A house with a cold attic is far from uncommon in modern construction. This solution is especially important for outbuildings, as well as summer cottages. Often, a cold roof made of corrugated board is also made in residential buildings, when the main area of the house is sufficient for its owner and there is no need to make an attic.
Cold roof device made of profiled sheet
The device of a cold roof is advisable, first of all, for economic reasons. Firstly, you save on materials, and secondly, by isolating a large 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 cake.
This article is devoted to how to correctly make a cold roof from corrugated board.
Installation of a cold roof from corrugated board in a residential building
Cold roof construction is very simple. On the slopes, you do not need any insulation, no vapor barrier, or, especially, finishing. Naturally, the savings in this case are very significant, given that the price of 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 board with your own hands fits without any problems.
Cold roof cake consists of the following elements:
- rafters;
- waterproofing film or membrane;
- counter lattice;
- lathing;
- corrugated board.
Cold roof waterproofing: is it necessary?
Cold roof waterproofing will protect the premises from possible leaks and condensation that forms on the inside of the metal roofing. Since condensation is released on metal surfaces when the temperature changes, there is a common misconception that it will not happen when an insulated roof made of corrugated board is installed.
Naturally, such an opinion does not correspond to reality, since, despite the fact that the under-roof room is not insulated or heated, the temperature inside will still differ from the outside temperature, and often quite significantly. Therefore, the answer to the question: "Will there be condensation on the corrugated board if the roof is cold?" - unambiguous: "Yes, it will."
In this regard, it becomes obvious whether waterproofing is needed under the cold roof sheeting. The consequence of its absence will be that condensation will fall on the ceiling, increasing the humidity in the attic. This will lead, at best, to accelerated damage to wooden structures, and at worst - also to a catastrophic decrease in the thermal insulation properties of the insulation, if it is unprotected.
Sagging waterproofing film installation
The waterproofing membrane of the cold roof is laid on the rafters and fixed with a counter-lattice, after which the lathing is already mounted for installing the corrugated board.
If you are not going to insulate a cold roof in the future, then a micro-perforated film can be used as waterproofing, which is much cheaper than special membranes. However, it must be mounted with a mandatory sagging of 20-30 mm in order for moisture to drain into the space between the rafters, and not moisten them, seeping through due to the capillary effect.
Vapor barrier and cold roof ventilation
Since micro-perforated films prevent the penetration of moisture from the outside, but do not interfere with the passage of water vapor, vapor barrier of the cold attic on the roof slopes is not required. Water vapor, passing through the film, finds itself between the waterproofing layer and the corrugated board, from where it is removed by the air stream.
If a waterproofing film for a cold roof traps water vapor, this will lead to excessive moisture in the room and, as a result, dampness. In addition, with increasing humidity, steam will condense already on the film from the inside. Therefore, ordinary polyethylene and polypropylene films, as well as outdated materials such as roofing material or glassine, are not suitable for waterproofing a cold roof.
Ventilation of a cold roof is very simple and is ensured by creating a gap with a counter-lattice: the air flow enters under the roof covering through the eaves and exits through the ridge.
Always make a counter grill
The presence of a counter lattice is a prerequisite for good ventilation. It is this gap of a few centimeters between the film and the crate that allows the air flow to pass unhindered under the roof covering.
Ventilation of a cold attic is carried out using conventional dormer windows, which should be positioned in such a way as to ensure the passage of air flow during ventilation throughout the entire room. If the size of the under-roof space is large, ventilation of a cold attic in a private house can be improved using a classic supply and exhaust system.
If you are planning to insulate a cold attic in the future
In the event that a cold roof made of profiled sheet is a temporary option, and in the future you plan to insulate it to create a full-fledged living space, micro-perforated film should not be used as waterproofing. The fact is that it is impossible to mount a heater close to it - if this is done, the film will lose all its waterproofing properties and will begin to let water through.
This film must be replaced with a nonwoven vapor permeable membrane. In particular, those types of Tyvek or Dorken membranes that can be laid directly on the insulation are perfect for these purposes. They are, of course, more expensive, but their use will reduce the thickness of the roofing cake by 80-90 mm. If you already use micro-perforated film as waterproofing for a cold roof made of corrugated board, you must provide a gap of at least 50 mm between its lowest point, taking into account sagging and thermal insulation.
In addition, the vapor barrier of a cold roof, converted into an insulated one, is not needed, since the steam will pass through the insulation and, without lingering in it, will be removed through the film or membrane.
Cold corrugated roof in utility rooms
For sheds, change houses and other utility rooms, a cold roof made of profiled sheet is the best option. In this case, it is recommended to use a special corrugated board with an anti-condensation coating.
Profiled sheeting, covered from the inside with anti-condensation coating
Such a profiled sheet on the reverse side is covered with a special synthetic compound, which is similar in structure to felt. Due to the large number of small air pockets, this material can retain a fairly large amount of moisture - up to 1 liter per m2. Thus, when the humidity rises, the anti-condensation coating absorbs water, which is then evaporated by the ventilation of the cold roof.
Thanks to the use of a profiled sheet with an anti-condensation coating, the construction 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, awnings and other open structures, since in principle waterproofing is not used in them, and condensation appears no worse than in a cold attic.
Installation of a cold roof from corrugated board
First, the waterproofing is mounted, with sagging, if a micro-perforated film is used as it. It is fixed with the help of counter-lattice bars nailed to the rafters parallel to them.
Then the lathing of the house is performed. How to make it and what step to choose depending on the brand of the profiled sheet -.
Further, the direct installation of the cold roof from the corrugated board 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 transverse joints at all, which makes it possible to improve 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 the installation of a cold roof made of corrugated board.
Do not forget to process the rafter system
Cold roof technology is quite simple, so its installation is quick enough. However, all wooden components of the roof must be pre-treated with special compounds that will prevent them from rotting, as well as mold and mildew damage.
How to insulate a cold roof?
Often a cold loft is just an intermediate step. Most cold roofs are insulated over time in order to increase the living space of the house. This is easy because there is no need to redo the cold roof pie - it is, in fact, the top 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 and not a micro-perforated film as waterproofing, then the material for thermal insulation is placed close to the rafters. Then an internal lathing is made with bars of the required thickness, between which a second layer of insulation is mounted. It is also possible to fix the finish on them - wooden boards or drywall.
Insulation of a cold attic using polyurethane foam spraying
When insulating a cold attic, a vapor barrier is not needed, since water vapor from inside the room will pass through the insulation and exit the roofing cake 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 decay.
In addition to this method, the insulation of the cold roof attic can also be performed by spraying polyurethane foam. This is one of the fastest and easiest options, and besides, this insulation is considered one of the best on the market. It is fireproof, has excellent thermal insulation properties, is durable, resistant to acids and alkalis, and does not rot.
In addition, the insulation of a cold roof made of corrugated board with the help of polyurethane foam allows you to create a continuous layer of thermal insulation, in which not only there will be no cracks, but the rafters will also be closed. The only drawback to this method is the cost. Also, you will not be able to do this work yourself, as it requires expensive equipment.
If earlier slate was widely used to cover the roof of a house, nowadays there are many more materials that look great, are practical and durable. One of them is corrugated board - a universal metal profile used for various purposes. You can choose corrugated board of any color and cover the roof with it without any problems. It is a reliable and durable material suitable for both warm and cold roofs. But, profiled sheeting cannot completely exclude the ingress of moisture into the attic. After all, even slanting rain in a strong wind or blizzard will penetrate under the roof. In addition, the attachment points of the corrugated board itself can allow moisture to pass through when the sealing washers deteriorate over time or they loosen the tightening of the self-tapping screws during thermal deformation of the sheet. This phenomenon negatively affects not only the insulation material, but also the entire structure of the cold roof. This way, the coating will not last long and may deteriorate. To eliminate this problem, it is imperative to waterproof the roof of the house under the sheets of corrugated board.
But a number of questions arise: what kind of waterproofing is needed? What functions does it perform? Do you need a waterproofing layer under the cold roof sheeting? How is the work done? Let's look at the answers to these questions.
Functional waterproofing layer
What is waterproofing for corrugated board? This is a roll material with which the roof is sheathed. If it is warm, then the material is attached directly to the insulating layer, and on the cold roof, the waterproofing is attached to the crate. In this case, the waterproofing material is laid in the first place, and only then the roof can be covered with corrugated board.
Note! The waterproofing film is often a special membrane that is not affected by ultraviolet radiation, temperature extremes, etc.
Waterproofing performs many tasks that are very important from a technical point of view. The main one is the protection of materials inside the roof from the harmful effects of moisture. If the roof is insulated, then the insulation will rot and lose its properties. But what about the installation of a cold roof? After all, there is no insulation, so there is nothing to rot. Is it possible then to make a roof from corrugated board without waterproofing? Not recommended. Indeed, in addition to insulation, the roof has other structural elements, such as rafters, lathing, etc. If moisture gets in, the material will also deteriorate. The wood will rot and the metal will rust. Waterproofing is done so that precipitation does not penetrate inside, and the condensate that forms on the inside of the corrugated board is removed through special gaps.
Advice! If, however, you decide to make a cold roof without waterproofing, it is important to provide good ventilation in the attic. This requires holes in the gables of the wall or in the filing.
To understand how much waterproofing is needed for the roof of a house, we will give a simple example. Without it, the entire roof structure and its elements will serve you half the time. Therefore, if you want to extend its life, its device is necessary. But, before making waterproofing under the corrugated board on the roof, it is important to choose the material. What should be considered when buying?
Material requirements
You should know in advance what you are taking, since the assortment in stores is large enough, and you can get confused. The product must meet the following requirements:
- resistance to various influences, both physical and weather;
- the ability to withstand heavy loads without losing their original properties;
- have an elongation at the time of rupture not less than 10%;
- do not fall under the weight of the liquid, which may accumulate on the surface;
- do not emit harmful substances when heated;
- strength, reliability and stability, material density from 0.04 to 0.06 kg / m 2;
- the material must meet standards and be environmentally friendly;
- have a long service life;
- so that it can be easily stacked;
- be fireproof (according to GOST 30244-94), water and vapor tight (not less than 0.75 kg / m2 per day).
If the waterproofing meets all these requirements, then you can be completely sure that the roof of the house will be reliably protected and will serve you much longer. It is clear that the price of the material will be rather high, but still, the quality is above all. Now, let's look at exactly what materials are used to waterproof a cold roof under corrugated board.
Materials for waterproofing works
To perform waterproofing, two types of materials are most often used - polypropylene films and membrane ones. If your budget is tight, you can be content with plastic wrap. It has high hydro and vapor barrier, protects both structural elements and insulation (if any) with the highest quality. The material is made of polyethylene fiber, and to make the film more durable, it can be additionally reinforced with a special fabric or mesh. There are non-perforated and perforated polyethylene films. Some are intended for vapor barrier, others for waterproofing.
Nevertheless, if you want to have high-quality cladding that can last 30-50 years, then use membrane materials. It is a modern waterproofing material that meets all the requirements in terms of its technical properties and parameters. The material easily releases steam generated during the convection process, prevents corrugated board corrosion, lathing and rafters rotting and absorbs noise. The membrane film is made of synthetic fiber with a microstructure with high vapor permeability. There are two types of material - diffusion and super diffusion. The former have characteristic small holes. But if the material is tightly pressed against the insulation, then they will overlap. Therefore, it is important to provide a ventilated gap. The latter have a higher coefficient of vapor and waterproofing. They can be installed without ventilation gaps. The price of the material is slightly higher.
Now, let's look at how you can install waterproofing under a cold roof.
Step-by-step instructions for roof sheathing
So, if you bought the material, you can start installing it. The roll material is laid on top of the crate even before the corrugated board is fixed. There is a special instruction on the package where you can find out which side to attach the film to. It is necessary to move horizontally in the direction from the ridge to the cornice or from bottom to top in overlapping layers. What kind of overlap is needed depends on the slope. If the roof has a slope of less than 30˚, then overlap at least 15-20 cm, and if the slope is 12-30˚, then it should be 25 cm.
Note! If work is being carried out on the waterproofing of a hip-type hipped roof, then the overlap of the film on the ridges must be added by 5 cm.
It is better to connect the edges of the waterproofing with a special adhesive tape so that the joints do not allow moisture to pass through. How is the film fixed? With metal brackets directly to the battens.
To ensure high-quality fastening, slats with galvanized nails are stuffed on top of the film to the crate. So, the technology is as follows:
- The first strip of film is laid, starting the process from the bottom. The roll is rolled across the rafters.
- With the help of a construction stapler, the film is fixed on the roof of the house. Alternatively, you can use galvanized nails with a wide head.
- Lay the next strip higher, moving in the direction of the ridge. Remember to overlap according to the slope of the roof.
- After the two sheets are ready, reinforce them with a counter rail, which is 2-4 cm wide.
- So cover the entire area until you reach the ridge.
The same should be done on the other side. When everything is ready, you can proceed to waterproofing the ridge of the roof of the house from corrugated board. How exactly this can be done, learn from the following video.
As a result, we can say that waterproofing for the roof is very necessary and needs to be done with both warm and cold roofs. Then you will significantly extend the life of the entire roof.
Roofing profiled metal sheets are one of the most common roofing materials. The popularity of corrugated board is due to the democratic price, ease of installation, and low weight. However, along with the obvious advantages, this material has no less noticeable disadvantages. One of them is increased condensation. Under certain conditions, heavy dew falls on steel sheets, both outside and inside. Because of this, from time to time a little rain literally drizzles under the roof. Wooden structures and insulation have to be protected from condensation. The authors of some articles posted on the Internet claim that a waterproofing layer should be located under the steel sheets and even allow themselves to give advice on the choice of material. However, in fact, waterproofing for corrugated board is not needed, and sometimes it is contraindicated.
It should be understood: by no means all materials designed to protect against moisture are waterproofing.
Waterproofing
It is absolutely waterproof, withstands a fairly large water pressure (continuous flow of water), is very durable and resistant to atmospheric influences, ultraviolet radiation, which allows it to be used open. Waterproofing is suitable for the construction of hydraulic and underground structures, building foundations, flat roofs. Waterproofing materials include bitumen and bitumen-polymer roll insulation, mastics, polymer membranes, special cement-polymer penetrating compounds, bentonite clay slabs.
When installing a flat roof, the waterproofing layer can simultaneously serve as a roof covering
Vapor barrier
As the name suggests, it does not allow water vapor to pass through. Rolled waterproofing materials and polymer membranes cope with this task, but they are inconvenient for use in lightweight wall and roof structures. It is much easier to attach thin and lightweight reinforced polyethylene vapor barrier films to the frame. And they are much cheaper. The vapor barrier is also waterproof and able to protect against rain. But it does not have sufficient mechanical strength and resistance to ultraviolet radiation, which does not allow the use of vapor barrier in an open form, but only under the protection of roofing, wall cladding.
For the construction of roofs, mainly reinforced polyethylene and polypropylene vapor barrier films are intended. The mounted truss structures in the warm season are allowed to be left uncovered for a couple of months, protected only by a vapor barrier. It will protect the wood from precipitation. But no longer, the resistance of the film to ultraviolet light is limited, it can also not withstand the snow load.
Wind and moisture insulation
Wind and moisture insulation for the roof is able to protect the fiber insulation from being blown by the wind, to a certain extent retains liquid water, but at the same time freely passes water vapor. Due to such selective properties of moisture transmission, wind and moisture insulating films are also called diffusion membranes. They can be made of polymer fibers (non-woven canvas) or perforated film, there are also combined options.
Due to the presence of pores, the diffusion, wind and moisture protection membrane allows water vapor to pass through. But the size of these pores is so small that water droplets falling on the surface do not penetrate the film. Surface tension prevents this from happening. However, if the membrane is wetted for a long time and abundantly, sooner or later it will get wet, "it will leak." Wind and moisture protection is not suitable as protection against heavy rain; immediately after its installation, the roof should be covered with a roof covering
What is a roofing film (membrane)
It is clear: if the film is under-roofing, it means that it is placed directly under the roof covering. One of its main functions is to protect the rafter system and insulation (if any) from condensation, which can abundantly fall out on profiled metal sheets. Any of the above insulation materials will cope with it: hydro (steam) insulation, diffusion membrane (wind insulation). However, these are not all the tasks that the roofing film is designed to solve. What exactly is required of it and how to choose the right under-roofing film (membrane) directly depends on the type of roofing. Consider two types of roofs: cold attic and warm attic.
Recently, there has been a tendency to call vapor barrier a roofing film, and wind moisture insulation - a roofing membrane. This is not entirely correct use of the terms, but it just so happened. The main thing is in the difference in the physical properties of these materials.
It is important to know: unfortunately, the Internet is full of confusion on this topic; ignorant sellers of building materials and illiterate builders also contribute. Often, wind and moisture insulation and vapor barrier are called waterproofing. This is wrong, you need to understand that this is not the same thing, materials have different physical properties, they are designed for different types of roofs.
Roof above the cold attic
There is no need to insulate the attic roof, but you can ventilate it by making holes in the gable walls or filing.
In our case, the fundamental difference between a cold attic and a mansard (combined) roof is how they are ventilated, how excess moisture is removed from wood and insulation
Thus, moisture from the inside of the attic is removed due to good internal ventilation, it is only necessary to protect the structures from condensation that forms on the underside of the roofing. Installation of waterproofing under the corrugated board is possible. Once they did it, they rolled roofing material under corrugated asbestos-cement sheets (slate). Theoretically, you can use old linoleum, sheets of plastic, tin and other unnecessary trash that does not allow water to pass through. However, a special vapor barrier film will last longer, it is easier to fix, it is very inexpensive. You can also use a diffusion membrane, but there is not much sense in this: it will cost more, and its properties of passing water vapor will be unclaimed.
The roof structure of a cold attic should include a vapor barrier film
It is important to know: for a cold attic roof, the best roofing film is a vapor barrier, but any type of moisture-wicking material will do.
Roof over a warm attic
The mansard roof has to be insulated, and the insulation and wooden structures have the ability to absorb moisture from the air. It will not work to ventilate them from below, from the side of the premises, the air there is more humid than outside. On the contrary, from the inside, the roof must be protected from moisture by covering the rafters with a vapor barrier film. The only way to prevent wood and mineral wool from damp is to ensure their ventilation from the outside, be sure to leave a ventilated air gap with a height of at least 4 cm between the roofing and the under-roofing film.Hydro (steam) insulation will not ensure the release of water vapor, therefore, for mansard roofs, only vapor-permeable wind and moisture insulation is used (diffusion membrane).
Correct construction of the attic roof and walls of the frame house. From the inside, the structure should be protected by a vapor barrier, from the outside by wind and moisture protection. But not the other way around!
It is important to know: the only suitable option for a roofing film (membrane) for a standard attic roof structure is a diffusion membrane.
There is a version of the combined (attic) roof, in which a vapor-proof hydro or vapor barrier is used as a subroofing film. But in this case, it is necessary to ensure effective ventilation of the space both above and below the film, the total height of the ventilation gaps will reach 10 cm. This solution is effective, but complicates the design and is rarely used. Please note that the underlay (4), closer to the overhang, is brought out over the steel apron (15), and that into the gutter of the gutter system. This should always be done, this is to ensure that condensate flows out of the roof structure.
In conclusion, let us say that not only the comfort of living in the house, but also the durability of the structure depends on how correctly the roof structure is selected and the materials for its installation are chosen. If you do not have sufficient knowledge in the field of construction, do not have the time or desire to delve into the intricacies of modern technologies, the best solution would be to entrust the execution of important work to experienced professionals.
Video: what is waterproofing for
The air of a heated living space always contains a certain amount of moisture in the form of water vapor. Most of this moisture is removed from the room through the ventilation system, but some of it remains inside the house. It is to protect the insulation from these excess moisture that the vapor barrier film is used under the corrugated board.
Installation of a vapor barrier film on a corrugated roof using special tape
Do you need a vapor barrier for corrugated board?
The amount of moisture that can be contained in the air depends very much on its temperature - the higher it is, the more humidity. Warm and, therefore, more humid air is lighter than cold air and always accumulates in the upper part of the room under the ceiling or roof. There it gradually cools down, releasing the moisture released at the same time to the surrounding building structures.
If the inner space of the house is protected from the sides by walls, then from above the only protection from the cold is a layer of insulation. And due to the fact that heat-insulating materials have a porous structure, they very intensively absorb the moisture contained in the air. At the same time, their thermal insulation characteristics are greatly reduced. The dependence of the thermal conductivity of the insulation on its moisture content can be seen in the table below.
It is here that the vapor barrier of the roof made of corrugated board comes to the rescue. It protects the insulation layer from moisture contained in warm air. That is why a vapor barrier is laid below the insulation from the side of the warm room. At the same time, it also protects the building structures from the ingress of condensation on them, which can form on the lower surface of the thermal insulation layer.
On the types of vapor barriers, as well as on which vapor barrier is best for the roof and under what conditions, we will describe in detail in the next section.
What is the vapor barrier under the profiled sheet?
Vapor barrier materials are produced in the form of films. Most often they consist of several layers, each of which performs its own, special task. The most common types of roof vapor barrier are discussed below.
Glassine as a vapor barrier for corrugated board
Glassine is one of the classic options for vapor barrier, which has been used for more than a dozen years. It is durable, reliable, robust and has excellent water vapor retention. In addition, using glassine for vapor control is one of the cheapest options.
However, it is better not to use this material for residential buildings, especially if there is a living space under the roof. The fact is that when heated, glassine begins to emit a not very pleasant smell. He, of course, is not dangerous, like a pair of roofing material, but for the house it is not the best option. Since a metal profile is used as a roof covering, the vapor barrier will be heated quite often, especially in summer.
Glassine in a standard roll, which is mounted as a vapor barrier
In addition, glassine as a vapor barrier is not very convenient to install, since it weighs a lot and is produced in narrow rolls. After all, it is intended to be laid on top of a solid sheathing as waterproofing.
Advantages:
- Durability;
- Reliability;
- Strength;
- Flexibility;
- Low cost.
Disadvantages:
- Large weight;
- Even with low heating, it emits an unpleasant odor;
- The complexity of installation as a vapor barrier.
If you do not know which vapor barrier to choose for the roof of a bathhouse or a summer cottage with a non-residential attic, then glassine will be an excellent option in all respects. For a residential building, this will not be the best choice, unless, of course, cost is your priority.
Polyethylene film vapor barrier device
Quite often, the choice of a vapor barrier film stops at ordinary household polyethylene. This is the most famous and very long used vapor barrier material. It perfectly retains water vapor, completely isolating insulation and other elements of the roofing cake from moisture from inside the room. In addition, ordinary polyethylene film for vapor barrier is very cheap - at least several times cheaper than specialized films from the same material, and an order of magnitude cheaper than various membranes.
A roll of regular plastic wrap that can be used as a vapor barrier
However, this is where the benefits of using this material end. Plastic sheeting as a vapor barrier is very cheap, but difficult and impractical. It is not durable and is easily damaged during installation. In order to avoid this, it is necessary to use a very thick film, which makes it almost impossible to fix it without assistance. In addition, due to its weight, the plastic film under the metal profile is poorly attached using standard methods.
If for you, nevertheless, the issue of price is fundamental, then a vapor barrier layer from a polyethylene film can be made. It must be fixed with a construction stapler to the inner crate. The frequency of attachment depends on the thickness of the film and is usually 1-1.5 meters. Puncture points and film joints must be glued with special construction tape. In order for such a vapor barrier under the corrugated board to be reliable, it is recommended to make two layers.
Advantages:
- Cheapness;
- Extremely low vapor permeability.
Disadvantages:
- Complexity of installation;
- Large weight;
- Low strength;
- Fragility;
Thus, if cheapness is the main criterion on the basis of which you decide which vapor barrier to choose, then the use of a simple plastic film is justified. In all other cases, this is far from the best option.
Reinforced polyethylene vapor barrier film
Modern vapor barrier films for roofs are often multi-layer and consist of the same polyethylene, which is reinforced with auxiliary materials.
The most budgetary and common option is a reinforced vapor barrier film. It consists of several layers of polyethylene with an obligatory reinforcing layer of polypropylene mesh or fabric. Such a structure provides the film with a fairly good strength - it is difficult to tear it with your hands or damage it by an accidentally dropped tool.
Vapor barrier polyethylene film reinforced with polypropylene
In addition, the reinforced vapor barrier has greater rigidity than conventional polyethylene film, and, despite its multilayer nature, is quite lightweight. These properties facilitate its installation, as well as make it possible to connect and fasten it using special self-adhesive tapes.
Advantages:
- Decent strength;
- Ease;
- Low vapor permeability;
Disadvantages:
- A large amount of condensation may form, which drains off without remaining on the surface.
Reinforced polyethylene vapor barrier is the best vapor barrier film if you need an inexpensive but high quality solution for your home. The best option in terms of value for money.
Polypropylene film for vapor barrier is made according to the same principle as multilayer polyethylene film. The use of polypropylene is caused by the need to increase the strength of the vapor barrier film in order to facilitate its installation.
In addition to the material used, the structure of polypropylene films is slightly different - they have an additional embossed layer. It is necessary, since a large amount of condensation forms on these films, which can lead to deterioration of the insulation.
Multilayer polypropylene film for vapor barrier with anti-condensation fabric layer
In order to prevent such a development of events, an additional anti-condensation layer is applied to the polypropylene films, which, as a rule, consists of a mixture of viscose and cellulose. It absorbs condensation, preventing droplets from breaking off, which then evaporates as soon as the humidity in the room decreases.
As a rule, films with an anti-condensation surface are mounted with the rough side towards the room, and the smooth side outward. However, it all depends on the manufacturer, so read the instructions carefully before installation.
Advantages:
- High strength;
- Reliability due to multiple layers;
- Ease;
- Low vapor permeability;
Disadvantages:
- Films without an anti-condensation layer spoil the insulation.
Polypropylene film is the best vapor barrier for roofs in the budget segment. Due to its increased strength and anti-condensation coating, it is practically devoid of disadvantages and is the best option in terms of reliability and strength.
Foil vapor barrier
Foil vapor barrier film is a special case of polyethylene or polypropylene film. In this case, it is not only reinforced, but also supplied with a reflective aluminum layer. This aluminum vapor barrier reflects infrared radiation, preventing it from leaving the house, thereby creating a kind of "thermos effect".
Foil vapor barrier material was originally intended for use in saunas and greenhouses, but now it is often used for ordinary living quarters. Its efficiency is quite high - on average, heat losses are reduced by 10-15%, which allows you to significantly save on heating the house. For example, laying Izospan under the corrugated board increases the temperature of the heated room by about 2 ° at the same costs.
It should be borne in mind that the effect of heat reflection is possible only in air, therefore, vapor barrier with aluminum foil must be installed with a gap. Regardless of the finishing material, it should be 4-5 cm between the reflective part and the wall material. In addition, the aluminum vapor barrier should not fit close to the insulation - you need to leave a small gap.
Advantages:
- High strength;
- Reliability due to multiple layers;
- Ease;
- Low vapor permeability;
- Reflect infrared radiation and save heat.
Disadvantages:
- Price.
Undoubtedly, foil vapor barrier film is one of the best options among non-breathable materials. If you are not very limited in finances and firmly decided to use a vapor barrier film, and not a membrane, do not think about which vapor barrier is better - take an aluminum one. It will not only perfectly fulfill its direct functions, but also keep warmth in your home.
How to choose a vapor barrier for corrugated board?
Above, all common types of vapor barrier for the roof have already been discussed in detail. Each material has its own scope and features of application, therefore, before choosing a vapor barrier film, you must decide exactly what result you want to get.
First of all, you must answer the question, which is more important to you: price or effect? If price is of the utmost importance, then it is worth determining the budget and choosing the best option within it. If efficiency is more important, then which vapor barrier film to choose will depend on the operating conditions.
So, for a small country house with a cold roof, ordinary glassine is quite enough. For a rarely used cottage with an attic, you can use polypropylene or plastic wrap - if the house is not heated all winter, then it makes no sense to use expensive foil materials. If we are talking about a residential building, then, of course, the best option would be a vapor barrier with a reflective layer of aluminum.
The roofing corrugated board is reminiscent of production - it also represents cold rolled galvanized steel sheet coated with polymers. The difference lies only in the profile pattern - the metal tile imitates the real one, while for the manufacture of corrugated sheet, the rolled steel is simply corrugated, giving the profile the appearance of a zigzag, sinusoid, etc.
Unlike metal tiles, corrugated board looks simpler (and is cheaper), but at the same time it is more reliable, lighter and more durable.
In the event that your future home is spacious enough to do without an attic, it makes sense to equip a cold attic isolated from the living space. This way you get threefold savings.
Roof plane
The easiest option for this element of the ventilation system is to install conventional dormer windows, i.e. small through grids, protected from rain and snow by canopies from above.
You can also carry out the installation of full-fledged ventilation shafts, but this will cost much more, and, in addition, requires compliance with a number of rules and regulations related to safety. So, for example, you should take into account the height of the shaft relative to the ridge, etc.
Skate
The roof made of corrugated board allows you to use any standard ridge and install it very simply, without any additional elements. The fact is that the profile of such a coating implies a wave, the height of which is at least 30 mm., which provides sufficient clearance for the free passage of air flows.
Ridge bar
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What is a roofing pie in practice:
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