Of course, the city dweller will also note that the attics contain some communications, for example, heating ones, but not each of these premises is used only for such technical purposes. By the way, using the example of city houses you can see how many holes are in the attic. And these are not glazed windows, namely through holes, so you can understand how strong the drafts are under the roof of the house.
They are simply necessary there, because they carry away not only heat from the house, but also excess moisture. And if there were no such ventilation in the attic, it would become useless. Then a reasonable question arises: how are attics made in houses where people live, full heating works and windows can be closed hermetically in case of wind, cold and rain? Is it really possible that real “” is being created in these premises? Not at all. More precisely, ideally, the attics should have exactly the same microclimate as in the rest of the house, and only if attic space insulated with gross errors, the microclimate becomes much worse, and not only in one attic.
Even the attic roof must be ventilated, and this is achieved different methods. Their essence boils down to one thing: the under-roof space must be ventilated. And for this purpose, a special gap is made between the actual roofing material and the rough roof. As a rule, the latter is a “multilayer cake”, in which at least two membrane materials are used, as well as insulating mats. The structure of this “pie” is well known to every modern professional roofer.
But let's return to the under-roof space. Sometimes the roof area is so large, and the configuration is so complex, that it is impossible to ventilate this entire space using gaps alone. Therefore, they mark out places where special fans have to be installed. Often changes are made to the attic design itself related to the installation of dormer windows or so-called roof bay windows. External windows are often made, but their design is not directly related to roof ventilation, and can even complicate it, since the roof surface becomes much more rugged.
What causes poor roof ventilation?
You should never ignore the roof ventilation system, because otherwise undesirable processes will occur, leading to the destruction of the 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 were not provided for, completely flat rooms were built above top floor. Their function was to ventilate the roof almost constantly. IN multi-storey building under such a roof it was no longer as warm as directly in heated apartments, so condensation did not accumulate there as much, and it was easier to get rid of it by ventilation.
How can poor ventilation affect soft roof? Also very negative. As a rule, these materials lie on a continuous sheathing or on concrete base. But excess moisture coming from inside can cause the roofing material to delaminate and peel away from the base. This will further lead to its depressurization, as a result of which the roof will begin to leak.
Roof, covered with iron, may rust over time, which will also weaken the protective properties of the roof, as in the first case. In addition, the shedding of hard roofing material from the roof is also a danger for all those who are below near the house.
And if in urban buildings it is unlikely that anyone will decide to build a roof with a violation of its ventilation, then with private buildings everything is somewhat different, and there roofing specialists often have to correct mistakes made by unprofessional builders.
How to ventilate a roof in a private house
There are several ways to provide under-roof space in private buildings. This:
- attic dormers, which are widely used for non-dormer roofs;
- ridge ventilation gable roof, which will also help for the attic;
- cornice type of ventilation;
- installation of roof fans;
- use of piece elements with ventilation holes;
- installation of specially designed skates;
- ventilation gaps initially provided during installation or 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 meat tiles, with all their external similarity - various materials, and if the first is an exclusively piece material, and also very fragile for some types of impact, then the second can be classified as a sheet type. In this regard, metal tiles are even closer to corrugated sheets. And if this material is not brittle, then it is susceptible to corrosion in those places where its protective coating has been damaged.
The metal tile itself is a material that is pressed onto the sheathing, which is not always continuous. Installing a counter-lattice under it is an ideal way out if you need warm attic. The counter-lattice not only raises the sheathing to a certain height in order to maintain 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, releasing 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 condensation, they are picked up by the air and carried outside from under the roof.
With this type of roof construction, gaps appear at the eaves. Ridge vents are also installed on roofs to ensure constant draft, which ensures effective ventilation.
It is often possible to reclassify an attic into an attic if the room there is made all-season. At the same time, do not forget about the roofs. But what if it’s laid out so well that you don’t want to take it apart, and it’s not properly ventilated? There is a way out of the situation. As a rule, there is at least some gap in the sheathing, and our task is to make it ventilate. To make ventilation effective, you can install 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, since they are not afraid of weather influences. They need to be installed closer to the roof ridge, cutting holes in the metal tiles for them. The number of pipes is calculated based on the roof area - one piece per 50–60 m2.
If the house is located in snowy areas, then you need to calculate the height of the pipes based on the maximum snow cap, and cover each pipe with fungus to prevent precipitation from getting 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 pipe roofs. They ensure a tight connection of the pipe to the roof and facilitate installation of the pipe in a vertical position. These elements contain a sealing ring that needs silicone lubricant to perform its function better.
You should also pay attention to the tools that will be used to cut through the metal tiles. If you take metal scissors, they will not tear apart the coating of the sheet, but, on the contrary, will press it at the cut site to the base, since they work on 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 you not to rebuild the roof, but to make it ventilated. If you still feel 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, they are used in the construction of roofs of private houses. bitumen shingles. It is easy to install, makes little noise, and also has a beautiful appearance, which can compete with metal tiles. But the softness of the material leads to the fact that quite often under flexible tiles lay a continuous sheathing, 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 sheathing must be done with gaps, even small ones. Indeed, often when building an attic, instead of a conventional 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 insulation “pie”, which is very heavy). Therefore, it can be removed from the roof rigid tiles and replaced with flexible tiles.
When arranging the rafter system, it is necessary to maintain a distance from the roof to the insulation of at least 5 cm. Aerators or ridge vents must be provided at the top of the roof. Air intake into the ventilated space will be carried out from the lower edges of the slopes, and a problem may arise here: 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 grill.
Since the rafter system is made in insulated attics with double sheathing, it is possible to make two ventilation circuits in it at once. One will pass directly under the roof, between it and the sheathing. The second “channel” will be located between the insulation covered with the membrane and the upper membrane laid on top of the counter-lattice. In this case, the type of the lowest membrane covering the insulation is a wind barrier, 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 ridge, but did not go into the details of this design. The horse can do this in several ways. Note that due to its upper position, air flows to 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 precisely to the ridge if it ends up in the gap between the roof and rafter 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 removed depends on the design of the ridge ventilation. It can be implemented:
- on pipes;
- in the form of a continuous aerator;
- using 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 become clogged. Deflectors are also effective where snow does not accumulate on the roof. The principle of their operation is that they help create a vacuum and additional draft under the roof.
But for snowy regions and with small angles of roof slopes, other methods have been invented, in particular - a solid ridge. It makes the roof structure interesting, and it all depends on the imagination of the architect: such a house either acquires something ancient Japanese in its style, or is associated with ancient Russian towers. The idea is that over the ridge there is, as it were, another roof 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 provides protection from birds, dust and slanting rain. Sometimes so-called fluffy membranes are used, on which the fluff collects the smallest droplets, preventing them from turning into a continuous layer of moisture.
If 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, ventilation under the roof will still not stop. Forced roof ventilation will also work great with pipes. 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 within half an hour. Fans will save you from the hassle of installing additional pipes.
There are also deflectors of this design that ventilate the attic space itself, removing steam from it immediately above the roof. These devices save the room itself very well, especially in winter, when you won’t ventilate it often. The attic experiences the heaviest load from warm air, because this 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 be saturated with water condensate, which is not able to overcome this membrane.
The deflector with an exit from the attic to the roof has a small cross-section, compared, for example, 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 penetrate into the insulation and under the roof.
It should also be clarified what a multi-layer attic “pie” is. So, it consists of several layers, which from the roof side will go like this:
- roofing material;
- sheathing;
- counter-lattice;
- wind protection;
- rafter system and insulation (can be laid between the rafters);
- vapor barrier;
- rough finishing (plasterboard or plywood);
- fine finishing.
How to ventilate a pitched roof
If the house has a roof with one slope, then it is very simple. Once you make the correct gap between the roof and the rafter system, traction in the gap will arise by itself due to the difference in height. If the gap is not enough for complete air exchange, then additional ventilation pipes, as it was done on a gable roof.
How to ventilate hip and hip roofs
With this architecture, roofs do not have gables. But this is not an obstacle to organizing ventilation. It is built on the same principle as on gable roofs, but at the same time we must not forget what needs to be done entrance clearances for air around the entire perimeter of the roof. No matter how many stingrays there are hip roof No matter what, each of them must be ventilated.
A big “temptation” to forget about ventilation of the under-roof space is given by a half-hip roof, because its inclined end elements have relatively small dimensions. Ventilation here can be built in exactly the same way as on the main roof slopes.
It is somewhat more difficult to think through the ventilation of the end slopes of a Dutch roof, since there is a window 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 roof lining is made, it should not be continuous, since air must flow into the under-roof space through its gaps.
But, in addition to the above installation rules, it is also important to make an accurate calculation so that normal draft is created under the roof. Otherwise, all this will not work.
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Last revision: 01/29/2016
The operation of any building requires provision necessary measures aimed at extending the service life of all structural elements. In this regard, the roof is no exception. Any type of roof requires adequate ventilation to increase the life of the roof. If this is not done, then condensation from moist air masses will be absorbed into the insulation and structural elements made of wood. This may result in the roof collapsing. You should know for sure how to ventilate the roof to ensure proper removal of air flows in the attic space.
Relevance of ventilation
Condensation accumulated under the roof in winter time can lead to the formation of ice and cause various destructions of the drainage system.
Note! If there is insufficient air circulation in hot weather, the roof can become overheated, causing an undesirable increase in temperature throughout the building.
Ensuring sufficient roof ventilation in a private house is the only in an effective way get rid of excess moisture accumulating underneath. Properly arranged air ventilation will ensure the removal of unwanted condensation that comes from interior spaces structures. Availability normal temperature and humidity under the roofing pie will ensure the preservation of the thermal insulation properties of the roof insulation, will not allow deformation of the roof structure, and will also prevent rotting processes.
Types of ventilation
Modern roofing technologies involve the installation of several main types of ventilation. The first option involves ensuring air circulation in the attic space if the roof is not insulated. In this case, the roof is equipped with only one waterproofing layer. The second option involves the presence of a layer of insulation in the roofing pie. In this case, ventilation must ensure the circulation of air masses between the insulation, the waterproofing layer and the roofing material.
Another way to ensure a ventilation effect under the roof is to arrange eaves circulation using perforated soffits or embedded ventilation grilles. In this case, you should not use insulation in the eaves space, since it will close the ventilation ducts. Today, to improve air circulation, roof aerators, which are ventilation rolls or special tiles with air channels and insect mesh, have become more often used. They are usually installed along the ridges or on the slope. They do their job perfectly, freely releasing air masses.
For flat roofs exhaust hoods are provided electric fans or turbines, as well as special ventilation nozzles and passages. The most common roof ventilation option can be considered dormer window. Such an element copes well with its technical function and can also significantly decorate the gable of the house.
How to ensure roof ventilation
You need to know how to properly ventilate your roof to prevent the above problems. On practice, key point The key to ensuring sufficient roof ventilation is to create a ventilation gap between the roofing material and the waterproofing layer. Usually an additional vertical beam, which lifts the roofing material above the inner layers, allowing free air flow from the eaves of the roof to its ridge. You can install a special aerator on the roof ridge, which has many holes for the release of air masses.
If necessary, you can install point aerators if the roof structure is too complex. The principle of their operation is the same as that of a ridge aerator, so they are also effective in ensuring the necessary air circulation in the under-roof space. If the roof is made of metal tiles, then special fans and passage ducts can be used for ventilation. They are installed by cutting out fragments of such a roof and installing devices to ensure the necessary tightness.
Video
See below for how to ventilate an attic roof.
