Cold metal roofing. Roofing pie for metal tiles: device with and without insulation Cold roof. Is waterproofing necessary on outbuildings?
The cold type attic is simpler than the insulated type, but there are subtleties here too. We analyze the arrangement of a roof with a cold attic, as well as advice from experienced builders.
The cold type of attics is most common in individual construction. It is rightly believed that building such a roof is easier than doing full insulation of the space under the roof. However, even when arranging a roof with a cold attic, there are non-obvious points. Let's figure out what mistakes are most often made experienced builders and how to make a cold roof according to all the rules.
Thermal protection of a cold attic
According to physical laws, heated air rises and cold air sinks. In application, this means that heat from the house will tend to escape through the roof through any crack in the insulation. Therefore, it is necessary to create a reliable insulating layer in the path of the ascending warm flow. Its recommended thickness is 30-35 cm.
At the same time, the upward flow of air removes not only moisture, but also water vapor from living spaces. If you do not block the way for moisture, the wet insulation will cease to perform its functions and will turn into an ideal place for the development of bacteria and mold fungi. To block the path of water vapor, a layer of membrane material is laid under the insulation, permeable to gases, but retaining water.
Another problem when creating thermal insulation for a cold attic is the almost inevitable condensation of water on the underside of the roofing material in the evening. After sunset, the temperature outside drops quickly, so the roof cools down in just an hour. The air in the attic space remains warm much longer. In this case, dew will inevitably fall. To prevent falling drops from soaking the insulation, the roof is lined with a layer of waterproofing underneath.
The appearance of condensation on the insulation is unlikely. If the “pie” is designed correctly, its bottom side will be warm and the top side will be cold. The air in the attic is renewed through the ventilation holes, and moisture does not accumulate in the insulation layer. Thus, the insulation of the floor provides reliable protection against heat loss, and the layers of waterproofing do not allow water vapor to accumulate in the attic.
Having understood the basic principles of thermal protection of the attic space, we will consider in detail all the components of a properly equipped cold roof to find out what pitfalls may be encountered during construction. To find out how best to insulate a ceiling under a cold roof, read this article.
Rafter system: how to correctly calculate the number of legs
The main task of the rafters is to become a reliable support for the roof. The rafter legs must confidently support the weight roofing material and additional load created by wind and snow masses. While the weight of the roof is easy to calculate based on the properties of the selected material, the snow load is individual for each region. You can obtain data on average and peak loads from the regional meteorological service.
Since the roof will not be insulated, when calculating the distance between the elements of the rafter system, the width of the insulation layers is not taken into account. There are many frame options for cold roofs. The most common solutions fit into the following parameters:
- The lumber used is a board with a width of 10 to 20 cm and a thickness of 5-7 cm.
- The pitch between the rafter legs is from 0.6 to 1.2 m.
- The counter-lattice is made of boards 3-4 cm thick.
Online calculators will help you calculate each roof frame element that is optimal for the planned roof load. Such services (for example, kalk.pro) allow you to determine the geometric dimensions of each element, build a three-dimensional model and print drawings.
When creating a rafter system, it is extremely important to ensure that the outer surface of all rafter legs is positioned strictly in the same plane. If the rafters are not level enough, problems cannot be avoided when creating sheathing and roofing. In order to perfectly align all the elements, the outer rafters are rigidly secured with spacers, and a cord is pulled between them. To find out how to properly install a gable roof rafter system with your own hands, read.
Roof waterproofing: is it worth doing?
Insufficiently experienced builders often question the fundamental necessity of constructing a waterproofing layer on a cold roof. An example is given as an argument village houses old buildings that have stood for decades without needing roof repairs, despite the lack of moisture-proof layers.
However, this argument does not apply to modern construction. The fact is that there are a whole range of significant differences in old and modern construction technologies:
- Old construction technologies involved the use of absorbent insulation. In different regions, mixtures of clay and sawdust, various industrial slags and other porous materials were used. Thick layer The backfill served as insulation and at the same time perfectly absorbed condensation. Modern insulation materials are hydrophobic, so water will flow into the ceiling, and this will not end well.
- In the old days, gables and roof overhangs were covered with boards without much effort, leaving many gaps. This roof structure was perfectly ventilated, so any leaks and condensation dried out quickly. Modern materials much less permeable to air.
- Modern complex architectural forms of roofs make ventilation significantly more difficult compared to the simplest gable roofs.
- Roof village house almost never got off from below. This made it easier to inspect and find damage. In addition, the attic was almost always used for storing various things. This means that any leak was detected (and corrected) very quickly. Modern house it is built in such a way that there is no need to visit the attic, and it is much more difficult to detect a leak.
All these changes in construction technology have made roof waterproofing not an empty precaution, but a completely necessary element. Modern waterproofing films (for example, Yutafol D110, Yutakon, Izospan D) are cheap, easy to install and allow you to get rid of condensation forever.
Layers insulating film laid across the rafters. Each new layer is laid higher than the previous one. To prevent moisture from seeping between the strips, the installation is done with an overlap (the new sheet is layered on top of the previous strip by 6-8 cm).
After the entire roof slope is covered, the hydraulic barrier sheet is secured using a counter-lattice. She will firmly press waterproofing film to the rafters and will create an additional gap between the roofing and the waterproofing. The gap will facilitate the evaporation of condensate.
Installation of sheathing
Lathing across the rafters is done in two ways. Lathing made of solid sheets (OSB or moisture resistant plywood) is done if it is planned to use soft tiles or corrugated sheets for the roofing. Under the impact of raindrops, these materials make a lot of noise. Solid sheathing will reduce noise. In addition, it is easier to attach roofing decking to a continuous sheathing.
Lay the sheets from the front gable to the rear. Then all the additions will be located in that part of the roof that is least noticeable. With temperature changes, plywood (like OSB) will expand and contract, so leave a gap of 1-1.5 cm between the sheets. When installation is completed, the gaps are filled roofing sealant to block the water's path.
In order not to doubt the reliability of the sheathing, use OSB with a thickness of at least 1.2 cm, and plywood - at least 0.8 cm. These parameters are optimal for a rafter pitch of 0.6 m. As the pitch increases, the thickness of the sheets continuous sheathing increase proportionally.
The second method of constructing sheathing involves the use of boards. In this case, both edged and unedged varieties are suitable, the main thing is that the thickness of the boards is the same. The boards are nailed to the rafters using regular nails. It is better not to use screws or self-tapping screws for this work.
Before installation, the boards are sorted by width. The widest lumber is placed along the slope so that it hits the joint between the sheets of roofing material. Narrower boards are allowed between the main elements. The pitch between the boards is selected based on the recommendations of the roofing material manufacturer.
Attic ventilation
There are two requirements for ventilation of the attic space:
- Sufficient vent area. So, if the roof area is less than 300 sq. um, that's enough front door into the attic and one window on the opposite gable. If the roof area is large, additional vents are made in the upper part of the slope.
- Possibility of air flow control. In the summer heat, the ventilation holes are opened as wide as possible; in the winter frost, they are closed to prevent the attic from freezing out.
Total area ventilation holes determined based on the area of the attic. 1 sq.m. vents will provide reliable ventilation of an attic of 500 sq.m. In this case, heat loss will not be any noticeable. The minimum acceptable ratio is 1 to 300.
To make it easier for you to imagine all the stages of work, watch the proposed video materials. They contain advice from experienced builders who will help you avoid mistakes in selecting materials and arranging a roof with a cold attic:
To ensure that the roof does not require repairs, and the house is warm in any weather, the construction of a cold roof must be approached as responsibly as possible. If each stage of construction is carried out in strict accordance with technology requirements, the roof will last for decades without requiring repairs.
Today, more and more developers are asking this question. The fact is that a cold roofing system allows you to erect a residential building for relatively little money, while an insulated roof requires enormous costs, both in financially, so in terms of effort and time. Having realized that such a system is in some sense better, many developers asked themselves the question: is a vapor barrier needed under a cold roof?
Cold roof design in a residential building
Many developers who want to save some money on construction strive to purchase the cheapest materials, but at the same time, so that the quality of the entire building does not suffer much from this.
This is possible if you use primitive two slopes as a rafter system, corrugated sheets as a covering, and make the roof cold. The design features of such a roof can be listed on one’s fingers, since there is no need to lay thermal insulation material , vapor barrier layer and other components often found on insulated roofs. If you all doubt the savings, then it is safe to say that cold version
the cost will be 50-60% less than an insulated structure. In addition, the work can be carried out independently, therefore, the savings will increase even more.
- The cold roof pie, in most cases, includes the following products:
- Rafter legs
- Waterproofing material
- Counter-lattice
- Lathing Profiled
a metal sheet
Is waterproofing necessary for metal tiles on a cold roof? It is worth noting that everything metal surfaces 
have one similar feature, they collect condensate. The waterproofing included in the roofing pie with a cold roof will correct this problem and protect the room from incoming moisture both from the outside and from the inside. Many developers, when constructing an insulated roof, advise their friends not to lay a vapor barrier layer if they build a building with a cold type of roof. They think that the cold will remove the condensation that is visible on metal products, but they are very mistaken. Naturally, when the attic is not heated and is not insulated in any way, the difference will be small, but still it is sufficient to provoke the release of moisture from the air. As you can see, condensation will form regardless of the type of roof, therefore, the question posed at the beginning of the paragraph can be answered unequivocally: yes, it is necessary.
An example is outbuildings whose owners do not care much about their service life. In such buildings, the roofing pie is the most primitive and even violates building codes and rules. Most often, a roofing pie consists of rafters, sheathing and roofing. All layers of vapor barrier and waterproofing were simply thrown away. Despite this fact, this building can stand for a significantly long period, or, conversely, it can collapse in just a couple of years. It depends on your luck, but why take risks if you can do everything in a high-quality manner?
You cannot afford to take risks on residential buildings, as someone’s life may depend on it. I am not exaggerating, because if condensation affects the rafter system and other roof elements long time, then he will simply destroy them, which can lead to the fall of the entire roofing pie.
IMPORTANT: If at the beginning of construction you decide to build a cold roof, but later after a certain period you will insulate it, then it is most advisable to lay micro-perforated film as a waterproofing product. Its properties are practically no different, but the price tag is much lower than membranes.
Waterproofing and ventilation of cold roofs
If you are laying a micro-perforated product, then such a layer will block the access of moisture from the outside, but at the same time water vapor can pass through this area without problems. It can be said that laying vapor barrier products on roof slopes in this case is optional. After steam penetrates inside, it ends up between the waterproofing material and the metal coating, from where it is removed by natural ventilation. 
IMPORTANT: When a dense waterproofing film that retains water vapor is used, this leads to a significant increase in air humidity and, as a rule, dampness in the room.
At high humidity air, condensation processes begin, so moisture accumulates on the back side of the film and penetrates all roofing materials. Due to this fact, for the construction of a cold roof it is not recommended to use materials such as polyethylene and polypropylene, roofing felt, and glassine.
The ventilation system for cold roofs is quite simple. To create it, gaps are left, which, as a rule, are located along eaves overhang. Air masses pass through them, collect all the humidified air and remove it through the cold triangle located in the ridge part of the roof.
The counter grille is a design to provide additional ventilation. Most often it can be found on difficult roofing systems, where products with a high degree of waterproofing are used as a coating, for example, metal, bitumen shingles and others. The gap that is created by installing counter battens allows fresh air dry the roofing pie on both sides, so structures with such a pie last much longer than others.
Cold roof. Is waterproofing necessary on outbuildings?
First of all, it is worth noting that outbuildings differ significantly from residential buildings both in their structure and volume. The vast majority of developers are trying to save money on the construction of secondary structures, so the issue of waterproofing is more relevant than ever. Before answering the question, let's look at the coating. Today, corrugated sheeting is one of the cheapest materials, so I will talk about buildings covered with it.
Manufacturers different countries strive to produce such products so that the whole world can use them. If you are a fan of corrugated sheets, then today such material is a sheet of metal with an anti-condensation coating. 
In my own way appearance it is practically no different from its counterparts. A synthetic composition is applied on the inside, it resembles felt. Due to the large number of pores, this material is able to retain square meter up to 1 liter of water. After the surface has been saturated with moisture, ventilation comes into play and if it is carried out according to all the rules and regulations, the drying process will not take much time.
Thanks to the installation of such a “tricky” coating, the need to lay a vapor barrier and waterproofing layer is eliminated, but it should be understood that the weight of such a coating will vary depending on weather conditions. Committing necessary calculations It is very important to take these parameters into account and use them in calculations. It is worth noting that finished roof it will be much cheaper, because it will not contain almost half a roofing pie.
Installation of waterproofing for cold roofs
So, based on the information obtained above, you understand that waterproofing material is installed regardless of the type of roof and the functional purpose of the building. However, if you want to save money, you can use roofing coverings with an anti-condensation layer, but not all people like metal coatings, so I’ll tell you now general principle laying waterproofing.
- First of all, an inexperienced roofer must repeat safety precautions and the principle of working at height. After this, he dresses in special uniform, which should include the following: means personal protection, good shoes with non-slip sole and mounting belt.
- After rafter legs secured in place, you can begin laying the vapor barrier layer. It is attached to the rafters using a construction stapler and pressed against the sheathing. With a small slope, strips of material are placed across the slope, and along highly inclined slopes. To improve the quality of laying this layer, the joints are coated with bitumen or taped with double tape.
IMPORTANT: Before installing the sheathing, it is very important to treat its elements with special protective solutions, which will increase the degree of ignition of the wood and protect it from rotting.
- Next, the counter-lattice is laid. It creates the necessary air gap, thanks to which moisture will be removed from the roofing pie.
- Waterproofing material is laid on top of the conro-lattice.
- After this, they begin to install the corrugated sheets.
Most developers strive to cover as much length as possible with one strip of corrugated sheet. This is justified by the fact that in this way fewer joints are obtained, therefore, the waterproofing qualities of the entire roof are significantly increased. You can do all the work yourself, but to increase efficiency it is better to invite 1-2 partners.
The Internet and all kinds of thematic printed publications are full of advertisements for the construction of a turnkey dacha. As a rule, the proposal indicates the construction of a roof with a “roofing pie” and describes the advantages of some kind of insulation. But a natural question arises: is it always necessary to insulate the roof?
Is there any point in insulating an outbuilding, say, a barn, or in the costs of insulation? non-residential attic? Maybe, after all, it’s enough to limit ourselves to insulating the floors last floor under the attic? But the consumption in the latter case will be significantly less, since the treated area is significantly smaller than the roof area.
Obviously, for some types of buildings there is absolutely no need for roof insulation.
In what cases is it better to have a cold roof, and how to arrange it in the best way?
Cold roofing is usually constructed for two reasons:
- when a warm roof is simply not needed or
- for reasons of economy.
Construction specialists consider insulation baseless attic space, if the house under construction does not have an attic. This can equally be applied to outbuildings.
It should be noted that the installation of a cold roof , does not mean at all that there is no need for ventilation of the under-roof space - it must be present in any house or building. This can be accomplished by arranging double roof or using dormer windows.
Cold roof design
The cold roof has a fairly simple design.
On inner surface metal roofing quite often condensation occurs, which negatively affects the attic space. To protect against it, it is enough to lay a film or waterproofing membrane on the rafters
- first nail the counter-lattice on top,
- then the crate,
- then the roof covering is installed directly.
Water vapor is removed from the under-roof space through special ventilation outlets under the ridge and on the slopes. As for the attic space, it is additionally ventilated through the existing dormer windows.
Thanks to the simplicity of the design, the process of designing, installing and operating a cold roof is greatly simplified.
Choosing a material for a cold roof
The design of a cold roof and the materials used have some features. For example, you need to choose carefully waterproofing materials. Usually for cold roofing they use micro-perforated roofing, which, by the way, is quite affordable. It is mounted with a sag of 20 mm, which allows water, which due to capillary effect seeps through the film, flows freely to the middle of the run and does not wet the rafters. To allow air to escape unhindered, a gap is made in the waterproofing under the ridge.
However, it is impossible to mount insulation closely to such a film. The fact is that when it comes into contact with the insulation, the film loses its insulating properties and the insulation actually gets wet. So, if you plan to equip an attic in the future, it is better to use a waterproofing membrane.
When installing a cold roof, you can use everything as a covering traditional materials, which do not require a solid base. However optimal solution, according to experts, is a profiled sheet or metal tile, which are technologically advanced, durable and reliable roofing materials.
Steel profiled sheet
The most simple solution Cold roofing in the case of non-residential buildings is the use of profiled steel sheets equipped with an anti-condensation coating. This material, which has the structure of synthetic felt, is applied to reverse side profiled sheet directly during the manufacturing process.
Between the interwoven fibers of synthetic felt there are many tiny air cavities, due to which the coating accumulates and retains a certain amount of moisture (up to 1 l/sq.m.). As the air temperature rises, it begins to evaporate intensely. In this case, there is virtually no need to install a counter-lattice or lay a waterproofing film.
Installation of a roof made of profiled sheets with an anti-condensation coating is carried out similarly to the installation of conventional corrugated sheets. For installation work no specialized tools or additional devices are needed. When using this material, a 30% cost savings is achieved according to the estimate.
The anti-condensation coating reduces the noise of wind, hail and rain, prevents the formation of mold and mildew, and is easily cleaned under pressure using water to remove contaminants.
All roofs for houses can be divided according to configuration into: flat, pitched. Flat, have a flat roof with an inclination angle of 3-5 degrees. These days they are used extremely rarely, since water stagnation often occurs in them. This type of roof installation is suitable exclusively for outbuildings, as well as for small baths.
In turn, pitched roofs are used much more often. They, in turn, are divided into:
- (pincer);
- semi-hip gable;
- semi-hip hipped;
- multi-pincer (multifaceted).
The most popular among the above are single- and gable roofs, which are often also called “cold” and “warm” due to the design of the rafter system and roofing pie.
Cold roof construction technology
It can only be used in cases where the room has the necessary thermal insulation, including from the ceiling adjacent to the attic, or if a small room is being built.
The main difference between a “cold” roof is that it is installed directly against the wall of the house. That is, the main load will not go to the rafters, but to the room. The beams will directly support the roof, so their thickness can be selected from 5 centimeters or more.
The rafters are supported on the mauerlat. Purlins, struts, racks and beams, in most cases, are not equipped, since even ordinary crossbars are quite enough to reliably hold the shape of the roof and prevent it from beveled later during operation (due to wind and rain). The ridge purlin rests directly on the rafter legs.
Roofing pie for a “cold” roof it consists of one level of sheathing, an external roof (which can be tiles, slate), vapor and waterproofing. There is no insulation layer provided, since the attic of a cold roof is not intended for use as a living space.
However, thanks correctly established system ventilation, the temperature inside the roof attic is 5-10 degrees higher than environment. Thermal insulation is attached to the floor of the attic, which protects inner space living part of the house from cold air. This is also where ventilation pipes, fits vapor barrier membrane, which protects the house from condensation.
The design of a cold roof is simple, so it is suitable for construction summer kitchens, closed gazebos, construction modular block containers(which are initially insulated).
For more information on installing a cold roof under metal tiles, watch the video.
Arrangement of a warm roof rafter system
Rafter system for warm roofs somewhat more complicated, since it involves using the attic as a living space. Most the best option for this type of roof - attic system, which allows you to get a fairly large amount of free space. The structure of the roofing pie in this case looks like this:
- roof;
- sheathing and counter-lattice;
- steam and waterproofing;
- thermal insulation (mineral wool or polystyrene foam board);
- decorative layer ( interior decoration).
The main difference between the design of the rafter system is that it is supported by supporting
beams, as well as mauerlat. Additionally, the roof is divided into purlins and struts (for gable systems). The angle of inclination of such roofs, as a rule, is divided into two parts: at first it is about 120 degrees, then (after the last support beam) - about 35.
Enough known technology roof arrangement is a system with layered rafters. But today it is rarely used because it requires a large amount wood materials, although it does not make it possible to arrange a full-fledged living space in the attic.
The undeniable advantages of this technology include: high-quality load distribution, adjustable roof height (the angle can easily be changed during construction). But still, roof structures with hanging rafters are much more often used.
also in rafter systems warm roofs are equipped with a so-called “wind beam”, which is responsible for the stability of the roof. The side rafter legs, as a rule, are lengthened due to wooden “fillies”, to which it is convenient to subsequently install drainage systems.
Installation of the central beam is carried out in cases where the running length of the roof is more than 7 meters. If the length is shorter, the decision should be made depending on the load on the ridge span. If it is too high, it will lead to penetration into interior space the attic additional moisture, condensation, which, of course, must be avoided.
Sheathing and reinforcement strips
Counter-lattice is an additional layer of thin rafters that are used in warm roofs for installing internal thermal insulation. This type of lathing can also be attached directly to retaining strips if they are provided for in the overall design.
Installation of reinforcement strips begins with the installation of the upper retaining beam. A mauerlat is laid along the perimeter of the roof, which is tightened with ties (the beams are laid directly on the roof and secured with solid staples or studs). The fastening of the retaining strips to the main beams is carried out through metal corners(tightened with 4-6 screws).
Roof insulation and waterproofing
As waterproofing for warm roofs, mineral wool reinforcing mesh or simple polyethylene film. In some cases, it is recommended to install it in two layers: above the thermal insulation and below the thermal insulation. It should be borne in mind that this option is only possible in cases where a basalt mat that is resistant to moisture is used as insulation.
It is important to note one more point: waterproofing will reliably protect the roof from condensation only if it is laid between the sheathing and the counter-lattice. At the same time, it is most convenient and reliable to install the heat-insulating layer directly on internal bars(laying mats vertically between them). But it is also possible in two layers, while the inner layer must be installed horizontally (depending on how the counter-lattice was installed).
In most cases, installation of sound insulation is not necessary, but if you decide to use it, then it is recommended to lay a layer behind the insulation before interior finishing (plasterboard).
Roof ventilation system
The roof ventilation system can be configured in two ways. The first one is suitable if you do not intend to use the attic for living. The most rational way to arrange a traditional natural ventilation through the side slopes. But keep in mind that if there is a warm chimney passing through the attic, cold air will accumulate in the lower part of the room. If it is simply removed through the attic internal ventilation, cold air, as well as condensation, will form directly under the roof.
Warm roof systems typically include artificial ventilation premises. Its performance is calculated based on the volume of the attic divided by 3 or 4. This system is necessary in any case, since an anti-condensation membrane is additionally installed in such roofs. And it significantly worsens the air exchange between the external and internal environment.
Instructions for laying metal tiles
Starts with installation cornice strip, lower valley, as well as adjacent panels. Then the sheets of metal tiles themselves are laid along the rafters, which are attached to the wood base using self-tapping screws (roofing fasteners are used) and ends with the installation of the ridge element, upper valley and end strip.
For more information about editing and its main mistakes, watch the video.
The cost of installing metal tiles depends on the complexity of the work (the height of the roof, the angles of inclination) and whether it is insulated or not. On average in Moscow, the price for installation will cost 400-450 rubles per sq.m., if insulation is necessary, then the cost increases by 70 rubles per sq.m. for each layer (50 mm.). Often, in addition to installation, dismantling is necessary old roof, and this is an addition to the cost of about 100 rubles. per sq.m.
Completion of roofing work
Work on arranging the roof and roofing ends with removing the roof from unnecessary elements: sticks, tools, sawdust, shavings, etc. It is necessary to paint the metal tiles in the areas where trimming and cutting them with paint in the color of the roof - to prevent metal corrosion.
If the interior decoration of the attic is intended, it is most convenient to use plasterboard or plywood board. In order for the inner decorative layer to be absolutely smooth and even, it should be mounted on aluminum profiles(they are also attached to the counter-lattice using corners and straps). After this, you can begin installing gutters around the perimeter of the roof.
The installation of a cold attic in a building involves, as is known, the use of a lightweight version of the roof, which is also called “cold”. Characteristic feature Such roofs are characterized by the absence of a layer of insulation installed between the vapor barrier layer and the membrane waterproofing.
Note! This type of covering is usually made in cases where the attic space located underneath is not residential and is used only as an auxiliary room.
Thus, the implementation of a cold attic project comes down, as a rule, to arranging the roof, which should include the following elements:
- roofing material of the type you have chosen;
- protective waterproofing layer;
- main sheathing;
- counter-lattice.
The presence of an additional sheathing with a layer of waterproofing attached to it entails the formation of free spaces used as ventilation ducts, protecting structural elements from condensation.
From a purely technical point of view, installation of roofing structures similar type simple enough. When organizing it, due attention must be paid to the choice of roofing material that ensures the required tightness of the surface and eliminates the possibility of moisture penetration into wooden structures.
Metal roofing
Preparing a “cold” roof for metal tiles is the simplest and most convenient option its arrangement, which results in a kind of cake made from roofing material, a layer of waterproofing and wooden sheathing.
Preparing such a roof is not particularly difficult and includes the following simple operations:
- First of all to rafters Using small nails or a construction stapler, the waterproofing film is hemmed.
- Then this film is covered with counter-lattice boards, which are mounted on the rafters using wood screws (the selected installation step depends on the size of the metal tile sheet).
- IN in some cases To prepare the surface of the counter-lattice, a continuous coating made of sheets of moisture-resistant plywood is used.
As a waterproofing layer, a special PVC membrane or a regular polyethylene film can be used, attached at its location with a slight sag (from 15 to 25 mm). Such sagging creates conditions for ventilation of the waterproofing layer and removal of condensate formed on it towards the eaves strip (gutter).
You should draw your attention to a number of conditions that must be taken into account when installing a cold roof. Firstly, the counter-lattice boards must be installed parallel to the rafters used as the base of the entire structure, thereby providing additional fastening for the waterproofing attached to it.
Secondly, the sheathing of such a roof should be made of wooden beam with a cross section of 50×50 mm, installed in increments of 35–45 cm along its slopes. In this case, the choice of step size (as well as the material for the sheathing) depends on the type of metal tile you use, as well as on the angle of inclination of the blood.
When installing a cold attic under the tiles, you should understand that a thin metal sheet and a layer of waterproofing will not provide you with proper sound insulation. At the same time, the noise level in the under-roof space (during heavy rain, for example), due to the absence of a layer of insulation, can significantly exceed the value normalized in SNiP.
Some subtleties of roof installation
Experienced experts advise paying attention to the following circumstances when arranging a cold attic:
- If you plan to insulate your attic space in the future, you must approach the choice of a moisture-proof membrane with full responsibility. The most the best option in this case, it is possible to use a waterproofing layer in the form of a PVC membrane.
- If roof insulation is not expected in the near future, it is best to use micro-perforated waterproofing film, designed specifically for cold roofs.
The fact is that when using such a film, its contact with insulation materials is unacceptable, therefore, in the case of insulation, you will have to first dismantle it and only after that lay new waterproofing. If this condition is not met, the required reliability of structural protection is not guaranteed by the manufacturer, and the insulation placed in the “pie” will be exposed to moisture.
Among the materials present on the Russian market, most often used for arranging cold roofs, the following items can be distinguished:
- superdiffusion membrane of the TechnoNIKOL brand;
- polymer coatings under the names “Pural” and “Prisma”;
- metal tiles of the Supermonterrey brand.
The product under the name "Technonikol" is a film membrane consisting of 2 layers of non-woven polypropylene and a layer of polypropylene film and providing the possibility of one-way vapor diffusion.
Polymer coating “Pural” is a material membrane type, made on the basis of polyurethane and having excellent anti-corrosion properties. In addition, it is resistant to mechanical stress and can be used in a wide temperature range.
The product called “Prisma” (UK) is a metallized film coating consisting of 95% zinc and only 5% aluminum. Adding aluminum to the material increases its protection from corrosive and mechanical influences.
Multi-colored tile covering "Supermonterrey" is made in the form of metal sheet blanks standard size, having a thickness of about 0.5 millimeters.
Video
This video provides an overview of cold roofing materials:
