Lossless: Combating thermal bridges in mansard roof construction. What is a valley and how to arrange it

The size of suburban areas and the desire of their owners to use the fertile soil layer to the maximum convinces them to make decisions about expanding usable areas in a vertical rather than horizontal direction. It is easier and more profitable to equip an attic over a bathhouse than to attach an additional rest room to it or build a separate house. True, this option will be acceptable only if there is more than 50% of the useful under-roof space with a height of 2.5 m, and if the ceiling above the bath is designed so that you can safely walk along its upper plane. In the presence of the above prerequisites, the insulation of the attic will turn it into an excellent living compartment.

• Let's start with the fact that the configuration of the roof is far from the shape of a classic cube. Insulation will have to be mounted on inclined surfaces. And since we are considering the insulation of the attic from the inside, it is impossible not to take into account the complexity of installing soft and flexible roll materials.
• Recall that the vast majority of the area of ​​​​the upper fence is a roof structure with a truss system. Its coating is made of extremely light materials with high waterproofing qualities, but also with considerable thermal conductivity. The wooden elements of the lathing of the truss structure are laid with gaps that do not form a thermal barrier.

• We take into account that in the attic floor there is not only a roof surface, but also at least two gables and a valley. Leaving them without insulation or poorly insulating them means reducing all efforts to zero in general.
• Let's not forget that roofing material, which does not allow atmospheric moisture to pass through, at the same time prevents the release of fumes that are natural for a bath and not only for it.
• We will ensure the safety of the use of residential premises by insulating the roof of the attic with materials with the environmental and hygienic characteristics required for housing arrangement.

Summing up the above criteria, we will draw up a kind of formula from the requirements that the thermal insulation system under construction must meet. According to the tasks set before the insulation, we will select the material and find out all the technological nuances. For effective work thermal insulation is necessary to:

• the insulation layer completely covered the internal surfaces without “holes” in a kind of carpet, so that there would be no weaknesses in the form of an unprotected ridge and gables not covered by an insulator;
• the insulating material, which resists the attacks of the cold atmospheric front from the outside and the warm wet front from the inside, was protected from the condensate formed as a result of their confrontation;
• moisture did not accumulate on the outer surface of the heat-insulating layer, which was not let through by the waterproofing roofing, so that excess moisture was removed through the ventilation ducts;
• light roofing insulation was equipped with wind protection, which prevents heat from blowing out of the attic on windy days;
• the material is suitable for technical, technological and sanitary-hygienic parameters.

The listed requirements are a detailed answer to the question "how to properly insulate the attic." If the thermal insulation system meets all conditions, then it will serve for a long time and work efficiently.

Choosing the right insulation

From a technological point of view, slabs are best suited to create a thermal insulation system from the inside. Using a shape-holding material is easier, faster and more convenient to do-it-yourself attic insulation with a minimum number of additional fixing devices. For their correct installation longitudinal bars are nailed to the rafters with dimensions that allow for a ventilation gap. The outer plane of the bars must coincide with the outer plane of the elements truss system, the inner plane of the heat-insulating material must coincide with the inner plane of the rafters.

Note. If the power of the selected insulation is greater than the width of the rafter, each of the elements of the rafter system will have to be nailed or installed on the screws with an additional beam. Wooden additions must be treated with an antiseptic before installation.

In any case, both with sufficient and insufficient width of the rafters, the ventilation space between the insulation and the roofing material must be left.

The indicators of the thermal properties of the material determine climatic features region. The collection of building codes under the number 23-02-2003 will help to find them out. According to the indicator specified in the SNiP, it is necessary to select the material.

• Styrofoam is a budget material and a convenient way to insulate. Lightweight slabs will be easy to install, the thermal insulation system will slightly increase the weight of the roof. However, the weak ability to conduct steam and attractiveness as a delicacy for mice make you think about whether it is worthwhile to insulate the attic with foam.
• Minvata is also a convenient and democratic option. Cut to size a couple of cm more than the gap between the rafters, the slabs are easy to install. Before installation, the insulation element must be slightly compressed and positioned in the required place. Having straightened out, elastic mineral wool will firmly “sit” in its nest. Glass wool can be used as an almost equivalent alternative.

• Expanded polystyrene is usually laid on top of the truss system, forming a ventilation gap by installing a counter-batten between the insulation boards and the roofing. It is not suitable for insulating the roofing system from the inside, but can be used to insulate gables.
• Polyurethane foam - easily applied to the surface of any complexity by spraying. A contractor with a portable installation supplying foamed insulation under pressure is subject to planes with any slope. Attic insulation with polyurethane foam will create a monolithic layer without the slightest gaps. In addition, a vapor barrier layer will not be needed to protect the interior from the effects of condensate.
• Ecowool is a heat insulator from the category of sprayed materials. It is similar in properties to wood, it contains an antiseptic that prevents damage to the insulation layer and the wood in contact with it. Just like the previous analogue, it creates a continuous cover that does not sag during many years of use. To insulate with ecowool, it will be necessary to mount a hemmed ceiling and install a crate for attaching a vapor barrier material to it.
• Foil materials that work not only as a heater, but also as a mirror reflector of the heat tending to go outside. In order for the foil heat insulator to work perfectly, it is necessary to deploy it during installation with an aluminum layer inside the room and leave a distance of 5 cm between it and the vapor barrier layer.

The list is quite sufficient to have something to focus on, but mineral wool is recognized as the most popular material for insulation from the inside. Spraying with polyurethane foam is popular, but not available to everyone due to the lack of an apparatus, which, however, can be rented from a construction organization for a while. It remains only to figure out how to insulate the attic with your own hands and get an excellent result.

What should be the correct constructive pie?

An exaggerated thermal insulation system is the following constructive pie, if you start listing the layers from the side of the equipped space:

• Plasterboard cladding.
• Vapor control layer, preferably a variant of the membrane type. It is a continuous shell created from strips of rolled material laid with a 10-centimeter overlap. Cloths are fastened along horizontal and vertical joints with a special adhesive tape.
• A crate that performs three functions. The slats attached across the rafters hold the insulation, serve as the basis for fixing the vapor barrier and form a ventilation space, which is especially necessary when using foil material.
• Insulation, laid in one or more layers, depending on the thermal effect created. When insulating the attic from the side of the room, it is mounted between the rafters.
• A waterproofing layer that protects the insulation from getting wet, which results in a decrease in thermal properties.

Note. Builders who thoroughly know how to insulate the attic are strongly advised to leave a ventilation gap between the heat-insulating material and waterproofing. According to technological standards, its absence is considered a gross mistake.

• Another counter-lattice that creates a ventilated space between the waterproofing and the roofing material. Ventilation in this case is necessary to remove moisture accumulating on the waterproofing membrane. To remove moisture, holes are provided in the area of ​​\u200b\u200bthe base of the slopes and in the region of the valley. The width of the ventilation gap is determined by the roofing material. If the roof is covered with tiles, slate, corrugated board or corrugated ondulin, it is enough to leave 25 mm, if with flat material without a profile relief, 50 mm should be left.
• Windproof vapor barrier equipping the ventilation space. It is needed to preserve heat in the case of active ventilation in the ventilation gap. It is laid above the rafter legs, fastened with rails, on top of which the roofing is mounted.

By doing the attic insulation with your own hands, observing all the subtleties, the owner of a bath with an attic will provide himself with a comfortable living space that eliminates the need to build on suburban area house. To equip a mansard roof for housing, you do not need to obtain permits and seek the consent of neighbors. But benefit and economic effect obvious.

Internal insulation of the attic is one of the most difficult construction tasks. And all because the result is important here: how the roofing cake behaves in winter, whether there will be smudges, whether there will be a smell of dampness and whether it will be necessary to disassemble it all later. Why such difficulties? The fact is that no matter how carefully the budget for building a house is planned, it, as a rule, is still not enough for everything. Up to the fact that even the owners of the future family nest decide to buy a laminate cheaper - just to finish the repairs and just start living. And the most popular item of expenditure, which is immediately reduced as soon as the lack of funds becomes clear, is the insulation of the attic. “Later, in the future,” the owners promise themselves, especially since warming the attic from the inside is not a problem at all, and you can start it at any time, even in winter.

In fact, there are a lot of subtleties and nuances, and therefore, if you have already taken up this matter, carefully study this article. And everything will work out!

Why are there problems?

There are statistics: up to 30% of attics have to be redone after the first winter. Removing the roofing interior decoration and films, and the insulation dries. A lot of materials have to be thrown away, and this is another unplanned cost. Even if you hired a professional team of builders, this is still not a guarantee of the well-being of the future attic, especially if the roofing pie is thought out without taking into account the local climate.

Why is this happening? So, in Russia, dampness, cold and round-the-clock negative temperatures are not uncommon. And the lower the ambient temperature, the greater the volume of steam that penetrates through the vapor barrier - all due to an increase in the partial pressure drop. And at the same time, the migration of moisture through the cold membrane slows down significantly, although it does not stop. Bottom line: the situation is even worse than under standard proven conditions. And therefore it is impossible to test vapor permeability roofing cake in European conditions, and at the same time expect the same good result in the Siberian regions.

Here is a simple illustration to help you understand what we are talking about here:

Note that the maximum pressure of water vapor on the roofing pie is in the residential attic. And the point is not even that there is a person in such a room much more often than in an ordinary cold attic - it’s just that the pressure of warm air is additionally added to the vapor pressure. Moreover, these processes are so clear that they can be observed in the form of real leaks!

The fact is that wet insulation loses its properties very quickly. And the more humid the air that gets to it, the faster the thermal insulation decreases. For example, a basalt insulation with a moisture content of only 5% already loses its heat by 20% than a dry one.

For example, just one cubic meter of air space, if its relative humidity is 100%, at a temperature of 20C contains 17.3 grams of water - just in the form of steam. And the lower the temperature, the more difficult it is for air to hold water in a bound state. And when the temperature drops to 16C, there will already be only 13.6 grams of water vapor in the same air, and the rest will settle in the form of water in the heater. We conclude: moisture in the insulation appears due to the condensation of excess water vapor from the air in the process of lowering the temperature. And she needs to actively fight. And this is not the only problem - now we will deal with all.

Let's start warming - work technology

Let's start with the first problem - the insufficient thickness of the log if you insulate the attic after the construction of the whole house and the installation of the roofing. Why is that? Let's look at this issue in detail.

So, attic insulation can be divided into basic and additional. Basic - this is insulation, which is carried out even during the construction of the roof of the house and involves the use of light insulation directly into the truss structure. But additional insulation already turns a non-residential attic into a full-fledged attic.

With basic insulation, the main task is to minimize the heat loss of the house through the roof, and such basic insulation may well replace additional internal insulation, if only you correctly approach the choice of insulation, do not spare its thickness and think over the truss system well. This is often done by those builders of their own home who understand that even 20 rooms may not be enough in the future, and an additional room for a billiard room, a library or a sauna cannot interfere. And therefore, it is initially better to build it completely residential, and not to finish something later.

But, if during the construction of your house you decided to get by with elementary thermal insulation and now you enthusiastically set about arranging a residential and cozy attic, then the only option for you is additionally internal insulation with all its nuances, the main of which is the insufficient thickness of the rafters, which were not originally designed for dense internal insulation. But the problem is completely solvable, as proof of which we have prepared for you detailed master class:

And now we move on to more insidious moments that are no less important: proper vapor barrier and waterproofing, which you may need to redo.

No - dampness and smudges!

For any heater it is extremely important to create right conditions, otherwise the material will quickly become damp and instead of a heat source it will become a source of dampness, mold and cold. What are these conditions? Let's find out more!

What is dew point?

The first and most important quality of any insulation is low thermal conductivity. Thanks to it, the insulating layer rigidly separates the warm air inside from the cold outside. It would seem that they inserted a heater into the rafters, fixed it - and everything else is needed? It wasn't there!

Firstly, from the outside, this whole thing must be carefully waterproofed from rain and damp air, because. such a roofing cake in this regard is a real sponge. Secondly, any insulation also has a second quality - vapor permeability, i.e. "breathes". And now let's remember the physics: warm, moist air inside a room under a roof (always humid!) Without finding an obstacle, it easily passes inside the insulation and collides with its colder part, the one closer to the roofing pie. And there this air condenses, settling in the form of droplets, which is called the dew point. And then what's the point of external waterproofing? Mineral wool heaters are especially susceptible to this phenomenon, we note.

Therefore, our first task is to ensure that as little steam as possible passes through the insulation, because even super-diffuse membranes in the cold do not cope well with the removal of water vapor, due to a significant slowdown in moisture transfer processes. And this is already a question of the correct vapor barrier of the attic insulation.

Here is a clear example of the unpleasant consequences of ignoring the concept of dew point:

Vapor barrier: warm European winters and Russian frosts

In fact, in Western Europe, where winter has always been mild, there is no need for a vapor barrier with special properties - simple packaging films are quite similar. So they just sometimes end up in Russia, although their vapor barrier properties are not high. These are roll films of LDPE, which stands for "low density polyethylene". In such films, non-uniformity in thickness and microdefects are noticeable. Their main purpose is product packaging.

Slightly better are reinforced materials, which are made by hot pressing a film to a mesh of twisted thread. In production, such films are injured by mesh nodes, and as a result, low vapor barrier properties are further reduced. Although the film itself is much stronger than usual, of course.

More reliable can be called bag fabrics made of polypropylene yarns and spunbonds. The former are additionally laminated with molten HDPE, but a uniform and continuous film is still not obtained, however, the strength pleases. And the latter are made from non-woven polypropylene fiber, but its vapor permeability is still in the range of 15-25 g / m2 per day, and this is a very low figure.

And aluminum foil boasts the best vapor barrier properties, which is suitable even for arranging steam rooms, in which the pressure and volume of water vapor are the highest. The only point: such a vapor barrier additionally creates the effect of a thermos in the attic, simultaneously reflecting invisible heat rays back into the room. And therefore it is better not to insulate a small attic room like that, but for a spacious one - that's it.

Therefore, if you want to save heat as much as possible, or in the attic you plan to make a good sauna, then you need such a vapor barrier:

Or immediately purchase a heater with an aluminum side:

Close access to water vapor

But remember that a good vapor barrier film is still important to properly lay and waterproof, otherwise water vapor will still find its way.

The joints of the vapor barrier sheets are usually sealed with a special butyl rubber adhesive tape, but even in this case it is impossible to guarantee complete tightness. The thing is that over time, the adhesion of the sticky layer decreases, and with an additional load, the canvases become unstuck. That's why when the device exterior finish when it is possible to attach the same drywall directly to the vapor barrier, many put an additional crate. Its task is not so much to ensure that the finish is fixed more evenly (which is also important), but to press the tape or sealant with slats.

In addition, this crate (usually with slats up to 3 cm thick) additionally allows for laying electrical wires right under the skin, and not through the insulation, as many do and which can hardly be called a technically competent solution.

But the places where the vapor barrier adjoins the passing pipes and brick walls be sure to isolate with special sealants or tapes.

Another important point: never stretch the vapor barrier - fasten with a small margin. The point is that everything wooden structures, which is the truss system, naturally dry out and become slightly smaller. The frame itself becomes mobile, and under the roof outside and under the sheathing inside, there is a risk of ruptures. And then - a surprise!

Does external waterproofing "breathe"?

So, on the warm inner side of the insulation we put a vapor barrier, which does not allow moist air to flow from the room. And on the outer, colder side, we are already fixing waterproofing, which will protect the insulation under the roofing pie from external accidental leaks of melt water or rain.

And further development events already depends on how "breathable" the upper waterproofing film will be. So, if you purchased the most common roll of inexpensive waterproofing, things are bad, moisture from the roofing pie will evaporate for a long time and hard, as a result - dampness and gradual destruction of the insulation. But modern vapor-permeable membranes are called “smart” for a reason: they do not let moisture in, but take water vapor out. It's all about their unusual, well-thought-out structure. Why does it turn out that when using cheap barrier films, even expensive insulation does not last long, and repairs are not far off.

Please note that the diffuse membrane should fit as tightly as possible to the insulation, without any gap, like with a conventional film. Otherwise, the membrane material will cool more strongly, and the temperature will become lower than the steam migrating through the insulation. You will see the result in the form of ice right on the membrane, which will make it lose its vapor-permeable properties even more.

When should the roof be removed?

Quite often, during the construction process, roofing felt or reinforced films. And after a couple of years, when the attic turned out to be very necessary and all the households enthusiastically began to repair it, it turns out that without full parsing the roof won't work.

What's the matter? The fact is that such waterproofing does not “breathe” at all, and any insulation under it will completely bend. That is why, if the roof of your house is still under construction, but you are thinking about how to postpone attic insulation for the future, immediately use a good super-diffuse membrane as waterproofing.

But how can something get into the insulation if we have already installed a vapor barrier? The fact is that not a single film in the world is capable of 100% retaining water vapor - they are very small. And no matter how hard manufacturers try, there is no absolute barrier. And even more: modern vapor barrier films, in fact, do not even half do their job, and only the highest quality ones are able to retain steam by 75-80%. Everything else, unfortunately, gets inside the roofing pie.

let's sum it up ogi. You should end up with a roofing cake with two films that have absolutely opposite properties: the inner one does not let steam into the insulation, and the second saves it from a small amount that accidentally got there.

Thermal insulation of complex structural elements

If you have decided on a heater and insulating materials - congratulations! Prepare everything carefully, calculate everything you need and boldly proceed. The main thing, installation work exercise only in a well-ventilated area. And finally, when working with modern heaters many manufacturers advise using a vacuum cleaner before insulating the roof of the attic from the inside, and at the end.

It is not difficult to insulate pitched and straight attic walls, and the first difficulty you will encounter is windows and other complex structural elements. It is also important to properly insulate them, leaving no chance for moisture or water vapor to seep through. Do you know what are usually the most problematic places in attic rooms that “please” with mold and smudges? Therefore, take this question seriously:

And, finally, after insulating the attic, make sure that snow does not accumulate later in the drains and on the ridge - the entrance and exit of the movement of under-roof air. For this, a more rational installation ventilation pipes along the entire roof ridge, and make the ridge itself non-ventilated. That's all the difficulty!

Completion of construction is marked by the final stage in the arrangement of the roof space.

The valley is installed in the inner corners of the roof at the junction of its slopes.

Your comfort and durability of the structure depend on how competently the calculations were made during the design, what material was preferred and how professionally the valley was installed.

The most important element of a metal-tiled roof is the arrangement of a valley - a specialized gutter tray in the inner corners of the roof at the junction of its slopes. Functionally, the valley, more than other structural parts of the roof, is subject to heavy loads, such as containing the accumulation of snow masses and diverting storm flows. With improper installation and insufficient sealing, the valley will soon begin to suffer from unpleasant leaks up to the possibility of the roof collapsing completely.

The design of the locations and the method of installation of the valley must be approached with special responsibility. And the more complex the roof, the more money and time will have to be spent on its proper arrangement, and it will be more difficult to maintain. The project plan for the device of the valley should provide for all the features of the building design: a veranda, a terrace adjacent to the house, dormers and dormer windows on the roof of the building.

Necessary materials and tools

When trying to save on the choice of material for the valley, the main argument is that this element of the roof is practically invisible and therefore does not need special aesthetics and expensive materials. This approach is fundamentally wrong. By using cheap materials, you are not only putting the most important element of the roof at risk of corrosion, but you are putting the entire structure at risk.

Due to the fact that the valley is not visible, you will miss an important moment of its deformation, and the subsequent repair with the complete dismantling of the metal tile and the replacement of elements will become an event that is quite tangible financially.

The presence of a valley in the place of water accumulation necessitates the choice of more durable metal sheets as a material for it than for the metal tile itself, with a zinc coating density of at least 275 g / sq.m or with a durable polyurethane coating. It must also be remembered that it is advisable to choose the valley planks of the same color as the roof.

To mount the valley, you will need to purchase the following materials:

• special brackets for fastening the groove;
• foam self-adhesive strip for protection from snow, water and dust;
• high-quality installation of the valley involves the use of half tiles;
• tape for valley joints;

For high-quality and accurate arrangement of the roofing valley, you should have all the necessary tools at hand:

For cutting metal tiles and valley planks:

1. Power saw with carbide teeth for cutting thick metal.
2. Special nozzle for a drill with the function of slotted scissors for cutting metal up to 1 mm.
3. Limited volumes can be trimmed with slotted and lever hand shears.

For mounting fasteners:

1. Electric drill or screwdriver for screwing in self-tapping screws.
2. Plier bender for installation of fastening structures for valley system gutters with metal bar thickness up to 0.8 mm.
3. Klepochnik for corrugated folds of ends of drain structures.
4. Sealant gun for efficient joint sealing.
5. Stapler for attaching waterproofing material to the crate.

Valley design

The image of the roof plan consists of square and rectangular sections indicating the premises of the building, main and secondary runs, as well as lines indicating the junction of the main roof with the corners of the outbuildings. All these connection lines are places for further installation of valley structures.

Diagonal rafters are mounted at the joints of the slopes. Given the height of the roofs, the ends of the rafters are installed on the main run and the Mauerlat - the lowest support for the rafters. The size of the corners of the slopes depends on the size of the room.

By varying the length of the runs, it is possible to achieve the desired geometric shape of the roof: half-hip, hip, tent. But a complex multi-pitched roof will also require a more complex installation of the valley with the installation of additional bars for fastening. By making the slope of the junction of the valley at different angles, you can also create a roof various forms and sizes.

The valley structure lies below the roof covering with ventilation gaps to remove steam. The rafters under the valley are reinforced with boards laid on them in a continuous array. The superdiffusion membrane is located above, there is no need to leave a gap under it.

Structural details of the valley

The valley consists of two parts: the upper and lower slats.

The lower part, called false, is used in the form of a wide plate, bent at an angle corresponding to the angle of connection of the roof slopes. It is installed at the junctions of negative angles and serves to protect the under-roof space from moisture flowing through the joints of the slopes. Installation is carried out before the installation of metal tiles. To fix the lower valley, roofing screws are used in well-chosen places for this. In addition, in order to avoid leakage under the valley, a special valley carpet is laid - the lining layer.

The plank of the upper valley serves to cover the functional parts of the structure for aesthetic purposes. Install it at the end of the installation of roofing material. Often, decorative overlays are used for these purposes, which must be mounted from the bottom up with a minimum overlap of 10 cm without installing a seal.

An important step is the installation of the truss system for the installation of valleys, since it bears the main load of the roofing planes. Particular attention should be paid to waterproofing. The key to a durable non-leaking structure here will be a well-drawn drawing and strict adherence to it during installation.

The device of the valley at the junction of the main slope and the flat roof of the veranda or mezzanine requires special attention when installing the roof. After installing the rafters, a metal tile is mounted with an output to the inner corners using two lining layers superimposed on each other.

Installation of the base under the valley

For competent laying of the valley, it is necessary to prepare the right foundation under it - waterproofing material on a full frame.

Along the lower element of the false valley for additional sealing, another layer of waterproofing material or sealant is laid. A special valley carpet made of corrugated rolled roofing or non-corrosive metal can act as an additional sealant. A layer of rolled roofing material is made from polyester fiber impregnated with bitumen High Quality and covered on both sides with sprinkles: basalt on top, sandy on the bottom.

Such a carpet will effectively protect the joints from moisture penetration, has high strength and turns the gutter into a solid element. The installation of the carpet is carried out by gluing or nailing every 20 cm.

Scheme of laying the valley carpet: 1 - the axis of the valley. 2 - self-adhesive bitumen-polymer material. 3 - valley carpet. 4 - lining carpet.

Installation of the base under the valley:

1. A waterproof membrane is laid under the valley carpet to prevent the formation of condensate.
2. Corrugated roll roofing is laid in the center of the valley with a sandy surface down.
3. The valley carpet is pressed against the ridge and fixed with nails at 2.5 cm intervals, starting from the outer ends.
4. The lower edges of the roof are trimmed. On both sides of the roofing strip, strips of plastic cement 10 cm long and 1.5 mm thick are applied. When butt-joining the roof, the upper section should overlap the lower one by 30 cm and be fixed with plastic cement.
5. Then a strip of corrugated rolled valley carpet is laid on top of the previous one, also face up and reinforced with cement and nails.
6. Before laying the roof panels, two lines are drawn with chalk along the length of the valley with an indent of 10 cm from each side of the ridge.
7. A waterproof membrane is laid under the anti-corrosion metal or valley carpet. Installation of such a waterproofing layer will provide maximum protection against moisture and condensation and extend the life of the roof.

Stages of installation of valley elements

Installation of the valley is carried out from the roof ridge to the eaves and consists of several main stages:

• installation of an additional board in the roof valley;
• installation of planks from the bottom up with an overlap of 20-30 cm;
• the lower bar is cut off under the cornice and finished with a flanging;
• installation of a sealant under the ridge and flanges of the valleys;
• after the installation of the metal tile, the process ends with the installation of the upper valley with a fastening step of 3-5 cm at the top of the wave;
• the nodes of the valleys are isolated with a sealing tape.

To prevent leaks, when fixing sheets of tiles with a valley in the roof, it is necessary to observe a single distance of 25 cm from the axis, and the gap between them must be at least 6-10 cm on both sides.

Basic rules for fastening and connecting valley gutters.

If it is necessary to increase the length of the valley, an overlap of 20-30 cm is made. The junctions of the two valleys are fixed with self-tapping screws and sealant. The main slope is mounted in sheets above the valley gutter so that it is located between the rows with an overlap of about 20 cm.

At the junction of the slopes on a continuous crate, the lower valley is installed with a self-adhesive porous seal between the lower element and the metal tile.

The false valley plate is attached to the crate with self-tapping screws every 30 cm. It is necessary that the lower edge of the valley is above the cornice board. If the false end has several elements, then they are mounted from the bottom up, sealing the joints with sealant.

Places for installing roofing screws must be chosen very carefully, trying not to damage the middle part of the false valley.

Having installed the lower element and the waterproofing layer, proceed to the installation of the upper valley bar. In addition to functional protection of the roof by draining rainwater from roof slopes the upper part performs a decorating function. Therefore, the material for the top bar is chosen in the same color as the metal tile.

The roofing material is laid on two sides from the inner corner by 10 cm. Finally, the upper valley or a decorative overlay replacing it is mounted. In this case, you must follow the same rules as when installing the lower part of the valley: installation from the bottom up with an overlap of 10 cm.

Valley mounting methods

Installation of the valley is carried out in various ways:

• open;
• closed;
• articulated or intertwined.

Regardless of the installation method, the valley is installed in the negative corners of the joints and slopes. To do this, on both sides of the joint, a continuous crate is laid and a waterproofing device is installed along a wooden gutter. The lower part of the valley is fixed on top with self-tapping screws.

In this case, the following features must be taken into account:

• with horizontal joints of the elements of the valley, the overlap is maintained by more than 100 mm;
• with flat-angle slopes, an additional waterproofing device is necessary;
• for metal-tile roofing, it is recommended to use a self-expanding sealant as a sealant.

The articulated laying method is used for roofs with equal slopes. For compaction with this method of installation, the width of the valley carpet is about 90 cm. A waterproofing membrane is applied on top, which is fixed on chipboard or moisture-resistant plywood sheets with nails. In the case of interlacing ridge joints, the roof tiles are installed first. The interlaced or articulated valley is completely covered with roofing material. with this method of laying, the rows of tiles are intertwined and laid through the valley. The joints are reinforced with bituminous mastic.

After installing the waterproofing system, which is typical for pitched roofs, the first row of roofing material is completely laid down to the lower end of the valley. Then the open valley plank itself is mounted directly.

The device of steep roofs with butt-joined adjoining slopes implies the use of a closed valley installation method.

The adjacent roof slope must be marked with a chalk line, moving away from the inter-ridge joint by 5 cm. This line will serve as a border for laying tiles and driving nails during fixation.

Before laying the roof tiles, 90 cm wide corrugated waterproofing material is placed under the valley. Next, the rows of tiles are laid along the slopes and, continuing through the valley plank, are superimposed on the adjacent slope for 30 cm. The top corner of the roof panels is cut diagonally to improve water drainage.

Basic rules for the device of the valley

• for any type of roof, tubular and lattice models of snow guards are suitable;
• strict control of the absence of mechanical deformations and tears of the sealing tape for joints. It is necessary to provide small gaps for small debris and water;
• must be performed on the crate;
• installation of a valley starting on the eaves on droppers;
• the top is overlapped with a distance of 10 cm;
• fastening with self-tapping screws at least 25 cm from the axial center of the valley;
• alignment and fitting is done with a rubber mallet;
• the installation of valley planks on the roof overlaps from the bottom up. The lowest part is cut below the eaves.

Dormer window device

In the presence of dormer windows and other elements on the roof, installation has some features:

1. The valley starts and ends on the slopes.
2. The metal tile sheet is cut 20 cm above the exit of the valley planks to the connection of the slopes, a sealant is glued to it along the walls of the dormer window.
3. The cornice of the dormer window is protected by a plank.
4. The device of the valley, the edges of which are cut off along the eaves and along the edge of the slope. The latter must fit snugly against the sheets of roofing material, for which it is formed manually with the application of force.
5. When extending, self-tapping screws with sealant are used; it is necessary to adjoin the elements of the valley with an overlap of at least 25 cm.
6. The flanges of the valley are reinforced with a sealant.

Bridges of cold call the sections of the building envelope through which the largest occur, which leads to a number of negative consequences. Today we will talk about how to prevent the appearance of cold bridges in an insulated (mansard) structure.

Cold bridges in the construction of an insulated pitched roof cause many problems:

1. Firstly, they reduce the effectiveness of the thermal protection of the building, which increases energy consumption by , which, in turn, results in an increase in the cost of operating the house.
2. Secondly, during the cold season, condensate accumulates in the freezing zone, which leads to wetting and gradual damage to the roof used for insulation (which also worsens the thermal protection of the building).
3. Thirdly, due to condensate, wooden roof structures can become moldy, rot and eventually collapse. Often, condensation causes deformation of the finish.
4. Finally, fourthly, condensate can freeze in winter and break the cracks and gaps that it filled.

Heating errors

What causes cold bridges? According to experts, in most cases this is due to errors in the construction of the heat-insulating layer of the roofing "pie". Recall that most common building technology mansard roof involves the insulation of slopes (which are at the same time the walls of the attic) with fibrous materials: slabs and - less often - mats based on or.

Another knot dangerous in terms of freezing is the junction of the roof with the gable of the building.

Valery Nesterov, CEO of Dörken:
“There is a very high probability of freezing at the junction of the roof with the pediment of the building. To prevent it in the West, there are special U-shaped elements made of extruded polystyrene foam, which are “put on” on the gable wall. On our market there are special diffusion hydro-windproof membranes with an integrated layer of insulation 30 mm thick made of non-woven material: they can also protect this area from freezing. However, the traditional solution is to fill with mineral thermal insulation the space between the outer rafter and the gable wall (usually about 50 mm), the gap between the upper surface of the wall and the hydro-windproof film, and also lay the insulation along the upper edge of the wall. As a result, a continuous heat-insulating contour is created that closes the pediment and transfers the dew point inside the wall, thereby eliminating the possibility of condensation in the thickness of the roofing insulation.”

1. The first difficulty lies in the fact that often on the entire upper part of the sloping gable wall there are ledges formed due to masonry (made of bricks, blocks). To level the wall, a “cold” cement-sand mortar is often used, which becomes a cold bridge. It is better to use a "warm" solution with the addition of it instead. Or fill the irregularities with thermal insulation.
2. The second difficulty is to insulate this place with high quality. It is necessary to leave a distance of at least 50 mm between the rafter leg closest to the gable and the gable wall, filling this space with thermal insulation. In addition, it is desirable that the upper plane of the wall be 50 mm lower than the upper plane of the rafter legs, and then the insulation is also laid on top of the wall at the height of the leg, ensuring its snug fit to the insulation running along the rafters. If possible, the insulation is also mounted along its edge from the side of the street - with a layer of thickness equal to the thickness of the insulation on the roof slope.

Here you can use both fibrous thermal insulation and materials from. It is preferable to put insulation on top of the pediment even before laying the hydro-windproof membrane - for the same reasons that we talked about a little higher.

Freezing through the rafters

Joints are also problematic. wooden elements roofs (located between its warm and cold zones), as well as composite rafter legs, made by combining two beams into one. Cold bridges can appear here for several reasons: due to the loose fit of the elements to each other (caused, among other things, by their curvature), due to the settlement of the truss system, etc. To avoid this, joints should be laid with sealing materials, for example, synthetic winterizer or polyethylene foam. However, a number of roofers believe that the latter reduces the reliability of the connection of wooden elements. If you have to seal the joints after the installation of the rafters, then you can use specialized sealants, PSUL (pre-compressed self-expanding sealing tapes) or mounting foam, but this is not cheap and rather laborious. This solution has one more significant disadvantage: the foam, being inelastic, can collapse when the wooden structure is upset.

An effective way to prevent heat loss- create an additional layer of roof insulation, blocking possible cold bridges.

On the picture:
1. On roofs of complex configuration, it is inevitable to cut the insulation boards in order to fit them into the space between the rafters.
2. Fastening the vapor barrier film to rafter leg.
3. Installing the undercut slab in the ridge area.
4. Slots in the insulation layer are caulked with fragments of the same heat-insulating material.

Freezing is also possible at the exit points through the wall to the street of the Mauerlat, ridge or intermediate runs, on which the extended rafters rest. To prevent the movement of cold air here, you must first seal the gaps between the beam and the wall, and also do not forget to seal (glue with glue or special tape) the places where the vapor barrier and hydro-windproof films bypass the beam.

The roof window area is another section of the roof where cold bridges can occur.

Often this happens due to the absence or insufficient thickness of the insulation layer around the perimeter of the window frame and along the slopes. To prevent freezing, it is necessary to leave a gap of 20-30 mm around the frame, filling it with thermal insulation, which should be brought to the roof insulation contour.

To simplify installation, window manufacturers offer ready-made kits for thermal insulation around the perimeter of the frame(e.g. polyethylene foam). Some companies produce windows with heat-insulating ones already provided on the frame. Note that window manufacturers categorically prohibit insulating the frame with mounting foam.

Marina Prozarovskaya, Velux chief engineer:
“Among the reasons for freezing in the area of ​​the roof window is the lack of thermal insulation around the perimeter of the window frame. Often this is caused by too small mounting gaps between the box and the rafters. It is necessary to leave a gap of at least 30 mm around the perimeter of the frame, installing either a ready-made heat-insulating contour made of polyethylene foam or a fibrous insulation around it. Mounting foam cannot be used for these purposes: it is inelastic and under the influence of periodic loads (roof settlement, snow, wind load) crumbles, resulting in cracks in the thermal insulation. If the width of the window is equal to the width of the inter-rafter opening or exceeds it, then in order to provide the necessary mounting gaps around the frame, it will be necessary to adjust the rafters, while maintaining their bearing capacity. Sometimes this can be done without special calculation according to the schemes indicated in the window installation instructions. Usually this involves the installation of an additional beam, the section of which coincides with the section of the rafter leg.

In most cases, cold bridges are the result of condensation leading to wetting of the insulation in the window area. There can be many reasons for its formation. In particular, non-glued joints of the vapor barrier film with window frame: water vapor has a high penetrating power, and when it enters the cold zone, it condenses. Often, condensation is a consequence of certain errors in the installation of the ventilation system of the roof structure.

For example, there are no conditions for air inflow or its exhaust, a counter-lattice that forms a ventilation gap is not provided, or its height is insufficient to provide the necessary air movement under. However, non-sealed joints and junctions of both roofing films, as well as insufficient ventilation of the roofing space are errors that lead to condensation and freezing. not only in the window area, but throughout the roof. It's just in the window area that it becomes noticeable in the first place. Moreover, many errors cannot be corrected during the operation of the building without the complete dismantling of the roof.

According to experts, in the conditions of the Moscow region every 5 cm of thermal insulation saves on heating an average of 18 rubles. per 1 sq. m of roof area per year.

A few more words about the roof window. Problems arise and in case of improper installation of the drainage gutter above the window opening. This gutter removes water (leaks, condensate) from the window, which flows down the hydro-windproof membrane to the window. Before laying it, the membrane is cut, and then its edge is inserted into it, securing it with a special clamp, after which the upper edge of the window waterproofing apron is already inserted under the gutter. If the gutter installation technology is not followed, leakage into the insulation is possible with all the ensuing consequences.

Heat-conducting inclusions in the roof structure become certain passage elements - pipes, antennas, flagpoles, etc. Therefore, they must be insulated with high quality and vapor barrier and hydro-windproof films should be hermetically joined to them.

To minimize freezing through the walls, experts advise creating an additional heat-insulating belt about 250 mm high on top of the standard insulation contour (that is, above the roof). To protect against precipitation, the belt must be closed with one or another apron.

Ekaterina Kolotushkina, Product Manager, Saint-Gobain CIS:
“To make the attic as comfortable as possible for living and to ensure the durability of the roof structure allows the creation of an additional insulation circuit. The fact is that the wooden load-bearing elements of the roof are, to some extent, cold bridges. In addition, according to calculations, the thermal insulation layer in the central part of Russia should be 200 mm, however, the thickness of the most popular beams on the market used for rafters is 150 mm (and the insulation is placed in the space between the rafters). Thus, it makes sense to create an additional heat-insulating layer that will provide the required thickness of insulation and block the cold bridges going through the rafters. This layer can be placed above and below the rafters, laying the insulation between the bars nailed across the rafters. Thermal insulation above the rafters is preferable, because in this case they do not freeze through.

Additional layer of insulation

Despite all the efforts of roofers, heat losses are inevitable in those places on the roof where the area of ​​​​the inner “warm” surface is less than the area of ​​\u200b\u200bthe outer “cold” one. These are mainly the corners of hip or hip roofs (in the zone of convergence of the ridge and the cornice overhang), the places where the slope adjoins the gable, etc. In addition, wooden rafter legs are also, to a certain extent, cold bridges. Yes, and it is difficult to insulate complex sections of the roof where filigree pruning is required (valleys, ridges, junctions). Finally, the thickness of the heat-insulating layer in central Russia should be, according to SNiP 23-02-2003 "Thermal protection of buildings", not less than 200 mm. While the most popular material for the construction of rafters is still a section of 150 × 50 mm, which implies a thickness of the inter-rafter insulation layer of 150 mm. All these factors justify the need for additional contour of the thermal insulation of the roof.

It can be mounted over the rafters and under them. In the first case:

1. Wooden blocks of the required section are stuffed across the rafters, between which insulation plates are installed.
2. A hydro-windproof membrane is laid over the bars.
3. A counter-lattice, crate or solid flooring is fixed on it, and roofing material is placed on them.

This option is effective in terms of thermal protection, because the truss structure will be entirely in the "warm" zone. However, it is not without drawbacks:

• Fixing the roof to the base is less reliable due to the additional wooden substructure.
• In addition, when installing hydrowind protection, the joints of the sheets may be on a heater (and not on a wooden base), and the installers will push through the film, moving along the roof.

Therefore, the optimal technology is additional insulation under the rafters. In this case, from the side of the room, transverse bars are attached to the rafters, thermal insulation is laid between them, and then it is covered with the attic finishing material.

There is another effective, but so far almost unused method of insulation - installation over rafters continuous flooring, on which slabs of high density stone fiber, wood fiber, polyurethane foam are laid. The roof is mounted directly on the slabs.



1. Rafter leg.
2. Additional contour of warming.
3. Cross bar.
4. Finishing the attic.

Let's note one more point. In the fight against freezing of the roof will help modern methods for detecting cold bridges- examination with a thermal imager or hot-wire anemometer. The cost of purchasing or renting these devices is less than the cost of repairing a freezing roof.

In most cases, it is more profitable for a private developer not to buy a thermal imaging camera, but to contact a specialized company that deals with thermographic examination of buildings.

Types of insulation for pitched roofs

To insulate a pitched roof, slabs (or mats) made of stone or glass fiber are most often used.

• In our market, stone fiber materials are represented by Rockwool (Denmark), Paroc (Finland), Nobasil (Slovakia), TechnoNikol, Isoroc, Knauf (all Russia) and others.
• Glass fiber insulation is offered by Isover (France), Ursa (Spain) and others.

Materials made of extruded polystyrene foam or polyurethane foam, although they have very good thermal insulation properties, are not fireproof: expanded polystyrene belongs to the group of highly combustible materials (G4), and polyurethane foam belongs to the group of moderately or slightly combustible (G2-G3). At the same time, fibrous heaters are non-combustible (NG).

The material was prepared by Alexander Levenko.

In order for the roof to meet all the architectural features of modern buildings, it is often made in the form of structures from many multi-pitched roofs. Geometrically complex frames of the truss system have a large number of junctions of pitched surfaces that form the inner corner of the roof. Such areas in the design wooden roof are called valleys. Another name for this element is the groove or gutter of the valley. Having a v-shape, the roof valley actually plays the role of a gutter along which water flows are directed and removed. Competent installation This element is of great importance, since installation errors can lead to leaks, damage to the insulation and additional repair costs.

Valley device diagram

The valley is one of the most important and complex elements of the roof structure. The junction line of neighboring slopes during operation is subjected to serious climatic loads. During rain, water flows down it from neighboring slopes, and in winter snow accumulates here.

A properly installed valley not only protects the house from bad weather and precipitation, but also extends the life of the roof.

Typically, a valley consists of a decorative upper plank covering the junction of two slopes, and a lower gutter, which is located under the roofing.

The number of valleys depends on design features roofs, as well as from the presence of additional skylights.

Depending on the design features of the roof, the number of installed valleys will be different.

The design of the valley implies the construction of a base in the form of a continuous crate, along which a layer of waterproofing is laid, as well as the presence of a lower and upper element. The lower bar of the valley acts as a gutter, and the upper element serves as a decorative detail that covers the joints of the slope. Most often, these elements of the roof are made of metal. The highest quality material for the manufacture of valleys are steel sheets with applied polymer coatings and special coatings. In some designs, the upper part of the valley is not used.

To improve the waterproofing properties of the lower valley, its upper shelves can be sealed with a self-expanding porous material.

Depending on the angle formed at the junction of the joints of the roof, there are three types of valleys:

The design of the truss system, which serves as the basis for the installation of valley planks, depends on the intended type of roofing. In this regard, there are several types of crates for laying valley planks:

1. A solid crate is used during installation soft roof. In this case, the valley is made in the form of a continuous coating of waterproofing layers. Mounting the valley in this way is the simplest.
2. If slate, profiled sheets or tiles are used as roofing for a gable roof, the sheathing will have a completely different look. For its device use 2 or 3 edged boards, which are mounted along the joints of the roofing in increments of 10 cm.
3. Crate with additional elements. When using metal tiles, intermediate strips can be installed to the main laths of the lathing.
4. The wooden base for ondulin is made of two boards 10 cm wide, which are mounted in increments of 15–20 cm. Such a base will not allow the groove to sag.

Video: valley and junction device

Valley installation sequence

The installation of the valley is carried out in the following sequence:

1. Before installation, a dripper is installed along the entire length of the cornice overhang to drain condensate from the under-roof waterproofing.

   The drip is made from the same material as the main roofing.

2. On both sides on the bone rafter leg with a gap of 5 cm from its edges, bars of a horizontal counter-lattice are nailed. The lower ends of the bars must be sawn flush with the cornice overhang.
3. Higher demands are placed on waterproofing in the valley area. Three layers of diffusion membrane are laid here. Its task is to protect the underlying structures and thermal insulation materials from moisture ingress, but not to prevent the release of water vapor. The first layer of the membrane is laid out along the valley over the horizontal counter-lattice. The film inside the counter-lattice forms a kind of gutter that protects the wood from getting wet from the side in case of under-roof condensate. The membrane is attached with brackets to the top and side faces of the slats. Then the membrane is cut off along the edge of the dropper and the counter-lattice.

   The waterproofing material protects the planks of the counter-lattice from getting wet from the side and is attached to them with a construction stapler

4. Further, the diffusion membrane is laid out along the slopes on the rafters according to the pre-made markings. Laying waterproofing on the slopes is done with a pigtail, that is, alternately on both sides of the valley. In this case, the membrane is transferred through both horizontal counter-lattices and cut off behind its opposite edge. The fastening of the membrane from the slopes is also carried out using a stapler on the side and upper faces of both horizontal counter-lattices. The joints of this waterproofing barrier can be glued with double-sided tape.

   When gluing the membrane, it is necessary to overlap at least 10 cm and glue it with double-sided tape

5. So that the membrane does not slam on the drip from the wind and does not fray over time, it is necessary to glue it to the edge of the drip gutter with double-sided tape.
6. Over the waterproofing, bars of the valley board are stuffed, which form an air gap for ventilation of the under-roof space and removal of condensate from the film.
   

   A gap is left between the bottom bar of the valley and the waterproofing film to drain condensate

7. Laying the membrane from the opposite slope, as well as fastening with staples to the horizontal counter-lattice and gluing with double-sided tape, takes place in a similar way.
8. After both adjacent slopes and the valley are closed with a membrane, the packing of the counter-lattice is completed on them and the installation of the lathing bars begins. Installation of the lower lathing along the cornice overhang is carried out flush with the ends of the counter lathing.

   A wooden crate laid on the bars of the counter-crate is necessary for ventilating the under-roof space and for fixing the finish coating

9. In the area of ​​​​the valley, on the lower laths of the crate, markings are made at an angle for precise docking with each other. A ventilation tape is installed along the entire cornice overhang to protect against the entry of birds.

   The lower laths of the lathing in the valley area are cut to form an even joint

10. The ends of the lathing from the side of the gable overhang are closed with a membrane flap wrapped up, which is fixed on the bars with a stapler. A frontal board is stuffed on top of it. If it is provided for by the project, brackets for fastening the gutters are mounted along the entire cornice overhang.
11. In the valley area, in the middle between the ordinary laths of the crate, additional bars are stuffed that support the gutter, preventing it from deforming under the weight of snow. At the same time, thanks to the rapid crate, the space under the groove of the valley is well ventilated. In the presence of a drainage system, a plastic overhang apron is mounted. Its task is to prevent water and snow from entering the ventilation gap between the tiles and the waterproofing.

    To counteract snow loads, a quickened crate is arranged under the bar of the lower valley

In the absence of a drainage system, the installation of an overhang apron is not mandatory.

Video: installation of a valley on a metal roof

Connection of two valleys on a slope

The installation process at the junction of two valleys is carried out as follows:

1. If the project provides for a junction of the valleys below the ridge, then the gutters on both sides are cut for tight mating and fixed with self-tapping screws. The joint of the gutters is carefully glued with a sealing tape along the entire length, profiled along the ribs and rolled with a roller.
2. The valley plank in the upper part is attached to the crate with brackets. The upper corner of the joint is formed by hands, and the flanging is pressed against the surface of the grooves.

   In order to prevent moisture from penetrating into the under-roof space, bends are made along the edges of the valley planks

3. The flanging is completely bent inward along the entire length, while applying efforts is possible only in places above the crate. Foam strips are glued along the entire length of the valley groove on both sides. They protect the roof space from precipitation and dust. The lower edge of the foam strip should fall on the overhang air element. If the foam strips were not used for some reason, water, snow and dust will constantly get under the roofing, thereby reducing the life of the structure.

   Foam strips must be installed to protect the space under the valley bar from water, snow and dust

4. Roofing material is laid on both adjacent slopes in the direction from the gable overhang or valley ridge, covering the groove as much as possible. In order to ensure unhindered runoff of rainwater and snow to fall along the valley chute, the coating on both sides is cut at the same level. The overlap of the cut tiles on the groove of the valley should be from 13 to 15 cm or 8–10 cm from the center of the bottom bar.

   Sheets of metal tiles are cut so that they go to the bottom plank of the valley by 13-15 cm

A smaller overlap will lead to the fact that the foam strip will collapse due to exposure to solar radiation, and a larger one will complicate the fastening of the tiles.

The cut line is applied with a coloring cord along the marks located at the top and bottom of the valley, and is marked on both sides of the groove.

Video: valley with access to a slope on a metal roof

Features of fastening the elements of the valley node

The valley node looks like a concave angle between two roof slopes. To fix this roof element, roofing screws are used, which are equipped with a rubber or plastic washer. The washer performs several functions:

• protects the surface of the roofing material from scratches and damage;
• serves as a waterproofing layer between the self-tapping screw and the hole in the roof, hermetically closing all the cracks.

Rubber washer provides soft clamping of the self-tapping screw and waterproofing of the hole

When installing the valley plank, it is necessary to overlap at least 10 cm.

For better sealing of these roofing elements, it is necessary to use sealing tape.

The planks of the lower valley are mounted directly to the wooden crate using clamps fixed with nails or self-tapping screws. The upper element of the valley must be screwed to the metal tile with self-tapping screws. It should be noted that the screws for fixing the upper valley should not rest against the lower gutter. The gaps between the roofing and the groove sheets must be filled with foam sealant.

Clamps secure the bottom plank of the valley without damaging its edges

When installing the nodes of the valley, special attention should be paid to the quality of the crate. It is recommended to install the lower gutter on a continuous crate, the width of which should not be less than the width of the valley itself.

The installation of the nodes of the valley is carried out as follows:

The brackets should not be fastened to the ordinary, but to the fastened crate, otherwise they will interfere with the even laying of the tiles.

The upper groove is laid on the underlying one with an overlap of at least 10 centimeters. When laying, it is necessary to combine the transverse edges of the gutters and fix the subsequent grooves in the same way as the first.

When installing a valley from several planks, it is necessary to overlap by 10 cm

Overhang Aeroelement Installation

An overhang air element is installed to provide additional support for the bottom row of metal tiles, as well as to prevent birds from entering under the roof.

If the offset is larger, it will keep debris and fallen leaves in the gutter, as well as prevent snow and rainwater from sliding.

Strengthening the valley

The functionality of the valley is directly related to the quality of its foundation. To strengthen the valley, it is better to use a solid crate.

1. A waterproofing layer is installed along the entire length of the base. The best option to strengthen the nodes of the gutter is the use of a valley carpet. This protective coating is made of non-woven polyester material impregnated with concrete mixtures with the addition of modifiers. A topping of basalt chips is applied to the upper side of the valley carpet, its lower part is covered with sand granules.
2. The waterproofing material is fixed with special stickers or nails. If the carpet is nailed, the distance between them should be about 20 cm.
3. The lower elements of the valley, roofing, seals and decorative details are mounted.

Non-woven polyester materials can be used instead of standard waterproofing to reinforce valley knots.

Installing a polyester fabric with bituminous impregnation allows you to solve a number of problems:

• provide reliable protection of the internal bends of the structure and other places most vulnerable to moisture ingress;
• create a shock-absorbing layer that will soften the load from snow;
• improve the aesthetic qualities of the roof;
• completely eliminate leaks.

Trimming tiles when arranging a valley

If the valley is arranged on a tiled roof, trimming of the elements of the roofing material is often required:

1. First, a rough fit is performed, and then a fine marking and trimming of the tiles exactly along the line drawn on the groove of the valley.

   Cutting tiles must be done on a machine with a circular saw

2. The spike of the tile that falls on the valley is beaten off or cut off so that it does not crack on the groove.
3. The foam strip under the tiles should be cut - this allows you to immediately lay the roofing evenly, without waiting for it to push through the strip under its own weight and fall into place.
4. A hole for a self-tapping screw is pre-drilled in the trimmed tile so that it does not fall on the groove.
5. The prepared roofing element is installed in place and fastened with a self-tapping screw.

   All stacked elements must form a straight line parallel to the axis of the groove

6. Sometimes, when marking up, it is clear that after cutting off some elements, a small triangular fragment remains, which is difficult to fix. This happens if the cut line falls on the right side of the tile, then the cut line is shifted by 5 cm, and a half tile is used next to it. It is installed instead of the usual ordinary one column from the cropped one. The consumption of half roofing elements is one piece for two rows on each side of the valley.

   Half tiles add the missing roof fragment if in this row most of the surface of the last roofing element falls under cutting on the valley

7. The prepared trimmed tile is laid in its place and fixed with a self-tapping screw. The tile from the top row moves down and presses the trimmed element.
8. The rest of the roofing material in the valley is laid in the same way. When laying on a ridge, the extreme ridge tiles, which go to the junction of the valleys, are cut along the same line as the tiles located in rows on the slope.
9. The upper cut of the extreme ridge tile is closed with a special tape for adjunctions. The installation of the valley is completed.

   Corrugated tape is a convenient and effective material for sealing the protruding parts of the roof.

It is impossible to fasten the tiles through the groove of the valley, since in the place where the self-tapping screw passes, precipitation will flow under the roof.

Video: installation of ceramic tiles - the formation of a valley

Errors during installation of the valley

Installing a valley gutter requires care and skill. Since this roof element carries a large amount of rainwater, the slightest mistake during its installation can lead to serious problems and additional costs. The most common errors when installing a valley are:

1. An attempt to cut the shingles right on the valley using a grinder. This often leads to damage to the already fixed groove. In addition, it is very difficult to achieve a straight cut line along the entire length of the groove, so the valley and the entire roof will look sloppy, and water runoff and snow will be difficult.

   If the tiles are cut unevenly, the roof will look sloppy, and water and snow will come off it intermittently.

2. Fastening the groove with nails along the entire length.
3. Installation of valley planks from the ridge to the bottom edge. In this case, the lower bar will cover the upper one. At the junction of these elements, moisture will get inside the roof, and will not drain down.
4. Narrow crate or lack of additional rails. This error will cause the weight of the snow to deform the valley. As a result, cracks and gaps are formed through which moisture will penetrate.
5. Twisted or insufficiently tightened self-tapping screws. In the first case, the roofing is damaged, in the second, moisture will penetrate under the self-tapping screw.

   If the self-tapping screws are not tightened correctly, water will flow into the under-roof space, contributing to the destruction of the rafter system

The installation process of the valley requires special knowledge and building skills. Therefore, it is better to entrust the installation of this roofing element to experienced professionals. In this case, errors that lead to serious problems will be excluded.