Roof waterproofing for metal tiles. Waterproofing under metal tiles - which is better and why it is needed. Waterproofing with one ventilation gap
Increased humidity under the roof covering leads to rotting of wooden roof structures and wetting of the thermal insulation material. Damage to the structure of the tree leads to its destruction and large-scale and costly repairs cannot be avoided.
Roof waterproofing under metal tiles is designed to protect wooden elements and thermal insulation (if any) from moisture, which different ways can penetrate under the roof:
- from condensation, formed on the inner surface of the metal tile when high humidity air and/or penetration of moist fumes from living quarters into the attic;
- from moisture penetrated through the holes in the fasteners.
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Types of waterproofing films
All waterproofing roll materials for roofs under metal tiles are divided into two main types:
- waterproofing films;
- diffusion membranes.
The main difference between waterproofing films and diffusion membranes is that the former do not allow both droplet moisture and water vapor to pass through, while the latter retain droplet moisture, but are easily overcome by water vapor.
Waterproofing films are several times cheaper than membranes. Therefore, it is better to use them for moisture protection of a cold roof. This will reduce material costs without losing protective properties.
The technology of waterproofing depends on the brand of material used and the type of roof - cold or insulated.
For a cold roof
A cold roof means there is no insulation in it. When waterproofing it can be used as diffusion membrane, and a waterproofing film with low vapor permeability - polyethylene or polypropylene.
* Strength - maximum tensile force in the longitudinal and transverse directions.
The film is laid directly on the rafters with a slight (about 20 mm) sagging. Laying is done in strips starting from the eaves upwards with the bottom layer overlapping the top layer by 50-100 mm. The joint between the sheets is sealed with adhesive tape.
If a “breathable” film is used, you need to pay attention to which side it is laid up, it depends on this correct work. This information can be found in the instructions for the material, usually the side with the logo should face up.
Higher waterproofing film there must be a ventilation gap. To install it, counter battens 50 mm thick are nailed onto the rafters on top of the film, and the sheathing is already attached to them.
For roofs with insulation
Waterproofing an insulated roof is more difficult and expensive. There are two options for waterproofing depending on the type of material used.
Waterproofing with two gaps
If you are using low vapor film throughput, it is necessary to create two ventilation gaps - between the insulation and the film and between the film and the sheathing.
Typically, insulation is laid between the rafters flush with their top surface. Therefore, to create the first gap, you need to nail the counter-lattice strips to the rafters and lay the film on them without sagging. Then, strips are placed on top of the film to the counter-lattice, providing a second gap, and to them.
The advantage of the two-gap method is that a cheaper waterproofing film can be used instead of a diffusion membrane.
The disadvantage is that it is more labor intensive. In addition, ensuring double clearance in areas of valleys, chimney outlets and roof windows can be difficult, and sometimes impossible.
Nowadays, metal tiles are often used to decorate the roofs of buildings - the material is reliable and beautiful. However, the durability of any roof and its performance characteristics largely depend on how well the roof space is constructed. Waterproofing a roof under metal tiles 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 covered with metal tiles? Isn't just one enough? finishing material to drain water? So, waterproofing performs several functions, providing reliable protection for the roof, the space underneath 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 implement, and its structure is multi-layered. During construction, wooden boards, bars or metal elements are used as rafters and beams, as well as to create sheathing. 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 is 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 internal part home and street and can also provide Negative influence for all materials used in the construction of the roof. Condensation can gradually destroy them and cause leaks and reduce the service life of materials.
On a note! The waterproofing layer will make it somewhat easier to convert the attic into an attic space, if such a desire arises among the owners of the house.
Materials used
We found out that waterproofing is the most important element roofs, covered with metal tiles. But what should a high-quality water-protecting layer be like? The requirements for waterproofing are as follows:
- it must have increased fire resistance;
- good steam flow;
- strength and reliability indicators must be high;
- the material should not deteriorate due to sudden temperature changes and should not be afraid of ultraviolet radiation;
- the layer must withstand a certain level of mechanical loads;
- waterproofing should not be susceptible to pest attack or mold development;
- it must also cope well with its main tasks and not cause harm to human health.
Can be used for waterproofing different kinds materials. They all have a lot of differences from each other, including different resistance to light, strength, quality and durability.
In most cases, special roofing films having several layers are used for waterproofing metal tile roofs. There is a reinforcing and absorbent layer. 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 will not form. Also, on both sides the material usually has a polyethylene lamination.
This coating has special pores that allow the passage of vapors that form inside the house, but at the same time do not allow moisture coming from outside to spoil the materials from which the roof is made. This material feature, called vapor permeability, is especially important if attic space Converted into an attic and used as a living space.
Advice! When choosing a material for waterproofing, it is important to pay attention to its service life. It should coincide with the service life of the metal tiles, so that you do not have to dismantle the roof and lay waterproofing again if it fails, and the main roofing material will still be usable. The service life of the special film used under metal tiles is 50 years.
| Name | Short description |
|---|---|
| A film with low vapor permeability, for which it is important to equip the so-called double-circuit ventilation, which will be located between the roofing and waterproofing materials, as well as between the film and the insulating layer of the roof. The gaps between them should be 3-5 cm. The material is ideal for constructing a cold roof or a roof with a simple design. |
| A material that also requires the creation of dual-circuit ventilation. The film is equipped with a moisture-absorbing fleecy layer that perfectly retains excess water. This is a fairly dense material, rough to the touch, durable and resistant to ultraviolet radiation. But the vapor permeability of such a film is low. |
| Most best material for waterproofing the roof, as it has increased vapor barrier performance and does not require the installation of double-circuit ventilation. It is enough to leave gaps between the film itself and the roofing. Installation of this film is simple, it has a long service life. The main disadvantage is the high price. |
On a note! Hydrobarriers made from bitumen and bitumen mastic, which are widespread and still in use today, should not be used for arranging a metal tile roof.
Of course, for a temporary roof you can use a cheaper film, but for capital construction It’s better to take high-quality, albeit expensive, material. There is no need to save money 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/m2. A bright representative The optimal material for laying under metal tiles is Izospan AM or AS.
Prices for under-roof waterproofing films
Under-roof waterproofing film
Preparing for work
Laying the waterproofing layer requires preparatory work. They include the creation of a rafter system designed according to preliminary calculations, installation of cornice and end boards. Only after this the waterproofing is laid.
Certain tools will be useful for installing waterproofing. These are a tape measure, scissors, a hammer, a marker, a construction stapler, and a screwdriver. You will also need to purchase bars and screws.
Laying process
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 cornice and attached 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 to the counter-lattice above the rafters. The film can also be mounted perpendicular to cornice strip. Here it is laid on the finished sheathing and fixed by tension.
Let's look at how the waterproofing layer is installed under metal tiles using a detailed example.
Preparatory work
Step 1. According to the house design, a rafter system is being erected. IN in this case it is made of wood, which especially needs protection from moisture, so there is no question of installing waterproofing.
Step 2. The vapor barrier layer is being installed. The special film is attached using construction staples along the perimeter of the building under the rafters and directly to them. Work is carried out in the inner part 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, with all overlaps, as well as the joints of the material with all structural elements roofs (pipes, ventilation, etc.) are sealed hermetically with adhesive tape.
Step 4. Counter-lattice slats are nailed to the frame on top of the film - it is on them that the entire interior decoration attic space.
Step 6. Thermal insulation is laid on the vapor barrier between the rafters. The laying is done very tightly in order to reduce the number of cold bridges. This concludes the preparatory work.
Prices for thermal insulation materials
Thermal insulation materials
Laying the waterproofing layer
After all the preparatory work has been completed, the waterproofing film is installed. In this case, the Tecafol Super membrane is used as a material protecting 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 facing the roofing where the edge tape has a bright and rich 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 sudden temperature change.
Attention! The film should initially be laid on the correct side. You cannot twist or turn it over during installation, as it will lose some of its waterproofing properties.
Step 2. The film is fixed to the wooden rafters using a construction stapler. Instead, you can use nails with a wide head.
Step 3. Next, the second strip of waterproofing is spread. It is laid with an overlap on the first one (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 taped with double-sided adhesive tape.
Step 4. The second strip of the waterproofing membrane is fixed. This way the film covers all the heat. insulating material. In places where pipes, hatches and other structural elements are located, it is necessary to securely fix the material. It is also important to remember that the waterproofing layer is not brought to the ridge of the roof - 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, sheathing bars with a cross-section of 4x5 cm are attached using self-tapping screws. They will additionally fix the film on the rafters.
Step 6. Counter-lattice bars are fastened across the sheathing bars in increments of 35 cm - it must correspond to the pitch of the metal tiles. Next, the tiles themselves are installed directly.
It is worth remembering that a gap of 5 cm must be maintained between the tiles and the waterproofing. Otherwise, the required air circulation will not be ensured. There may be no gap above the insulation if a high-quality diffuse membrane is used.
Video - Installation of a hydraulic barrier
Rules for installing hydrobarrier film
When working with waterproofing, it is important to remember several installation rules:
Cold roofs – do you need waterproofing?
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 pie and will be provided good ventilation materials, then you can use roofing felt or glassine, which will be cheaper than expensive film. But in this case, it is necessary to form a ventilation gap between the roofing felt and the metal tile.
Waterproofing is a very important layer in the roofing pie of a roof covered with metal tiles. You should not neglect it, so that later there will be no problems with leaks or a reduction in the service life of the materials used to create the roof.
Prices for metal tiles
Metal tiles
Video - Installation of metal roofing
The design of a cold roof includes a layer of waterproofing, as well as sheathing, supporting frame, counter-lattice and roof decking.
When installing a cold roof, a ventilation gap is provided between the waterproofing and the roofing material.
The gap ensures active air circulation in the under-roof space, promotes effective evaporation of moisture from the surface of the waterproofing and prevents corrosion of the metal roof.
Why is it necessary to install waterproofing under an uninsulated metal roof?
Condensation protection
The waterproofing layer primarily serves to protect the metal roof from condensation appearing from the side interior spaces due to the difference in temperature inside and outside the house.
In the absence of waterproofing, condensation will accumulate on the inner surface of the metal roof and gradually destroy it. This, in turn, will lead to leaks and a reduction in the service life of both the roofing material and the supporting roof frame.
Protection from precipitation and leaks
For all the apparent strength of the metal tile, it has “weak links”: the points where the decking is attached to the sheathing and the overlaps of the modules.
During heavy rainfall and gusty winds, moisture can penetrate into the under-roof space along the joint line of metal tile sheets, and if the hardware is loosened and the sealing elements are deformed, through the mounting holes.
Converting an attic into a living attic
If in the future you have a desire to re-equip non-residential attic into a living space, then with the existing waterproofing layer the process of arrangement roofing pie will be greatly facilitated.
What is suitable for waterproofing a cold metal roof?
When choosing a hydrobarrier for a metal-tiled roof, you should not save unnecessarily - major repairs of the roof in case of corrosion of the decking and deformation rafter system will cost much more. Therefore, it is better to prefer more effective superdiffusion and anti-condensation membranes to cheaper polyethylene and polypropylene films.
For waterproofing under cold roof film will do
Metal tiles - wavy metal sheets various configurations, can be copper, aluminum, steel. Thanks to its qualities ( strength, durability, lightness, low price), the material ranks first among roofing coverings.
The installation of a roof under metal tiles requires the correct installation of vapor barrier, heat insulation, and waterproofing layers. Each material should be installed according to installation rules. Then the roof will last a long time, and the house will be warm and dry.
If you have not yet decided on the choice of coating, you can read the article in which we compare the characteristics of metal tiles and soft roofing.
Waterproofing a metal tile roof is one of the most important stages of roof construction.
Types of waterproofing materials
The roof should always be waterproofed. Depending on the purpose of the room, the shape of the roof, the cost of materials and other indicators, waterproofing materials are classified into several groups.
Waterproofing membranes
Polymer membranes are a modern waterproofing material that has microscopic perforation, which allows air to pass through the material, but not water.
- anti-condensation(capable of absorbing drops of moisture, preventing the formation of condensation);
- diffusion(one side of the membrane absorbs moisture, the other prevents the passage of water droplets);
- superdiffusion(multilayer membranes).
Painting room
Refers to external waterproofing. Painting waterproofing is a roof coating with paints, varnishes, and various emulsions. This ensures that the roof is protected from water entering the roof. The service life of such insulation is short - up to five years. Typically this type of insulation is suitable for covering soft roofs.
Coating
Most often used for roofs flat type
. This insulation in the form of a bitumen mixture is applied to the roof surface in a thick layer. There is a cold and hot method 
application. Coated insulation tends to crack under the influence of temperature changes, and therefore requires replacement after five years. The bitumen-polymer mixture is more stable and may not lose its properties for up to 15 years.
Waterproofing film
The most common method of waterproofing. Installed on the rafter system before laying the roofing pie or covering.
Suitable for flat roofs. The roof is covered with roofing felt or similar material made from vinyl plastic, polyethylene, isoplast, mostoplast, polyvinyl chloride, isoelast, ecoflex. This method of waterproofing is quite economical and has a long service life.
Sprayable
It is used for surfaces with a porous structure: cement or concrete. Using a spray bottle, a special impregnation is applied to the porous material, filling the smallest pores.
Under metal tiles, the most suitable waterproofing method is to lay a waterproofing layer under the metal tiles. It is advisable to use membrane or anti-condensation films.
Is it necessary to install waterproofing under metal tiles?
Without waterproofing, condensation will form on the roof indoors. This applies to both an insulated metal roof and a cold one. The inner surface of the roof will begin to deteriorate, leaks will appear, which will begin to destroy the roof frame.
The main reasons For which it is imperative to lay a hydrobarrier under metal tiles are:
- preventing dust and moisture from entering the room;
- preventing the formation of condensation in the insulating layer;
- ensuring the thermal insulation properties of the roof.
DIY waterproofing for metal tiles
Important steps in preparing for laying a waterproofing layer are:
- correct and reliable roof frame installation- rafter system;
- installation of the cornice and installation of the front board to the end of the rafter legs;
- attaching hooks gutters for drainage structures.
Waterproofing can be installed two ways:
In the first case, the film is rolled out parallel to the cornice. The film is placed in such a way that it can sag down to the sheathing strips. The overlap width must be at least 10 centimeters.
To provide ventilation between the metal tile and the film, the film is secured using a counter-lattice.
The second case is laying a waterproofing film perpendicular direction of the cornice. The anti-condensation film under the metal tile is stretched over the prepared sheathing. With this option, the overlap should not exceed 10 centimeters.
Properly performed waterproofing of the roof under metal tiles directly contributes to increasing the service life and ensuring the functional loads of the roofing pie.
While maintaining the moisture protection of the roof, the protection of the under-roof space and the protection of the entire house are maintained.
Waterproofing the roof of a house under metal tiles step by step:
- roofing film is laid under metal tiles from the cornice to the ridge, observing the overlap. The film is attached to the rafters with a stapler. The overlap should fall on the rafter boards;
- in the spaces between the rafters should be left slight sagging (about 2 cm). This ensures the integrity of the film during sudden temperature changes;
- if an anti-condensation or diffusion film is used, then the height of the rafter system must exceed a thermal insulation layer of several centimeters. Sometimes, to achieve the desired height of the bars, they have to be increased;
- waterproofing is not laid on the formwork. In this case, logs are laid along the slope at a distance of more than 1 meter;
- along the ridge part the ventilation gap must be at least 5 cm. The edge of the film must reach the bottom gutter;
- ventilation gaps must be arranged in such a way that prevent insects and birds from entering the roof;
- The film should be secured with a special adhesive rubber tape;
- the overlap of the film at the pitched joints should be 15-20 cm;
- when installing pipes stove heating or ventilation outlets, the film is laid with an overlap of 5 cm;
- When laying a superdiffusion membrane, it is not necessary to provide gaps between the insulating layer. This material is laid on the rafter system. When the rafters are larger than the thickness of the insulating layer, the membrane is laid, laying it along the profile of the rafters;
- attic windows are equipped with a waterproofing layer according to the rules constructive leadership window.
Sectional roofing pie
Installation of waterproofing film
After laying the waterproofing, proceed to the installation of the next layer.
Experienced professionals share tips, guided by which you can avoid common mistakes when working:
It is better to clarify any installation issues with professionals who know first-hand the rules and subtleties of performing the work.
Vapor barrier for metal tiles
Vapor barrier layer - a necessary stage in arranging a roofing pie for metal tiles.
Vapor barrier protects the penetration of vapors into the under-roof space from the room side.
The material is laid according to the principle of laying a waterproofing layer.
Vapor barrier film for tiles
The films must be laid in the correct sequence and according to the rules for applying layers of the roofing cake. Replacing the vapor and waterproofing layers in places ensures that moisture enters the rafter system and the thermal insulation layer, which reduces the quality and service life of the roofing structure.
Waterproofing under metal tiles: selection of under-roofing anti-condensation film and its installation
Details about waterproofing under metal tiles: choosing waterproofing for the roof, laying and installing under-roofing film. Do you really need an anti-condensation hydrobarrier under a metal tile roof and advice from experienced craftsmen?
When using a roofing carpet made of metal tiles, condensation forms on the inside of the covering. And this process does not depend on the person in any way. There will be condensation anyway. Correct styling waterproofing under metal tiles will help prevent its formation. And, at a minimum, it will prevent moisture from seeping into the roofing carpet.
Characteristics of waterproofing film
The roofing film, no matter what it is made of, must protect the attic space and the thermal insulation layer. In other words, to prevent processes from starting under the metal tile that will eventually destroy it and have a detrimental effect on the base of the roof, special protection is needed.
A priori, the waterproofing properties for metal roofing are micro-perforation to ensure ventilation of water vapor. To achieve this result, the substrate under the metal tiles must
- Consist of several layers
- Possess a reinforcing polyethylene grid
The thickness of each layer varies depending on the type of film. Moreover, in addition to moisture removal, the protective waterproofing film can have
Each manufacturer indicates what qualities are inherent in its material.
Types of waterproofing substrates
IN quality roof it is necessary to provide for the formation of condensation not only directly under the metal tile, but also from the insulation side. To do this, first of all, an anti-condensation layer is applied to the inside of the film and a gap is left for ventilation.
The formation of condensation depends on whether the roof is warm or cold. Its intensity and volume are directly related to the temperature above and below the substrate.
There are three types of films in total:
- Classic film. It is important to maintain 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 roof covering
- Anti-condensation film. Here the basis of the material is a fleecy moisture-absorbing layer and double-circuit ventilation is important for it
It is also customary to separate the substrates directly from the type of roof. In this case, the following is taken into account: will the roofing pie
Substrate and “warm” roof
If the roof is heated from the attic side (most likely, this is a residential area), the roofing pie is constructed in stages and is quite complex. So, how to install waterproofing under metal tiles? Installation consists of the following steps:
Substrate and “cold” roof
Roofing pie for cold roofs is carried out according to a more simplified scheme, which means it is done faster. The layers in this cake will be like this:
- Creation of sheathing and counter sheathing
- Laying the waterproofing layer
- Creating a rafter system
If there is an unheated attic space under the roof, almost any film can be used as waterproofing:
- Anti-condensation
- Diffusion membrane
- Any material that can not allow moisture to pass through, including roofing felt or greenhouse film
Roofing felt backing
Roofing felt is 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 last even a little longer, since it will not come into contact with the sun.
Ruberoid is a fairly popular material for creating a primitive waterproofing layer in a “cold” roof.
The disadvantages of roofing felt, which even a low price cannot offset, include the fact that
- Over time, moisture will damage the integrity of the bitumen coating.
- The cardboard base will resist (fiberglass will last longer than cardboard, but it is not durable without a top coating)
- Belongs to the category of fire hazardous materials
As a waterproofing layer, roofing felt and its analogues can only be used in the roofing pie of a “cold” roof.
Tips for installing waterproofing under metal tiles
The selected waterproofing for the roof under Country or Ruki metal tiles must be fixed so that air flows can easily pass through the ventilation openings. They must be installed at the highest point of the roof.
To avoid material rupture when low temperatures The film must be laid so that there is 2 centimeters of sag between the rafters.
The film must be laid from the cornice to the ridge, making an overlap of 1.5 centimeters at the joints. Secure the joints with either adhesive tape or a construction stapler.
Insulation and vapor barrier for roofing
Insulation in the roofing pie, regardless of whether the roof is heated or not, must always be present. This material, even the most minimum thickness, low thermal conductivity.
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 done in a checkerboard pattern. And the joints need to be foamed.
The insulation can perform its functions of preserving heat only when the roofing pie contains waterproofing (as described above), and for a “warm” roof there is also a vapor barrier.
We are talking about film-type materials. Their task is to maintain the required level of thermal insulation background.
In other words, they are an important participant in the roofing ventilation system, having moisture blocking functions.
The roof must be strong, capable of protecting the house from snow, wind, and rain. Metal tiles can perfectly cope with such functions, but provided that the roofing cake is made in compliance with technology. This means that it necessarily contains waterproofing, as well as insulation and, in some cases, vapor barrier.
Before doing any further installation work, think about how to cut metal tiles. An incorrectly selected tool can shorten the life of the material. There are three options for cutting: die-cut or electric scissors, as well as a drill attachment. It is prohibited to cut metal tiles with a bolt cutter!
To cut other elements that are needed for installing metal tiles, the use of a grinder is also prohibited. For example, metal scissors are suitable for a valley. Read more about installing valley metal tiles here. This element must be done as correctly as possible so that the roof does not leak.
Laying waterproofing under metal tiles
When making a metal tile roof, it is very important to lay a waterproofing layer.
It protects the rafter system and insulation from moisture.
If this is not done, then after some time the quality of thermal insulation will decrease and the rafter system made of wood will begin to rot.
Roofing device
When installing a metal tile roof, as a rule, a vapor barrier film is used, laid on rafter legs. It is attached using a construction stapler.
If a layer of insulation is fixed from the inside of the attic, then such a film provides protection against condensation accumulating on the inside of the metal roof.
Waterproofing under metal tiles is a non-woven material with microscopic holes. These openings do not allow warm air to escape from inside the room, and at the same time do not allow moisture to penetrate into the room.
The vapor barrier for metal tiles has three layers: a two-layer coating of perforated polyethylene and a base.
There are also vapor barrier materials coated with aluminum foil. It has several layers:
- Reinforcing mesh;
- Aluminium foil;
- paper impregnated with a fire-resistant composition;
This film provides wind protection and reflects heat. It is perfect for creating a vapor barrier layer in insulated pitched roofs.
Before laying waterproofing under metal tiles, you should read the instructions for its use.
The fact is that for some films the outer and inner sides work differently: for steam inlet and outlet. Therefore, it is very important not to confuse the sides.
Laying the waterproofing layer
The installation of almost all vapor barrier films is carried out using the same technology, since they protect the thermal insulation layer from condensation.
But at the same time vapor barrier materials are being manufactured various methods and have certain differences in their design.
For this reason they require different technology styling
If the vapor barrier has one smooth side and the other rough, then in this case it is laid with the smooth side facing the heat-insulating layer.
First, the vapor barrier is secured with galvanized nails or a stapler. However, the final fixation is carried out using counter-lattice slats. Due to these slats, a ventilation gap is created.
It is desirable that the cross-section of the counter-lattice bars be 4x5 centimeters.
In any case, the ventilated space under the metal tiles should have a height of at least 4-5 cm.
Waterproofing under metal tiles is installed in horizontal rows. It is fastened from bottom to top parallel to the roof ridge. The overlap of the panels should be 10-15 centimeters. Some manufacturers recommend laying vapor barriers in vertical rows. In this case, the overlap of the panels should be 15-20 centimeters.
It should be noted that the joints must be glued using a special adhesive tape or double-sided tape, regardless of the order in which the vapor barrier is laid.
It is necessary to pay special attention to the junctions of the roof with chimney or ventilation pipes, parapets, roof windows and other roof elements. In such places it is necessary to seal the vapor barrier joints with tape.
Waterproofing the roof of a house under metal tiles
The main task of waterproofing the roof of a house under metal tiles is to protect the rafter system and the installed thermal insulation material from the harmful effects of moisture. Moisture can penetrate under the roofing material both from the outside (rain, snow) and from the inside in the form of condensation.
An example of a roof structure.
There is an opinion that waterproofing in a roofing pie is an additional layer, that is, it is not necessary to install it. However, this statement is completely incorrect. You can do without a hydraulic barrier only if the attic space is unheated. In the case of a residential attic, waterproofing is simply necessary.
Some developers use regular roofing felt instead of a special film. Although it has a lower cost, its performance characteristics and service life leave much to be desired. Therefore, it is better to make a high-quality hydrobarrier immediately at the stage of roof construction and forget about it than to constantly have problems with roofing felt.
Waterproofing functions depending on the purpose of the attic space
Properties of waterproofing film.
Despite the use of different materials, waterproofing for metal tiles is designed according to a single principle. Only the constituent elements of the roofing pie may differ, the installation of which depends on the purpose of the attic: whether the attic will be used as a living space or not.
If the attic is non-residential, that is, there are no plans to heat it during the cold season, then the roof structure can only include a rafter system, a water barrier, a counter-lattice and the roofing material itself. The air gap obtained between the metal tile and the film performs the function natural ventilation, preventing the formation of condensation. In this case, waterproofing is a reliable protection of the attic space from precipitation.
In the case of a heated attic, the main elements of the roof are:
- vapor barrier - protects the insulation from condensation rising from inside;
- thermal insulation - reduces heat loss through the roof;
- waterproofing - prevents moisture from penetrating through metal tiles;
- rafters, sheathing and counter-lattice - are not only load-bearing elements of the roof, but also create a ventilation layer between the insulation, water barrier and metal tiles;
- roofing material.
Properties of film waterproofing
Diagram of a roof structure using a waterproofing film.
In most cases, a special three-layer laminated film is used as a waterproofing material for metal tiles, which has the following advantages compared to other types of waterproofing:
- excellent moisture protection;
- vapor permeability;
- high strength and wear resistance;
- fire safety;
- environmental safety;
- resistance to temperature changes;
- protection from mold, fungi and other harmful microorganisms;
- simple installation;
- long service life.
The vapor permeability of the material is considered no less important quality than moisture resistance, especially when using a waterproofing film under metal tiles for heated attics. Water vapor, which is formed during human activity, rises to the roof and accumulates in the insulation. Due to the difference in temperatures outside and inside the room, steam is converted into condensate, which not only increases the thermal conductivity of the insulation, but also leads to its destruction. To prevent this process, it is necessary to ensure the unimpeded escape of vapors to the outside.
The film hydrobarrier is produced in rolls 50 m long and 1.5 m wide. Moreover, its density is at least 140 g/m2.
Types of roofing waterproofing for metal tiles
Waterproofing under metal tiles.
Today on the market you can find materials for roof waterproofing, both domestic and imported, which differ from each other technical characteristics and cost. The most popular materials are:
- glassine;
- polyethylene and polypropylene films;
- polymer membranes.
Let's look at each option in more detail.
Glassine. In the recent past, roofing felt and glassine were widely used as roofing water barriers. However, these materials are characterized by fragility and low strength, so today they are used only in cases of very limited budgets or when constructing temporary floors.
Polyethylene. A fairly strong and dense material, which is one of the most popular waterproofing materials not only for roofs, but also for floors, foundations and others structural elements building.
Waterproofing the chimney passage.
Polyethylene film is available in the following types:
- Perforated. It has micro-holes, thanks to which the vapor permeability of the material increases. Its use is associated with some difficulties:
- when the air is highly dusty, the micro-holes become clogged, resulting in a decrease in the throughput of the film;
- at mechanical damage its moisture resistance is lost;
- Installation of the film involves creating a ventilated gap.
- Non-perforated. They are characterized by lower cost and worse vapor permeability, so they are recommended for use in unheated rooms.
- Reinforced. They are characterized by increased strength and throughput, so they are successfully used when installing waterproofing under metal tiles in rooms with high humidity levels (for example, in bathhouses).
Polypropylene. Used for the same purposes as polyethylene films, however, it has greater strength and is also resistant to sun rays. Some brands of polypropylene films have an anti-condensation layer. In this case, one surface of the material will be smooth and the other will be fibrous. This film should be laid with the smooth side up.
Polymer membranes. They belong to a relatively new waterproofing material. According to their characteristics, they resemble natural leather. The membranes have a non-woven structure and perfectly transmit all the steam from the inside to the outside space. Wherein external moisture cannot penetrate through them. This material can be laid directly on the insulation, that is, without creating air gap. However, there must be an air gap between the metal tile and the hydraulic barrier, as otherwise the roofing material will begin to rust.
Installation of waterproofing film under metal tiles
Connecting vapor barrier film sheets to each other.
It is necessary to lay the film in a horizontal direction, moving from the eaves to the ridge of the roof. In this case, the cornice and ridge must also be covered. Installation is carried out directly on the rafter system, to which the hydraulic barrier is attached using a counter-lattice. This allows you to create the required air gap of about 5 cm wide between the metal tile and the film.
The roll is rolled out without tension. Between the lags the material should sag by approximately 25 mm. This approach will protect the film from damage due to strong temperature changes. The overlap of the material when laying must be at least 15 cm. It is done along the colored strip located on the film. To fix the waterproofing film, it is recommended to use construction stapler and special waterproof staples, although you can also use stainless steel nails.
The logs to which the film will be attached must be installed in increments of no more than 120 cm. If the finishing surface is flat, then you will additionally need to lay logs that allow you to obtain a ventilation gap and the desired degree of sagging of the material.
If the roof is equipped skylights, then the hydrobarrier near them should be mounted in such a way as to prevent the appearance of unventilated zones.
This is achieved by drilling side holes in the rafters above and below the window or installing special ventilation holes for metal tiles in these places.
Properly performed waterproofing for roofing under metal tiles is the key to reliable protection thermal insulation material and rafter system from the destructive effects of moisture. Remember that the film should be laid with the bright side of the tape facing up. Otherwise, the effectiveness of the hydraulic barrier will be reduced.
Waterproofing the roof of a house under metal tiles: installation, how to choose (video)
The main task of waterproofing the roof of a house under metal tiles is to protect the rafter system and the installed thermal insulation material from the harmful effects of moisture.