The under-roof ventilation scheme includes several types of devices, each of them performs its work, so the choice should be made taking into account the type and materials of the roof.
The design of all types of roofs includes several veins, like on a pie. And each layer needs free passage of air. Such a system protects each layer, and most importantly the insulation, from condensation and mold formation. Therefore, it is so important to know the features of each device, depending on the structural features of the roof.
If you hope to protect the insulation on one side with a layer of waterproofing, and on the other - with a layer of vapor barrier and at the same time refuse to equip the roof with a ventilation system, in this case condensation will occur. The homeowner suffers a deterioration in the thermal insulation of the roof, wooden structures rot, and the service life of the roof structure is reduced. Therefore, it is important to know the answers to the questions - why, why and what devices are better to install for your roof.
Reasons for the formation of moisture in the roofing cake
The question - why moisture occurs in the hermetic laying of thermal insulation, worries the owners of residential buildings. But the answer is very simple. Some content of moist air increases in damp weather. At high temperatures, a layer of condensate settles in the inner part of the roof and on the thermal insulation. Poorly made vapor barrier, voids in the masonry walls add moisture.
In the conditions of housing construction, it is almost impossible to ensure the complete tightness of the layer. These factors lead to the decomposition of the insulation layer and the destruction of the wooden structure of the roof. Therefore, ensuring reliable and sufficient ventilation of the roof structure is one of the main works in creating normal building operating conditions.
Important. Professionally and qualitatively manufactured structures of the roofing system and selected materials and devices are the main conditions for creating comfortable living conditions in the building and increasing the service life without accidents and roof repairs.
Rules and features of creating a reliable and durable roof
To ensure efficient removal of exhaust air from the premises and moisture from under the roof, the building is equipped with a system in which under-roof ventilation is one of the components of the entire cycle.
With a complex roof configuration with multi-level planes, air mass flows are separated. This is necessary to ensure the change of air in the under-roof space at least 4 times within 2 hours. In this case, the angle of the roof slope should be taken into account. When the tilt angle is less than 200, the ventilation system will work unstably. The greater the angle of inclination, the better the ventilation of the space under the roof.
For improvement, the installation of an additional exhaust device - an aerator is provided. These products are located in areas with a complex shape, with an insufficient level of removal of moist air. It is better to mount the aerator near the ridge. The normal level of thermal insulation of the roof and a long service life is ensured by means of ventilation devices, so even installation on a flat roof of a forced system using electricity will not be unprofitable.
Important. To ensure each individual ventilation outlet, various passage parts are used that are not included in the scheme package and require selection taking into account the roofing material.
Details for roof ventilation
The roof air exchange system is mandatory for the arrangement of roofs of various configurations and materials. For such purposes, the installation of the following parts is provided:
- eaves and ridge products;
- roof fans;
- making special holes in the roof covering;
- ventilation skates;
- in the presence of an attic, the installation of dormer windows is provided;
- ventilation ducts;
- when installing the coating, it is provided for the manufacture of one or two gaps for ventilation.
Methods for arranging a roof ventilation system
One of the main methods is the installation of roof aerators near the roof ridge. A point location is possible, but the best solution would be to install a continuous trough of aerators. These devices are located along the entire edge of the roof structure, if possible, together with the main ventilation system of the house.
Such details do not violate the architecture of the house. The installation is carried out during the installation of the roof, the roof covering is installed on the aerators. With this method, mounting foam and a special tape for sealing joints are not used. This will block the flow of air into the under-roof cavities.
For the implementation of work, special devices are used to facilitate installation work:
- a stove equipped with channels for the passage of air;
- separate air element;
- ventilation roll.
Ventilated cornice device
This method provides a gap for the passage of air into the under-roof space, which leads to greater efficiency of the entire ventilation scheme of the house. It can be performed in several ways:
- the gap system between the flooring of the cornices and the material of the walls of the house - a soffit device;
- ventilation grilles are installed in the gaps;
- a device in which a special material with manufactured products is installed above the cornice overhangs.
Thermal insulation material is not laid in these places in order to prevent the flow of fresh air masses from stopping. Protecting the channels, they are covered with gratings, gutter parts or snow retainers
Valley device
This is the most complex device. It is also called the gutter of the roof. They are used with a short cornice overhang, longer grooves, and the installation of several ventilation gaps. To ensure ventilation of the thermal insulation, a number of ventilation openings are made in the film, on each span of the roof rafters, it is possible to manufacture a continuous channel.
In more difficult conditions, air aeration elements are located throughout the valley, this method is especially effective with a sharper angle of inclination of the roof. Flat roofs require the installation of fans, inertial turbines and high ventilation nozzles. But this method will require more work, an increase in the cost of installation work, equipment, and you will also need to pay electricity bills.
Arrangement of a dormer window
This is the most commonly used method for solving attic ventilation problems, it gives the roof an unusual appearance with reliable performance. Windows are made in different shapes, so they are used as a decorative decoration of the building. A gable window is installed on metal or soft roof coverings, a single-slope window is equipped with roofs made of any materials.
This type of ventilation is expensive, but it fully justifies them with its high ventilation rates and the beautiful appearance of the building.
Ensuring the free passage of fresh air into the under-roof cavities and removing moisture are the main tasks that ventilation of the under-roof space copes with. It is necessary to provide such a device for all types of roofs.
Depending on the material and type of roof, the use of various air supply designs is envisaged. They can be external and internal.
The ventilation system of the entire building will be more productive and inexpensive if the height of the roof and its shape are chosen in advance and correctly. Another factor is to determine the type of devices, their installation locations and the conclusions of all channels of the ventilation system at home. The fulfillment of these tasks and the subsequent high-quality installation of all parts will increase the life of the ventilation of the entire building and the safety of the roof.
In accordance with regulatory technical requirements, all rooms are equipped with an air exchange system. The exhaust pipe to ensure normal traction should end above the ridge of the house. Accordingly, it is required to equip the ventilation outlet to the roof of the building. Given that the roof itself and the outlet pipe of the ventilation shaft have a number of structural features and are made of various materials, the installation of a ventilation pipe on the roof requires compliance with a number of rules. One of them is to achieve maximum tightness of all connections, since the safety of operating the house as a whole depends on this.
Reasons for the withdrawal of ventilation to the roof
The end of the ventilation system above the roof of the house is due to the following reasons:
- the need to create traction to ensure a full-fledged air exchange of the interior;
- installation of a competent ventilation scheme.
Building codes require proper ventilation of the living space. If everything was correctly taken into account in the construction project, then you can find exhaust vents on the walls in the toilet, bathroom, wardrobe or pantry, as well as the kitchen. They are necessary to eliminate unpleasant odors, combustion products and excessive humidity from the premises. In order for all negative factors to be removed from the house, it is required to organize the end of ventilation shafts outside the building above the roof. Otherwise, they will again enter the house with the flow of incoming air.
Ventilation pipe installation
Varieties of ventilation pipes
By itself, the ventilation pipe for extracting to the roof is divided into several categories. First of all, the cross-sectional shape of the ventilation ducts differs:
- round;
- rectangular;
- non-standard.
During the production of ventilation ducts, various types of materials can be used. The most popular are aluminum, stainless or galvanized steel, polyester-based fabric and plastic.
Primary requirements
A number of requirements are imposed on the ventilation system, which have not bypassed the duct itself. You can check them out in the list below.
- The minimum cross-sectional diameter that the ventilation duct has is fifteen centimeters. A galvanized air duct with such parameters shows good work efficiency.
- In the process of arranging the supply and exhaust ventilation system, it is necessary to make sure that the pipeline has an increased annular rigidity in the design of the outlet part. The reason is as follows - in the area that rises above the roof, the pipe is constantly faced with a significant wind load. Therefore, the design must effectively cope with it.
- The ventilation pipe must have an increased margin of safety while simultaneously having a minimum wall thickness. The smaller the thickness index, the higher the overall throughput will be.
- Metal ventilation ducts should not become covered with a layer of rust over time. In the room there are moisture vapors that settle inside the pipeline. They should not cause the development of corrosion processes.
- The chimney itself must not emit harmful gases during operation and must not become a source of fire spread.
- The design must have a minimum weight.
It should be noted that brick and galvanized ventilation ducts fully comply with almost all the qualities indicated above. The brick pipeline has a weight that meets regulatory requirements. A metal pipe during operation is capable of attracting dust to itself, as static electricity accumulates on the walls.
Ventilation outlet to the roof
Stages of installation work
Before bringing the ventilation pipes to the roof, it is necessary to complete the installation of the ventilation system wiring inside the building. The duct itself must be securely fixed. The list of tools depends on the material of the roof of the house. For comfortable performance of work, the following basic list of tools and materials will be required:
- chisel;
- electric drill;
- building level;
- jigsaw (highly desirable - electric);
- Screwdriver Set;
- insulating material;
- scissors for metal or "grinder";
- marker;
- hardware for fixing;
- sealant;
- rags;
- passage node;
- individual protection means.
When performing independent installation of ventilation outlets to the roof, you should use the assembled passage assembly, thereby greatly simplifying your work. The sequence of actions is as follows:
- Markup. Using a marker, make marks according to the template (depending on the section and size of the ventilation outlet pipe to the roof) in the place where the ventilation shaft will exit.
- Creating a slot. It is necessary to cut a hole in the roof using a tool for processing a certain roofing material (usually this is a “grinder”).
- Removal of the top layer of the roof.
- Drilling holes for fastening the outlet segment of the ventilation shaft.
- Marking for mounting the passage assembly.
- Creation of grooves in which self-tapping screws will be placed in accordance with the previously carried out markings.
- Installation of the pass-through node.
- Its fixation with self-tapping screws.
- Installing the ventilation pipe, fixing it with the appropriate hardware.
- Insulation of all cracks and openings.
Installation Features
During the planning and installation of the ventilation system, it is first necessary to check the calculations for compliance with the technical rules. It is highly recommended to entrust the design to specialized specialists who understand all the features and technical nuances of the building.
There is a difference between the temperature readings at the inlet and outlet of the ventilation duct. Inside the channel, there is an increase in thrust due to the difference in temperature inside and outside the room. This is the main reason why ventilation tends to work at higher productivity in winter than in summer.
Even at the design stage, you need to think about the thermal insulation of the channels that pass under the roof. This is required so that air draft does not decrease over time. This solution effectively affects the protection of the exhaust channels from the accumulation of moisture. If the ventilation pipe is located along the chimney, it is necessary to take care of its heating (the quality of operation of the ventilation system as a whole changes positively). On the other hand, there is also a downside here. In such channels, the draft is different, therefore, if the calculations are made incorrectly, you may encounter a violation of the ventilation.
Properly designed ventilation output contributes to effective air conditioning indoors. Self-installation does not cause difficulties, subject to preliminary familiarization with the features of the work.
Fixing the top of the ventilation riser
Consequences of installation errors
Proper installation of the ventilation pipe on the roof is the key to the full operation of the entire system. If the recommended installation standards are not met, the following negative consequences will occur:
- weakening of traction;
- the presence of unpleasant odors in residential premises;
- accumulation of moisture in rooms;
- condensate inside the system;
- lack of oxygen;
- the appearance of a fungus on the surface of the walls;
- deposition of soot on facing materials installed in the kitchen;
- an increase in the intensity of the occurrence of diseases in all residents;
- freezing of certain structural elements of the building.
The correct installation is the main factor that determines the usefulness of air exchange and the comfort of living.
Structures of almost all types of roofs, consisting of several layers that form a roofing pie, need ventilation. The passage of air flows through the gaps between the individual layers protects the insulation material from the accumulation of condensed moisture on its surface.
Some developers believe that protecting the insulation with waterproofing on the one hand and vapor barrier on the other is enough to prevent water from falling on it, and do not care about arranging ventilation ducts, all the more so, building codes do not standardize methods for arranging roof ventilation systems. This fairly common mistake leads to a significant deterioration in the thermal insulation properties of the insulation, rotting of wooden structures and a reduction in the life of the roof as a whole.
Where does the moisture in the roof come from?
Where can moisture come from in a practically hermetic space? First of all, a certain percentage of moisture is always present in the air, and at high humidity during fogs or rains, as well as in the heated indoor air, it increases significantly. Some amount of moist air passes through the vapor barrier, some through foam concrete or brickwork, etc. It is almost impossible to create a vacuum between the layers where air does not penetrate. Water vapor under the influence of temperature difference condenses on cooled surfaces, penetrates into the insulation material, and destroys wooden structures. Thus, ventilation of the roof and under-roof space, with rare exceptions, must be organized.
Roof ventilation device
The most common and effective type of roof ventilation is the installation of special ventilation holes in the ridge and under the overhangs of the roof structure. Under the influence of wind and temperature difference, air enters the holes under the overhangs, passes through the ventilation gaps between the insulation and waterproofing, and exits through the holes in the ridge. The value of the ventilation gap depends on the parameters of the roof and averages 5 cm, for roofs with a slight slope slope - 8 cm. Such ventilation is natural, that is, it does not require additional equipment for air injection. If the system is done correctly, the airflow will be able to completely pass along the entire roof twice in 1 hour.
There are other ways to arrange ventilation, for example, exhaust holes are made not on the ridge, but on the slopes using special elements. For tiles or other piece roofing materials, special tiles with ventilation holes are produced.
Roof ventilation through skylights
Another option is dormer windows on slopes. This is one of the oldest ventilation methods, which has rarely been used on its own lately - only as an addition to ventilation gaps. The fact is that when using such windows, unventilated zones are formed around the windows themselves. For ventilation to be as efficient as possible, you need to make two windows - one opposite the other. Their size is usually 0.8x0.6 m. Windows are made during the installation of the truss system, their frame is attached to the rafters using racks. The canopy above them and the "walls" are most often covered with roofing material, the same as the entire roof. "Walls" can also be sheathed with plastic clapboard. After manufacturing is completed, the opening is filled with a window frame or ventilation grille. When choosing the size and location of the dormer windows, you need to take into account the design features of the roof and its appearance, you do not need to install them too close to the cornices or ridges. The distance between the dormer windows on one slope should not be less than 1 m, the total number of windows should be reduced to an optimal minimum, because they greatly complicate the process of installing the truss system.
Other ventilation options
As an option, the organization of a forced ventilation system using turbines or deflectors can also be considered. They are mounted in such a way that it is possible to draw air directly from the under-roof space.
If the roof design provides for a small angle of inclination of the slopes, care must be taken to protect the ventilation openings from snow drifts. Usually in these cases, instead of exhaust holes, pipes are used, the length of which is chosen above the snow layer.
The method of ventilation also depends on the purpose of the under-roof space. For non-residential attics, holes along the overhangs and the ridge, as well as gable windows, are quite enough. For attic ventilation, aerators are often additionally used - elements that increase air exchange.
roof insulation ventilation
How does the ventilation of the insulation layer take place and is it really important to keep the insulation dry?
First, a few words about the thermal insulation of the roof. The heat-insulating layer is the thickest in the roofing pie; the total thickness of the roof, as well as its energy-saving properties, largely depends on it. High-quality insulation allows you to create and maintain the most comfortable microclimate inside the house, regardless of weather conditions. Depending on the climatic area of building, the thickness of the insulation can vary significantly. On average, it can vary between 10-15 cm.
Almost all heaters absorb moisture, which significantly impairs their thermal insulation capabilities, since water, which conducts heat well, pushes air out. Even with 5% moisture, the insulation loses 50% of its properties. Ideally, the heat-insulating layer is protected on both sides by hydro- and vapor barriers, as mentioned above, but even they are not able to completely isolate the insulation from steam and its condensation. That is why the surface of the insulation must be constantly dried by a stream of air, preventing drops of moisture from settling on its surface. To do this, there must be a gap between the insulation and the waterproofing layer, which is formed due to the boards of the counter-lattice. Air enters the gap through holes in the overhangs of the cornices and exits through holes in the ridge. If the slopes have a large area or a slight slope, for more effective ventilation, deflectors can be used to create forced draft.
What are vents and why are they needed?
Ventilation openings through which air enters the ventilation gaps and exits are called vents. As you might guess, the vents are cornice and ridge, depending on their location. Eaves are best done along all eaves. At their core, these are gaps between the roof and the wall, the width of which is about 2-2.5 cm. There are also point vents, which are not a continuous gap along the eaves, but separate holes. The diameter of such holes depends on the slope of the slope: at an inclination of more than 15 degrees, it is 10 mm, less than 15 degrees - 25 mm. All vents must be closed: point ones with gratings, and slotted ones with nets or slats (soffits).
Ridge vents are also slotted (gap width 5 cm) and point. Spot blows are made at a distance of 6-8 m from each other. Piece roofing materials have special additional elements with ready-made ventilation holes. For example, when laying natural tiles, the second row from the ridge is laid out with special ridge tiles.
Elements of the ventilation system of the roof can usually be purchased together with the roofing material. Many large manufacturers produce such additional elements for all types of coatings. They are combined with the color, texture, material of the roof and fit perfectly into the overall look during installation. Ventilation elements include ridge and cornice air vents, exhaust openings, through channels.
Exhaust openings located closer to the ridge are of several types: in the form of a gable lattice on the gables, a roof outlet on the slopes. Also, the hood can be placed on the ridge itself in the form of an aerator. For effective ventilation, the area of the exhaust openings should exceed the area of the supply openings by 10-15%, which will increase the draft. The total area of the vents is selected at the rate of 1/300-1/500 of the area of the under-roof space. In other words, for 200 m2 of the attic area, it is necessary to provide the amount of air with a total area of at least 40 cm2.
Roof aerators
One of the types of exhaust products is an aerator. In principle, this is the same hole for removing air and moisture, only slightly “cultivated”. In appearance, aerators are pipes covered with umbrellas installed near the ridge. The principle of their operation does not differ from conventional air vents: air also enters the under-roof space through the cornice air vents and rises up under the influence of pressure and temperature differences. Aerators are continuous and point, and the latter - pitched and ridge. Point aerators are used for local ventilation of individual sections of the attic. More modern models are mushroom-shaped and have built-in fans to create additional traction in the system.
Continuous aerators provide ventilation for the entire under-roof space and are placed along the entire ridge. Usually these are plates with exhaust holes hidden by roofing material. Such aerators are almost invisible from the outside.
The choice of the type of aerator depends on the type of roof, roofing material, and the purpose of the under-roof space. There are aerators for flat roofs, natural, bituminous tiles, metal tiles, as well as universal models. They, like other ventilation elements, are often sold together with roofing materials.
Why do you need roof penetrations?
Pass-through elements or simply penetrations allow you to install fans and ventilation ducts on any roof, while ensuring the tightness of the unit due to seals. Pass-through elements are selected depending on the roofing material, the roof structure and the diameter of the ventilation passage. Manufacturers of roofing materials produce penetrations for tiles, soft roofs, metal tiles, seam roofs. Penetrations may differ among themselves in elements of adjoining to the roof, and in the method of installation. They are usually installed in parallel with the laying of roofing material, but some models can be mounted on a finished roof.
Ventilation of the under-roof space
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Last revision: 01/29/2016
The operation of any building requires the provision of the necessary measures aimed at extending the service life of all structural elements. In this regard, the roof is no exception. Adequate ventilation is necessary for any type of roof in order to increase the life of its roof. If this is not done, then condensate from moist air masses will be absorbed into the insulation and structural elements made of wood. As a result, this can lead to the destruction of the roof. You should know for sure how to ventilate the roof to ensure proper air flow in the attic space.
Relevance of ventilation
Condensation accumulated under the roof in winter can lead to the formation of ice and cause various damage to the drainage system.
Note! Insufficient air circulation in hot weather can lead to excessive heating of the roof, causing an undesirable increase in temperature throughout the building.
Ensuring adequate ventilation of the roof in a private house is the only effective way to get rid of excess moisture that accumulates under it. Properly arranged air ventilation will ensure the removal of unwanted condensate that comes from the interior of the building. The presence of normal temperature and humidity under the roofing cake will ensure the preservation of the thermal insulation properties of the roof insulation, prevent deformation of the roof structure, and also prevent decay processes.
Types of ventilation
Modern roofing technologies involve the installation of several basic 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 provides for the presence of a layer of insulation in the roofing cake. In this case, ventilation should ensure the circulation of air masses between the insulation, the waterproofing layer and the roofing material.
Another way to ensure the ventilation effect under the roof is to equip the cornice circulation with perforated soffits or embedded ventilation grilles. In this case, insulation should not be used in the space of the eaves, as it will close the ventilation ducts. Today, to improve air circulation, roofing aerators, which are ventilation rolls or special tiles with air channels and a mesh against insects, have become more often used. They are usually installed along the skates or on a pitched space. They do an excellent job of releasing air masses freely.
For flat roofs, electric exhaust fans or turbines are provided, as well as special ventilation nozzles and through channels. The most common option for roof ventilation can be considered a dormer window. Such an element does an excellent job with its technical function, and can also significantly decorate the pediment of the house.
How to ventilate the roof
You need to know how to properly ventilate the roof in order to prevent the above problems. In practice, the key to ensuring adequate roof ventilation is to create a ventilation gap between the roofing material and the waterproofing layer. Usually, an additional vertical beam is used for this, which raises the roofing material above the inner layers, providing a free flow of air from the roof eaves to its ridge. On the ridge of the roof, you can install a special aerator with many holes for the release of air masses.
If necessary, point aerators can be installed if the roof structure is too complex. The principle of their operation is the same as that of the ridge aerator, so they are also effective in providing the necessary air circulation in the under-roof space. If the roof is made of metal, then special fans and passage channels 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
How is the ventilation of the mansard roof, see below.
When building a private low-rise building, it is necessary to carefully consider all engineering systems, including natural or forced ventilation in the house. Without it, finished housing will not meet sanitary and hygienic standards suitable for human habitation.
As a rule, in a one- or two-story house, ventilation ducts from living quarters, kitchens and bathrooms are led to the roof.
The vertical outlet of the ventilation, ending in the form of a pipe, rising above the roof, provides maximum air draft. This way of organizing ventilation outlets makes the air in the room clean, since all odors - from the bathroom, kitchen and living quarters - are removed together with the air through the shaft to the outside.
Natural draft is formed due to the action of physical laws - due to the difference in air pressure outside and inside the premises.
According to the norms of SNiP, the output of ventilation pipes through the roof is necessary:
- for the supply of fresh air, saturated with oxygen, to the house;
- installation of the fan part of the sewer shaft (fan pipe connects the sewer riser with ventilation to remove unpleasant odors);
- air exchange in the attic or attic part of the house.
Ventilation planning
Ideally, the planning of ventilation passages should take place at the design stage of a residential building, or during construction, before the building contour is closed (arrangement of windows, doors and roofs).
But in practice, one often has to deal with the reconstruction of engineering systems in an already finished house and build on the existing design features and layout of residential and technical premises.
If there are flaws in the system design, this is fraught with the accumulation of unpleasant odors in the room, an increased concentration of carbon dioxide and carbon monoxide, and the occurrence of reverse thrust during changes in weather conditions.
Vent pipe passage assembly: design features
Roof ventilation through-hole is a metal, plastic or combined pipe. It is placed in a through hole in the roof and fixed in a metal cup. The hole after installation of the node is sealed and insulated from the outside and inside. An air duct of the ventilation system is connected to the unit from below, and a protective drip or deflector is installed on top.
