Waterproofing a roof from a metal tile, how to choose the right one, how to do it right. Features of waterproofing a roof under a metal tile: schemes, materials, installation technology What kind of insulation is better for a roof made of metal

A roof made of metal tiles especially attracts the attention of owners of townhouses or cottages. But you need to be more careful with this material: in case of improper arrangement of waterproofing, metal tiles will cause rapid damage to the entire load-bearing structure roofs. Installation of a waterproof sheet under a piece of metal roofing is a responsible mission.

The need for waterproofing a metal roof

Waterproofing is one of the most milestones in the work of installing the roof and the basis for the reliable and successful functioning of the house for a long time.

Experts indicate the following reasons for the mandatory waterproofing of roofing metal tiles:

• the formation of a large amount of condensate on the corrugated material made of galvanized steel - the “product” of the loss of a significant amount of heat by the metal;
• the risk of damage to the truss system leaked into the " roofing cake» moisture, which leads to a change in the configuration of the roof under the influence of the “attack” of fungus and mold;
• the danger of moisture penetration into the insulation, which, without a special barrier, is saturated with water and becomes useless (even after drying);
• the threat of rust on the inner surface of the metal roofing, especially in the areas of material fixation on the rafter legs.

Condensation is the main enemy of roofing

Ignoring the requirement to lay under the metal tile waterproofing material fraught with a significant reduction in the life of the roofing.

Search for waterproof material

When looking for a suitable roof waterproofing made of metal tiles, you will have to make a choice between three materials: roofing material, film and membrane.

Ruberoid

Ruberoid is famous for its durability and reasonable cost. But it is taken only in a situation where it is necessary to protect a cold-type roof from moisture, because the roofing material blocks access to steam.

The roofing material will be able to protect the layers of the "roofing cake" from the effects of dampness and wind. But if these adverse events are overly pronounced, then the effect of styling roll material will become insignificant.

Ruberoid - durable and inexpensive waterproofing material

Waterproofing film

A waterproofing film is a thin polyethylene-based sheet created by forcing a material melt through a forming hole in an extruder. Such building materials have earned a reputation for being relatively inexpensive and good in terms of material operation.

Waterproofing with a film based on polyethylene is a wise decision if you need to protect a mansard roof from moisture.

Waterproofing film - the most popular material for waterproofing

To prevent damage to the roof by moisture, films of several types are produced:

• classic film, main feature which - double-circuit isolation;
• membrane superdiffusion film, characterized by single-loop insulation, which allows the roofing insulation to serve as long as possible;
• anti-condensation film, characterized by double-circuit ventilation and hairiness, which contributes to the absorption of moisture.

The waterproofing film is also evaluated negatively: it is not able to withstand the negative effects of ultraviolet radiation, due to which it turns into a brittle material.

Membrane

Membrane is the thinnest film material made from modern polymers, that is, from polyethylene low pressure or polyvinyl chloride. The ultra-modern waterproofing sheet acts as a barrier to water and at the same time does not block the path of vapors escaping through the ceiling of the house. Unlike the film, the membrane is immune to ultraviolet radiation and water pressure, therefore it unquestioningly serves for the period declared by the manufacturer.

The membrane becomes an unsurpassed material in the fight against dampness, since its pores are distinguished by a specific structure. The thinnest canvas, as it is not surprising, consists of many layers.

The waterproofing membrane is a material exclusively for a "warm" roof

The membrane is placed under metal tiles only in the case of creating a "roofing cake" of a warm type. The roof structure is best protected from the effects of dampness by a material with an anti-condensation effect, which includes a reinforced and absorbent layer. Together they protect the roof from the effects of precipitation and "capture" drops of liquid.

An improved waterproofing material - a membrane - is more reasonable to use if the building is located in an area where it often rains.

Laying waterproofing under metal roofing

Installation of waterproofing material is a stage roofing works performed after the construction of the structure from the rafter legs.

To properly lay a film or membrane under a metal tile, proceed as follows:

1. The material is cut into separate fragments, the length of which is 15% greater than the size of the roof slope.
2. With the perforated side outward, the canvases are spread on the rafter system, moving from the eaves to the ridge. Each strip is laid perpendicular wooden elements load-bearing roof structure. At the same time, the material is not stretched, but laid freely, allowing it to sag a little between the rafter legs. Otherwise, soon the canvases will tear under the influence of sudden changes in temperature.

   The film is laid on the side with which it is untwisted

3. The strips are connected by edges, making overlaps of 10 cm with a roof slope of more than 30 °; and 20 cm each - if this indicator fluctuates within 20 °. When the roof is tilted by 21–31 °, the edges of the pieces of material are connected by 15 cm. When performing this task, make sure that the areas where the “ribbons” overlap each other fall on the surface of the rafters. To fix the material on wooden elements, stainless staples and a construction stapler are used. The places where the strips overlap are insulated with adhesive tape.
4. On a fixed film or membrane with an interval of 10 cm, slats with a section of 40 × 25 mm or a little thicker are nailed. These are elements of a counter-lattice, the task of which is to create a gap for ventilation of the layers of the “roofing cake”. A crate is installed over the rails.

   Waterproofing is laid between the rafters and the counter-lattice

The roofing material is laid out on the roof in almost the same way as a film and a membrane. But as fasteners, ordinary or galvanized nails are used. The seams obtained by imposing strips of material on top of each other are coated with a moisture-resistant sealant or sealed with construction tape.

Video: roof waterproofing

The nuances of waterproofing roofing elements from metal tiles

In the process of laying waterproofing material, one question most often arises: how to lay the film through chimney. And a little less often, home craftsmen think long and hard about how to join the film strips on the roof ridge and how to lay the material in the location area window openings attic.

To fix the waterproofing sheet on the roofing element, rubber adhesive tape is used.

Laying material at the chimney

The insulation of the junction of the waterproofing sheet to the chimney is performed in a few simple steps:

Installation of a waterproof sheet near the ridge

How to lay a film in the area of ​​\u200b\u200bthe roof ridge is a topical issue. Anyone who seeks to properly lay waterproofing over the entire roof area needs to know the following:

This approach to waterproofing the roof ridge guarantees normal ventilation of the space under the roof.

Video: roof ridge waterproofing

Adjacency of matter to the roof window

The waterproofing film is placed before the window is installed. The material is cut in the form of an envelope, the resulting valves with a width of more than 6 cm are lifted and brought to the crate.

At the location of the window, a bend of 6–15 cm is made

Errors in laying waterproofing under a metal tile

Unfortunately, home craftsmen tend to do serious mistakes when installing a waterproofing sheet. Usually these oversights are as follows:

The issue of waterproofing a roof made of metal is approached responsibly. Improper laying of waterproof material leads to sad results - corrosion of the finish coating and even damage to the entire roof structure.

When operating a roofing carpet made of metal tiles with inside condensate will form. And this process does not depend on the person in any way. There will always be condensation. Proper styling waterproofing under the metal tile will help prevent its formation. And, at a minimum, it will prevent moisture from seeping into the roofing carpet.

Characteristics of the waterproofing film

Roofing film, no matter what it is made of, must protect attic space and thermal insulation layer. In other words, so that processes do not begin under the metal tile, which over time will destroy it and have a detrimental effect on the base of the roof, special protection is needed.

A priori, the properties of waterproofing for a roof made of metal are microperforation to ensure ventilation of water vapor. To achieve this result, the substrate under the metal tile must

• Consist of multiple layers
• Have a reinforcing polyethylene grating

The thickness of each layer varies depending on the type of film. At the same time, in addition to moisture removal, the protective waterproofing film may have

• fire resistance
• UV protection

Each manufacturer indicates what qualities are inherent in his material.

Types of waterproofing substrates

In a high-quality roof, it is necessary to provide for the formation of condensate not only directly under the metal tile, but also from the side of the insulation. To do this, first of all, an anti-condensate layer is applied to the film from the inside and a gap is left for ventilation.

Condensation formation depends on whether the roof is warm or cold. Its intensity and volume are directly related to the temperature above and below the substrate.

In total, there are three types of films:

• Classic film. It is important to observe ventilation in two circuits:
  • Between roofing material and waterproofing
  • Between waterproofing and insulation
• Diffusion membrane. It has high vapor permeability. Therefore, the ventilation gap should only be between the membrane and the roofing
• The film is anti-condensation. Here, the basis of the material is a fleecy moisture-absorbing layer, and dual-circuit ventilation is important for it.

It is also customary to separate the substrates directly from the type of roofs. In this case, the following is taken into account, whether the roofing cake will

• heated (warm)
• unheated (cold)

Substrate and "warm" roof

If the roof is heated from the side of the attic (most likely, this is a residential area), the roofing pie is built in stages and is quite difficult. So, how to lay waterproofing under a metal tile? Installation consists of the following steps:

1. The initial layer is a crate, and also
2. Waterproofing
   

   It is important! waterproofing underlay for warm roof should not only protect the roof from condensate vapors (and there will be a lot of them due to the fact that immediately under the metal tile there will be one temperature in winter, and under the substrate an order of magnitude higher), but also ensure the release of water vapor from the warm attic. In other words, the film is also required to have vapor barrier properties.

3. Air layer. The ventilation layer will help the film perform its functions well. Its height is from 2 to 3 centimeters
4. Thermal insulation layer. Materials to prevent heat loss are placed in truss system and their thickness depends on the temperature conditions of the area
5. The penultimate layer is directly vapor barrier, which prevents the penetration of condensate drops into the roof space from the living quarters
6. The last layer can be considered the presence of a mandatory inner lining attic ceiling and walls

Substrate and "cold" roof

Roofing cake for cold roofs is performed according to a more simplified scheme, which means it is done faster. The layers in this cake will be like this:

1. Creation of battens and counter battens
2. Laying a waterproofing layer
3. Creating a truss system

If there is an unheated attic under the roof, almost any film can be used as waterproofing:

• Anti-condensate
• Diffusion membrane
• Any material that can not pass moisture, including roofing felt or greenhouse film

Substrate from roofing material

Roofing material is understood as a material that consists of cardboard (fiberglass or fiberglass), coated with bitumen or polymers. The service life of such material as a roofing covering is from one to three five years. As a substrate, it can even last a little longer, as it will not be in contact with the sun.

Roofing material is a fairly popular material for creating a primitive waterproofing layer in a "cold" roof.

Attention! Ruberoid and all its polymeric derivatives can be used as a substrate for metal tiles in those roofs where the angle of inclination does not exceed 25 degrees.

To the disadvantages of roofing material, which even low price, it applies that

• Over time, the integrity of the bituminous coating will be violated from moisture.
• The cardboard base is wet (fiberglass will last longer than cardboard, but it is not durable without a top coat)
• Belongs to the category of flammable materials

As a waterproofing layer, roofing material and its analogues can only be used in the roofing pie of a "cold" roof.

The selected waterproofing for the roof under or Rukki should be fixed so that air flows can easily pass through the vents. They must be installed at the highest point of the roof.

To avoid tearing of the material at low temperatures, the film must be laid so that there is a sag between the rafters of 2 centimeters.

The film must be laid from the eaves to the ridge, making an overlap of 1.5 centimeters at the joints. Fasten the joints with either adhesive tape or a construction stapler.

Roof insulation and vapor barrier

Insulation in the roofing cake, regardless of whether the roof is heated or not, must always be present. This material, even the smallest thickness, has low thermal conductivity.

For the roof (meaning external insulation), it is best to use glass wool or something made of polyurethane foam. Such materials are denser than, say, ordinary foam, repel moisture better, and therefore can last longer.

Moreover, than north region, the greater the thickness of the insulation, as well as the possible number of its layers. All of them must be completed in checkerboard pattern. And the joints need to be foamed.

The insulation can perform its functions of preserving heat only when there is waterproofing in the roofing cake (as described above), and for a “warm” roof and vapor barrier.

We are talking about film-type materials. Their task is to maintain the desired level of thermal insulation background.

In other words, they are an important participant ventilation system roofing cake with moisture blocking functions.

The vapor barrier is laid in 2 - 3 layers, with an overlap of up to 10 centimeters. Joints must be sealed or reinforced with a stapler.

The roof must be strong, able to protect the house from snow, wind, rain. A metal tile can perfectly cope with such functions, but on condition that the roofing cake is made in compliance with the technology. This means that it necessarily contains waterproofing, as well as insulation and, in some cases, vapor barrier.

Before doing further installation work, think about it. The wrong tool can shorten the life of the material. Three options are suitable for cutting: carved or electric scissors, as well as a drill attachment. Cutting a metal tile with a grinder is prohibited!

For cutting other elements that are needed for the installation of metal tiles, the use of a grinder is also prohibited. For example, metal scissors are suitable for a valley. Read more about installing a metal roofing valley. This element must be performed as correctly as possible so that the roof does not leak.

Video about waterproofing for metal roofing

Vapor barrier, insulation, roof waterproofing. The organization of the ventilation gap in the under-roof space.

Do you need waterproofing under metal roofing? What is it used for.

A very important element of any building. It protects the house from the penetration of precipitation and the effects of winds. Properly protected from moisture, the roof significantly extends the life of the wooden frame elements. About how waterproofing is made under a metal tile and what materials are used for this, read in this article.

As roofing protection is used:

• Ruberoid
• glassine
• Polyethylene reinforced membranes

Let us consider in more detail which one to choose for a metal tile and what you should pay attention to.

Roll materials from roofing paper impregnated with bitumen, such as roofing material and glassine, are traditional materials. They are used to protect wooden roof on which slate laying is planned. However, it should be noted that these materials have a low service life of 5 years.

In the event that a metal tile is used as a roofing, then the waterproofing for a roof made of metal should be special. Such protection is a polyethylene film reinforced with a strong mesh of polyester threads. The service life of this is 50 years, exactly as long as a modern metal tile will last.

The film under the metal tile has small holes in order to pass water vapor that rises from the inside of the house, but at the same time the water is completely retained outside. Vapor permeability is very important if the under-roof space (attic) will be used as a residential attic. In this case, the roof frame is insulated between the rafters.

If glass wool or mineral thermal insulation is used as a heater, then it should be well ventilated. If this is not the case, then the water will nourish the insulation, and it will lose its heat-shielding properties. The protective substrate under the metal tile is called a hydrobarrier. also performs anti-condensation protection for metal roofs.

From the temperature difference (cold outside and warm inside), water condensate forms on the sheets of metal tiles, which can also cause damage to the insulation and wooden elements of the roof frame. The substrate under the metal tile usually has specific gravity 140 g/m2, width 150 cm and length per roll 50 m.

Three-layer perforated waterproofing under the Isospan metal tile can serve as a bright representative of this class. Izospan AS or AM is ideal for a protective substrate under a metal tile coating. The low weight of the film allows for quick installation. Only two people are enough to carry out the work on laying the waterproofing barrier.

Do you need a metal tile for a “cold roof”? The answer is unequivocal - it is simply necessary. In the event that the roof is "cold", that is, not heated and has good ventilation, roofing material can be used as a substrate. However, it is necessary to observe the ventilation gap between the roofing material and the sheets of metal tiles to ensure ventilation.

The procedure for laying a hydrobarrier under a metal tile

Before installation under a metal tile on wooden frame, it must be carefully treated with an antiseptic composition. This is necessary for the prevention of wood rot and fungi. Can serve as an antiseptic water solution deep penetration primers, for example, Ceresit. They process all the wooden parts of the frame - Mauerlat and rafters.

Important to remember! for a roof under a metal tile it is laid from below the roof (from the system of ebbs) and continues to its highest point - the ridge.

Before laying the first sheet under the metal tile, it is rolled out in a horizontal direction perpendicular to the rafters. For convenience, the film is attached to the rafters with a construction stapler. The brackets must be galvanized. After the sheet is fixed, it is finally fixed with a clamp wooden lath and nails 70 mm with an interval of 20 cm. This is the so-called "counter-lattice".

The next sheet is laid with an overlap on the first one of 150 or 250 mm. If the slope is less than 30 degrees, then the overlap must be more than 15 cm. The roof ridge must pass exactly in the center of the hydrobarrier sheet being laid.

It's important to know! If a micro-perforated membrane is used as for a metal tile, then it must be laid against the metal tile only on the side indicated by the marking. Often this is a red stripe or the name of the manufacturer's company, written in bright paint.

From above, a crate made of timber with a height of at least 20-25 mm is attached to the counter-lattice. Such a gap between the metal tile is necessary for ventilation. The slats are attached to the rafters with nails, while the distance between adjacent beams should be 350 mm.

If the roof is planned as “warm”, then insulation is placed in the space between the rafters. In this case, from the inner surface of the roof, it is installed under a metal tile made of vapor-permeable polyethylene film. It will provide ventilation of the mineral wool insulation.

After the outside and inside is finished, the crate is made, you can lay the metal tile. If you have any questions, you can see how the laying under the metal tile is done in the video presented in this article.

Nowadays, metal tiles are often used to decorate the roof of buildings - the material is reliable and beautiful. However, the durability of any roof and its performance characteristics largely depend on how correctly the under-roof space is made. Roof waterproofing under a metal tile is one of the main elements that should not be forgotten during the construction of a building for any purpose.

Why is it so important to have a waterproofing layer under the roof, including under the one that will be shaped with metal tiles? Isn't just one finishing material to drain water? So, waterproofing performs several functions, providing reliable protection roof, space under it and the inside of the building.

The main function is protection of all elements located in the under-roof space from moisture. The roof is far from the simplest structure to perform, and its structure is multi-layered. During construction, as rafters and beams, as well as to create battens, wooden planks, bars or metal elements. Both materials categorically do not like excess moisture. And waterproofing will provide reliable protection of these elements from it.

Attention! If the roof is insulated, then inside its pie there are both heat-insulating and insulating materials. They also do not like moisture and only a waterproofing layer can provide them with protection from its effects.

Properly installed waterproofing will also allow get rid of the accumulation of condensation moisture in the under-roof space. It is formed due to the temperature difference between the inside of the house and the street and can also have Negative influence for all materials used in the construction of the roof. Condensation can gradually destroy them and cause leakage and reduce the life of materials.

On a note! The waterproofing layer will make it somewhat easier to convert the attic into attic room if such a desire arises from the owners of the house.

Materials used

We found out that waterproofing is essential element roofing, covered with metal tiles. But what should be a high-quality layer that protects against water? The requirements for waterproofing are as follows:

• it must have increased fire resistance;
• pass steam well;
• indicators of strength and reliability should be on top;
• the material should not deteriorate with sudden changes in temperature, be afraid of ultraviolet radiation;
• the layer must withstand a certain level of mechanical stress;
• waterproofing should not be afraid of pest attack or be prone to mold development;
• also, it should cope well with its main tasks and not harm human health.

Can be used for waterproofing different kinds materials. All of them have a lot of differences from each other, including different resistance to light, strength, quality and durability.

For the most part, special roofing films with several layers are used for waterproofing metal roofing. There are reinforcing and absorbent layers. The first provides protection from precipitation, and the second is able to absorb moisture coming from the inside, so that condensation cannot accumulate on the waterproofing and mold pockets form. Also, on both sides, the material usually has a lamination of polyethylene.

Such a coating has special pores that allow the passage of vapors that form inside the house, but at the same time do not allow moisture from the outside to spoil the materials from which the roof is made. This feature of the material, called vapor permeability, is especially important if attic space converted into an attic and used as residential.

Advice! When choosing a material for waterproofing, it is important to pay attention to its service life. It should coincide with the life of the metal tile so that you do not have to disassemble the roof and lay the waterproofing again if it fails, and the main roofing material will still be usable. Service life of the special film used under a metal tile makes 50 years.

On a note! Common to this day used hydrobarriers, made on the basis of bitumen and bituminous mastic, should not be used for arranging a roof made of metal.

Of course, a cheaper film can be used for temporary roofing, but for capital construction it is better to take high-quality, albeit expensive material. It is not worth saving here and it is better to buy a diffusion membrane coating. All indicators of the purchased film are shown on the edge tape that frames the material. The film is produced in rolls 1.5 m wide and 50 m long. The density of the material is about 140 g/m 2 . bright representative the material that is optimal for laying under metal tiles is Isospan AM or AS.

Preparation for work

Laying a waterproofing layer requires preparatory work. They include the creation of a rafter system designed according to preliminary calculations, the installation of cornice and end boards. Only after that the waterproofing is laid.

To work on the installation of waterproofing, certain tools are useful. This is a tape measure, scissors, a hammer, a marker, a construction stapler, a screwdriver. You will also need to purchase bars and screws.

Laying process

The installation of the layer can be carried out in two ways: in the first case, the film is laid directly on the rafters in strips parallel to the eaves, and fastened with a slight sag between the rafters. If you need to leave a ventilation gap between the metal tile and the film, then the film is fixed on the over-rafter counter-lattice. Also, the film can be mounted perpendicular to eaves plank. Here it is laid on the finished crate and fixed tight.

Consider how the installation of a waterproofing layer under a metal tile takes place using a detailed example.

Preparatory work

Step 1. According to the project of the house, a truss system is being erected. AT this case it is made of wood, which especially needs protection from moisture, so the question of laying waterproofing is not worth it.

Step 2 The vapor barrier layer is being installed. The special film is attached with construction staples along the perimeter of the building under the rafters and directly to them. Work is carried out on the inside of the roof. The roll is carefully rolled out and the film is mounted in its intended place.

Step 3 Separate vapor barrier strips must be laid overlapping each other, while all overlaps, as well as the junction of the material with all structural elements roofs (pipes, ventilation, etc.) are hermetically glued with adhesive tape.

Step 4 On top of the film, the rails of the counter-lattice are nailed to the frame - it is on them that the entire interior decoration attic space.

Step 6 Thermal insulation is laid on the vapor barrier between the rafters. Laying is done very tightly in order to reduce the number of cold bridges. This concludes the preparatory work.

Laying a waterproofing layer

After carrying out all the preparatory work, the installation of a waterproofing film is carried out. In this case, the Tekafol Super membrane is used as a material that protects against moisture.

Step 1. The membrane roll is rolled out on the surface of the insulation along the roof eaves. It is important to lay the material on the correct side, which will be determined by the installation instructions for the selected type of film (usually the material is fixed on the side to the roofing where edging tape has a bright and saturated color). The film is laid with a slight sag (about 2 cm). This measure will allow you to get rid of excessive tension and rupture of the material in the event of a sharp temperature drop.

Attention! The film should be laid initially on the correct side. It is impossible to twist and turn it over during installation, as it will lose some of its waterproofing properties.

Step 2 The film is attached to wooden rafters with a construction stapler. Instead, you can use nails with a wide hat.

Step 3 Next, the second strip of waterproofing is spread. It is laid with an overlap on the first (15 cm). If the angle of inclination of the slope does not exceed 30 degrees, then the overlap between the individual layers should not be less than 25 cm. The joints can be additionally glued with double-sided adhesive tape.

Step 4 The second strip is fixed waterproofing membrane. Thus, the entire thermal insulation material is covered with a film. In places where pipes, hatches and other structural elements are located, it is required to securely fix the material. It is also important to remember that the waterproofing layer is not brought to the roof ridge - there should be a ventilation gap of 5 cm. It will be closed with a ridge strip.

Step 5 Along the rafters, directly through the waterproofing film, 4x5 cm lathing bars are fastened with self-tapping screws. They will additionally fix the film on the rafters.

Step 6 Across the bars of the crate, the bars of the counter-bar are fastened with a step of 35 cm - it must correspond to the step of the metal tile. Next, the installation of the tile itself is carried out directly.

It is worth remembering that a gap of 5 cm must be observed between the tiles and the waterproofing. Otherwise, the required air circulation will not be provided. There may not be a gap above the insulation if a high-quality diffuse membrane is used.

Video - Installation of a hydrobarrier

Rules for installing a hydrobarrier film

When working with waterproofing, it is important to remember a few installation rules:

Cold roofs - is waterproofing necessary?

The answer to this question will be unequivocal - a waterproofing layer is needed in any case. But since in this case there will be no insulation in the roofing cake and it will be provided good ventilation materials, you can use roofing material or glassine, which will be cheaper than expensive film. But in this case, the formation of a ventilation gap between the roofing material and the metal tile is required.

Waterproofing is a very important layer in the roofing pie of a roof covered with metal tiles. It should not be neglected, so that later there are no problems with leaks or a reduction in the service life of the materials used to create the roof.

Video - Installation of metal roofing

Today, more and more developers are asking this question. The fact is that a cold roofing system allows you to build a residential building for relatively little money, when an insulated roof requires enormous costs, as in financial terms, so in terms of time and effort. Realizing that such a system is in a sense better, many developers have wondered if a vapor barrier is needed under a cold roof?

Cold roof construction in a residential building

Many developers who want to save some money on construction tend 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 primitive two slopes are used as a rafter system, corrugated board as a covering, and the roof is made cold.

The design features of such a roof can be listed on the fingers, since there is no need to lay thermal insulation material, vapor barrier and other components often found on insulated roofs. If you all doubt the savings, then it is safe to say that the cold version will cost 50-60% less than the insulated design. In addition, the work can be carried out independently, therefore, the savings will increase even more.

A cold roof pie, in most cases, includes the following products:

• rafter legs
• waterproofing material
• Control lathing
• crate
• Profiled metal sheet

Do I need waterproofing under the metal roof of a cold roof?

It is worth noting that all metal surfaces have one similar feature, they collect condensate. Waterproofing, which is part of 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 building an insulated roof, advise their friends not to lay a vapor barrier layer if they are building 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 wrong.

Condensation occurs due to the temperature difference between the roof space and the external environment. Naturally, when the attic is not heated and not insulated with anything, the difference will be small, but still it is sufficient to provoke the release of moisture from the air. As you can see, condensate 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 needed.

An example is outbuildings, the owners of which do not care much about their service life. In such buildings, the roofing cake is the most primitive and even violates building codes and regulations. Most often, a roofing cake consists of rafters, discharged lathing and roofing. All layers of vapor barrier and waterproofing were simply thrown out. Despite this fact, this building can stand for a significantly long period, or vice versa, fall apart after a couple of years. Here you are already lucky, but why take risks if you can do everything in a quality way?

Risks cannot be allowed on residential buildings, as someone's life may depend on it. I am not exaggerating, because if the condensate affects the truss 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 decided to build cold roof, but in the future after a certain period you will insulate it, then it is most expedient to lay a microperforated film as a waterproofing product. Its properties are practically no different, but according to the price tag, it is much lower than membranes.

Waterproofing and ventilation of a cold roof

If you are laying a micro-perforated product, then such a layer will block moisture from the outside, but water vapor can pass through this area without problems. It can be said that the installation of vapor barrier products on roof slopes is not necessary in this case. After the steam penetrates inside, it is between the waterproofing material and the metal coating, from where it is removed by natural ventilation.

IMPORTANT: When using thick waterproofing film, retaining water vapor, 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 reverse side of the film and penetrates into all roofing materials. In connection with this fact, it is not recommended to use materials such as polyethylene and polypropylene, roofing felt, and glassine for the construction of a cold roof.

The ventilation system of cold roofs is quite simple. To create it, gaps are left, which, as a rule, are located along the cornice overhang. Air masses pass through them, collect all the humidified air and remove it through a 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 complex roofing systems where products with a high degree of waterproofing are used as a coating, for example, metal, shingles and others. The gap that is created by installing the control battens allows fresh air dry the roofing cake on both sides, so structures with such a cake last much longer than the others.

Cold roof. Do buildings need waterproofing?

First of all, it should be noted that outbuildings differ significantly from residential buildings both in their structure and volume. The vast majority of developers are trying to save on the construction of secondary structures, so the issue of waterproofing is more relevant than ever. Before answering the question posed, let's deal with the coverage. To date, corrugated board 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 begins to use it. If you are a fan of corrugated board, then today, such material is a sheet of metal with an anti-condensation coating.

In my own way appearance it practically does not differ from its analogues. A synthetic composition is applied from the inside, it looks like felt. Thanks to a large number pores, this material is able to detain in square meter up to 1 liter of water. After the surface has been saturated with moisture, ventilation comes into play and if it is done in accordance with all the rules and regulations, then the drying process will not take much time.

Thanks to the laying of such a “cunning” coating, the need for laying a vapor barrier and waterproofing layer is removed, but it should be understood that the weight of such a coating will vary depending on weather conditions. Making necessary calculations it is very important to take into account these parameters and use them in the calculations. It is worth noting that finished roof it will be much cheaper, because it will not have almost half a roofing pie.

Installation of waterproofing for a cold roof

So, based on the information obtained above, you understand that the waterproofing material is laid regardless of the type of roof and functional purpose the buildings. However, if you want to save money, you can use roof coverings with an anti-condensate layer, but not all people like metal coatings so I'll tell you now general principle waterproofing installations.

• First of all, an inexperienced roofer must repeat the safety precautions and the principle of working at height. After that, he puts on a special outfit, which should include the following: personal protective equipment, good shoes with non-slip sole and mounting belt.
• After the rafter legs are fixed in place, you can start laying the vapor barrier layer. It is attached to the rafters with a construction stapler and pressed against the crate. With a small slope, the strips of material are placed across the slope, and along the strongly sloped slopes. To improve the quality of laying this layer, the joints are smeared with bitumen or glued with double tape.

IMPORTANT: Before installing the crate, it is very important to treat its elements with special protective solutions that will increase the degree of ignition of the wood and protect it from decay.

• Next, the counter-lattice is laid. It creates the necessary air gap, thanks to which moisture will be removed from the roofing cake.
• A waterproofing material is laid on top of the konroblattice.
• After that, proceed to the installation of sheets of corrugated board.

Most developers strive to cover as much length as possible with one strip of profiled sheet. This is justified by the fact that in this way fewer joints are obtained, therefore, the waterproofing qualities of the entire roof increase significantly. You can do all the work yourself, but to increase efficiency it is better to invite 1-2 partners.