If you do not plan to do in the attic living room, the attic can be left cold - store some things here, arrange a workshop, hayloft, etc. The roof does not need to be insulated. How is a cold roof made of soft tiles, are there any features?
The device of a cold roof from a soft tile
The basic rule for cold attics does not depend on the coating: a full-fledged cake is made in the attic floor, otherwise the house will be cold.
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There are more insulation options on the floor than on a pitched roof: expanded clay, sawdust-clay mixture can be used as a heat insulator. The layer will turn out to be thick, but for an unexploited attic, this does not really matter. But cheap.Otherwise, the cake is made according to all the rules: vapor barrier, waterproofing, the floor is sewn up with boards from above.
The second feature concerns ventilation. This is where the material differences come into play. Soft roofs (unlike profile metal) do not have waves that would serve as ventilation. The bituminous covering is completely tight, does not breathe.
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A ridge aerator for flexible tiles should be installed in any case, it does not depend on the roof structure or on its insulation.The rest of the technology cold roof from soft tiles differs from insulated ones: on cold roofs, a continuous crate can be laid directly on the rafters (without a counter beam). The entire attic serves as a ventilation gap. The crate and rafters are not closed from the inside.
Features of ventilation of a cold roof from a soft roof
When installing a cold roof, additional measures are taken to ventilate the attic:
- v wooden houses with gable roofs on all gables, boards are loosely fitted, air penetrates through the cracks. This method is easy to perform, but it is not suitable for houses with stone / brick gables, as well as for hip roofs, which have no gables at all. Another disadvantage is that rainwater penetrates into the cracks along with the wind;
- ventilation holes are made in stone and brick gables. Their total area is 0.2 percent of the area of the attic itself, otherwise it will not be enough for full ventilation. Ventilation grilles are placed with holes down so that rainwater does not flow into the attic;
- hip roofs have one air vent located in the filing of the cornice, the second - at the ridge. Loosely fitted boards or perforated plastic soffits can be used as filing;
- hipped and round roofs do not have a ridge. This will require the installation of point aerators.
More about ventilation soft roof I already wrote in one of the articles. You can get to know her.
Our work
Approximate instructions for installing a cold attic on a soft tile roof
Due to the lack of a pie, it is easier to make a cold roof than a warm one:
1. Lay a solid sheathing of plywood or OSB on the rafters. Plates must be laid with a gap between the joints. The joints should fall on the rafter legs. Between adjacent plates/sheets - a technological gap of 3 mm. Fastening with screws or nails.
2. Underlayment: on flat roofs, cover the entire area of the roof.
note
Installation of the carpet starts from below: the lining is rolled out along the cornice overhang and fixed with roofing nails after 20 centimeters. The upper strip is laid with an overlap on the lower one by 10 cm. The overlap of the transverse joint is 15 cm. All joints of the strips are sealed.3. Install cornice drip strips over the edge of the carpet. Fix with nails in a zigzag after 10 cm.
4. Install the end strips in the same way.
5. In the valleys they lay over the lining. Fix the edges with nails after 20 cm.
6. The tiles are laid in rows from the eaves to the ridge. Installation of tiles on gable roofs starts from the end, on hip roofs - from the middle of the overhang.
7. Lay on top of the plank with an indent from the edge of 3-5 cm. Put it on glue (or on a self-adhesive layer), fix it with nails. The joints of the cornice strips should be closed with petals.
8. The next rows are laid so that the petals overlap the attachment points of the previous ones.
9. In the valleys and at the ends, the tiles are cut and put on glue. Fixation with nails.
The Internet and all kinds of thematic print publications are full of announcements about the construction of a turnkey cottage. As a rule, the proposal indicates the installation 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?
Does it make sense to insulate an outbuilding, say, a barn, or in the cost of insulating a non-residential attic? Maybe, after all, it is enough to confine ourselves to warming the ceiling of the last floor under the attic? But the consumption in the latter case will be much less, since the cultivated area is significantly less 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 equip it in the best way?
A cold roof is usually built for two reasons:
- when a warm roof is simply not needed or
- for reasons of economy.
Builders consider it groundless to insulate the attic space if an attic is not expected in the house under construction. The same applies to commercial buildings.
It should be noted that the device 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. It can be carried out by arranging a double roof or with the help of dormer windows.
cold roof construction
The cold roof has a fairly simple design.
Condensation quite often falls on the inner surface of a metal roof, which negatively affects the attic space. To protect against it, it is enough to lay a film or waterproofing membrane on the rafters.
- First, a counter-lattice is nailed on top,
- followed by a crate,
- then install directly roofing.
Water vapor is removed from the under-roof space through special ventilation outlets under the ridge and on the slopes. As for the attic, it is additionally ventilated through the existing dormer windows.
Due to the simplicity of the design, the process of designing, installing and operating a cold roof is greatly facilitated.
The choice of material for a cold roof
The device of a cold roof and the materials used have some features. For example, you need to carefully choose waterproofing materials. Usually, a micro-perforated roof is used for a cold roof, which, by the way, is quite affordable. It is mounted with a sag of 20 mm, which allows water, which, due to the capillary effect, seeps through the film, flows freely to the middle of the run and does not moisten the rafters. In order for the air to escape unhindered, a gap is made in the waterproofing under the ridge.
However, it is impossible to closely mount a heater to such a film. The fact is that when in contact with the insulation, the film loses its insulating properties and the insulation actually gets wet. So, if in the future it is planned to equip, or attic, it is better to use a waterproofing membrane.
When installing a cold roof, all traditional materials can be used as a coating, for which a solid base is not required. However, according to experts, the optimal solution is a profiled sheet or metal tiles, which are technological, durable and reliable roofing materials.
Steel profiled sheet
by the most simple solution cold roofing in the case of a non-residential building is the use of a steel profiled sheet provided with an anti-condensation coating. This material, which has a synthetic felt structure, is applied to reverse side profiled sheet directly in the manufacturing process.
Between the intertwined 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 intensively. In this case, there is practically no need for a counter-lattice or laying a waterproofing film.
The installation of a roof from a profiled sheet with an anti-condensation coating is carried out similarly to the installation of a conventional sheeting. For installation work No specialized tools or additional accessories are needed. When using this material, a 30% savings on the cost according to the estimate is achieved.
The anti-condensation coating dampens the noise of wind, hail and rain, prevents the formation of mold and mildew, and is easily cleaned under pressure with water from contaminants.
The roof of the building is exposed to a particularly intense effect of various natural factors, therefore, not only comfort inside the house, but also the duration of operation of the entire structure depends on the reliability and quality of its construction. Particular attention should be paid to the choice of material and the sequence of installation of the layers of the roof pie under the metal tile. The article provides information on the materials necessary for arranging a reliable roof - the main performance characteristics, the need for use, installation features, etc. After reading the article, you will be able to control the quality of the work of builders, and if necessary, do not allow them to "save" on the purchase of cheap building and insulating materials or "simplify" the installation technology.
Source spb-artstroy.ruThe sequence and purpose of the layers of the roofing pie of the roof with thermal insulation
A roofing pie made of metal tiles with insulation consists of several layers, each of which has its own purpose:
External coating. Metal tile or its budget option - metal profile (profiled sheet, corrugated board). The metal profile is recommended to be used to cover household buildings and technical structures in the roof structure without insulation;
crate. wooden frame to which the outer coating is attached;
Waterproofing. Protects the rafter system and thermal insulation from moisture;
Control grille. Wooden slats that create a ventilation gap between the outer covering and insulating materials. Thanks to the counter-lattice, humid air and condensate do not come into contact with the thermal insulation;
Sound and vibration isolation. Damper elements are part of the roof frame of a large area. It is allowed to use such brands as Isoplast bi-not, Sylomer, etc. Roof structures of small and medium sizes can do without them, subject to careful installation of the supporting base (flooring), the use of fibrous thermal insulation and strict adherence to the metal tile fastening technology;
truss system. The totality of the load-bearing elements of the roof, which is the basis for fastening all layers of the roofing pie;
thermal insulation. Reduce building heat loss. It is recommended to use fibrous thermal insulation materials having a high degree of sound insulation: mineral wool, basalt wool, glass wool;
vapor barrier. Protects the roofing pie from moist air coming from the interior of the structure;
Internal counter grille. Wooden slats of small section, creating a ventilation gap between the vapor barrier membrane and internal finishing materials;
sheathing. Draft: plywood, OSB, drywall, designed for fastening decorative and finishing materials. Decorative: plastic or wooden lining, false timber, decorative panels.
Sequence of cold roof layers
The technology for arranging a cold roof is much simpler than an insulated one:
To the rafters with a construction stapler fastened waterproofing membrane;
Along rafter legs slats are installed counter-lattices;
Lathing elements are fixed perpendicular to the rafters;
Is fixed roofing material- metal tile.
Cold roofing is used for technical structures, garages, warehouses and other outbuildings.
The main characteristics and features of the use of roofing elements
truss frame
For a roof made of metal, a standard truss system for light roofing materials is used. The cross section of the beam is 50x150 mm, the pitch of the rafter legs is 600-950 mm. As a rule, a step of 600 mm is adopted for the convenience of installing heat-insulating materials. This distance allows you to place entire insulation boards between the rafters without gaps and without the need to cut them, which will significantly speed up the installation process.
In the northern regions of Russia, it is recommended to use a bar with a section of 50x200 mm for rafters. This is due to the need to withstand increased snow and wind loads, and also allows you to place a thicker insulation between the frame elements.
Waterproofing
The choice of waterproofing material, which is part of the roof under the metal tile, depends on the purpose of the structure. The use of ordinary polyethylene film, glassine or roofing material is allowed for the insulation of non-insulated roof structures used in unheated technical buildings.
Two-layer polymer- consists of two layers of polyethylene film with a reinforcing mesh between them;
Super diffusion membrane- characterized by one-way vapor permeability. Its location during installation - with a permeable side towards the insulation, so that moist air is removed from the thermal insulation into the ventilation gap.
Fluffy waterproofing- is also a diffuse material that removes moisture. In addition, it prevents the formation of condensate. It is installed with a fleecy, vapor-permeable side to the insulation.
Any of the waterproofing membranes is laid on the roof plane parallel to the ridge, starting from the bottom. The overlap between the panels is 10-15 cm and is additionally glued with construction tape. Fastening to the rafters is carried out with a construction stapler.
Control grille
It is located between the elements of the crate and the rafters, forming a gap between the waterproofing layer and the roofing material. It is made of wood in the form of bars 30x50 mm. If the roof has complex structure, a large area or a significant length of the slope, then bars of increased cross section are used for the counter-lattice - 50x50 mm. It is located along the rafters and is attached to them with nails or screws with self-tapping screws 50-75 mm long.
crate
Is an bearing base for sheets of metal. It is made of boards with a section of 50x200 mm or a bar of 40x60 mm, located perpendicular to the rafters. In practice, these elements are often used together, if it is necessary to secure the extreme sheets of metal tiles, in case of increased wind loads in the region and / or high windage of the roof structure. In this case, the main area of the roof is covered with timber, and the lower part of the slope is covered with a solid board flooring. The step of the elements of the crate depends on the wave of the metal tile and is 800-1000 mm. Fastening is carried out using nails or wood screws (self-tapping screws) 60-75 mm long.
Important! All wooden elements of the roof structure must be treated with antiseptic (against fungus, mold, rot) and fire retardant (increase flame resistance) impregnations. Manufacturers of construction chemicals also offer universal wood treatment products that significantly increase the service life.
On our website you can find the most . In the filters, you can set the desired direction, the presence of gas, water, electricity and other communications.
thermal insulation
The traditional heat-insulating material, a roof pie under a metal tile with a heater, is mineral (basalt) wool. It is sold in rolls and slabs. The size of the plates from most manufacturers is 1000x600x50 (100) mm. They are installed in the inter-rafter space by surprise.
The use of slabs is preferable, since when laying them, additional fasteners are not required to hold the material between the rafters. The insulation is laid as tightly as possible, but at the same time it is necessary to ensure that the material does not deform or shrink.
To insulate technical buildings, it is more advisable to use expanded polystyrene, since it is better resistant to moderate mechanical stress and does not need additional protection from inside the building.
It is advisable to fill the gaps between the expanded polystyrene plates and between the insulation and the rafters mounting foam. This will not only eliminate the leakage of warm air from the room, but also give the entire structure additional strength.
vapor barrier
It is one of the most important layers of the roof pie under the metal tile. Its main purpose is to protect heat-insulating materials from the influence of warm, moist air coming from inside the premises. The use of vapor barrier is mandatory when using fibrous heat-insulating materials, since absorbing moisture, mineral wool significantly reduces its effectiveness.
The most common vapor barrier material with an affordable cost is glassine. However, it has low strength and durability. Polypropylene "woven" membrane is more durable and efficient. It is produced under many brands and is positioned by the manufacturer as a universal insulating agent - hydro-wind-vapor barrier. In addition, this material prevents the formation of condensate.
Sound and vibration isolation
One of the specific properties of metal tiles is a high level of noise from external influences. Therefore, special attention is paid to sound insulation:
All structural elements are fixed screws. The parts to be connected must be securely pulled together to prevent the formation of cracks and play;
Calculated the position of the elements of the crate so that the edges of the sheet of roofing material are located on the carrier rail;
Installation of all elements of the batten and counter batten is carried out without deviation from the working plane, as evenly as possible, without bumps and depressions. This will avoid distortions during the installation of metal tiles.
The noise level is significantly reduced by the use of fibrous heat-insulating materials. Some manufacturers produce specialized brands of thermal insulation with a high sound absorption coefficient, from 0.5 to 0.8.
It is advisable to carry out special measures for vibration isolation if the house is located near a railway, a highway with heavy traffic, or if the roof slopes have a large area. To do this, special damper pads separate the layers of the roof under the metal tile between the bars of the counter-lattice and the rafters.
Video description
In the video you can see the rules for installing a roofing pie:
Roofing
A high-quality metal tile has a thickness of 0.4-0.6 mm and several layers of protection. Visually, the presence of internal protective layers is almost impossible to check, so when purchasing roofing material, ask the seller for a certificate. To protect against corrosion, the metal tile is painted with inside, and on the outside it has a polymer coating, which resists external influences much better than paints and varnishes. The durability of operation and the cost of the roof depend on the type of external protective layer. The most common are the following types of polymer coatings:
Polyester. The thickness of the protective layer is 25-30 microns. It has an affordable cost and relatively high performance. The warranty period of operation of a metal tile with a polyester coating is 8-10 years;
Polyurethane. It is characterized by resistance to mechanical damage, temperature extremes and various chemicals. When the sheet is bent, such a coating does not lose its integrity;
PVC. Demonstrates high resistance to mechanical, chemical and thermal influences. Has high plasticity. Metal tiles with such a coating are recommended for laying on relief surfaces. It is advisable to use in regions with extremely hot climates;
Plastisol. Consists of polyvinyl chloride with the addition of a plasticizer. It is applied with a layer up to 200 microns, which allows applying a relief pattern to the surface of the metal tile. They have low resistance to high temperatures, which does not allow it to be used in regions with a hot climate.
Interior decoration
A ventilation gap is also formed between the vapor barrier membrane and drywall or OSB sheets. For this, they are used wooden slats with a section of 20x30 mm., Attached to the rafters perpendicularly.
Video description
From the video you can learn how to properly make a roofing cake for a metal tile:
Conclusion
Despite the high cost of materials and significant labor costs when constructing a roofing pie for a metal roof, it is highly discouraged to “simplify” the technology by skipping layers or using cheap insulating membranes from unknown manufacturers. The consequences can be the saddest, up to the complete replacement of the roof.
Today, in the construction of a residential building, various options for roof structures are used, but the simplest is a cold roof. Such a device is great when the attic space is not used as a residential additional space. The very scheme of such a roof is very simple: load-bearing structures, waterproofing, lathing and counter lathing, plus roofing material.
The features of the installation of such a cold roof are that it is necessary to provide a ventilation gap for the removal of condensate in order to protect not only the supporting structures, but also the roofing in the form of a metal tile from the negative effects of moisture.
The installation of such a roof itself does not differ in any difficulties, the main thing is to correctly fix the profiled metal sheet so that precipitation does not penetrate through the joints under its surface. Before starting construction, you should make all the required calculations, calculate the angle of inclination, the step of the crate, decide on.
Features of a cold roof
A cold roof differs from a warm one in its design, although its design itself is extremely simple. The only thing to consider is the option of roofing. When using metal tiles, it is necessary to provide a ventilation gap for the correct removal of condensate from the under-roof space. This is done so that the steel sheet does not corrode.
The device of a cold roof is the installation of a truss system, on which a membrane or plastic film is laid for waterproofing. After that, a counter-lattice, a crate and a coating in the form of a metal tile are nailed.
The features of this roof are complete absence a layer of heat insulator, the presence under the ridge and on the slopes to remove moisture. Design and installation are not difficult, the main thing is to correctly carry out all preliminary calculations.
The installation itself includes the following features:
- If it is planned in the future, then it is necessary to approach very carefully the choice of a membrane to protect against excess moisture. For the future attic, only specialized waterproofing in the form of membranes made of PVC is suitable.
- If further insulation is not planned, then microperforated waterproofing is used, designed specifically for cold roofs. Such a film does not allow thermal insulation materials to be laid next to it, that is, with further insulation, you will have to spend money on a new membrane. If this condition is not met, then the roof will practically not be protected from moisture in the future, the insulation will be constantly wet, and the roof covering will be subject to corrosion.
Sequence of work
To lay the waterproofing membrane, it must be remembered that its installation is carried out with some sag, approximately 20 mm. Such a device allows the condensate to drain, that is, the rafters and other roof elements are protected from moisture. In order for the water to evaporate effectively, and not to stagnate, creating an unfavorable atmosphere, it is necessary to ensure the presence of a ventilation gap, which is made between the waterproofing film and the roof ridge.
Such a gap allows air to circulate unhindered in the under-roof space, removing all traces of condensate. The roof protection membrane itself should not have ruptures or other defects; it should be fixed using a construction stapler.
Be sure to overlap, the edges of the film must be fixed with adhesive tape.
Of the features that distinguish a cold roof, it should be noted that it can be built for any climatic region. Many mistakenly believe that this type of roof is completely unsuitable for the northern region, but this is not so. It is here that a cold attic is a traditional solution for a residential building. Samo attic floor is insulated, that is, the use of a cold roof does not affect the internal microclimate of the upper floors. The attic itself may not even be used, since the installation of a layer of insulation between the upper floor and the under-roof space solves all problems regarding heat loss.
When constructing a cold roof, one should not forget about such a stage of work as proper insulation technological openings and exits. To do this, all ventilation shafts, chimneys, entrances to the roof surface must be insulated. This will avoid such troubles as icing, condensation, penetration of precipitation, heat loss.
To cover the roof of this design, you can use a variety of roofing materials. Most often it is a metal tile, the installation of which does not pose any problems. This option is considered optimal, since all laying work is carried out in the shortest possible time, no additional work is required. You can use other materials for coating, for example, flexible tiles. But here a number of technological difficulties already arise that can make installation more expensive and complicated. Therefore, the use of a metal profiled sheet is preferable in this case.
Roofing pie under the metal tile
The device of a cold roof under a metal tile is one of the most simple options. In addition to load-bearing structures, such a roof includes roofing material in the form of metal tiles, a crate, and a waterproofing layer. The installation of such a roof is very simple: a waterproofing film is attached to the rafter system using a construction stapler or small galvanized nails. After that, it is pressed with self-tapping screws on wood, with which the counter-lattice will be attached, the step of which depends on the type of metal tile sheet. The size of such boards should be 25 by 100 mm, in some cases a continuous coating of plywood or chipboard sheets is used.
A waterproofing film (it can be a special PVC membrane or a polyethylene film) should be laid on the roof with a slight sag. At the same time, gaps and other defects are unacceptable on it. The level of sagging of the roofing film should be from 15 to 25 mm. This will ensure proper ventilation of the underside of the waterproofing, removal of condensate from it to the eaves, and then to the gutter. If this is not done, it will be subject to the negative effects of moisture, and this will lead to destruction.
When installing a cold roof made of metal, it must be remembered that the metal sheet and a thin layer of waterproofing do not provide adequate protection against noise, which can occur during heavy rain. It is for this reason that cold steel sheet roofs are rarely made without insulation, which acts as an excellent sound insulator. Cold attic therefore it turns out to be unused.
The structure of such a roof includes the following mandatory layers:
- From the side of the residential premises, first there is a layer of vapor barrier with one-sided permeability, that is, condensate is released from the room, but does not penetrate inside.
- Roof truss system, longitudinal runs, that is, the supporting structure.
- Waterproofing. The film should sag a little to allow condensation to escape.
- Control grille, which is installed in parallel installed rafters. The boards of the counter-lattice press the waterproofing, providing its additional fastening.
- The cold roof sheathing is made of wooden beam, the cross section of which is most often 50 by 50 mm. Its installation is carried out in increments of 35-45 cm along the slopes. The step may vary, as well as the material for the crate, it depends on what type of metal tile is used, what slope for the roof was chosen.
- Sheets of metal tiles.
What else is required?
To install a roof with such a design, it is necessary to take the most simple tools and materials that are not very expensive. Besides wooden planks for the construction of the rafter system, battens and counter battens, a vapor barrier, a waterproofing membrane, and the estimated number of metal tile sheets should be prepared. Staples, galvanized nails, self-tapping screws for wood and metal are used as fasteners. When calculating steel sheets, it must be remembered that various additional elements may be needed, for example, ridge tiles, valleys, cornices, and so on.
The device of a cold roof differs from a warm one in that in this case a layer of insulation is not used, that is, between the vapor barrier and waterproofing membrane no insulation layer. Such roofs are applicable in the case when the attic space under them is not used.
In individual, and not only in individual construction, when the scope of work reaches large volumes, some work and technological elements provided for in the project can be postponed for more late deadline focusing on the main direction. One of these options is the installation of a roofing system. And here the point is not only to save on materials, postponing the attic equipment for later, simply erecting walls, interfloor ceilings and laying the main communications without a device reliable roof in no way possible. And if for the speedy settlement it is necessary to carry out a mass finishing works indoors, then it is possible to wait a little with the insulation equipment in the attic.
What does cold roof mean?
Modern roofing materials, despite such a variety of forms, materials, technologies and prices, are in many respects similar to each other in one thing - they can be used both for installing a cold roof of a building, and when building a roof with a layer of insulation. In fact, these are materials of universal use, but when working with them, you need to know and take into account the specifics of their application.For a roof equipped for attic rooms, a layer of insulation is used to prevent heat loss in winter time and maintaining a comfortable indoor temperature in summer. For such options, they are used as traditional insulation technologies using as a heater mineral wool, polystyrene, sprayed types of insulating foam, as well as new types of new heaters on a natural basis that are just coming into fashion. The roof of such a building makes it possible to obtain additional space in the building, which can be used as a workshop, library or billiard room.
A cold roof, in contrast to a design with insulation, has a simpler device. This is a standard roof structure, the main purpose of which is to protect the building from precipitation. At the same time, a cold roof device can also be made as an intermediate solution, in which it is planned to install a roofing pie from insulation and all related layers of hydro- and vapor barrier in the future.
A cold roof can be made from almost the entire range of roofing materials; for its construction, the following can be used:
- Slate;
- Profiled metal sheet;
- metal tile;
- roofing iron;
- Roll roofing materials;
- Ondulin;
- Bituminous materials;
- Tiling.
Cold rolled metal roof
In order to quickly erect the roof of a building with the least losses, the most rational today is the use of sheet metal products as a coating material. Metal profiled sheets or metal tiles, compared to other types of roofing materials, have several advantages:- Coatings made of metal tiles or profiled sheets are highly reliable and durable, the service life of such coatings is at least 50 years, however, subject to all the rules of roof construction technology;
- Metal tiles and corrugated sheets are truly universal materials for their intended purpose - they are easily used both to cover large areas and small-sized roofs.
- The material, unlike tiles or slate, has a lower weight, which means that lighter structures can also be used for the roof structure;
- The strength of the material, as practice shows, without a doubt, it perfectly withstands heavy loads, copes with its functions on various roof slopes from 14 to 65 degrees;
- The convenience of roofing from these types of materials is indisputable, except large sizes and ease of installation of the roof, the metal profile itself and the metal tile contain many additional accessories, allowing you to mount all elements of the roof without any special difficulties.
Metal as a roof covering, in addition to all the above positive qualities, also has negative ones, which very seriously affect both the condition of the roof itself and the condition of the metal. Firstly, the diurnal temperature difference in the spring-summer period makes it possible for a drop of condensate to appear on the inner surface. Secondly, metal roof requires the installation of special additional elements for laying communications through the coating. Thirdly, the roofing material itself is still very noisy, during rain or hail, those under the roof will clearly hear how literally every drop of rain or a grain of hail falls.
Based on this, for a cold roof device using metal materials requires the use of special, recommended by the manufacturer additional materials and laying technologies.
The specificity of equipping a building with this type of roof lies in the use of materials that make it possible to completely or partially rid the internal space of the formation of condensate, and in case of its occurrence, remove it from the attic space as quickly as possible.
The basis of such a roof, however, like any other roof of this type, is roof structure, the standard set of which is rigid rafters located in strict accordance with the project, interconnected into a rigid structure. The dimensions of the rafters themselves, the shape and methods of docking with each other in this case do not play a special role, it is important that the slope of the rafter legs provides the most optimal slope angle from 14-65 degrees.
A layer of waterproofing material is laid on top of the rafters. The essence of this layer is the ability to prevent moisture from entering the attic space from leaks in the roof. Modern nonwoven materials make it possible to solve the problem of moisture from condensate in a complex way; today, a vapor-permeable membrane is used as such a material, capable of passing steam in one direction and not allowing moisture and steam to pass back. Such a layer of waterproofing is laid on the rafters and fixed with building brackets.
On top of the membrane along the rafters, counter-battens are fastened. Planks not only fix the membrane itself, but also form, thus, an additional volume between the membrane and the coating. Further, as in a conventional roofing structure, lathing strips are installed and metal sheets of the coating are already on top.
Such a schematic representation allows the main elements of a cold roof, however, to complete the picture, it is necessary to dwell in more detail on some of the nuances of the design.
The vapor-permeable membrane waterproofing, installed over the rafters, is laid in sheets horizontally from the bottom up, so that the layer located above overlaps the bottom layer by at least 10-12 cm. This arrangement will allow moisture to quickly drain down when it gets under the metal coating. However, when laying a sheet of a waterproofing layer, the material is laid without tension, with a deflection between adjacent rafters of 1.5-2 cm. Such a deflection provides more efficient removal of moisture and at the same time increases inner space under the metal roof.
Below, on the beams of the rafters, not only droppers are installed - solid metal strips along which water flows from the tiles, but also a special perforated strip or mesh with small cells to ensure unhindered passage of air under the roof. Perforation securely closes the space from the penetration of birds, bats, animals and large insects into the attic and at the same time provides air flow under the metal surface.
Constant air circulation is ensured by the presence of additional holes in the upper part of the roof under the ridge strip, allowing the passage of heated air. This roof design allows air to circulate with the greatest efficiency, air passing under the metal coating, gradually heating up, exits through the holes under the ridge bar.
Conditions for laying communications under a cold roof
As well as for the usual roof structure of the house, the space under the roof of a metal profile or metal tile can be equipped with a chimney, cable or antenna lines, ventilation ducts and viewing windows or glass inserts.
For a cold roof, the placement of these communications has some features. For chimneys passing through the attic space, especially those used as pipes metal constructions needed in without fail conduct insulation, since it is these elements that will cause condensation on the profile. For cable lines passing through the metal coating of a cold roof, it is necessary to use special antenna outputs that fit snugly against the surface of the metal tile.
A cold roof, in addition, requires that, in addition to the main ventilation system, auxiliary ventilation ducts be installed to bring air outside. Most often, special ventilation outlets with deflectors are used as such channels, providing air draft.
A little about saving
Considering the option of building a building with a cold roof, as a permanent or intermediate option for roofing, it is necessary to understand some of the nuances associated with the economic aspects of this type of construction. Comparing the design of a cold roof for a two-story single-apartment residential building with the same roof, only with insulation, it is necessary to add another 10-12% of the amount of annual costs to the heating costs of the task. At the same time, simple insulation of the attic surface gives the opposite effect in the form of energy savings of 3-5% of the annual requirement.Assessing the construction of a cold roof, it will undoubtedly cost less, while the cost of the project can be 35-50% less than the cost of an insulated roof. But in order to carry out work on insulation in the future, the cold roof as an intermediate option is the most optimal, because the space can also be used as an additional storage space for the material. True, the insulation of such a ready-made roofing system will be a more complicated process than building a roofing pie right away.
