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 covering will be a reliable barrier to the surprises of nature, 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 and 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 preventing them from settling as condensation on the inside of the roof.
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 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 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 confused the purpose of the 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 water accidentally gets through the roofing (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 you correctly fix the waterproofing material on the ridge, 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 to lay a waterproofing film instead of a vapor barrier film. 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 roofing of additional condensation. But here is the second point: where will the moisture go from the heat? insulating 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. It does not require a ventilation gap, but lies directly on 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.
Constant and high-quality air exchange under the roof guarantees a long service life of both the roof itself and the entire building. The comfort of people living in the house also depends on ventilation, since it plays a key role in shaping the microclimate.
Peculiarities
Ventilation of a 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. To effectively remove destructive moisture from residential premises through the roof, it is necessary to analyze the ventilation of all elements of the house as an integral process.
If the roof configuration is complex, has many transitions and valleys, the process of removing exhaust air must be divided into sections and air flows in the roof must be organized separately.
As a result of good ventilation, the air in the space under the roof should change approximately 2 times per hour.
The performance qualities of a ventilated roof depend on the slope of the slopes. The steeper they are, the more intense the ventilation process occurs.
And, on the contrary, in roofs with a slope of less than 20%, ventilation of the under-roof space is unstable and effective only under wind pressure.
A useful addition is the construction of auxiliary exhaust components (aerators) on the roof, which help to enhance the natural ventilation of the roof. They should be installed on roofs of complex configurations, when ordinary means are no longer sufficient.
Aerators are installed near the ridge. In roof coverings made of fused materials, consisting of two layers, aerators are installed on the bottom layer of material.
The thermal characteristics of insulation and the durability of roof structures directly depend on the presence of moisture in them. As a result, a ventilated roof and room ventilation device are economically viable, even when forced air exchange is required.
Advantages and disadvantages
The main purpose ventilation system- this is to ensure the passage of atmospheric air, which facilitates the extraction of heated air from under the roof covering. The exhaust air provides ventilation to the attic.
If under-roof ventilation is done correctly, then such air flow occurs naturally and there is no need to use additional mechanical equipment.
Aerators are available in various diameters and heights. Their size and quantity are selected depending on the area of the roof made of flexible tiles.
Having a ventilated space under the roof has the following advantages:
- consistently cool and dry condition attic;
- outside air from the attic can escape naturally;
- load-bearing roof components, coverings and thermal insulation layers are not exposed to high humidity;
- absence of conditions for the formation of mold and rot, prevention of damage finishing materials roofs;
- reduction in electrical energy costs.
Experts have found that when using soft coverings the main disadvantage is the accumulation of excess moisture in the screed and thermal insulation.
High humidity These layers of roofing provoke a number of negative consequences, such as:
- Bloating roof covering resulting from its heating in summer due to the delamination of bitumen-polymer materials under the influence of high temperature.
- Increased thermal conductivity causes accumulated under waterproofing material moisture, which impairs thermal properties. It has been theoretically proven that with an increase in moisture content by 1-2%, the heat-conducting properties of the material increase by 30-40%. This leads to increased costs for heating the facility. 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 caused 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 increases. This process entails the appearance of microcracks and destruction of the screed. Similar negative processes occur in the waterproofing layer, destroying its integrity.
Varieties
Roof aerators come in various designs and sizes. They are used to ventilate the space under the roof, eliminate condensation and remove moist air outside. Before purchasing an aerator, you need to understand the features of their design and types.
Spot
These aerators are otherwise called roof point valves. They are mounted on roofs that do not have a ridge - hipped and flat. The roof aerator itself is made of high-strength plastic, resistant to mechanical stress and impact sun rays(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 hip roof types, and flat roofs are installed on flat roofs. 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 install two.
Skate continuous
According to the name, they are installed on pitched roofs equipped with a skate. They are a permanent exit located at the very top of the slope. The ridge aerator is implemented in the form of a square equipped with through holes, which are called products.
Ventilations can be point vents (made at a distance of 6-8 m from each other) and slot vents (5 cm gap). There is a protective mesh to prevent insects from entering the roof. Such a device is mounted along the entire ridge and attached to the roofing material. Its individual components form an integral system. The aerator perfectly retains moisture and allows air to pass out, preventing it from stagnating 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.
At the time of buying Special attention It is required to pay attention to the completeness of the set and the absence of mechanical damage (scratches, chips, cracks and deformation).
When choosing aerators for a soft roof, you need to take into account the complexity of its structure, the climate and the level of moisture saturation in the attic. As a rule, one point aerator must be installed per 100-150 m2.
When installing a ridge aerator, a different approach is used. A ventilation slot is constructed along the entire length of the joint, and air enters from under the overhangs, where a specialized aero element (perforated tape) is placed on the slot.
All types of aerators come with a range of technical specifications which they must comply with:
- 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 procedure.
Point devices are mounted on flat roofs and roofs with an inclination angle of less than 12 degrees. They can also be used as a complement to ridge aerators.
Let's take a closer look at the technology for installing point aerators:
- We determine the location of the aerators. Place the base of the aerator on the installation site and trace the outline with a pencil. According to the applied mark using electric jigsaw make 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, apply to the inner segment of the skirt bitumen mastic, glue to the base and secure with nails.
- Coat the top of the skirt with bitumen glue.
- We cover the skirt with soft tiles, cutting the shingles at the points of contact.
- We put the aerator mesh on top of the skirt and screw it with self-tapping screws. Then we install the cap (lid), snap it in place and also screw it in with self-tapping screws.
We install the remaining point aerators in the same order.
Installation of a ridge aerator is quite simple; it is installed along the entire length of a pitched ridge and its variety - a hip roof, the slope of which ranges from 12 to 45 degrees. There are two methods for installing a ventilated soft roof ridge.
Installation technology:
- In a solid base through circular saw cut a ventilation groove. It can be single (at the highest point of the ridge) or consist of two parts (on the sides of the ridge). The total thickness of the ventilation gap should be 3-8 cm (depending on the instructions of the manufacturer of the aerator used). The ventilation groove should end 30 cm before the edge of the ridge on both sides, that is, the covering remains continuous.
- Areas where the ventilation gap has not been cut are covered with ridge tiles.
- We install the aerator. Each section is fixed using special roofing nails or screws screwed through the existing factory holes.
- Place on top of the aerator profile ridge tiles. We lay its petals overlapping, using standard installation technology along the ribs. The only difference is the fastening elements. In this case, we nail the tiles to the aerator with special roofing nails.
- We seal the joints between the aerator and the roof with silicone-based sealant. It is necessary to ensure that a depression does not form around the device for ventilation of the under-roof space. These depressions will retain water and snow, which over time will certainly find a place to seep under the roof.
The second method involves fixing wooden blocks at the highest point of the roof slopes. It turns out to be a kind of lathing for the ridge strip. We nail plywood strips to the top of 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 valves can be installed together with ridge ventilation.
Houses with hip 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 gable roofs, but at the same time we must not forget that it is necessary to build entrance clearances, providing air passage along the entire perimeter of the roof. How many stingrays hip roof would not have, each of them should be ventilated.
A half-hip roof gives a great desire to forget about the ventilation of the space under the 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 roof slopes.
It is a little more difficult to calculate the ventilation of the end slopes of a 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 grilles can be installed there.
In all the described cases, if the roof lining is made of wood, then it should not be monolithic, since air must pass through its gaps into the space under the roof. But in parallel with the above installation rules, it is also necessary to make the correct calculation so that normal draft is formed under the roof. Otherwise, all this will not function.
Regardless of the method of installation, ventilation must guarantee:
- passage of air vapor;
- protection of the space under the roof from precipitation and melting snow;
- No moisture should pass through the ridge structure;
- ensuring the evaporation of excess liquid from the room.
When installing ventilation of the under-roof space with your own hands, you must take into account a number of important points.
- If you intend to get a stronger effect from the movement of air currents, then it is necessary to use steam and hydro barriers located under the sheathing. They are specialized meshes that easily allow air to pass through, but prevent the passage of moisture and steam.
- To ensure ventilation under an ordinary roof pitched roof A small number of vents placed in the lower and upper parts in equal numbers will suffice. If necessary, you can supplement the ventilation system with a fan for forced exhaust.
- If you install the fan in a structure that is located in an area with higher than normal humidity, then the fan must be equipped with a higher electric motor power. Fans must be installed parallel to the roof structure. Inserting the device into finished roof more complicated and will cost significantly more.
- The combination works great on the roof– full ridge ventilation and auxiliary elements to enhance air flow. If, for example, in winter one of them is damaged, the rest will remain in working order. The under-roof space will be one hundred percent protected from condensation accumulation.
- Also It is necessary to pay attention to the total component of all precipitation falling during the year. In areas with heavy snowfall, it is necessary to raise the air ducts to a higher level, otherwise snow drifts will block low-mounted aerators.
- And the last thing - the desire to save money when installing roof ventilation can end badly, being a source of problems with both the roof covering and structural elements. Proper organization effective air exchange guarantees that the roof will last for decades without the need for repairs, providing thorough protection of the entire structure and comfortable living conditions.
It is not so difficult to arrange ventilation under the roof with your own hands for any type of roof, and such a design has a considerable number of positive effects.
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.
Why do you need roof ventilation?
The importance of the roof is difficult to overestimate. Therefore, when erecting a building, experienced builders 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 the load-bearing elements of the 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:
- dormer windows;
- ridges of pitched roofs;
- gaps provided in the roofing pie and eaves strips;
- exhaust fans on roofs and other piece elements of the ventilation system with holes.
For small or medium-sized roofs, natural ventilation is sufficient. Elements forced ventilation installed on large roofs, where natural air exchange There is not enough under-roof space.
Elements of roof ventilation system
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:
- removal of steam entering the under-roof space from interior spaces Houses;
- reduction in heat flow penetrating under the roof due to its heating in the sun;
- equalizing the temperature of the roof to prevent the formation of icicles on the edges of the eaves and ice on the roof surface.
The ventilation system of the building consists of various elements, performing one common task: to ensure normal temperature regime roof and under-roof space
Ventilation roofing tape
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:
- ridge ventilation tape;
- perforated cornice tape (overhang aero element).
Advantages of using roofing tape:
- creates good breathability;
- emphasizes the decorative finish of the roof;
- Provides protection from moisture, debris and insects.
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 provides additional protection of 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 laid under metal plate skate
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
Ventilation roofing mesh
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 both a budget option painting mesh with small cells. Its advantage is its low cost and ease of installation - the mesh is laid overlapping and fastened with a stapler to the wooden parts of the roof. 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.
Roof ventilation passage elements
Passing elements (penetrations) - component 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.
Aerator for roof ventilation
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.
An aerator for ventilating roofs made of soft tiles reduces the 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:
- aerators are installed in the highest places of the slopes along the entire length of the roof for uniform ventilation of the entire under-roof space;
- the distance between adjacent devices is maintained at least 12 m;
- aerators are mounted on dowels or anchor bolts and equipped with filters that prevent the ingress of dirt, moisture and insects;
- to set up the system during roof construction, select areas at the joints of the seal;
- To prevent leaks, use sealant or special tape.
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
Video: installation of the Systemair DVS roof fan
Ventilation passage through the roof
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:
- metal thickness for manufacturing is at least 11.9 mm;
- the size of the support ring is 30–40 cm larger than the diameter of the pipe;
- mandatory treatment with anti-corrosion compounds;
- the length of the unit design without valve is no more than 1 m.
The passage units for chimney ducts are arranged in strict compliance with fire safety regulations.
Ventilation gap on the roof
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.
Metal roof ventilation
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:
Video: ventilation of the under-roof space in metal roofs
Ventilation of soft tile roofs
Ventilation of a soft roof faces the following tasks:
- removal of condensate;
- preventing overheating of the lower layers of the roofing;
- ensuring temperature balance on the roof surface.
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 when correct device ventilation
Ventilation of soft roofs can be single- or double-circuit. But for it to be sufficient, a number of conditions must be met:
- the thickness of the air gap between the sheathing and the insulation is calculated in advance based on the angle of inclination and the length of the slopes (but less than 4 cm);
- make additional holes along the bottom of the slope, tightening them with perforated tape, mesh, comb, lining the roof overhangs with breathable soffits;
- arrange gaps on the roof in the form of ventilated ridges or aerators for forced ventilation.
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.
Video: ventilation of the under-roof space in roofs made of flexible bitumen tiles
Hip roof ventilation
Ventilation of hip roofs can be 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 time Due to the accumulation of snow, 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.
Video: how to eliminate condensation in the attic
Ventilation of insulated under-roof space (attic)
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 for the required gap, 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.
Video: ventilated ridge on an attic roof
Seam roof ventilation
A seam roof, like all other types of roofs, requires normal air circulation in the under-roof space. And this is ensured by a gap between the coating and the heat-insulating layer of at least 50 mm, for which a sheathing of 50x40 or 50x50 mm timber is assembled. 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.
Pitched roof ventilation
To equip the ventilation of pitched roofs you need:
- supply gaps in the lower roof area;
- channels for air circulation above the insulation (due to the sheathing);
- hoods at the top of the roof have an area of 15% larger than the area of the supply openings, since good ventilation requires reduced pressure in the attic.
It is not difficult to arrange ventilation with your own hands. The general scheme is the same - 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.
Video: installing a ridge aerator
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 highest point of the roof.
With this arrangement, the aerator ventilates 5 m² of the attic space, but if the building is located in a well-ventilated area, then its capacity increases to 25 m².
Video: installation of a point aerator
Ridge vent size
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.
How to remove a pipe through a roof made of corrugated sheets
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.
- First you need to make sure correct location chimney pipe - the exit point should be in the darkened northern side, where little sun reaches.
- The shape of the pipe and the size of its cross-section are selected, taking into account the climatic conditions of the area, the topography and the temperature of the outlet gases.
- Then they are determined with the height of the pipe according to SNiP.
- They make the pipe themselves, or buy a ready-made one and carry out installation.
Video: pipe passage through a corrugated roof
Height of ventilation shafts according to SNiP
When calculating the height of ventilation shafts, take into account:
- the elevation of the pipe relative to the highest point of the roof and adjacent buildings;
- total length of the smoke channel;
- head size;
- design height.
Requirements and standards according to SNiP:
If there are outlets of other ventilation ducts nearby, the height should exceed the others by 20 cm.
Video: how to calculate the height of the chimney
Ventilation aerators - special devices for ventilation of the under-roof space and removal of 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 effective 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.
Installation of aerators on a flat roof
With double layer coating roll materials aerators are installed in the bottom layer:
- A hole along the diameter of the aerator tube is cut through the screed and layers of insulation.
- Cover with gravel and attach the aerator to hot mastic.
- After cooling, fix with self-tapping screws.
- Surfacing upper layer roofing decking in such a way that the aerator is at the point of overlap (15 cm) of the sheets; the junction points are sealed.
Video: DIY aerator installation on a two-layer soft roof, part 1
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.
Video: installation of an aerator on a two-layer soft roof, part 2
Installation of aerators on metal tiles and corrugated sheets
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.
- Apply the template (included in the kit) to the installation site, outline and carefully cut a hole along the intended line.
- The seal is secured with screws and sealant is applied.
- Install the aerator, secure it with hinges and additional screws.
- From inside the attic, the passages of ventilation pipes are puttied with sealant.
When installing ventilation elements, you must use proprietary fasteners, which are included in the kit.
Video: installation of ventilation on metal tiles
Main mistakes in installing a ventilation system: how to avoid them
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.
- SNiP standards are not taken into account.
- Unsuitable ventilation elements selected.
- The ventilation ducts are not located symmetrically.
- The system throughput was incorrectly calculated and the heat balance was not taken into account.
- Installation work was carried out incorrectly.
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.
Overview of ventilation systems
When setting up ventilation, sometimes it becomes difficult to select components. Let's look at the most popular manufacturers whose products deserve attention.
Roof ventilation "Virplast"
WirPlast equipment is used for different purposes - installation of ventilation of rooms or sewer outlets (sewage system), as kitchen hood, for installing antennas or constituent elements solar panels.
Advantages:
- easy installation due to the built-in spirit level, which eliminates any errors;
- complete tightness on the roof;
- stylish design;
- a variety of models for all types of coverage;
- 10 year warranty.
WirPlast ventilation equipment is different high quality, which is confirmed by a ten-year guarantee for all products
Roof ventilation "TechnoNIKOL"
TechnoNIKOL ventilation systems are available in two variations:
- for ventilation of the under-roof space;
- For forced circulation air in attics and attics.
Advantages:
- aesthetic design and affordable price;
- increased reliability and impact resistance of all elements. Achieved thanks to additives introduced into the composition of the base material HDPE;
- easy installation with detailed instructions.
Roof ventilation Vilpe
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:
- made of impact-resistant polypropylene and therefore not subject to corrosion;
- resistant to ultraviolet radiation and climatic changes;
- ecologically pure material, withstands constant temperature changes from -40 to + 80 °C and occasional surges from -55 to +120 °C;
- Wide variety of colors and modern design.
Vilpe roof ventilation is made from impact-resistant polypropylene and can withstand large temperature changes
Roof ventilation Kronoplast
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.
Video: installation of ventilation on an ondulin roof
Installation of roof ventilation is an important and necessary process that requires attention and responsibility. It is not difficult to make it yourself, following mandatory rules and standards. Only in this case the roof of the house will never “cry”. Good luck to you.
A large country means large volumes of housing construction. Not only multi-storey, but also private. And every developer needs and needs knowledge on general construction issues, norms and rules, including roofing processes.
Properly executed roofing structures are the key to not only warm home and a comfortable atmosphere, but also the durability of other elements of the structure.
Roofing is an important stage in the construction of buildings.
Physical heat transfer processes
In a heated house, temperature changes and the presence of moisture in the air in the form of steam and condensation are inevitable. Steam is produced by human or animal activity, penetrates into building structures, cools and moisturizes them. Overwhelming majority building materials allow air to pass through to varying degrees. Therefore, any residential building, individual or multi-apartment, is an air volume in which warm air rises upward through all structures.
In tall multi-storey buildings, a traction effect appears. Warm air rises to the upper floors, this is especially noticeable in the entrances, and penetrates outside through windows and attics. On the lower floors, on the contrary, there is an influx of outside cold air. This process also occurs in a one-story heated house, only with less dynamics.
On the other hand, warm air steam condenses in structures into water, which not only moistens them, but also has the ability to flow down, filling the cavities in the structures. The main function of condensing water vapor is assumed by the uppermost part of the building - the roof. In winter, this process occurs intensively and constantly, and in summer, mainly during the cool night time.
The most modern and effective way to prevent or significantly reduce moisture condensation in the roof is to make it ventilated naturally or forcefully. Natural cold ventilation will not require energy costs, so its design is preferable. However, there are roofs of complex architecture that lack the strength of natural ventilation, then forced ventilation comes to the rescue.
Ventilation removes warm wet air into the surrounding space, thereby leaving bearing structures, insulation is dry, extending service life and providing thermal insulation. We need to manage this process, which is done using the so-called roofing pie.
The concept appeared relatively recently and denotes a multi-layer roof structure, in which the leading place is given to the creation of ventilation ducts. There are two types of roofing pie: for heated and insulated rooms and for cold roofing. Each layer is functionally interconnected with other layers, and the absence of any reduces the protective properties of the entire cake.
If the attic is a cold, uninsulated part of the building, it is done in several successive layers. The following tools will be required for the work.
- hammer;
- drill with drills 4-12 mm;
- wood hacksaw;
- stapler (stapler) electric or mechanical with staples 14x8 mm;
- level, meter ruler, square;
- scissors;
- screwdrivers of different sizes;
- brush-fleet for antiseptic cutting of wooden parts;
- construction sealant.
A waterproofing film (not to be confused with a vapor barrier) is laid on the upper side of the rafters. The film sag should be 20-40 mm to drain condensate. It is secured along the rafters with a counter-lattice 30-50 mm thick and a width equal to the thickness of the rafters themselves. It is better to glue the film at the attachment point with double-sided tape.
To reduce waste, the film can be laid in horizontal rows from bottom to top and with an overlap of 100-150 mm. The junctions of the strips are glued, creating a continuous web. The water generated from condensation will flow down the film to the roof eaves.
After installing the waterproofing layer, the roofing lathing is sewn across the rafters onto the counter-lattice. The width of the boards and the gap between them are selected depending on the roofing material.
- For ceramic and soft tiles, use an inch board 100 mm wide for the sheathing. It is laid with a gap of 50-100 mm, after which the top is completely covered with building board or waterproof plywood with a thickness of at least 9 mm. Under soft tiles The underlying layer is still being laid.
- Lathing made of boards 30x100 and in increments of 300-400 mm is made under metal tiles or corrugated sheets;
- For a metal seam roof, use a lathing made of an inch board 150-250 mm wide, sewn onto a counter-lattice with a minimum gap of 20-50 mm.
Finally, the roofing material is laid directly on the sheathing or building slab. It is attached with special nails, screws or clamps to the sheathing. The roof fastening points are protected with sealants, and the sheathing is pre-treated with an antiseptic. Additionally, you can perform rough filing along the rafters from the attic side.
Between the roof there was a ventilation gap equal to the total thickness of the sheathing and counter-lattice. This is 55-80 mm of the height of the under-roof space along the slope of the rafters. In winter, warmer attic air, partially penetrating through the waterproofing, will rise to the roof ridge and be released into the atmosphere without having time to condense moisture. And in summer, the air heated by the roof is also removed from under the roof.
Attic ventilation is important for the under-roof space. It is carried out through dormer windows located on the gables from different sides. Ventilation of the living space, attic and under-roof space are interconnected, and one of their goals is to reduce steam and condensation in the roofing pie.
Ventilated insulated roof design
Often attic space used as an attic, insulated from the roof side. In this case, several more layers are added to the roofing pie. Now there is no attic air gap between the living space and the roof. Warm and humid attic air immediately penetrates into the under-roof space. And if you don't accept additional measures Once it is removed, there will be much more condensate and the structures will begin to get wet. Thermal insulation materials will cease to perform their functions and the air in the room will be cold. We'll have to turn up the heating.
In addition to those layers that are already made in cold roof, add a thick layer of insulation, laid between the rafters on the inside. If ordinary rafters are 150 mm wide, then the thickness of the insulation between the rafters can be no more than 100 mm. The reason is the need to leave a minimum gap (do not touch) until the waterproofing sag, which reaches 40 mm. If there is a touch, water flowing down the insulation will get into the insulation. To increase the thickness of the layer, timber of the required thickness is sewn onto the rafters and insulation is added.
Then it is closed vapor barrier film. The goal is to minimize the penetration of steam from the room into the insulation so that it does not get wet. Wet insulation is no good, it does not retain heat and, in addition, moisturizes the surrounding structures. First, a rough lining is sewn onto the vapor barrier, and then a finishing lining.
Now the path of wet steam to the roof is blocked, and although a small part of it still penetrates, it is carried out into the atmosphere by the under-roof ventilation air flow, without causing harm to the roof structures. And if the warm room itself is not ventilated, where will the steam go? Through all sorts of microscopic pores and cracks it will still go up to the roof. This will be facilitated by overpressure, formed in a warm attic room.
Ventilation of the room itself will help relieve excess pressure, reduce the moisture content in the living room and thereby help under-roof ventilation remove moist air into the atmosphere.
Ventilated cornice device
Longitudinal ventilation ducts roofing pie will not work effectively if, on the one hand, in the lower part, at the very eaves, there is no influx of atmospheric air. On the other hand, it is necessary to allow the humidified air to escape from the very top part of the roof - from the ridge.
Waterproofing film is the strongest of all types of films used in home construction, so it does not allow water or moisture to pass through, even under high pressure.
The waterproofing film is removed and glued with sealant onto a metal cornice strip installed in the plane of the sheathing. The roof is fixed on top. Air flow is carried out in 3 ways. Firstly, through the gaps of the profile of the roofing material, secondly, through the gable overhangs and, thirdly, through the micropores of the waterproofing film, drawing vapor from the insulation.
When covering the cornice, ventilation holes or gaps are provided in its lower part, depending on the many options for the design of the cornice. One of modern methods- this is a continuous filing of the cornice plastic panels with perforations for roof ventilation.
Creating a ridge hood
Depending on the design of the roof covering, the air flow from under the roof is collected in the ridge and discharged into the atmosphere either through structural gaps along the length of the ridge, or through gable openings. For example, a set of ceramic and metal tiles includes special ridge elements with ventilation gaps. Additionally, there are additional elements for non-standard shape skate.
This is the outer part of the roof. The internal structure is performed in a certain sequence.
- the counter-lattice along the rafters is not brought to the geometric height at the same distance of 20-40 mm. The bars of the oncoming slopes do not join;
- sheathing in 2 solid boards from both slopes on the ridge is also performed with a longitudinal gap of 40-80 mm;
- the waterproofing film along the ridge is cut with a hem margin of 200 mm on both slopes;
- between the ends of the counter-lattice and the sheathing along the ridge, a ridge beam of 40x100 mm is installed vertically;
- a waterproofing sheet is attached to it and sealed with sealant;
- From above this structure is covered with a ridge according to the instructions and technology;
- Install ridge end elements on the gable side, in which ventilation holes or gaps are provided.
Some features of a ventilated roof
Roof ventilation is not an independent process. On the contrary, ventilation or its absence in the premises directly affects the air exchange in the roof. In order to effectively remove destructive moisture from residential premises through the roof, it is necessary to consider the ventilation of all building elements as a single process.
If the shape of the roof is complex, has many transitions, valleys, ventilation processes must be divided into sections and air flows in the roof must be formed separately. As a result of effective ventilation, the air in the under-roof space should be replaced approximately 2 times within an hour.
The effectiveness of a ventilated roof depends on the slope of the slopes. The steeper they are, the stronger the ventilation process occurs. And, conversely, in roofs with a slope of less than 20%, under-roof ventilation is unstable and effective only under wind pressure.
It is always useful to install additional exhaust elements (aerators) on the roof to help enhance the natural ventilation of the roof. They should be placed on roofs of complex shapes, when conventional means are no longer sufficient. Aerators are installed near the ridge.
The thermal insulation properties of insulation and the durability of roof structures directly depend on the presence of moisture in them. Therefore, a ventilated roof and the design of room ventilation are economically beneficial even when it is necessary to install forced air exchange.
From ancient times to the present day, the purpose of the roof was to protect any structure from the destructive effects of wind, precipitation and scorching sun. Therefore, the qualities that were required of it were appropriate: maximum resistance to gusts of wind and tightness. The first is to eliminate drafts, and the second is to prevent melt or rain water from leaking from the roof into the attic (if there is one) and into the living quarters.
The technologies for the production of roofing materials are based on these principles. The coatings offered today are airtight and more than reliably protect the house from precipitation. But usually modern roofs consist of several layers, and the more airtight the top covering of the roof, the worse the ventilation of the under-roof space will be. Lack of ventilation will lead to increased humidity levels, which can cause roof structures to become unusable. To avoid this problem, install a roof ventilation system.
Ventilated roof installation
The roof of a house is a complex and multi-layered structure. Made conscientiously, it will protect the house from heavy rain, withstand the fall of heavy branches broken by a hurricane, and in winter it will allow you to save on heating due to heat-resistant materials and high-quality insulation. As a rule, it consists of a layer of roofing and two insulating layers, one made of waterproof material, the second of heat-proof material. In turn, insulating materials can also be multilayered.
A ventilated roof is designed based, first of all, on the characteristics of the roof:
- In pitched roofs, a gap is left for the free movement of air along the entire length of the slope, and the air flow must pass from the overhang to the ridge. This direction of ventilation allows the use of insulation from any material, although it is better to give preference to vapor-tight insulation boards. When installing ventilation on such roofs, it is imperative to use protective grilles, since the air channels can easily become clogged with debris falling on the roof - branches, leaves, etc.;
- If the house has a flat roof, you need to take care of installing small ventilation holes along the edges of the roof. Air will circulate through them. The total area of the ventilated layer must be at least 5-6 cm, and the total area of the channels for air movement must be at least 0.2% of the roof area. If we talk about insulation, then the most suitable material in this case is mineral wool.
Materials used for ventilated roofs
The good thing about roofing with artificial ventilation is that any roof covering is suitable for its installation. The size of the ventilation holes depends on the thickness of the selected material: the thicker the roofing material, the larger the holes should be. On average, their diameter ranges from 5 to 10 cm. For example, a metal tile roof will require small holes, since its sheets are quite thin. But for a roof made of natural tiles, large diameter holes are already needed. In addition to the thickness of the roofing material, the size of the ventilation gaps and their number also depend on its weight and density.
Waterproofing materials
The choice of insulation material depends entirely on the roof covering. The main purpose of insulation layers is to prevent heat from escaping outside and water from seeping inside. Waterproofing membranes are available in anti-condensation and diffusion types. The former are used with euro slate and metal tiles, that is, with materials for which contact with condensate is undesirable. The latter can be used with natural materials that are not afraid of contact with moisture, for example, ceramic or bitumen shingles. Right choice materials for waterproofing are the key to the durability of the roof of your home!
Thermal insulation materials
Granular materials such as polystyrene, perlite or mineral wool are ideal for insulating a ventilated roof. The thickness of the insulating layer must be at least 25, or even 30 cm. When laying insulation on flat roof You need to make sure that when blowing in granules, the ventilation holes do not become clogged. It is better to entrust this work to a specialized installation team.
Advantages of roofing with artificial ventilation
For those who still doubt the need for ventilation in the roof, it would be useful to familiarize themselves with the results that the use of such a design gives.
- By preventing the formation of condensation in the roof layers, ventilation ensures the durability of the roof.
- Due to air gaps and thermal insulation, the possibility of additional heat loss is minimized.
- Thanks to constant air circulation in the inter-roof layers, the ventilated roof does not heat up in summer.
- No air stagnation – a healthy atmosphere throughout the whole house!
