Roof waterproofing under corrugated sheets, cold roof. In what cases is it justified to install waterproofing under corrugated sheets? Polypropylene film

The roof is playing key role in protecting the house from precipitation and other adverse influences. A number of materials are used to preserve heat and maintain a comfortable microclimate. All together they make up a roofing pie. To prevent heated air from leaving the room during the cold season, use thermal insulation materials under corrugated board. A vapor barrier will help maintain a low degree of thermal conductivity.

Why do you need a vapor barrier under corrugated sheets?

Vapor barrier (as well as waterproofing) is installed under corrugated sheeting to achieve two goals:

1. Protect the thermal insulation layer from moisture. When wet, its thermal conductivity increases. Also, the penetration of liquid leads to the gradual destruction of the insulation.
2. Prevent the accumulation of moisture in the thermal insulation layer and direct water vapor outward.

There is always water vapor in the air of a residential building. Partially they escape through the ventilation system, while a certain proportion remains in the room. Warm air, saturated with vapor, rises upward towards the ceiling. There it cools, and moisture is transferred to the roofing materials.

Due to its porous structure, insulation absorbs moisture. As it gets wet, its thermal conductivity increases, and it retains heat in the room less well. To prevent moisture from penetrating into the pores of the insulation, use a vapor barrier film under the corrugated sheeting. It is laid from the side of the room and is needed to protect the insulation and other structural elements from the ingress of water vapor.

What to consider when choosing a vapor barrier

IN construction stores There are many types available vapor barrier films for roofs - both cold and attic. To do right choice, awareness of the following factors is required:

• price;
• efficiency;
• expediency.

Before purchasing materials for corrugated sheeting, you need to decide on the amount allocated for construction. If the price of the material is decisive, you need to choose from economical materials.

The second point is efficiency. Vapor barrier films have different performance characteristics, which are important to familiarize yourself with before purchasing.

It is worth choosing a material that suits the characteristics of the room. For a heated residential building, foil film would be the best option, while for a cold roof country house building quite sufficient inexpensive glassine. If you are installing the roof of a rarely visited mansion that has not been heated for a long time, you need a simple vapor barrier made of polyethylene or polypropylene.

What materials are used for vapor barrier

The vapor barrier layer under corrugated sheeting or any other roofing material is made in the form of a film. The following are the most common types of it, which are presented in hardware stores.

Polyethylene film. Household polyethylene has long been used as vapor barrier material. It does not allow steam rising from the living space to pass through. Polyethylene - cheap material compared to reinforced films or membranes. Its significant disadvantage is its lack of strength. It is easy to damage the film during installation. For reliable vapor barrier it is laid in two layers and fixed to the inner sheathing with a construction stapler. The fastening step is from one to one and a half meters. If the film is still damaged, a patch is needed. The puncture site should be covered with construction tape. The joints also need to be secured with tape. Considering the above, polyethylene film is quite acceptable and cheap, but at the same time not the best option for vapor barrier.

Reinforced polyethylene film. Also inexpensive, but quality material for vapor barrier under corrugated sheeting. It is made of several layers of polyethylene and reinforced with polypropylene mesh. Such a film is light in weight and has sufficient strength; it is more difficult to damage during installation. Due to the reinforcing mesh, the material has greater rigidity. The film can be secured with a special tape. This - optimal combination low price and good quality material, suitable for vapor barrier of residential buildings.

Glassine. This material has long been used for vapor barrier. It reliably retains moisture, is durable and has a long service life, but has quite a heavy weight. Although glassine is a cheap material, it is not recommended for residential premises. When heated, it emits bad smell, and under the corrugated sheet its temperature will often rise, especially in the warm season. Therefore, glassine should be used only for a bathhouse or a cold roof. non-residential attic. It is more convenient to use it as waterproofing - then it will need to be laid on top of the sheathing.

Polypropylene film. Durable material for vapor barrier under corrugated sheeting. Manufactured similarly to multilayer plastic film. The two main differences are the use of polypropylene and the presence of a relief layer. The fact is that condensation accumulates on smooth polyethylene films, which collects in drops and periodically drips onto the floor. The rough anti-condensation coating is made from viscose and cellulose. It absorbs moisture and prevents it from beading. Subsequently, when the air humidity decreases, the collected condensate evaporates. As a rule, polypropylene film is placed with the anti-condensation surface down, towards the room. To clarify the installation procedure, you need to refer to the manufacturer's instructions. This variety vapor barrier film - one of best options for arranging the roof under corrugated sheeting.

Foil film. In fact, it is a type of polyethylene or polypropylene film. In addition to the reinforcing mesh, it has a thin aluminum layer. It reflects infrared rays and helps maintain heat in the house. Although at first this material was used in the construction of bathhouses, it began to be used for vapor barrier in residential buildings. After laying foil film, heat loss is reduced by 10 percent or more. Its price is higher than other types of vapor barrier films, but it justifies itself by allowing you to save on heating costs. The foil film is laid with an aluminum layer towards the room. Be sure to leave a gap between the material and the wall finish: a gap of about 5 cm is needed. A small distance should be left to the insulation. The film is fixed with self-adhesive tape, all joints are covered aluminum tape. Then the vapor barrier layer will be airtight.

Features of a cold roof

Although the space directly under a cold roof is not heated, the temperature inside will still be different from the temperature outside. Therefore, condensation will begin to appear on the underside of the corrugated sheet. In view of this, a waterproofing layer is necessary to prevent moisture from entering the wooden rafters and others structural elements cold roof.

Important ! The waterproofing layer is laid on top of the rafters. Then the material is fixed with a counter-lattice, followed by the lathing and the corrugated sheet itself.

If the waterproofing layer does not prevent steam from escaping to the outside, a vapor barrier for cold roof slopes is not required. Water vapor, having risen, will penetrate through the film under the corrugated sheet, and there it will be dried under the influence of air currents.

It is important to choose a material for waterproofing a cold roof that will not trap steam. In this case, polyethylene, polypropylene, roofing felt or glassine are not suitable. For a cold roof, a non-woven vapor-permeable membrane is recommended.

As you can see, vapor barrier is installed only for warm roof to protect the insulation from water vapor. There are several recommendations that will help you do this job efficiently.

1. It is better to place panels of vapor barrier material with an overlap of about 15 cm.
2. You need to select the appropriate connecting tape for the selected film or membrane.
3. Vapor barrier strips can be made of either wood or metal. They should be small in size.

When settling in warm roof vapor barrier is an important component roofing pie. The material is selected based on financial and practical considerations, and also based on its feasibility.

There is no need to install a vapor barrier under a cold roof. In this article we will take a closer look at why this is not necessary.

Why vapor barrier is not needed for a cold roof

Cold roofing is rafter system, on which waterproofing material is laid. It will prevent moisture from entering the under-roof space and protect the rafter system from premature destruction. Then a counter-lattice is installed to ensure natural ventilation: Air flow enters under the roof and removes excess moisture. Usually a 50*50 mm block is used.

Since there are no significant temperature changes in the roofing “pie”, the dew point will be shifted towards the insulation of the last floor ( warm air will condense in the insulation in front of the attic), so no vapor barrier is needed in a cold roof, but it will be needed before the insulation on top floor, in front of the attic.

Is cold roof waterproofing necessary?

Yes, definitely needed. Whichever perfect roof no matter how it was, no one is protected from water getting into a microcrack or a minimum gap. From such a gap in the future there may be big trouble, especially if access to inner surface hidden: something is undermining somewhere, but where is unclear. In such cases, waterproofing is needed, even if there is no insulation.

If the roof is metal, then waterproofing will protect against premature corrosion. Since the thermal conductivity of metal is higher than that of slate, ondulin or bitumen shingles, then condensation will form more often.

The waterproofing film is laid with a slight sag (about 20-25 mm) so that the condensate flows freely onto the cornice strip, and from it into the drainage tray. Also Basic structure In this case, the roof will be protected, and for effective evaporation of moisture, ventilation gap.

Ondutis films for waterproofing cold roofs

Waterproofing films Ondutis D (RV) are designed for waterproofing cold roof.

The film is a fabric gray with the addition of a protective layer and UV stabilizer. This film is used for waterproofing cold or insulated roofs with a metal coating. It retains moisture and protects the under-roof space from the harmful effects of condensation and cold air on the inside of the roof.

Ondutis Smart D (RV) is available with adhesive tape applied to the base, which simplifies installation and reliably isolates joints and overlaps.

The quality, tightness and durability of the roof of a house is determined not only by the characteristics of the roofing covering. Much depends on compliance with installation technology and the correct selection of roofing pie, the layers of which improve each other’s properties, extending the service life of the roof. When constructing a cold or warm roof from corrugated sheets, inexperienced craftsmen often wonder whether additional waterproofing is needed for this roofing covering. In this article we will talk about what waterproofing materials can be used for.

Waterproofing is an important layer of the roofing pie of a cold and warm roof of a house made of corrugated sheets, which is mounted on top of the rafters using a construction stapler. It is made from hydro insulating materials, which does not allow water to pass through, protecting wooden structures from getting wet. Waterproofing in corrugated roofing performs several functions:

• Protection of the inner surface of the corrugated sheet from corrosion. Weakness corrugated roofing is that the lower surface of this roofing material is protected only paint coating. Therefore, when wet and mechanical damage it can corrode.
• Preventing the thermal insulation material from getting wet. Waterproofing covers the insulation laid between rafter legs roofs. Indeed, as the humidity of the thermal insulation material increases, its effectiveness decreases sharply, but is not restored after drying. This function is relevant only for a warm roof of a house, since insulation is not used for installing a cold roof.
• Preventing the house roof frame from getting wet. Wooden elements rafter system, even if they are impregnated with an antiseptic, upon contact with water they begin to rot.

Note! Waterproofing is essential for both cold and warm corrugated roofs. Due to the difference in temperature inside the house and outside, condensation forms on the lower surface of the coating, so the service life of the corrugated sheet is reduced significantly.

Requirements for waterproofing materials

Waterproofing under a corrugated roof is used in difficult conditions, therefore it must have increased strength properties. Signs of a high-quality waterproofing material are resistance to moisture, high and low temperatures or changes therein, as well as vapor permeability. Experienced craftsmen When choosing, it is recommended to take the following factors into account:

1. Density. To withstand water pressure during leakage, and also not to be damaged during installation, waterproofing is needed with a density of 0.04 kg/m2.
2. Vapor permeability. To cope with the removal of heated air saturated with water vapor from the house, the level of vapor permeability must exceed 0.75 kg/m2.
3. Waterproof. High quality waterproofing film withstands water pressure of 10 MPa for 10 minutes.
4. Wide temperature range. Waterproofing must withstand temperatures in the range of -73/+100 degrees.
5. Fire resistance. Since the thermal conductivity of a cold or warm roof made of corrugated sheets is quite high, it is therefore recommended to use non-combustible materials for waterproofing.
6. UV resistance. Although the insulation is hidden under the roof finish, it must be able to withstand direct exposure. sun rays for 4 months or longer.

Please note that waterproofing for a cold roof made of corrugated sheets can be of any kind, but for a warm roof it is necessary to use only vapor-permeable materials. Using roofing felt or glass insulation to protect the structure from moisture only provokes even more active condensation, as well as accelerated wear of the coating.

Material selection

The construction market offers wide choose insulating materials for roofing, which differ in weight, strength and price. But not every waterproofing is suitable for metal profiles, since it must be vapor-permeable, dense, elastic and moisture-proof. There are 3 categories of waterproofing materials:

Experienced craftsmen point out that it is better to use diffuse and superdiffuse membranes for waterproofing metal coatings. Although they are more expensive, they have high strength, better air permeability and last up to 100 years.

Design Features

The design of a cold and warm metal profile roof differs in the presence or absence of thermal insulation material in the roofing pie. The second option is more expensive for developers; it is used if the project involves a heated roof space. There are different requirements for waterproofing cold and hot roofs:

1. To insulate a cold roof, it is necessary to use durable, durable materials capable of coping with high pressure water in case of leakage. You can even use roofing felt, roofing felt, steklomast or rubemast, despite the fact that they are not vapor-permeable.
2. To install a warm roof you need vapor permeable material type of diffuse or superdiffuse membrane, since it is characterized by increased condensation.

You cannot save on waterproofing material, since this little thing, which costs 100-200 rubles per 1 m2, depends on the service life of an expensive roofing covering.

Video instruction

The roof protects the residential building from precipitation. But how to protect the roof? The first thing that comes to mind is the topcoat. But its functions are slightly different, due to the fact that moisture can still penetrate through the roofing material. In the path of moisture, the real barrier and, in fact, the only protector of the roof from getting wet and the harmful effects of water is waterproofing.

The need for waterproofing a cold roof

The main task of roofing is to protect buildings from wind loads and precipitation. If there must be three layers under the roof of an insulated attic (insulation, vapor barrier and waterproofing), then there may be nothing at all under the roofing of an unheated attic. However, in practice, on the other side, a layer of waterproofing is still installed.

If the water sources were only outside, then you could, in principle, do without waterproofing a cold roof, while hoping that the quality of the roof itself would guarantee the absence of blowing, snow, rain and any leaks 100%. With proper installation of some types of roofing, this is true.

But the problem lies not in the precipitation itself, but in its condensate, that is, drops falling from inside roofing covering. The likelihood that condensation will occur increases if, for example, engineering equipment through the attic. These can be fireplace pipes, chimneys, as well as various elements heating and hot water supply systems.

No matter how effective the insulation is, heat is always released, which is why there is a significant temperature difference in the attic. Depending on the different temperatures is formed in the air different quantity moisture, and when warmer air is transferred to the roof, it reaches the “dew” point, which leads to condensation.

Therefore, there is no doubt about the need to waterproof a cold roof made of metal tiles, which makes it possible to facilitate the process of converting an attic into residential attic, if you have such a desire. Therefore, there is no need to neglect roof waterproofing, which protects the roof space from condensing and atmospheric moisture.

In principle, in cold attics, any type of material can be used for roof waterproofing: anti-condensation films, diffusion membranes and ordinary films. Homeowners most often choose anti-condensation films; they are cheaper than diffusion membranes. And their advantage over conventional films is that they have a fleecy layer on the inside, thanks to which they can retain condensation for a certain time until conditions are created for the evaporation of moisture.

In a cold roof, the waterproofing film is installed under the profiled sheets at a distance of 5 centimeters (an additional structure is made for this purpose). With this, the temperature will be equalized on the inside and outside of the sheets. A properly installed cold roof insulation system will bring no less benefits in terms of structural reliability than roof covering by itself.

Roof waterproofing materials

For a variety of roofs they are used as waterproofing various materials: ranging from common roofing felt in rolls and various mastics, to superdiffusion membranes. What material to buy depends on the roofing pie and operating conditions. First of all, you need to decide on the roofing pie, and the choice of waterproofing material for a cold roof will happen on its own.

Coating insulation

Mastics are used as independent species waterproofing for flat and self-leveling roofs. But usually they use coating insulation as an auxiliary measure. Namely, for the purpose of repairing various roll roofing, sealing displaced joints and cracks roll material, sealing dormer windows, pipe outlets, additional insulation of the ridge part, valleys, end parts and gluing bitumen shingles.

For device mastic roofing It is necessary to thoroughly clean the base from loose parts, dust, and dirt. It is also additionally recommended to impregnate the base with a degreasing compound or bitumen primer. But mastics cannot be used on sloping roofs as independent waterproofing.

Ruberoid

A very common and popular material for cold roofing, as it is relatively inexpensive. It is used for roofs with a slope from 0 to 25%. But still, he is rapidly losing his fans. The fact is that roofing felt has low durability, and after some time of use all its shortcomings appear: it collapses bitumen material under the influence of UV, the cardboard base rots, its integrity is compromised, and leaks begin. In addition, it is based exclusively on flammable materials.

Its new analogue with some eliminated shortcomings is euroroofing felt, which is based on a non-rotting material (polyester, fiberglass, fiberglass) that is coated with a special modified bitumen composition. Such euroroofing material has greater durability and, accordingly, highest price than its predecessor, but is still flammable and not environmentally friendly. It follows from this that the use of euroroofing material for roofing small areas often not profitable. But if this flat roofs, then this option is suitable.

Glassine

Glassine was once a fairly popular roofing waterproofing material that was used when installing cold roofs. It was he who replaced roofing felt, but also lost its popularity. The reason for this is rapid aging, low strength, loss thermal insulation characteristics, not environmentally friendly. This insulation option is the cheapest, but at the same time short-lived. It follows from this that glassine can only be used for temporary protection of roofing.

Membranes and films

Waterproofing films also include membranes made of polypropylene or PVC. Such materials are gaining popularity for several reasons: high waterproofing performance, greater foundation strength, vapor permeability, durability (up to about 50 years).

Membranes are divided into the following types: diffusion, pseudo-diffusion, super-diffusion and anti-condensation. Each type has its own application characteristics and its own purpose. Well, the price of membranes, unlike other waterproofing materials, is quite high. Moreover, their cost is often proportional to the characteristics of a particular material.

Pseudo-diffusion membranes are a film with quite low level vapor permeability - up to 300 g/m2/24 hours. This film can be used to protect a cold roof made of corrugated sheets. In this case, there are no restrictions on its adaptation. If it is used in an insulated roof pie, then it is necessary to create a ventilation gap between the insulation and the film. For its installation, additional sheathing should be made. Because of this, the cost of such insulation may increase and amount to an amount equal to a conventional diffusion membrane.

Superdiffusion and diffusion membranes are perforated films with high (more than 1000 g/m2/24 h) and medium (equal to 400-1000 g/m2/24 h) vapor permeability rates. For waterproofing a cold roof, this vapor permeability is sufficient. A ventilation gap is not required with this film. Such membranes have many advantages: they can be installed directly on the insulation; removes steam from the inside and at the same time does not let moisture in; acts as a wind barrier for the insulation, thereby retaining heat in the under-roof space; does not lose performance in a dusty environment.

However, such material forms condensation on the upper plane when steam is discharged, so it cannot be used under the roof because it can corrode. If the finishing coating is made of metal (zinc, steel, aluminum, copper), volumetric diffuse membranes are used. The layer that is in contact with roofing material, acts as a kind of separator that absorbs and thereby removes condensation from the metal roofing.

Anti-condensation membranes are also used for seam and metal tile roofs. The fleecy “carpet” is on one side of the film. This side is turned outward towards finishing coating, as shown in the video about cold metal roofing. It is necessary to create a ventilation gap under the insulation, since with such protection the vapor permeability approaches zero.

DIY cold roof waterproofing

Waterproofing that is properly installed should look like layered cake, which needs to create a substrate. Its composition depends on the type of substrate itself. Under a cold roof, this layer is performed as follows. The frame is laid on truss structures from counter-lattice and sheathing. Waterproofing material is laid on the lathing and pressed with a counter lathing.

For counter-lattice the best material is a strip impregnated with a fire retardant solution or antiseptic, 4-5 centimeters wide and 2-3 centimeters thick. It is necessary to lay the sheathing boards horizontally, and the counter-lattice boards vertically. In this case, channels should be formed between the slats of the counter-lattice, which have a height of 2-3 centimeters. They are needed for roof ventilation. Maintain such a distance between the slats that the entire area of ​​the channels is equal to 1/100 of the roof area.

Vapor moisture can be removed using ventilation. With a roof slope area of ​​one hundred square meters, the area of ​​common ventilation ducts should be one square meter. Roofs must extend all the way to the ridge ventilation ducts so that moisture vapor can escape freely through the holes in the upper part of the roof.

The procedure for waterproofing a cold roof structure is as follows. Lay overlapping waterproofing membrane along the roof eaves in successive rows. Lay the material horizontally, moving from the eaves to the ridge of the roof. The width of the overlap depends on the degree of roof slope, which is in the range of 10-20 centimeters.

The film is fixed using galvanized nails with a wide head or the staples of a construction stapler. The place where the film joins is taped with tape to ensure complete sealing of the attic waterproofing. Subsequent layers of waterproofing film are laid in exactly the same way. Their number is determined independently.

Between the rafters, the sagging of the film should be about twenty millimeters. There must be an air pocket of 40 millimeters between the thermal insulation and the film. In order to ensure ventilation of the under-roof space, a ridge vent should be made on the ridge, that is, a gap between the ridge axis and the edge of the film. Required distance the indentation is 50 millimeters.

In areas where pipes, antennas and other communications are installed, the waterproofing film is attached to closely spaced sheathing bars, having previously cut it. Use construction stapler or double-sided tape. When skylights decorated with film, you must always follow special instructions from the material manufacturing company. A counter-lattice is nailed on top of the film with an interval of 10-15 centimeters between the bars.

Thus, with properly installed waterproofing, it will last total term service of insulation, roofing, and, of course, the entire roof. Therefore, it is necessary to be responsible when choosing a protective material from moisture and strictly follow the technology for laying waterproofing.

A house with a cold attic is far from uncommon in modern construction. This solution is especially relevant for outbuildings, as well as dachas. Often cold roof Corrugated sheeting is also used in residential buildings, when the main area of ​​the house is sufficient for its owner and there is no need to make an attic.

Installation of a cold roof made of corrugated sheets

The installation of a cold roof is advisable, first of all, for economic reasons. Firstly, you save on materials, and secondly, by isolating a large area of ​​under-roof space from the rest of the house, you do not spend money on heating it. And thirdly, installing a cold roof is much easier than laying a full-fledged roofing pie.

This article is devoted to how to properly make a cold roof from corrugated sheets.

Installation of a cold roof made of corrugated sheets in a residential building

The design of a cold roof is very simple. The slopes do not require any insulation, vapor barrier, or, moreover, finishing. Naturally, the savings in this case are quite significant, given that the price of thermal insulation and finishing is 50-60% of the cost of the entire roof. In addition, due to the simplicity of the design, a cold roof made of corrugated sheets can be installed with your own hands without any problems.

The cold roof pie consists of the following elements:

1. rafters;
2. waterproofing film or membrane;
3. counter-lattice;
4. sheathing;
5. corrugated sheeting

Cold roof waterproofing: is it necessary?

Waterproofing a cold roof will protect the room from possible leaks and condensation that forms on the inside of the metal roofing. Since condensation is released on metal surfaces when there is a temperature difference, there is a common misconception that it will not occur if an uninsulated roof made of corrugated sheets is installed.

Naturally, such an opinion is not true, since, despite the fact that the under-roof room is not insulated or heated, the temperature inside will still differ from the temperature outside, and often quite significantly. Therefore, the answer to the question: “Will there be condensation on the corrugated sheeting if the roof is cold?” - unequivocal: “Yes, it will be.”

In this regard, it becomes obvious whether waterproofing is needed under the corrugated roof of a cold roof. The consequence of its absence will be that condensation will fall on the ceiling, increasing the humidity in attic. This will lead, at best, to accelerated deterioration of wooden structures, and at worst, to a catastrophic decrease in the thermal insulation properties of the insulation if it is unprotected.

Installation of waterproofing film with sagging

Waterproofing membrane cold roofing is laid on the rafters and secured with a counter-lattice, after which the lathing for installing the corrugated sheeting is already installed.

If you do not intend to insulate a cold roof in the future, then you can use microperforated film as waterproofing, which costs much less than special membranes. However, it must be installed with a mandatory sag of 20-30 mm so that moisture flows into the space between the rafters, and does not moisten them, seeping through due to the capillary effect.

Vapor barrier and ventilation of cold roofs

Since micro-perforated films prevent the penetration of moisture from outside, but do not interfere with the passage of water vapor; vapor barrier of a cold attic on the roof slopes is not required. Water vapor, having passed through the film, ends up between the waterproofing layer and the corrugated sheet, from where it is removed by an air flow.

If a waterproofing film for a cold roof retains water vapor, this will lead to excessive moisture in the room and, as a result, dampness. In addition, as humidity increases, steam will condense on the film from the inside. Therefore, ordinary polyethylene and polypropylene films, as well as outdated materials such as roofing felt or glassine, are not suitable for waterproofing cold roofs.

Ventilation of a cold roof is very simple and is achieved by creating a gap using a counter-lattice: the air flow enters under the roofing through eaves overhang and exits through the ridge.

Always make a counter-lattice

The presence of a counter-lattice is a prerequisite for good ventilation. It is this gap of several centimeters between the film and the sheathing that allows air flow pass unhindered under the roofing.

Ventilation of a cold attic is carried out using ordinary dormer windows, which must be located in such a way as to ensure the passage of air flow when ventilated throughout the room. If the size of the under-roof space is large, the ventilation of a cold attic in a private house can be improved using a classic supply and exhaust circuit.

If you are planning to insulate a cold attic in the future

In the event that a cold roof made of corrugated sheets is temporary option, and in the future you plan to insulate it to create a full-fledged living space, microperforated film should not be used as waterproofing. The fact is that insulation cannot be installed close to it - if this is done, the film will lose all its waterproofing properties and begin to let water through.

This film must be replaced with a non-woven vapor-permeable membrane. In particular, those types of Tyvek or Dorken membranes that can be laid directly on the insulation are ideal for these purposes. They, of course, are more expensive, but their use will reduce the thickness of the roofing pie by 80-90 mm. If you already use microperforated film as waterproofing for a cold roof made of corrugated sheets, you must provide a gap of at least 50 mm between its lowest point, taking into account sagging, and thermal insulation.

In addition, vapor barrier of a cold roof converted into an insulated one is not necessary, since the steam will pass through the insulation and, without remaining in it, will be removed through the film or membrane.

Cold roof made of corrugated sheets in utility rooms

For sheds, cabins and others utility rooms installation of a cold roof made of corrugated sheets - best option. In this case, it is recommended to use special corrugated sheeting with an anti-condensation coating.

Corrugated sheeting coated on the inside with an anti-condensation coating

Such a profiled sheet with reverse side covered with a special synthetic composition, which is similar in structure to felt. Due to the large number of small air cavities, this material can hold enough a large number of moisture - up to 1 liter per m2. Thus, when humidity increases, the anti-condensation coating absorbs water, which then evaporates under the influence of cold roof ventilation.

Thanks to the use of corrugated sheets with anti-condensation coating, the design of a cold roof becomes much simpler and cheaper, since neither waterproofing nor counter-lattice is needed. In addition, such material is indispensable for gazebos, verandas, canopies and other open structures, since in principle they do not use waterproofing, and condensation appears no worse than in a cold attic.

Installation of cold roofing from corrugated sheets

First, the waterproofing is installed, with sagging if microperforated film is used as it. It is fixed using counter-lattice bars nailed to the rafters parallel to them.

Then the house is sheathed. About how to make it and what step to choose depending on the brand of profiled sheet -.

Next, the direct installation of a cold roof made of corrugated sheets is carried out. If the width of the roof slopes is less than the maximum possible length of the corrugated sheet, then it is laid without any transverse joints at all, which improves the tightness of the coating. Side joints are made in 1-2 waves, depending on the slope of the roof and the grade of the profiled sheet. Read more about installing a cold roof made of corrugated sheets.

Don't forget to treat the rafter system

Cold roofing technology is quite simple, so its installation is quite quick. However, all wooden components of the roof must be treated in advance special compounds, which will prevent them from rotting, as well as mold and mildew.

How to insulate a cold roof?

Often, installing a cold attic is just an intermediate stage. Most cold roofs are insulated over time in order to increase the living space of the home. This is easy to do, since there is no need to redo the cold roof pie - it is, in fact, the upper part of the insulated roof pie.

In order to make an attic out of a cold attic, you just need to add a layer of insulation and finishing. If, as we recommended, you used a waterproofing, vapor-permeable membrane, rather than a micro-perforated film, as waterproofing, then the thermal insulation material is laid closely between the rafters. Then the internal lathing with bars is performed required thickness, between which a second layer of insulation is mounted. You can also attach a finishing touch to them - wooden boards or drywall.

Insulating a cold attic using sprayed polyurethane foam

When insulating a cold attic, a layer of vapor barrier is not needed, since water vapor from inside the room will pass through the insulation and exit the roofing pie through the waterproofing membrane into the under-roof space. Therefore, before insulating a cold roof, do not forget to treat all internal wooden structures with compounds that prevent rotting.

In addition to this method, insulation of a cold roof attic can also be done by spraying polyurethane foam. This is one of the fastest and simple options, besides, this insulation is considered one of the best existing on the market. It is fireproof, has excellent heat-insulating properties, is durable, resistant to acids and alkalis, and does not rot.

In addition, insulating a cold roof made of corrugated sheets using polyurethane foam allows you to create a continuous layer of thermal insulation, in which not only will there be no cracks, but the rafters will also be covered. The only drawback of this method is the cost. Also, you will not be able to do this work yourself, since it requires expensive equipment.