When building a house, it is imperative to consider high-quality roof ventilation. This is one of the main tasks of designing and constructing a durable home. Without good ventilation system the entire roof structure will very quickly become unusable. Everyone will suffer first from moisture. wooden elements, which will already reduce the degree of safety and comfort of the building. Then the roofing material will begin to deteriorate. Let's take a closer look at the issues of ventilating the roof of the house and natural ventilation of the roof.
Where does moisture come from in the roofing “pie”?
The roof of a residential building is a complex system consisting of wooden frame, roofing, as well as layers of waterproofing, vapor barrier, thermal insulation. In general, a high-quality roof is a sealed package. But moisture still gets onto the wooden elements and insulation. The point is that inside roofing pie air containing water vapor penetrates. When the temperature changes, steam settles in the form of condensate on the surfaces of the inner layers.
Even through the most reliable vapor barrier made of steam and waterproofing, some air still penetrates inside the “pie”. In addition, air can enter through "breathable" wall materials such as porous blocks, wood or cellular concrete. Therefore, condensation cannot be avoided. This phenomenon is especially pronounced during precipitation or fog, when the concentration of moisture in the air increases noticeably.
Purpose of roof ventilation
The ventilation system of the roofing system simultaneously performs several important functions, which increases the comfort of living in the house and extends the service life of the roof.
The main function of ventilation is removal of vapors from the under-roof space that rise from residential premises. During the ventilation process, circulating air prevents moisture from accumulating on the inner surface of the roofing pie, from where it can penetrate into the roof.
The movement of air masses in the roof ensures not only the weathering of excess moisture, but also uniform temperature distribution. As a result, all elements of the “pie” warm up quite well during the heating season. Therefore, a roof with good ventilation is less likely to become overgrown with icicles, which create additional stress on the roofing.
In summer, ventilation is necessary for roof cooling. This is especially important for houses with soft roofing, which gets very hot and can melt and slide even with a high slope.
Natural and forced ventilation
For their long and uninterrupted operation, both types of ventilation systems require careful calculations, which will show which one is better to use in terms of efficiency and economy. When making calculations, specialists must take into account the features of these systems.
Natural ventilation
It is carried out due to the convective flow, which arises as a result of the interaction of warm and cold air masses. For such ventilation to work, you need to assemble a roofing pie with a gap (at least 5 cm) between the bottom waterproofing layer and the roofing layer.
Efficient natural ventilation roofing is possible with proper design and competent work of builders. It is not easy to create conditions for it. It is necessary to carefully calculate the system of lathing and counter-lattice, and ensure the continuity of the ventilated circuit. But the most important thing is to provide ventilation vents. There should be at least two of them in the ridge area and the same number in the cornice area.
The air in the under-roof space heats up and naturally rises upward, where it is forced out through the ridge vents. Fresh air enters through the eaves openings. Thanks to this process, condensation does not settle on the roof surface.
If the slope of the slopes is small, in winter period ridge vents may be clogged with snow. To prevent this, you need to install special pipes along the ridge that will rise above the snow level.
Forced ventilation
Since organizing artificial ventilation requires additional equipment, from a technical point of view this is a more complex option. There are rare exceptions when designing forced ventilation is easier than calculating natural ventilation, but these are still exceptions that prove the rule.
It became widespread as a result of the fact that, firstly, low and completely flat roofs came into fashion, in which it is simply impossible to create natural ventilation. Secondly, new ones have appeared construction technologies, allowing to automate and improve the maintenance of cottages.
Forced systems are installed not only in houses with flat roofs, but also in houses that, for one reason or another, cannot be provided with roof vents. Recently, more and more often, solid cottages with standard roofs are equipped with forced ventilation, since it is more reliable than natural ventilation.
Forced ventilation can be carried out by installing a fan in the ridge vent. To do this you need to stretch top part roof wire The second option is to install special devices that increase the intensity of air movement.
On our website you can get acquainted with the most popular from construction companies, presented at the exhibition of houses “Low-Rise Country”.
Methods for arranging ventilation
Ventilation can be provided for the roof different ways. The choice of arrangement option depends on the architectural solution of the designer.
Aerators
Installing roof aerators is the most common option. The aerator is a piece made from a small piece of pipe with a flat base for installation on the surface and an umbrella that covers the upper hole of the pipe from precipitation. A protective filter is placed inside.
Aerators can be installed in various ways. The location of these devices depends on the type of roof and the degree of humidity in the region. Typically, aerators are located near the ridge. You can install them point by point. Experts believe that the most effective is to install a continuous aerator gutter stretched along the entire edge of the roof. It is advisable to install this type of ventilation simultaneously with the installation of the ventilation system of the entire building.
The advantage of aerators is that they do not interfere with the design of the house. Moreover, when using them roof covering does not have to be airtight, that is, it can be laid without the use of special tape and polyurethane foam.
On our website you can find contacts of construction companies that offer roof repair services. You can communicate directly with representatives by visiting the “Low-Rise Country” exhibition of houses.
Ventilated cornice
The use of a ventilated eaves provides air access to the under-roof space. As a result, the roof is well ventilated, and the entire ventilation circuit of the building works better. The eaves for roof ventilation can be arranged in different ways:
usage spotlights for roofing;
installation ventilation grilles;
installation of special eaves over eaves elements with vents.
Insulation materials are not laid in the places where the eaves ventilation channels are installed. To protect them from precipitation, elements are used drainage system and snow guards.
Dormer window
Ventilation with dormer window, this is also a fairly common option. Ventilating the roof of a house using this method, among other things, improves the aesthetics of the facades. Windows can be different in shape, and it is important at the design stage to think about the type of windows that will correspond to the overall style of the building.
Dormer windows are roof elements that are quite expensive to construct. But they have their undeniable advantages - high efficiency as a ventilation system and aesthetic appearance.
Ventilation of roofs made of metal tiles and corrugated sheets
These are the most common roofing materials in our country. They are very convenient in terms of application technology and price. They are manufactured using the same technology and differ primarily in shape. Corrugated sheeting looks less impressive, but at the same time has stiffening ribs along its entire length.
In the process of installing a metal tile or corrugated roof, difficulties arise with ventilation. The fact is that these materials are absolutely vapor-tight and thermally conductive. They heat up and cool down quickly, causing a lot of condensation to accumulate on the inside. But these materials also make it possible to create high-quality roof ventilation - roof ventilation, which extends the service life of the entire building.
Manufacturers of metal tiles and corrugated sheets produce special additional elements with which ventilation passages are equipped. The main thing is to entrust the installation of the roof to specialists who will think over a good ventilation system. Since these materials do not retain heat very well, when using them, additional layers of hydro and thermal insulation are provided. In addition, these roofing materials themselves must be protected from moisture with special care. Due to these features, roofs made of metal tiles and corrugated sheets are often equipped with forced ventilation.
Ventilation of soft roofing
Soft roofing under influence high temperatures may swell and melt. Therefore, it is so important for it to have ventilation that will not only remove moisture from the roofing pie, but also cool the roof during the summer heat. Typically, ventilation of a roof whose roof is made of bitumen shingles, is equipped with the help of aerators (valves).
Video description
Roof ventilation using valves (aerators)
Attic roof ventilation
Ventilation system mansard roof performs an additional function - temperature regulation in rooms top level Houses. It is designed more carefully than roof ventilation above the attic. On the other hand, it is easier to protect the attic roofing pie from moisture, since attic spaces, unlike attics, are heated and well ventilated.
In most cases, forced roof ventilation is not required to remove condensation from the attic roofing pie. But between the waterproofing and thermal insulation layers, space must be provided for the unhindered passage of air.
Video description
How to properly ventilate an attic roof
If the attic is converted into an attic
A simple attic can be converted into an attic to expand the living space. In this case, the roof is usually re-roofed. Insulation and roofing materials are replaced with higher quality ones. More than efficient ventilation roofing pie. However, if the roof was originally laid very well, you can improve it a little without disassembling it.
Any roof has at least a very small gap in the sheathing. It needs to be turned into a ventilation duct. This is achieved by installing special pipes in the roof plane through which the steam will ventilate. Closer to the ridge of the roof, holes are made with the calculation of 1 pipe per 50 sq. meters of roofing. Each such element must be protected from precipitation. As a result of installing a pipe vent system, ventilation on the roof will become more intense.
Video description
How to turn an attic roof without a ventilation gap into an attic
Stages of work
The process of arranging a ventilation system for any roof consists of several main stages. The first step is to provide for the presence of ventilation elements in the roofing system design. After this, during the construction of the roof, roof ventilation ducts and openings are made. In case of forced ventilation, special ventilation equipment is installed. At the last stage, the ventilation holes are protected from precipitation and dirt.
Conclusion
The roof of a private house must be well ventilated, otherwise the elements of the roofing pie will be negatively affected by condensation. They will quickly lose their original specifications, and there will be a need for replacement. In addition, without high-quality roof ventilation, the rooms of the house will be damp, and heating will require more energy consumption. Therefore, it is very important to correctly design and correctly construct a roof with an effective ventilation system, taking into account the type of roof structure, type of roofing material, climatic conditions of the region and other important factors.
Which differ not only in the complexity of the device, but also in characteristics and installation methods. Among these various types, in a separate group there is a ventilated roof, which is distinguished by excellent protection against swelling of the roofing carpet, wetting of the cake, mold, and mildew.
Today, such a roof is considered one of the most optimal; its construction is economical, possibly directly on top of the old structure. At the same time, it allows you to completely dry wet insulation and rafter systems. In our article we will look at the structure of such a roof and its features that made them so popular in private construction and construction apartment buildings, industrial, utility buildings. In addition, we will find out what options for such a roof exist, and how exactly they differ from each other. Our specialists will share the secrets of installation, which you can do yourself without calling a team of professional builders.
Ventilated roof design
Ventilated roofs, the designs of which are quite simple, include the following basic components necessary to ensure ventilation, such as:
- ventilation of the space that is located between the layers of waterproofing and insulation;
- ventilation between the waterproofing and the roofing itself, it covers all planes, even if the structure is complex;
- direct ventilation under the roof itself, which is an element of the overall ventilation system of the house.
It is the particular location of the ventilation that distinguishes such a roof from others; constant air flows allow not only to effectively remove moisture outside, but also to control the temperature level. In this case, ventilation will greatly depend on whether the roof sheathing system is installed correctly.
Scheme of ventilation of the roof of a non-residential attic space.
The process of installing a ventilated roof has its own specifics. So, for ordinary outbuildings and garages, a non-insulated type of coating is excellent, which consists of the following elements:
- rafter system;
- sheathing;
- waterproofing;
- roofing material.
The waterproofing film is attached to the rafters with slats; it prevents moisture from getting inside and extends the service life of the roof. But such a design is cold, that is, there is no thermal insulation layer in it. This is not suitable for private residential buildings; here it is necessary to arrange a different roofing pie. In addition to the listed layers, in this case it is necessary slab insulation, an anti-condensation film that prevents condensation from forming on roof elements. This material consists of several layers:
- two layers of laminated film;
- moisture-absorbing non-woven material;
- polypropylene fabric.
In addition, the installation of a ventilated roof requires the presence of vents in the lower part of the eaves and ventilated ridges.
Advantages of a ventilated roof
Ventilated roofing differs from other structures in the following advantages, which put it in first place:
- Installation of such a roof is possible even at sub-zero temperatures, the only exceptions being the presence of heavy rain, heavy snowfall, frost, which drops below minus twenty degrees Celsius.
- During reconstruction, the removal of old roofing is minimal, including preparatory work; This makes it possible to save money and time on installation; the cost of the roof is much lower.
- With further operation, everything is completely dried, including floor slabs, heat insulation, and old roofing (if any remains). This allows you to completely remove the risk of rot, mold, and mildew, which are very dangerous for the overall roof structure.
- The old roof covering, which is located under the new ventilated structure, after drying, completely restores all its functions, that is, a kind of double roof is obtained.
- The swelling of the roofing carpet is completely eliminated.
- The durability of the new coating increases; this roof is very resistant to frost, ultraviolet radiation, rotting, strong temperature changes, movements of ice and snow masses in winter, thermal expansion, and various mechanical damage.
How to design ventilation correctly?
Designing such a structure always requires careful preparation. When implementing a project, it is necessary to ensure that:
- water from the surface always flowed down, that is, proper protection against its influence must be created;
- steam rushed upward from the premises, that is, the presence of vapor protection is also mandatory.
The construction of such a roof is that rare case when the walls of the house should not breathe! Otherwise, the moisture that may be retained in them will lead to delamination of the building material.
Ventilated roof options
Today the most Various types ventilated roofs, among which pitched and flat ones stand out. They can be used for a wide variety of buildings, the materials for them, however, are the same, only the design differs. Let's consider these two main design options, their differences, device diagrams, and advantages.
Flat roofs
These began to be used in the early eighties, when it became possible to use heat-insulating materials with ventilation ducts that help remove excess moisture. Most often, such roofs were made for apartment buildings, where they were most effective.
The pie consisted of the following elements:
- concrete slab as a base for the roof;
- vapor barrier;
- a layer of mineral wool slab insulation, in the thickness of which there was the end of a ventilation pipe, the so-called aerator, which removes excess moisture;
- cement-sand screed;
- waterproofing layer made of bituminous materials;
- polyurethane material;
- a layer of polyurethane mastic;
- roofing material.
A concrete parapet was erected on the sides, which was protected from the roofing pie by a layer of sprayed or bulk material. Today, this function is performed by polyurethane foam, which provides excellent insulation and sealing. All outlets of ventilation pipes and aerators are also insulated with this material. All flat roofs are considered cold, but they still continue to be popular due to their convenience and savings. building materials during installation.
Pitched roofs
They differ from flat ones in that air flows enter through the lower overhangs and exit through the ridge, and with them all excess moisture that accumulates under the roof space in the insulation is removed. Ventilation in this case can be forced, for which roof fans are installed; the coating is recommended to be light, preferably having a wavy texture. The roof can be insulated or non-insulated; the roofing pie differs only in the presence or absence of a heat insulating layer. Residential buildings require insulation; in this case, mineral wool in the form of slabs is excellent; they are very easy to install, provide an insulated coating, and the absence of cold bridges.
Installation
The ventilated roof is installed in the following order:
- Preparing the base for work, including eliminating cracks and potholes. This could be a normal setup. cement mortar, leveling the entire surface, or paving the slab. It must be remembered that minimum slope such a roof should be between two and three degrees!
- Next comes the insulation, in which stripes and cracks are unacceptable. Most often, mineral wool or glass wool is used for this, which guarantee excellent quality and low installation cost.
- Depending on the type of roof, further installation work may vary, but basically a waterproofing layer and cement screed are laid.
- Roll fused materials are used as roof coverings, which provide excellent quality. Installation is carried out using gas burner, in this case the bitumen melts, the material itself is firmly glued to the base. The lateral overlap should be from one millimeter to five.
When installing, do not forget to mark the exit points of the ventilation ducts and insulate them properly to ensure the normal functioning of the roof. Only in this case will it acquire its proper qualities.
Construction technology numbers more than a dozen engineering solutions concerning the design. The comfort of residents depends entirely on how well and competently it is executed. All the power of the elements - rain, wind, and hail - falls, first of all, on the roof, so its design should be very carefully thought out.
Special requirements for roof construction are imposed in regions with high humidity, frequent rain or fog. Exposure to moisture significantly reduces service life wooden structures and roofing pie even despite treatment with special compounds and device. However, it is quite possible to minimize the problem of dampness; installing a ventilated roof will help with this.
The design of a ventilated roof has been developed quite a long time ago, its high efficiency has been proven by many years of practice. The popularity of this technology is due to the following advantages:
- high degree of protection of all layers of the roofing cake from getting wet;
- no swelling of the roof covering;
- possibility of using organic;
- economical due to the possibility of installation on top of an old roof.
If a ventilated roof is built on top of an old structure, then the latter “comes back to life”: the wooden elements become dry again, moisture is removed from the materials of the roofing pie. As a result, the roof appears to be double, its resistance to adverse weather conditions increases, and the whole house becomes truly warm and cozy.
The design of a ventilated roof provides for air circulation:
- between layers of insulation and waterproofing;
- between waterproofing and roofing material;
- in the attic space (as part of the general ventilation of the house).
Thus, the entire roof structure is very well ventilated, due to which it is not only possible to get rid of excess moisture, but also maintain optimal temperature regime. In this case, competent installation of the sheathing plays a decisive role.
The ventilated roof design has a number of varieties, which are related to the purpose of the building. For garages or outbuildings, use a non-insulated option, which consists of the following components:
- rafter system;
- lathing made of wooden slats;
- waterproofing;
- roofing covering.
Polyethylene film is used as waterproofing, which is attached to the rafter legs on slats.
For heated buildings Slab insulation and anti-condensation film are added to the roof structure, which protects wooden elements from condensing moisture. In general, the order of layers in such a roof is as follows:
- two layers of laminated film;
- non-woven material with high moisture absorption capacity;
- polypropylene fabric.
An important part of this type of roof is the vents located in the lower part of the eaves, as well as the ventilated ridge.
Project development procedure
During design work When installing a ventilated roof, the following must be provided:
- Proper drainage. The roof structure must be such that water flows freely from its surface. This is especially true for flat roofs, where, due to improper installation, depressions often form in the covering in which water accumulates.
- Steam removal exclusively through the roof.
Contrary to traditional concepts, the walls of a house with a ventilated roof should not breathe. For this purpose, their design contains a reinforced vapor barrier layer.
Such roofs began to be built in the 80s of the last century. It was during this period that it became possible to install a heat insulator with ventilation ducts to remove excess moisture. Roofs of this type were most widespread during the construction of apartment buildings. The roof structure consists of the following layers:
- reinforced concrete floor slab, which is also the basis for the roofing pie;
- vapor barrier;
- a slab heat insulator made of mineral wool, inside of which there is the head of an aerator - a ventilation pipe (excess moisture is removed through this pipe);
- screed made of cement-sand mortar;
- waterproofing based on bituminous materials;
- polyurethane;
- a layer of polyurethane-based mastic;
- roofing material
The roof structure is complemented side parapets, which are separated from the roofing pie by bulk or sprayed material. IN modern construction polyurethane foam plays this role, providing high insulation and sealing. It is also used to insulate the terminals of aerators.
Advantage flat roof is low cost and quick installation. Disadvantages: necessity frequent repairs and poor thermal insulation.
Pitched roofs
The design of this type of roof provides excellent air circulation, which penetrates into the under-roof space through the lower overhangs and exits through the ridge. In this way, it is possible to avoid the accumulation of dampness, which causes rotting or the appearance of fungus on the parts of the rafter system and roofing materials.
In some cases, a forced ventilation device is required. For this purpose, roof fans are installed on the roof.
As a covering Mostly lightweight materials with a wavy surface are used. Pitched roof can be either cold or insulated. The difference between these two options is the presence of an insulating layer. Mineral wool boards are usually used as an insulator.. Insulation with this material provides the following advantages:
- ease of installation;
- insulated coating;
- absence of cold “bridges”.
The list of roof installation operations is as follows:
- Preparing the base. At this stage, work is carried out to level the surface, eliminate cracks, chips and potholes. A screed made of cement-sand mortar or asphalting floor slabs is best suited for this purpose. The result should be a smooth surface with a slope of 2-3 degrees.
- Laying vapor barrier film and insulation. These layers must be laid in a continuous mass; cracks or breaks are not allowed.
- Installation of a waterproofing layer and cement-sand screed.
- Laying roofing. For flat roofs, fused rolled materials are used as a covering.
Despite the hype around some roofing materials, the comfort and warmth in the house is influenced not so much by them as by competent installation of the roof. If the construction was carried out professionally, observing existing standards, then any coating will be a reliable barrier to nature’s surprises, be it cheap slate or expensive metal tiles, and the entire roofing structure will save heat in the house and eliminate excess moisture. But the presence of condensation 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 may 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 roofing 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 mixed up the purpose insulating materials:
- If you laid a vapor barrier film instead of a waterproofing film. The vapor barrier film completely eliminates the ingress of moisture from both sides. If you lay it on top of the insulation, then the moisture that gets from the air into the heat-insulating material (and it will definitely get in, especially during seasons of high humidity!) will remain in it, because it will not find a way out. As a result, every year the insulation will become more and more moistened until it finally loses its properties completely, and the owners will be faced with high heat losses.
- If you laid a waterproofing film instead of a vapor barrier. Waterproofing films (also called diffusion membranes) have special properties: one side “breathes”, and the other is waterproof. They are laid under the roofing, turning the breathable side towards the heat-insulating layer. In this case, there should be a ventilation vent between the layers. Then the moisture from the insulation will partially escape through the air gap, and the rest will seep through the funnel-shaped holes of the film under the roof and evaporate. If 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 secured correctly waterproofing material on a skate, then the steam will not find a way out
When installing a waterproofing film, it is the other way around, i.e. on the “breathing side” of the insulation, water and moisture entering from the outside will easily enter the insulation through the funnels, and will no longer be able to get out. As a result, the entire design of the roofing pie loses its meaning.
Another option is 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, unknowingly, 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 thermal insulation material if it is not released under the roof? To do this, create a second layer of ventilation, leaving an air “cushion” between the insulation and the anti-condensation film.
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 is fraught with 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 what 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 downward 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.
Everyone who is somehow involved in construction should at least vaguely know the structure of a ventilated roof.
Let us remind you that there are 3 main ventilation circuits:
There should be a ventilated space with some room for fresh air to flow. It is they who will take the resulting moisture in the summer and remove it outside. In order for such a ventilated roof design to work efficiently and without interruptions, it is very important to competently approach the issue of laying the roof on the sheathing.
If the rafter system is already installed, take care of the roofing material. It must match the type of room. For example, if an unheated room is planned, then its service life will be limited only by the shelf life of the selected materials, and ventilation will be natural.
But to make the building last even longer, use forced ventilation, where the ventilation outlet to the roof, or more precisely, the outlet space, will be occupied by a weather vane.
Let's remember what elements an uninsulated roof consists of:
- Rafters;
- Lathing;
- Roofing material;
- Waterproofing films.
The waterproofing film plays an important role, because, attached to the rafters with the help of slats, even after the roof has worn out, it will provide some protection from moisture from the outside. Waterproofing also has a long service life, so it can reliably protect the passage of ventilation through the roof.
Especially similar material suitable for summer cottages. A film covered with slate under favorable conditions can withstand up to 50 years of constant use! But do not forget about the special structure of the “roofing pie” for all private houses.
In addition to insulation for ventilation, a diffusion waterproofing film is usually applied. Thanks to it, the under-roof structures will remain dry, and steam will be able to pass through the smallest pores of the material. Another advantage is also reliable protection from the wind while using this film.
But the use of diffusion film is justified only during the installation of certain gaps. The film can best show itself by filling the gaps between the thermal insulation structure, the roof and the film. In almost all other cases, this film will not allow water vapor to pass through, causing the roof ventilation outlets to stop working properly. Instead, it would be better to use anti-condensation film.
weather vane for the roof, which organizes forced ventilation. It is worth noting that it is possible to make.
Let us remember that a ventilated roof consists of finishing materials and insulation. Water vapor usually reaches the last layer and stops in this layer, due to which the insulation quickly loses its original properties. In the future, excess moisture will appear on the walls and ceiling, and this can have serious consequences.
To avoid bad consequences, ventilation is installed. But we must not forget about roofing materials, because they also play an important role in insulating the home. By showing balance, you will definitely be able to achieve the desired result in construction!