Roofing pie of a flexible tile.
roofing cake- so often called all the constituent materials and components included in the roof structure.
On this page we will talk about the design, types and device roofing cake for roofs with a covering from a flexible tile.
What is a roofing cake for a soft roof.
Roofing cake for a soft roof roof is of two types:
- For insulated (warm) roofs.
- Roofing cake for a cold roof.
The warm roof pie for bitumen includes a heater and the accompanying materials necessary for it. Also, depending on the installation of insulation, certain components can be added. A mandatory attribute of an insulated roof is a ventilation channel that provides ventilation of the under-roof space.
A standard warm roof pie with a soft roof looks like this:
Compound pie in execution order installation work:
- Rafter legs (rafter system)
- Vapor barrier
- Rough crate
- insulation
- Hydrobarrier or SDM membrane
- Counter beam (counter rail) to provide a ventilation gap on the roof
- crate
- Lining carpet
- bituminous tiles
- Interior decoration (indicated in the picture, but is not a roofing cake, as it refers to finishing work, not roofing).
It should be noted that this cake and the sequence of work is indicated for performing insulation work " above". That is, after installing the rafters, a vapor barrier and a rough crate are mounted, which will hold the insulation and prevent it from "waking up" forming cracks.
When insulating the roof from below"the sequence of work on the device of the cake is modified and such material as polypropylene twine is added, designed to hold the insulation before the installation of the vapor barrier and the rough crate.
The sequence of work on the construction of a pie with insulation from below is carried out in the following order:
- rafters
- Hydro barrier or SDM membrane
- counter beam
- crate
- Lining carpet
- bituminous tiles
- Insulation + polypropylene twine
- Vapor barrier
- Rough crate
Cold bridge scheme:
Also, in some cases, when the roof is insulated from below, a beam is added across the rafters (cold bridge). This is done for various reasons. Most often, these are cases when it is necessary to grow the thickness under the insulation to the required parameters. So, for example, when the rafter legs have a height of 150 mm, and the insulation needs to be done with a layer of 200 mm, a timber of 50 × 50 mm in size is grown from below. The growing beam itself is performed across the rafter legs with a step corresponding to the width of the insulation (usually 60 cm). This arrangement of the beam across allows you to increase the efficiency and reliability of roof insulation. It turns out that this roof pie differs from the previous one by the presence of this beam.
Many of those who have not closely encountered the construction of a private house believe that the roof is just a roofing. But in reality, the roof is a system consisting of a large number of technical elements and several functional layers. Depending on the type of roof (from single-pitched to multi-gable), its design has a certain degree of complexity.
The totality of all layers of the roof is also called the roofing "pie". Just as any cake has its own recipe for preparation and arrangement of layers, so the roof structure has its own “recipe”.
Typically, the composition of the "pie" of the roof includes the following layers (starting from the bottom):
- interior decoration,
- vapor barrier,
- insulation,
- ventilation gap (there are systems where two gaps are arranged),
- waterproofing (roofing film),
- roofing material.
Roofing cake recipe
A well-executed roof structure will serve as a guarantee that in winter period an ice barrier will not be created on the roof overhangs and a process such as "water return" will take place. The thermal insulation characteristics of such a roof will fully comply with modern building codes.
In the summer period of the year, the roofing system will operate in self-cooling mode, since inside the under-roofing gaps there will be movement of air masses directed from bottom to top. Together with the air flow, the heat that comes from the sun heated will also go away. roofing material. In the same way, moisture that may be in the insulation will also be removed.
Thanks to the exact observance of the recipe of the roofing "pie", you will be able to provide the load-bearing elements of the roof structure with durability. At the same time, correctly grouped layers can provide additional comfort and savings in thermal energy in your country house.
The technology of the device roofing "pie"
To date, several technically justified methods for constructing a high-quality roof have been developed. Below we will look at the two most popular methods.
In private housing construction, it is customary to arrange one of two types of attic: cold or exploited. In accordance with the chosen design of the attic, the design of the roof is also selected. If the attic is planned to be made cold, then only the ceiling is insulated. At the same time, the attic space itself is ventilated, so that moisture can freely and freely exit the heat insulator.
In the case when in the upper tier country house it is planned to arrange a residential attic, insulate the roof itself. And it is in this case that a multi-layer roofing “pie” is created (in this case, the roofing material and the insulation are elements of the same design).
It is extremely important here to strictly observe the order of all layers, since each of them has its own individual function. The slightest violation of the sequence can reduce to zero the thermal insulation characteristics of the roof, which in this case acts as the building envelope. In addition, if the layers of the “pie” are not properly arranged, the load-bearing elements of the roof will fail prematurely.
Stages of work
First, on top of the completed counter-lattice (there are options when the counter-lattice is stuffed from above), sheets of waterproofing material are spread. The canvases must be unfolded in a horizontal direction so that an overlap of about 10 cm is formed.
In this case, the waterproofing film cannot be stretched, but on the contrary, it must be laid with a slightly noticeable sag (in case of temperature fluctuations). The joints of the waterproofing sheets must be sealed.
Then mineral wool fills the space between the rafters. It is necessary to ensure that the insulation plates fit quite tightly, without the formation of voids and gaps. From the side of the premises, the insulation is sewn up with a layer of vapor barrier material - this will protect the structure from the penetration of water vapor from the premises into the insulation.
During the installation of the roofing "pie", it is extremely important to observe the ventilation gaps. The best option is the presence of two such gaps:
- the first - between waterproofing and roofing material,
- the second - between the insulation and waterproofing.
The height of the ventilation gaps must be at least 50mm. The upper gap is created by the lathing bars, the cross section of which is 40 mm x 50 mm (these bars serve as the basis for mounting the roofing material).
Lower gap - it is simply left when laying a layer of thermal insulation. That is, the thermal insulation is positioned so that to the lowest point of sagging waterproofing material there was still about 50mm left.
What should be paid special attention to?
When constructing a roofing "pie" Special attention should be given to such difficult areas as:
- ventilation outlets,
- stone and chimneys,
- roof windows.
It is these areas that usually cause depressurization and heat leakage. The reason for this is incorrect installation work.
Incomplete understanding of the processes of functioning of all technological layers of the roof structure often leads to serious errors, and, as a result, to various troubles. For example, the situation with the vapor barrier.
Not all vapor barrier films have the necessary throughput. The cheapest of them can pass only 30 mg/m 2, while a high-quality analogue can output about 1200 mg/m 2.
During the heating season, cheap vapor barrier may simply not be able to cope with its direct duty. As a result of this, both the insulation and the interior finish will suffer.
Some nuances
There are no trifles when installing a roof. If it says that waterproofing should be laid horizontally, then do it. At the same time, be sure to overlap at least 10 cm - otherwise the waterproofing will not be reliable. In addition, it is not allowed to fix the waterproofing film with nails - you can only use a construction stapler.
The lower edge of the film should be brought into the gutter of the building's drainage system, outside the cornice box. In turn, the edges of the vapor barrier material are brought out to the walls. When using diffusion or superdiffusion films, it is also important which side they face the insulation layer. If the sides are mixed up, the film will have the same effect as ordinary polyethylene.
It is necessary to mount the waterproofing film very carefully:
- wrinkling should not be allowed - they will retain water;
- it is also impossible for the film to touch the insulation in any place.
If we talk about insulation, then it should be laid in two layers and always with offset joints. When using rolled insulation, experts recommend additionally fixing them every meter and a half with boards.
Well, now it only remains to lay the roofing material and that's it - the roofing "pie" of your country house. Follow all the recommendations according to the recipe, and the "pie" will succeed.
Video. Organization of a roofing pie - vapor barrier, insulation, roof waterproofing
Video. ATTIC INSULATION. ROOF PIE
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A modern roofing cake should retain heat in the winter, and also contribute to its flow in the summer. Water vapor from the room must not penetrate inside the roof structure. An important function of the pie is the removal of water vapor from the room, which sometimes seep into.
The composition of the roofing cake should include several layers. In this case, the sequence of elements is as follows:
- interior decoration;
- vapor barrier layer;
- thermal insulation material;
- moisture insulation;
- gaps for ventilation;
- surface anti-icing system;
- roofing material.
Roofing pie device: vapor barrier insulation
The vapor barrier layer prevents water vapor from entering the thermal insulation layers from the room. When constructing a roofing pie, this layer is first of all arranged. Usually the layers are counted from inside the room. The vapor barrier film is laid by overlapping. Then, it is fastened with a special connecting tape. This tape ensures the tightness of the vapor barrier layer.
Modified materials will include a layer of aluminum foil. With its help, the fire resistance and thermal insulation characteristics of the roofing cake are increased. But do not forget that there must be an air gap between the film and the insulation layer. Note that due to its thickness of 2 cm, installation work will become more complicated, and the design will require significant financial costs.
Roofing pie device: thermal insulation layer
An important quality of roof insulation is vapor permeability. In other words, the material must freely pass water vapor. Those, in turn, penetrate the vapor barrier. As a rule, such characteristics are inherent in materials from mineral wool. It is very important that mineral wool boards do not deform over time. The type of construction affects the insulation. So, it is possible to insulate the ceiling of the upper floor or the fencing of the structure (roof).
Note that the insulation does not have heating properties. It simply contributes to the retention of air in its fibers. This layer acts as thermal insulation.
When moisture gets on the thermal insulation layer, the material immediately loses its properties. This is due to the fact that he is forced to retain water in himself. And if we take into account that the coefficient of thermal conductivity of water is 20 times higher than the thermal conductivity of air, then thermal insulation becomes unusable.
Tip: A roof pie should always have dry insulation.
Thanks to moisture impregnations for mineral and fiberglass boards, water and vapor barriers are protected. But do not forget that any thermal insulation is capable, one way or another, to absorb water. Extruded polystyrene foam - resists diffusion and capillary water absorption. However, its cost can scare away thrifty buyers. The material is more expensive than mineral wool and fiberglass.
The technology of laying roofing insulation involves installation work. At the same time, they should be carried out after reducing the moisture content of the wood to at least 18%. If this is not taken into account, then moisture from the tree will penetrate into the insulation. This is fraught with big troubles, because the waterproofing layer does not allow moisture to leave the roofing pie.
Ventilation and anti-icing device
The advantage of a ventilated roof is the separation of insulation and roofing material.
In the roofing pie ventilation device, certain steps must be followed:
- When using a corrugated sheet, it is very convenient to equip the ventilation holes and the ridge fan. You can even cover a wavy sheet with a flat ridge.
- Passive ventilation is not the last element. Today you can find equipment that provides forced circulation air flow in the under-roof space.
- Cornice boxes and ventilation outlets are arranged next to the ridge. Note that any set of materials for a soft roof has a ventilated ridge.
- The lower eaves must have special holes. These roof elements are protected from the penetration of small birds or insects. Next, the installation of ventilated skates.
- In the absence of the aforementioned possibility, ventilated gaps above and below are associated with the atmosphere. For this, special roof fans are used.
Roof icing is a serious problem for any owner of a country house. Therefore, very often the installation of a roofing cake includes anti-icing systems. It's kind of heating cables, temperature sensors and other equipment.
Stages of installation work of the system:
Roofing pie waterproofing device
Waterproofing material completely depends on the type of roofing material of a country house. During precipitation, moisture often penetrates into the attic. When using the attic as a non-residential premises with ventilation of the space under the roof, the moisture will evaporate very quickly.
But there is always a risk of damage to the wooden elements of the roof structure. It is worth noting that even if you carefully arrange the vapor barrier, elements of water vapor will still penetrate the insulation. Under these conditions, it is advisable to use a waterproofing layer that absorbs or transmits water vapor. When installing a waterproofing film, you need to know exactly the sides of the material. One of its sides should be directed to the insulation, the other - to the roofing material. Otherwise, the roofing cake will be executed with errors.
Thanks to the development of new types of modified bitumen and synthetic non-woven bases, soft roofs have acquired excellent performance, which has significantly expanded the scope of roofing materials. If earlier soft roofs were considered only the cheapest type of roofing, today it is not only cheap, but also a very high-quality, durable and beautiful material.
Soft coatings are mounted on various buildings and structures, they can be rolled or shingled. Most often used for residential buildings. Depending on whether the attic will be residential (mansard) or non-residential, is selected specific view roofing cake. Each type has its own characteristics, installation technology and design features.
Table. Types of roofing cake.
| Type of roofing cake | Brief description and specifications |
|---|---|
| The simplest and cheapest cake, used during the arrangement of cold roofs. Provides reliable waterproofing of the building, but does not retain heat. |
| It is used during the construction of attic rooms, requires strict adherence to the technologies recommended by manufacturers. A warm cake consists of several layers, each of which performs its tasks. The cost is several times higher than the price of a cold pie. |
The article will give step by step instructions for the manufacture of both types of pies for soft roofing.
Prices for various types and manufacturers of shingles
Warm roofing cake
A rather complex structure, during construction it is necessary to strictly comply with building codes / rules and recommendations of manufacturers of soft roofing materials. A warm roof allows you to turn a cold attic into a warm attic, increases the total living area at minimal cost.
But the violation of technology causes a significant decrease in the heat-shielding characteristics of a warm roof, the microclimate in the premises worsens, there are risks of leaks with all extremely negative consequences. In order for a warm roofing cake to provide the required performance indicators, all factors affecting the coating must be taken into account.
- Precipitation. The roof should not have leaks, the installation technology depends on the angle of inclination of the slopes. Another important point is that measures must be taken to prevent snow from blowing into the under-roof space.
- Dynamic loads. The roof is affected by permanent (weight of roofing materials) and temporary (mass of installers, snow and wind forces) loads. During the calculation of the truss system and the selection of coating materials, it is necessary to take into account the maximum values of the loads in the complex. Plus, a special design reliability coefficient is applied to these indicators.
The microclimate parameters in attic rooms should be stable and not depend on external conditions. A large temperature difference between indoors and outdoors leads to enhanced heat transfer and loss of thermal energy. To reduce them, an insulated roof with a complex roofing pie is mounted.
A warm cake is made up of several layers.
Vapor barrier
Installed from inside the room, serves to prevent moisture from mineral wool. Modern expensive membranes or ordinary polyethylene film can be used as a vapor barrier. If foam or expanded polystyrene is used as a heater, then it is not necessary to install a vapor barrier, these materials are not afraid of moisture, do not absorb water, do not increase thermal conductivity, depending on actual parameters relative humidity.
The difference in partial pressures of water vapor indoors and outdoors causes moisture to penetrate through the structures of the roofing pie. The vapor barrier must be made of materials with high strength and minimal vapor permeability., due to this, the risks of penetration of moist air into the insulation are minimized. If the vapor barrier is not made properly, then moisture condenses in the thickness of the wool. This is due to the fact that at low temperatures the maximum possible amount of water in the vapor state is much lower than at high temperatures. Condensation forms in the upper layer of wool, this is where the dew point is located. But in the future, under the influence of gravity, the water sinks down, due to this movement, the entire layer of mineral wool gradually gets wet. The accumulated moisture in the structure not only reduces thermal protection, but also causes decay processes.
Prices for different types of vapor barrier membranes
Vapor barrier membrane
insulation
Rolled or pressed mineral wool and polystyrene are used. Mineral wool has two advantages: it does not burn and does not emit harmful chemical compounds into the air. Disadvantages: high cost, high weight and negative reaction to increased humidity. To eliminate the shortcomings of mineral wool, additional materials and technologies must be used, which significantly increases the estimate for a warm roofing pie. Expanded polystyrene is much lighter and cheaper, no special construction measures are required to protect it from moisture and wind. Disadvantages: plastic burns and releases chemical compounds. But modern views expanded polystyrene almost got rid of these shortcomings and are allowed by sanitary organizations for use without significant restrictions.
The thickness of the heat insulator of the roofing cake is selected taking into account the climatic zone of the building. If it is less than the recommended standards, then the effect of thermal insulation is the opposite - instead of insulating the attic rooms, it is cooled. Why? Everything is very simple. Thin sheets of mineral wool quickly get wet and multiply the heat transfer coefficient. In addition, one should not forget about the negative impact of wet wool on wooden structures.
Another problem is insufficiently insulated roof. The warm air warms the snow on the roofing material. It is melting intensively, large icicles hang from the roof. Pay attention to their large number on old buildings, this is evidence of a very low thermal protection of buildings. The owners of such buildings buy expensive energy sources for street heating. Naturally, icicles pose a danger to passers-by. The recommended thickness of mineral wool in the Moscow region is at least 15 cm, keep this in mind.
Practical advice. For most rafter systems, there is no need to use 15 cm wide rafters, it is expensive and uneconomical. What to do if the thickness of the insulation exceeds the width of the rafters? It is necessary to lay the first layer of insulation to the width of the boards, then nail slats 4-5 cm thick across the rafters, the last five-centimeter layer of insulation will rest against these slats. By the way, at the same time it will protect the rafters from the cold and eliminate cold bridges.
Prices for thermal insulation materials
Thermal insulation materials
Wind protection
It is necessary in the case when mineral wool is used as a heater. The fact is that mineral wool is easily blown through, if it is not protected, then heat escapes into the atmosphere, the efficiency of insulation drops sharply. But there is another very important requirement for wind protection - it should not prevent the evaporation of moisture trapped in mineral wool. No matter how carefully the insulation is isolated, no one will give a 100% guarantee against breakthroughs or leaks, steam can enter the cotton wool and condense there.
Steam diffusion membrane - what is it for?
In addition to an increase in thermal conductivity, this phenomenon has an additional negative consequence- with prolonged contact of the wooden structures of the truss system with wet cotton wool, they are inevitably affected by rot and fungi. As a result, over time, the truss system loses its initial indicators of perversity, soft cover critically deformed and leaks. In the best case, you will have to do unscheduled repairs to the roof. At worst, completely change truss system and refurbish the interior.
Control grille
Needed to remove moisture evaporated from mineral wool due to natural ventilation. The cross section of the ventilated gap is selected so that the amount of fresh air inflow and humid air removal is the same. Otherwise, the importance can increase significantly and create conditions for steam condensation in the under-roof space.
To ensure the effectiveness of the functioning of the natural ventilation of the subroofing layer, it is necessary that the area of the ventilated gap is not less than 1/500 of the area of \u200b\u200bthe slope, but in any case, the distance between the control lathing and the coating must be at least three centimeters.
Solid crate
The most commonly used boards are OSB or plywood. It is recommended to take moisture-resistant plates, but we must not forget that all of them cannot withstand prolonged direct contact with water. They need to be further protected.
Purpose - additional insurance against leaks. In addition, the lining carpet serves as another protection for various engineering communications, chimneys and ventilation outlets from leaks. These places are considered the most dangerous, it is quite difficult to waterproof them only from the surface of a soft coating.
Prices for lining carpets
Carpet lining
Finishing decorative and waterproof coating. As can be seen from the list of layers, a warm cake is a complex and expensive roof construction. In addition, any deviations from the technology can cause not only a sharp deterioration in heat saving indicators, but also overhaul roofs.
Practical advice. If you don't have any practical production experience construction works then seek professional help. Trying to do everything yourself can cost a lot more than paying experienced builders for a job well done.
The service life of the whole house, and the comfortable atmosphere in it, depend on how well the roof is made. Heat loss through the roof can make the room too cold, and insufficient waterproofing will inevitably lead to
leaks. So each layer of coating in the so-called roofing cake has its own meaning.
What are the roofs?
Depending on what is determined and the materials necessary for its decoration. There are two main types of roofs: flat and more suitable for structures in temperate climates, as they can more easily tolerate large amounts of rainfall. Flat roofs are more suitable for service or technical premises, sometimes they are made as an exploited area, placing terraces or a winter garden there. Accordingly, the roofing cake is also changing. Not all materials are suitable for finishing, not everyone is suitable for creating a roof terrace. In addition, the role and purpose of the premises under the roof plays a role. If this is a technical room or a cold attic, work on insulation and insulation will not be the same as in
the case of an ordinary residential building.
What does a roofing pie include?
So what is the “recipe” for roofing cake? Its components include the interior trim of the space under the roof, a couple of centimeters of air gap for ventilation, a layer of special thermal insulation layer located between rafter legs, waterproofing, sheathing and roofing material, as well as gutters and railings or bridges for safe movement on the roof, snow retainers for safety in the cold season and decorative elements such as weather vanes. Roofing cake for does not involve snow retainers and decorative elements. In addition, in some cases, the roof is located on the ceiling, and not on the rafters. If the room under the roof is reserved for technical purposes, it does not require roof insulation and vapor barrier - insulation layers will be located on the floor, protecting from
heat loss of the room below.
Roof cake for bitumen and other materials
In the case of a roof covered shingles, a layer of waterproofing material can be excluded from the cake. Bitumen creates a waterproof coating without additional films, waterproofing is required only at joints, corners and cornices. Moreover, it is necessary to lay such a film right before the installation of the roofing material, and not under the crate. If a roofing pie is created for a roof from soft roll coatings, an additional element is required - a lining. It is a polypropylene film that guarantees waterproofing when covered with a layer of absorbent woven fabric made of viscose and polypropylene. For a roof made of or rolled sheets, an additional layer of sound insulation is required, otherwise it will be too noisy in the room during rain. Thus, it is obvious that some layers of the roofing cake are always present in it, and some are determined by the type of a particular structure.