Laying waterproofing under metal tiles. Selection and installation of waterproofing for metal tiles: overview of types of waterproofing and why do you need a water barrier under the roof? Which waterproofing to choose for metal tiles

Metal tiles are chosen as a roofing covering by many homeowners who prefer increased comfort, reliability and safety. The finishing coating allows not only to visually give the building perfect view, but also to create in its premises an ideal microclimate that is as favorable as possible for humans. Before installing metal tiles, it is necessary to properly prepare the base of the roof: build a frame, lay sheathing, lay thermal insulation. An equally important step is waterproofing under metal tiles. It is mandatory when installing a roof, since it allows you to effectively remove accumulated steam and condensate from the under-roof space, which have a destructive effect on the insulation and other structural elements of the roof. What is waterproofing under metal tiles?

Waterproofing under metal tiles is an under-roofing layer of up to three centimeters, made of special water-repellent materials based on polyethylene fibers, which most effectively removes condensate and steam accumulated on the inside of the coating through a special ventilated gap. It protects insulation from rotting, metal tiles from corrosion, and prevents snow, rain, hail, dust and dirt from entering the attic space. It is important to remember that installing a metal tile roof without a properly laid waterproofing layer is impossible, since metal tiles have poor insulating properties. If you install it directly on the thermal insulation layer, the roof will soon begin to rot and will not be able to properly perform its functions.

Special anti-condensation and membrane waterproofing films are used as a waterproofing material under metal tiles. Mastics and bitumen-based roll materials cannot be used in such cases. When laying the waterproofing layer, it is advisable to adhere to the instructions and professional recommendations. The slightest errors in operation can cause roof leaks and short service life.

Waterproofing under metal tiles is an under-roofing layer that protects the attic space and its structural elements from rotting and other damage

What should be the waterproofing for metal tiles: basic requirements

The waterproofing layer, made of both membrane and anti-condensation film, must meet the following requirements and recommendations:

be resilient and reliable;
excellent resistance to mechanical, natural and chemical influences;
not to deform and retain its shape in any circumstances;
have increased hydrophobicity and vapor barrier properties;
remove condensation and moisture without accumulating in its layers;
be characterized by high quality workmanship and fully comply with accepted standards;
have a long service life, not inferior to that of metal tiles;
withstand exposure to ultraviolet radiation, steadfastly respond to sudden temperature changes, cope with natural influences - the elements, snow, moisture, rain, hail, wind.

It is important to remember that waterproofing under metal tiles must be done as efficiently and reliably as possible, otherwise sudden rotting of the structure cannot be avoided.

The waterproofing layer must meet certain requirements

Characteristics of modern waterproofing materials for roofing

Under metal tiles, the waterproofing layer is best made from membrane waterproofing and anti-condensation films. What are they?

Membrane waterproofing film is a common type of adhesive waterproofing, the production of which is based on the latest technological approaches. It can withstand heavy loads, consists of thin and elastic systems reinforced with special material, and can be used in any climatic conditions, since it can withstand the influence of strong temperature changes, ultraviolet radiation and others. natural factors. Unlike other waterproofing materials, the membrane film does not settle during compression, which is why specialists have the opportunity to work with joints of flexible foundations exposed to vibration and dynamic effects, without the slightest defect.

Membrane film for waterproofing under metal tiles

The main advantages of the material include:

resistance to temperature influences: with repeated thawing and freezing, the membrane film retains its properties and characteristics;
ease of maintenance and repair: no material required special care, characterized by endurance, reliability and durability;
environmental cleanliness and durability: the membrane film does not emit health hazards and environment formaldehyde, allows you to create a healthy microclimate in the room;
good vapor permeability and hydrophobicity: condensate and steam accumulating in the under-roof space quickly evaporate through the ventilated gap;
strength at the joints due to double seam.

It is important to know: it is better to lay the membrane film in several layers, in which case the roof waterproofing will be more reliable and durable.

– a waterproofing coating that contains special additives that prevent the formation of condensation on the surface. It is particularly durable, has good vapor permeability, reliability and affordability. Thanks to its waterproofing and anti-condensation properties, it effectively removes moisture from the under-roof space, preventing rotting of the insulation and corrosion of metal tiles.

Important to know: if waterproofing under metal tiles is carried out using anti-condensation film, it is very important to preparatory work correctly, otherwise it will not perform its main functional tasks.

Anti-condensation polyethylene film for waterproofing

Features of installing a waterproofing layer under metal tiles

Installation of the waterproofing film under the metal tiles is carried out on a pre-built rafter system, the calculation of which was carried out at the design stage. Before starting work, it is very important to correctly position the gutter hooks under the drainage system and install the eaves board. The waterproofing film is laid in two layers on top of the insulation with an overlap of up to 150 millimeters horizontally in the direction from the ridge to the eaves. It should be laid out evenly and without jams, with a slight sag between the rafters (the desired sag is 20 mm). The edges of the film are sealed together using a special masking adhesive tape. The waterproofing sheet is attached to the base of the roof with metal staples or galvanized nails, it is fixed along the perimeter with counter-lattice bars with a cross-section of 40x20mm, and lathing is laid on top of it.

It is important to know: during the installation of waterproofing, you should leave a gap at the roof ridge - a gap in the film up to 50 millimeters wide. It will promote normal ventilation of the under-roof space.

Waterproofing films must be laid with a slack between the rafters (20 mm), which will prevent the material from breaking when the size is reduced in cold weather.

Important points for installing waterproofing under metal tiles

During the installation of waterproofing it is necessary:

prevent moisture from draining from the waterproofing film onto the thermal insulation;
carefully isolate intersections with structural elements such as fireplace and chimneys, chimneys, ventilation ducts, fasteners. How to do it? At the intersection, an incision is made in the film in the form of a trapezoid; using sealing tape, the lower and upper flaps are secured to the part or to a nearby horizontal sheathing element. The side flaps are attached to the penetrating elements in the same manner;
take into account all instructions and accepted standards;
first lay the film along the axis of the valley or ridge in the inclined and valley ridges of hip and hip roofs;
lay the film in horizontal stripes on the roof slopes, overlapping from above.

Laying waterproofing where the roof meets the wall

It should be remembered that the waterproofing material is mounted on the roof surface with the perforation facing outwards. If this rule is violated, the waterproofing will allow moisture to pass through. Despite the fact that the installation of waterproofing under metal tiles is quite simple, it is better to leave this block of work to specialists who will do everything correctly and strictly according to the instructions.

All developers are wondering what to put under metal tiles in order to preserve the wooden elements of the roof structure, and the roof itself, for many years. The choice of substrate for the tiles directly affects the durability of the rafters and longitudinal beams, the air temperature in the attic in summer and winter. First of all, you must follow all the recommendations of the tile manufacturer.

Metal tiles include several insulating layers, which have an important function in protecting the entire house from the negative effects of cold, moisture, and noise.

What role does the substrate play in the operation of the house, what types of substrate are there, and in what cases is one or the other used? Let's try to understand these issues.

Types of substrates

The substrate for metal tiles should be selected depending on the purpose of the attic space.
There are substrates for cold rooms and there is a substrate for residential, that is, heated rooms. Substrates for residential premises (such as an attic) are subject to certain requirements, and for a cold attic - others.

The underlay for a cold attic is much simpler than for a heated attic. The counter-lattice is attached to the rafters, and the sheathing is attached to it. Free space is left between them for air circulation.
A film is placed on the sheathing to protect wooden structures from moisture, which penetrates into the attic through leaks in the tiles.

For a warm attic, the design of the substrate looks different. The sheathing and counter-lattice are also attached. But more stringent requirements are imposed on waterproofing. In this case, it should not only protect the attic from moisture from the outside, but also from condensation that forms on inner surface metal tiles due to the difference in temperature between the outside air and the inside.

To top it off, the waterproofing film must ensure the removal of water vapor rising from the lower rooms so that the insulation remains dry and does not lose its qualities.

An air space of 2 to 4 cm is left between the waterproofing and the insulation for air ventilation.

Depending on the climate in your region, choose the insulation material and its thickness. An insulating film is placed below. And the living space is sheathed on top of the film at the request of the developer. This design is called a “roofing pie”. It is optimal for protection roofing structure from external and internal unfavorable conditions.

Roofing felt backing

It can only be laid if there is sheathing and only with a cold roof.

Roofing felt as a substrate is used only for cold attic spaces. Whether or not to put roofing felt under metal tiles is up to each developer to decide for himself. It should only be noted that if the roof is cold and the attic is well ventilated, then you can put roofing felt, but in this case it is necessary to provide an air cavity between the roofing felt and the tiles.

If the roof is old and already covered with roofing felt, then in this case it is possible on top of it, having previously installed a sheathing for an air gap.

But most experts are skeptical about such a device and believe that it is best not to put roofing felt under metal tiles, because, in the end, this will lead to damage to the roof.

Roof waterproofing

The waterproofing layer protects the thermal insulation material and the entire wooden roof structure from the effects of rain and snow that get inside when strong wind. In addition, the film prevents condensation from entering the thermal insulation from the inside of the tile.
can be done in two ways:

Mount the sheathing on the thermal insulation and put a film on it, thereby ensuring a gap of 2-4 cm between them for ventilation.

Or you can put the film directly on the thermal insulation without a gap. But in this case it is necessary to use a special membrane-diffuser. Such a film will not let moisture in from the outside and at the same time will absorb moisture that rises from the lower rooms in the form of moist vapor.

And although membrane-diffuser film has a higher cost compared to conventional film, it has undoubted advantages. It is placed directly on the insulation, and there is no need for an air gap. In strong winds, it significantly reduces heat loss.

Being waterproof on the outside, the film is able to absorb vapors from the inside, that is, such a roof will “breathe”. As a result wooden structures the roofs will remain dry and last much longer.

Insulation and vapor barrier

The thickness of the insulation depends on climatic conditions region and reaches 20 cm.

Depending on the climatic conditions in your region, thermal insulation for metal tiles is chosen with a thickness of 15 to 20 cm.

The insulation is made from mineral wool. It is produced in rolls or pressed slabs.

The insulation is cut 10 mm wider than the distance between the rafters. During installation, it is inserted into place and, starting from the middle, gradually pressed, trying to avoid crushing and deformation. In this case, the insulation must fit tightly to the rafters, and the joints must be sealed.

To protect the insulation from moisture that rises from the lower rooms in the form of vapor, you need to put the last layer of the so-called roofing pie. This layer consists of polyethylene film, reinforced with mesh. It must be laid with an overlap of 10 cm, starting from the bottom.

To ensure that the finishing material does not touch the film, strips are attached to it and the finishing is attached to them.

Ventilation under the roof

A waterproofing film/membrane protects against moisture from the outside, while a vapor barrier film protects from internal moisture. Installing such double-circuit insulation provides upper and lower air outlet/inlet.

Ventilation must be provided under the roof. This is due to several reasons:

Ventilation removes moisture from under the roof. The presence of moisture leads to corrosion metal structures and to the destruction of concrete and brick parts.

Ventilation equalizes the temperature under the entire roof and thereby prevents the appearance of ice, as it damages the roof and drainage system.

IN summer time the temperature in the attic decreases.

Air for ventilation enters through the eaves sheathing and exits through the ventilated roof ridge.

If the ridge does not have an air outlet, that is, a “blind ridge,” then in this case roof valves are installed.

They are used both on cold and insulated roofs under metal tiles. There are also valves that can be installed on the roof ridge.

Errors when installing a roof

Typical mistakes that must be avoided when installing a “roofing pie”:

Under no circumstances should a vapor barrier film be installed instead of a waterproofing film. In this case, the moisture that gets into the insulation will remain in it;

Also, you cannot use a waterproofing film instead of a vapor barrier. In this case, the roof will not “breathe”.

You cannot place the membrane-diffuser film in reverse. And in this case, moisture will get into the insulation and remain there.

It is imperative to comply with the number of all ventilation gaps in the “roofing pie”. Since metal tiles are very afraid of moisture appearing on its back side.

Don't skimp on roofing. It has long been known that the miser pays twice. Purchasing cheap, low-quality goods will cost you expensive repairs in the future.

It is much easier to do something well right away than to correct it later.

If you arrange your roof according to all the rules, it will serve you for many years, keep your home warm in winter weather and provide coolness in the summer heat. Installation of any roofing system based on metal tiles, or using corrugated sheets, is best done with mandatory protection from moisture. Otherwise, when cold iron interacts with air, condensation will form, which may have a negative impact on the entire rafter system. In each of the above options, waterproofing is performed in the same way. All necessary work

should be carried out with maximum care, precision and adherence to technology.

Selection of waterproofing components

cold, when the attic space is not used and not heated;
warm type, in which the attic can act as an attic space.

Both of the above cases of waterproofing for metal tiles involve the use of a specific material.

Ruberoid

The component is suitable for waterproofing metal tile roofs if it is made in a cold version, or in cases where another design is impossible for some reason. Installation is carried out on the lathing, which is quite possible to do with your own hands. This allows for a ventilated gap and condensate drainage. In cases where there is no ventilated system in the attic, then laying roofing felt is unacceptable.

Waterproofing for metal tiles using three-layer material

Most optimal choice for guard metal roof The use of a three-layer membrane is considered. It is made on the basis of polypropylene fibers, which provide reinforcement for the component, and two protective layers. The presence of special micropores helps remove moisture vapor from inside the room. The membrane is characterized by excellent protection, durability and ease of installation with your own hands.

The film is excellent for both warm and cold roofs. It is important to choose the correct direction of the waterproof side, which is done easily. Typically, the upper surface of the roll, after it has been rolled out, acts as a moisture insulator, which makes installation easier. Waterproofing for film-type metal tiles guarantees protection against water penetration from the outside of the roof, and the passage of steam from the inside of the building.

Installation of Tyvek waterproofing

What are film insulators?

Waterproofing a cold roof of a house can be done using the simplest version of a membrane film. It is advisable to treat a warm roof with a super diffusion component, despite its high cost. At the same time, it will be possible to ensure ventilation of the space between the waterproofing and the roof.

Experts recommend choosing an anti-condensation membrane film, since it has an increased density and a rough coating that can effectively prevent the accumulation of condensation. This solution is applicable for complex structures. Anti-condensation film has a high degree of fire resistance.

Cold house roof protection

The simplest type of “roofing cake” of a structure based on timber for metal tiles includes the following layers:

Counter-lattice and lathing, through which materials are fixed, thereby providing ventilation space under the roof waterproofing. This allows condensation to evaporate without problems and not accumulate.
Waterproofing for metal tiles, using technologically advanced membrane films that protect the rafters of the building from any type of precipitation.
Roof rafter structure.
Processing and design attic space home from the inside.

Waterproofing under metal tiles of a warm roof

The execution of the “roofing cake” in this case is somewhat more complicated, and it includes the following layers:

Counter-lattice and lathing as the basis for fastening insulating materials.
Water protection that takes into account difficult conditions operation. The components used must withstand significant changes in temperature conditions, the appearance and effects of condensation, have the required vapor permeability and provide protection against possible leaks. Ideally, installing waterproofing on a metal roof, including doing it yourself, should protect the insulation as much as possible so that it retains its shape, size and functionality.
Re-lathing to ensure a ventilated gap.
House roof insulation, selected according to the characteristics of a particular region. It can have different thicknesses and is laid between the “lags” of the rafters.
Vapor barrier, ensuring the safety of insulating materials from the effects of vapors and water from the inside of the attic or attic space.
Processing from the inside.

Installation of waterproofing for metal tiles

During roof construction, it is worth considering the need to avoid contact of the waterproofing with the insulation, otherwise there is a risk of loss useful properties material. Upon completion of fixation rafter system, move on to waterproofing. To do this, you will need to perform a counter-lattice. It is imperative to maintain a gap of at least 5mm between the insulation and the roof.

Rolling out the roll is not difficult with your own hands. It is advisable to avoid severe sagging (no more than 2 mm) and excessive tension. Ignoring these recommendations may soon lead to damage to the material due to any movements and temperature changes.

Video: installation of waterproofing under metal tiles

A ventilated space of over 50mm is maintained between the waterproofing and metal tiles. It is important not to miss creating a ventilated gap in the area of the roof ridge. This will allow the entire structure to be properly ventilated.

When doing the work yourself, you should know that the material is rolled out from the cornice to the ridge. Depending on the type of component used and technology, the manufacturer gives separate recommendations for overlapping. Typically, membrane elements have a special line that facilitates the installation process. Worth highlighting important points When laying waterproofing on a metal roof:

the lag pitch should not exceed 1200mm;
logs are installed even with a flat roof, to provide ventilation and control the sagging of insulating materials;
presence of attic window openings obliges the exclusion of unventilated and blind spaces;
numerous broken surfaces, complex designs roofs require overlapping waterproofing, with an overlap of at least 30mm, and in places adjacent to pipes - 60mm;
It is best to fix the film to wooden joists using metal clamps made of stainless material, which eliminates the occurrence of corrosion and damage to the membrane;
It is advisable to protect cold roofs with the simplest films that promote high-quality temperature normalization;
laying wide pieces of waterproofing will reliably protect the joints;
storage and storage of membrane components is best done in dark places, since Sun rays contribute to their destruction;
installation of anti-condensation film requires providing a ventilated gap of at least 40-50mm.

Conclusion

Proper implementation and adherence to the technology for laying waterproofing for metal tiles will ensure the required protection of the roof. It is good if the appropriate membrane components are selected from proven, popular and well-established manufacturers.

Many jobs can be done with your own hands, which requires minimal experience and knowledge. If there are any doubts, it is better to contact professionals who know how to correctly and safely build protective structures that can significantly increase the life of the house, as well as reduce the likelihood of repeated repairs.

The use of metal tiles for the roof will be a practical and attractive solution when arranging a private, country or apartment building. However, every master knows that laying such material without thoughtful waterproofing will cause a decrease in the service life of the entire structure, as well as the roofing itself.

In this material we will talk about how to protect rafters from moisture penetration by installing roof waterproofing under metal tiles.

What functions does roof waterproofing perform?

Metal tiles are galvanized roofing materials. To protect against corrosion and give the material an attractive appearance, metal tiles are coated with paint or polymer. It has high thermal conductivity, which quite often causes temperature changes from the outside and inside of the house. Because of this, condensation appears, which significantly reduces the service life of the roof.

No styling waterproofing membrane Under metal tiles near the roof, the following problems may arise:

Damage to the rafter system. When condensation gets on the rafters, it is absorbed by the wood, which causes mold and rotting of the entire frame.
Moisture getting into the insulation. If the insulation is not protected with a water-repellent layer, then after a while it begins to become damp, which greatly reduces its effectiveness. Please also keep in mind that the properties of the insulating material will not be restored even if you let it dry.
Roof covering rusting. Without waterproofing, condensation accumulates on the metal tiles on the inside of the roof without obstruction, which causes slow corrosion of the metal. The fastest and most severe damage occurs in areas where the material is attached to the wooden rafters. Rust, as everyone knows, significantly shortens the service life and reliability of the roof.

It is worth taking into account the fact that the installation of waterproofing under metal tiles must be done in any case if you are going to achieve maximum durability and reliability of not only the roofing covering, but also the roof as a whole. Without laying moisture-repellent material, the service life of the roof is reduced by at least half.

Types - which one is better to choose for the roof

Currently, you can find a huge range of waterproofing materials on the market, varying in cost, properties and scope of application. Which one better waterproofing What you choose for metal tiles will depend on the type of roofing pie being built, as well as on the finances that you are willing to spend on this material.

For waterproofing, you will need to install one of the following materials:

Ruberoid. Lining roofing felt is considered the cheapest; it has high water resistance and strength. It is usually used if it is installed cold roof, since the material is also a barrier to steam. Experts advise laying roofing felt under metal tiles only in cases where there is no other way out.
Film. Construction film is made from polyethylene - it perfectly protects from moisture. It is used most often because it is inexpensive and lasts quite a long time. Moisture barrier film is afraid of ultraviolet radiation, which makes it vulnerable to the sun - it begins to deteriorate.
Membrane. It is a thin film that retains moisture, made from more technologically advanced polymers. Such materials have a complex structure with a large number of layers. The membranes have a long service life; they are not afraid of water pressure and ultraviolet radiation.

What is the best waterproofing for a roof under metal tiles if you have a warm type of roof? It must be a material with vapor-permeable properties. At the same time, it must be laid in such a way that there is a ventilation gap between the roofing material and the insulation.

How to properly install waterproofing under metal tiles

When deciding which waterproofing to choose for a metal tile roof in a particular case, it is worth keeping in mind that its installation begins after the assembly and installation of the rafter system, but before laying the roofing material. Let's figure out how it's done and in what sequence.

Moisture-repellent material is laid using the following technology:

The material is cut into strips, and their length should be equal to the length of the slope plus 10-15 percent.
The waterproofing is laid with sagging, so that during a leak, water pressure does not cause the material to rupture.
Waterproofing strips are laid at right angles to the roof rafters with an overlap of 10-15 cm.
The membrane or film is attached along the entire length of the rafters using a construction stapler.
The roofing material must be secured to the rafters using galvanized nails.
The joints of the strips can be sealed with moisture-repellent sealant, construction tape, or everything can be left unchanged.
After fixing the moisture-repellent material along the entire length of the rafters, a counter-lattice is installed, which forms a ventilation gap.

Above, we discussed in detail which membrane to choose for metal tiles. Keep in mind that without high-quality waterproofing, the service life of a roof covered with metal tiles will be significantly reduced. This simple and at the same time inexpensive material will make it possible to extend the service life of the insulation, roofing material and the entire roof. As a result, the roof will last as long as possible, and you will not need to spend money on repair work again and again.