If you have ever come across exposed rafters in a residential building that have been deliberately emphasized and stylized, you will never forget this sight: such a fashionable architectural touch completely changes the whole look of the room, giving it volume, space and fullness. And at the same time, such elements also play a functional role, improving the ventilation of the room and serving as a good support for the installation of the necessary utilities.
Such rafters are installed on the ceiling as part of the overall truss system, and in the form decorative elements, which only imitate the massiveness and roughness of wood processing. Let's take a look at both technologies!
So, let's start with the features of the roof truss system and how exactly the device of a conventional horizontal ceiling looks like. In fact, in this version, there are no rafters as such at all - only floor beams and logs of the attic-mansard floor.
And therefore, if they talk about rafters on the ceiling, then they mean them open part or decorative imitation, which we will now discuss in more detail.
In many interior styles, open elements of truss systems are welcome. And at the same time, the decision to leave the beams or rafters open is made at the design stage of the house: the cross section of the rafters themselves and some insulation parameters depend on this.
The fact is that the dimensions of the rafters cannot be arbitrary - they have their own critical minimum, while the maximum is also important, because each board has weight, and all this puts pressure on the walls and foundation.
Usually, insulation is laid between the rafters in such a roof, and some of them peek out from under the finish, or such elements will have to be built up in special ways.
And, believe me, it’s definitely worth tinkering with all this: the open ceiling rafters, which are made in the form of rough wood, seem to let them into the interior warm shades, reminds of the past and always symbolizes some fashionable style.
Real rafters and extensions: we use the existing frame
Real exposed rafters on the ceiling, with their natural wood grain, always look amazing.
But, we can bet, here you probably won’t determine by eye which of them were specially supplemented with more expensive and beautiful wood on top:
That is, when you see such rafters, then you see either a real part of the roof structure, or its addition (or a dummy in general, but more on that later). Let's find out the secrets of both technologies!
Real rafters: competently place accents
Architecture and interior design have been in harmony throughout the ages, and only in the last decades of mass construction of faceless multi-storey buildings has this symbiosis been broken.
The geometry of the living quarters became sterilely simple, the long-awaited minimalism came into fashion, and bright strokes could always be added at will with the help of accessories.
But relatively recently, the fashion for involving in design not only the horizontal of the room, but also the vertical broke through into the Russian interior world! Podiums, height differences, open multi-level studios appeared. And the most important thing, stretch ceiling ceased to be the only possible style solution.
Instead of a perfectly smooth horizontal ceiling and a useless attic above it, non-attic buildings have come into fashion, in which there are much more usable space. And, instead of insulating the attic or the always stuffy attic, the under-roof space itself is already being equipped according to all technologies, its competent ventilation and maintenance are being organized.
And in this case, you have two options: build a roof without internal crossbars and puffs, where there will be only two even slopes (as in frame technology), or a roof in its classical sense, but you leave the entire truss system open.
If there are no lintels in the roof and you want to leave only parts visible rafter legs, expect some difficulties. Let's say there won't be many of them (if these are standard rafters).
In connection with this issue, let's take a look at the requirements that apply to the roof frame. According to modern SNiPs, a wooden rafter should have a heat transfer resistance, which is equal to R or 4.9 / 5 mm.
Based on these data, the rafter should have a maximum thickness of 22 cm, and usually the cross-sectional height is 18-20 cm at all. This is enough for a thermal insulation layer, and the rail of the required height fills the missing part. Therefore, either you have to be content with little, or go for tricks.
Also, if you are going to leave only the visible part of the rafter legs, then such rafters will have to be planed on four sides and carefully sanded, and those lumber that have been impregnated with green pigment are not suitable here, because. such impregnation penetrate too deeply.
Therefore, for such an undertaking, which we are talking about, wood of a natural shade is used and treated with colorless protective preparations, or with well-chosen toning, as here:
Note that in this tutorial, the rafters are not just visible - they are huge! This happens only if the house is being built in the fachwerk style, which is now fashionable, where the rafter system must remain open and carefully emphasized.
In all other cases, standard rafters are used, and they are barely noticeable under insulation.
Glued timber rafters: we achieve a special effect
If we already highlight the rafters, then a good replacement for natural wood is glued. Such beams are more expensive, but they are commercially available with a cross-sectional height of up to 60 mm. There is also the advantage that, in terms of strength and many characteristics, glued beams are superior to wood beams.
You will be interested to know that several thin lamellas are joined together to make glued rafters. And glued rafters are not only rigid and durable, but also light.
And, most importantly, a thin plank can be given a very different shape, and you can make open rafters on the ceiling in an original way, for example, in the form of a vault, which you cannot do with natural wood rafters.
I-beam: simplifying the implementation of the idea
Another great option for open rafters is an I-rafter, which has the letter H in its cross section. Such a profile has a fairly rigid base, and at the same time it has a minimum cross-sectional area.
It turns out that there is only a thin plate at the place of insulation, and a wider base holds the roof on one side, and serves as the visible part of the rafters on the other:
Another advantage of I-beams is the ease of installation.
Let's go for tricks: rafters outside the roofing pie
But in the previous method there is one important “but”: open, real rafters always run the risk of becoming the so-called “cold bridges”. And so you need to go to some technical tricks. For example, insert insulation not between the rafters, but above them, as one continuous layer.
For this method, the insulating material is needed especially rigid, with high strength, which can independently withstand such loads as snow, the weight of the roof and the weight of a person.
And it is polystyrene foam boards that are most suitable for this undertaking, because:
- they can be connected in a tenon-groove or by the method of steps. The result is a layer without “bridges” at all;
- in addition, modern extruded polystyrene foam is not susceptible to moisture, and therefore it does not need to be protected additionally;
- and finally the bearing capacity polystyrene boards allows you to withstand all the loads that are transmitted through wooden slats.
This is what such a roofing cake looks like:
The very same device technology roofing cake simple enough:
- Step 1. Laying polystyrene foam insulation with dressing of seams according to the model of brickwork, always with a tight connection.
- Step 2. We fill all the gaps between such plates and the connecting elements of the roof structure with mounting foam.
- Step 3. We prepare the rails in advance and drill them so that they do not crack later during operation.
- Step 4. We fix the insulation with special fixing nails through the same wooden slats - to the rafters.
- Step 5. Finally, think about providing ventilation air: make sure that the longitudinal rails are no more than 40 mm thick, then when this is enough to remove excess moisture from the roofing cake.
As a result, such a roof is both thermally insulated and protected from the stress caused by extreme temperatures. Here, the rafters perform only their holding function, and at the same time remain indoors.
Roof under roof: architectural art - inside the house!
But the whole truss system right under the ceiling looks much more spectacular. Here are the most functional and proven options for how this solution is implemented:
And this is what it looks like in real life technological solution:
Extended rafters: gently add volume
As we have already said, with regard to standard wooden rafters, you can leave only a couple of centimeters in sight, because the maximum height of the beam section is always limited by certain standards.
In addition, thicker rafters will cost much more. And therefore, in the necessary parts of the roof arch, such rafters can be “growth”. In this case, the real rafters will be completely hidden in the structure of the roofing cake. And you can simulate their presence in a residential area in two main ways.
The first of these is to adapt the bars of the desired section to the existing rafters, making the protruding part of more beautiful and noble wood.
This solution is most optimal when working with an I-beam. Here the bars stick on special composition. Just do not fasten them with through fasteners, because. then it will be enough to cover the heads of the screws, and all the same, those repeating dots will be noticeable.
This illustration clearly shows how exactly the rafters are built up and how this method differs from the previous options:
The second way is to organize the so-called "false" rafters, but there is a drawback - high price. But let's dwell on it in more detail.
"False" dummy rafters: for a full-fledged ceiling
For an inexperienced look, decorative rafters on the ceiling only at first glance seem heavy, massive and firmly crashed into the wall. In fact, this is a spectacular illusion! A great solution if real rafters were not provided when installing the ceiling.
Those. the whole secret is that in fact the entire roof truss system is under the skin, and a dummy is installed on it, between the slopes. Moreover, you can build all this on your own, within one day and on absolutely any surface! The main thing is to know what and how - and we will talk about this in more detail.
See how profitable these rafters look in a residential area:
Decorative rafters-beams: how to give the room clear lines
Let's start with the fact that many people actually perceive such trendy beams on the ceiling today as the lower part of the roof truss system.
For example, as a base roof trusses, which the builders deliberately left visible, according to the special idea of the architect. But such elements are just a spectacular imitation of massiveness. And such seemingly rough and heavy beams and boards are made of modern polyurethane!
Industrial polyurethane rafters simply imitate the texture of the desired wood species, and inside they are generally hollow:
And such Western fashion easily penetrated into the architectural world of Russian interior design. True, home craftsmen, seeing the price of a miracle rafter, roll up their sleeves and make such elements on their own, already from real wood, but adhering to the same principles of emptiness inside to minimize the weight of the structures.
And it will not be difficult to install this kind of structure, it is enough just to prepare the same bars, fix them in ceiling on nails, and on them - plant rafters.
It is enough to fix the rafters themselves with metal brackets, which for decorative effect Preferably painted black
As you can see, the technology is so simple and affordable that everything will take no more than two hours!
Decorative ceiling trusses: style and functionality
If decorative rafters-beams give the room geometricity and emphasize the lines of space and depth, then entire truss trusses are a very striking style touch, real art. Especially if there are gloomy vaults above the living space, like an attic. gable roof.
And with the help of such dummies of the truss system, the same horizontal line is visually created, which is so lacking in a typical attic. After all, what is a "ceiling"?
According to the official terminology, this is a set of structural and finishing elements that form an additional floor, "suspended" to the main one.
Why not arrange a normal horizontal ceiling, you ask? Yes, you can, and as a result, the space for good ventilation will be reduced by at least 20%. You remember that hot air always rises, and the attic generally likes to heat up and turn into a “sauna”.
And, finally, such rafters in any house look original and fashionable:
And today there are many houses with complex architecture, it is fashionable to combine a gazebo, a residential block and a garage into a single complex, to attach unusual verandas and barbecue areas. And the sharp gable ceiling sometimes turns out not only above the attic, as we are used to, but also in a variety of unexpected places. Then why don't you learn how to make such rafters on the ceiling yourself? Moreover, there is nothing complicated here, believe me.
The subtleties of the device and installation
Here is a good example of the manufacture and installation of classic triangular truss trusses with internal stiffeners. These always look win-win and have high strength:
By the way, if you paid attention, in this master class House master combined polyurethane roof truss bases with wood inserts for greater fixing security.
Such rafters ultimately have the same strength as those made of wood, but at the same time they have a beautiful smooth texture, which is difficult to achieve manually even for an experienced carpenter.
Additional Functional Benefits
Why do decorative ceiling rafters need strength, you ask? It's simple: it is beneficial to use such elements in practical terms, for example, by picking up on them lighting and thus solving the age-old problem of how to do it on ordinary inclined walls:
See how such decorative designs can also carry practical significance. For example, serve as a great base for embedding lighting elements:
Great ideas, right?
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The roof is of great importance for the integrity of the whole house. Therefore, many are interested in how to properly assemble the rafter system so that it is reliable and does not have to be repaired soon. There are many types of roofs, some of them can be seen in the photo, but the most popular are shed and gable structures. Let's figure out how to make the truss system correctly.
Roof types
Before moving on to how to make a truss system, you need to figure out what the common types of roofs are.
Shed roof - the simplest, even a person who does not have much experience in construction can handle its creation. However, this type of roofing is mainly used in the construction of outbuildings. For residential buildings, gable or mansard (broken) roofs are usually made. These designs are more complex, but you can easily deal with them on your own if you know how to make gable roof rafters and follow all the recommendations of specialists (read: "").
The most reliable roofs are hip ones, they can withstand even huge loads. They are recommended to be done in regions where there is a lot of snow and strong winds often blow. But their design is also very complex, so it is better to entrust their construction to professionals.
A hipped (four-pitched) roof is used in the construction of square buildings; in its design, it is a kind of hip roof.
The most complex roof is a cross. During its construction, complex structural elements are used - valleys (grooves). These diagonal auxiliary rafters are installed as additional elements. During the construction of such complicated roof haste is unacceptable. Most of the snow accumulates in the area of the grooves, and the reliability of the roof depends on how to make rafters in these places.
Each type of roof consists of rafters and roofing. The rafters are the load-bearing part of the roof, and the roof surface is the enclosing part.
Types of rafters
Before you put the rafters, you need to find out about them design features and decide on the installation option.
There are two types of rafters: layered and hanging .
hanging rafters - these are inclined beams mounted on supports with different heights. Support can be the outer walls of the house (in the case shed roof) or both internal and external walls (with a gable roof). Rafter legs do not have to be laid in the same plane opposite the slopes. They can be mounted alternately on the ridge run. Alternate laying of rafters in the ridge area makes it possible to create a truss truss. To this end, all parts are interconnected into a single rigid structure.
Materials for rafters
As for the rafters from the boards, they are not heavy, and they are convenient to install. You can easily work with this material on your own without resorting to outside help. Many experts do not advise making connections with nails - it is better to use self-tapping screws. If the work will be carried out with the help of nails, do not forget about the lining and liners.
As for how to build a truss system, it is better to use cuttings to connect racks with a run or a bed.
Do-it-yourself installation of the truss system, in detail on the video:
Rafter system connection options
The rafter system can be connected in three ways:
- struts;
- racks;
- at the same time struts and racks.
How to properly make the rafters depends on the span between the outer walls. A beam of 10x10 centimeters is used to create ridge run. Lezhen and Mauerlat can be made from logs, hewn them into two edges, or by taking a beam of 10x10 centimeters.
When making a ridge knot, it is necessary to nail special clamps made of steel strip to the Mauerlat and run with large nails, taking into account. You can not use steel clamps, but then you need twists of thick wire with a diameter of 6 millimeters.
Regarding how to make a brick or stone house, then a Mauerlat must be laid on the masonry. For its reliable fastening, it is recommended to place a piece of log or timber about 50 centimeters under each rafter leg. Then they are attached with clamps to metal hooks that were previously installed 30 centimeters below the Mauerlat.
Many people have a question about how to make rafters on the roof wooden houses. Rafters in wooden buildings are laid on top crown walls. A plank truss truss can be created using a crossbar or with spans (6-8 centimeters). Its structural elements are arranged as follows. Make a single puff with the help of boards, the thickness of which is equal to the thickness of the rafters. For double tightening, thinner boards are used (thickness from 40 millimeters). For the crossbar and overlays, 30 mm parts are taken.
How to determine the cross section of the rafters
Before you properly lay the rafters, you need to decide on their cross section.
This setting depends on:
- span dimensions;
- expected load (wind force, weight of snow cover and roofing material);
- step and angle of installation of rafters (roof slope).
There is a dependence of the cross section of the rafters on the length of the rafter leg.
It is expressed as follows:
- with a step of 300 centimeters, bars with a section of 10x12 centimeters or boards with a section of 6x14, 8x14 or 4x18 centimeters are used;
- with a step of 400 centimeters, bars with a section of 10x16 centimeters or boards with a section of 6x20, 8x20 centimeters are used;
- with a step of 500 centimeters, bars with a section of 10x20 centimeters or boards with a section of 8x22 centimeters are used.
").Roofing must be selected taking into account the slope of the roof. Also, the choice of material for the roof depends on financial capabilities. The greater the angle of the roof slope, the more funds required to create a roof - this is due to the increased consumption of materials. However, steep roofs are better rain water and snow, so they are more reliable and will last longer. But considering huge selection roofing materials on the market, this will not cause any difficulties.
Creating a truss system for a bath
As for how to make rafters for a bath, it is better to choose gable roof- then there will be an attic in the building, which can be used to store brooms and other bath accessories (read: ""). Thus, it is desirable to create a truss system for a gable roof, it is easier and more practical.
The wooden roof is different types rafters with other elements of load-bearing structures and roofing. When building such a structure, one does not have to deal with large quantity difficulties, which makes this type of roofing very popular and widespread. The truss system can have a different structure, and the components for its creation differ in their features and prices. This article will tell you about what a wooden roof includes and how it works. Also here you can find a lot of information about what materials are better to use for this design and how to optimize the cost of implementation. construction works without quality loss.
What are the components of the truss system
To begin with, it is worth saying that each roof has its own truss system with certain components. The choice of design depends on many factors. For example, this can include the number of slopes or slope angles, as well as the location of the chimney. But still, the composition of a wooden roof always includes the following elements:
Mauerlat It's a board on the wall. It serves as a support for the entire roof and evenly distributes the load on the building.
rafters ask appearance roof and give it an angle of inclination. They are necessary in order for the structure to be rigid and stable. Also, the rafter legs serve as a support for the lathing and roofing.
Run. Such a structural element is needed in order to connect the rafters to each other. Depending on its location, runs are ridge and side.
puff- this is part of the system that connects the rafter legs and does not allow them to diverge.
Racks give stability and fix the rafter legs. The same function is performed by roof struts.
Sill- This is a board parallel to the ridge. Struts and racks abut against this structural element.
crate consists of beams or boards perpendicular to the rafters. The roofing is attached to this composite.
Roofing ridge is a combination of two slopes. In this place, during construction, it is imperative to fill a continuous crate.
Roof overhangs- these are the protrusions of the roof, necessary to protect the walls of the house from getting wet.
The device of a wooden roof also provides for the presence of a truss truss. This part consists of elements such as stretch marks, racks and braces. We need such a design to evenly distribute the load and reduce pressure on the walls. Between each two roof trusses there may be a different distance, which is derived using calculations.
Types of wooden roof construction
There are three types of wooden roofing: with layered rafters, with hanging rafters and with wooden trusses. The first option provides that the rafters rest against the Mauerlat from the end side, and from the front to the wall of the building or to the rack. With this design, the distance between the racks should be from 60 centimeters to 2 meters.
The step length is calculated based on the expected load and the type of material used. In order to build such a structure, you need to use a beam 20 * 20 with a thickness of at least 5 centimeters. Between the racks you need to leave a distance of up to 2 meters. To increase the rigidity of the entire structure, the rafter legs should be additionally tied with a twenty board.
If it is planned to give the roof additional resistance to gusts of wind, then in this case the structural elements are fixed with wire, which in turn is attached with anchors to the Mauerlats and the bed. This kind roof structure nowadays it is the most popular and is used in the construction of most buildings with a wooden roof.
But it is worth noting that when arranging a layered truss system, it will be required that, firstly, there is at least one load-bearing wall inside the building, and secondly, the width of the building is at least 7 meters.
If it is impossible to make a wooden roof of a layered type, then it is recommended to resort to a structure made of hanging rafters. This option does not require upper vertical supports.
But it is worth paying attention that the width of the house should not be less than eight meters. But at the same time, such a truss system is most well combined with small technical buildings.
However, it is worth remembering that hanging rafters have high blood pressure on the walls, leaning on them with its lower part. In order for the structure to receive additional rigidity, the rafter legs are pulled together. To connect all constituent parts of this design, in addition to nails, bolts and metal staples are also used. And in order to be able to use the attic as a living space, the screeds must be placed at the highest possible height.
For use attic space as residential, it is necessary to place the screeds high
On our website you can find contacts construction companies who offer services roof design and repair. You can directly communicate with representatives by visiting the exhibition of houses "Low-Rise Country".
The truss structure with wooden trusses is practically not used in the construction of private houses. This type It is best combined with buildings with a span of more than 20 meters. This is due to the fact that this system is quite complex. It includes a whole complex of nodes, consisting of a large number beams, the width of which should be 150 millimeters.
It is also worth noting that it is beneficial to use such roof truss structures for wooden house. This is due to the fact that the elements of the roof frame will be very convenient to attach to the walls of wood.
How to choose roofing materials for a wooden roof
Exist different kinds wooden roof coverings. They differ significantly in their properties and capabilities. In order for you to have an idea about wooden roofing, some of them will be discussed below:
Shingle
Consists of small size plates. Between themselves, they are connected with spikes or grooves. For the manufacture of shingles, the most durable, durable and reliable types of wood are used.
This coating has one significant drawback: a shingle roof is very fire hazardous. However, you can deal with this by covering the surface of the planks with a special compound.
Of the advantages, it is worth noting a long service life, as well as high-quality sound insulation. In addition, the shingle has a low thermal conductivity, which makes it good insulation. Such characteristics are typical for all wood roofing.
On our website you can find the most - from construction companies represented at the exhibition of houses "Low-Rise Country".
Shindel
In shape, it is a chipped plate. Such material differs in the different size of the components. This roof covering has the longest service life among wooden materials.
It is noteworthy that the shindel is made by the method of manual stake. For its production, species such as aspen, larch or oak are used. Only mature selected raw materials with a high density of growth rings are selected. In addition, this coating is characterized by a small number of knots.
plowshare
It is one of the varieties of shingles. It differs in that it has complex shape. His top part represents an extension, and the lower one has openwork edges. Such a plank outwardly resembles a spatula, and its edges often have a rounded shape. For the manufacture of the most commonly used raw materials such as pine and spruce.
tes
This is one of the simplest wooden roofing. It is an ordinary edged board made of pine or spruce. However, the most reliable plank roofs are made from larch, although it is more expensive and more difficult to work with.
A wooden roof made of this material almost completely absorbs rain noise, and it is also environmentally friendly. pure material. Arrangement of a plank roof is quite simple process and does not require significant labor costs.
The problem is that it creates a large load on the walls of the house due to its rather large mass.
The procedure for the construction of a wooden roof
Before you begin work on the construction of the roof, you need to correctly and correctly select the materials. The wood must be dry, on its surface the appearance of fungi and tree cancer is unacceptable. In order for the structure to last longer, it is worth choosing materials that do not have a frame. It is also recommended to cover all components with antiseptics and flame retardants. Such funds will protect the roof not only from rot, but also from fire.
The first step in the construction of any roof is mounted Mauerlats. Use as this part better timber 150 mm wide. There are two fixing methods:
Rolled wire worn in advance drilled holes in the wall and beam, and then securely and strongly pulled together and tied with pliers. If there wooden house under the roof, then this method will be the best solution.
Installed on the wall upright bars not less than one and a half centimeters thick. It is possible to mount a concrete beam with metal studs pre-fixed on it. The distance between them should not exceed 10-12 centimeters. The beam is put on the studs with mounting holes, and then fixed with nuts.
If the Mauerlat is installed on the wall without using a roofing felt gasket, this will have a detrimental effect on the entire roof. Also, to protect this element, it is usually covered with bituminous mastic. After installing the "foundation", the wooden roof is erected in accordance with the following sequence of actions:
Parallel to the walls beds are laid. For the manufacture of these components, it is recommended to use a beam with a cross section of 150 * 150 millimeters. In the event that there are too short pieces of material, they are joined by means of spikes.
On the bed racks are mounted. Here it is better to use a beam with a width of 5 * 15. Such elements are always installed at a distance equal to the pitch of the rafter legs.
Next install extreme rafters. They are attached to the Mauerlats and must be fixed with the help of racks. The joints are always washed down, and metal plates are applied to them for reliability and stability.
Installed at the corners of the pediment skate.
After that all other rafters are mounted. At the same time, a distance remains between them, calculated using calculations, and they rely on Mauerlats, a skate and racks.
Gable sewn up board.
After everything bearing structures collected, the roofing cake is laid. The device of a wooden roof assumes the presence of a heater, as well as layers of vapor and waterproofing. It is better to sew up the entire system with boards from the side of the attic. If you plan to use the building as utility room, then you can save on the thermal insulation layer.
After all the above processes have been completed, it remains only to fix the crate and fix the roofing on it. Now you can hem the overhangs and wooden roof will be completely ready.
Video description
From the video you can see how the roof is built:
Conclusion
A wooden roof has a lot of advantages. In addition to its excellent thermal insulation and noise absorption, it also has good decorative properties. If you love traditional old Russian architecture, then the plank roof is suitable for you like nothing else. A roof made of any wooden materials will last for a long time, and with careful care and correct installation will delight you with its appearance for a long time.
As a rule, softwood lumber is used.
For various elements and details of the wooden truss system, a tree of a certain type and variety is used. When using lumber in a rafter-beam system, the following properties and indicators of wood should be taken into account: bending strength, compression, chipping, wood density and its moisture content.
Wooden truss structures must necessarily correspond to the special degree of fire resistance of the room. They must necessarily be treated with special fire retardants and.
There is a huge variety of options and elements for the device of wooden truss structures. Exist the following types roof structures: layered or hanging rafters, combined, with tightening, etc. The most popular truss structures are layered and hanging.
To avoid sagging of the entire structure, to the lower end of the beam, with the help of strip steel clamps, a horizontal puff is attached to support the beams of the entire attic floor. If the span is up to 12 m, then struts are introduced into the structure of the rafters, which reduce effective length all rafter legs.
hanging wooden rafters work both in compression and bending.
Below we consider the types of truss structures:
- conventional hanging rafters
- double hanging rafters
It is not uncommon to increase the entire area of \u200b\u200bthe attic in the system of wooden hanging rafters, puffs are not used, but struts are used.
Mauerlat roof AT this case rafter legs are cut into the Mauerlat itself. The lower plane should lie on the wall, and certain cuts must be made in the upper one for proper connection with the rafter legs.
All struts rest against the end of the wooden one. In this case, the loads that the tightening would compensate for are directly transferred to all walls. As a result, this solution of a wooden truss system is possible only if there is a special massive structure.
Hanging rafters are parts and elements of truss structures that are located in one vertical plane and are connected to each other with the help of cuttings, bolts, nails, clamps and staples.
There is a combined truss system - this is the installation of both a layered and a hanging truss structure, which alternate in turn. Where there are no intermediate supports, hanging truss systems are used, and where present, layered truss systems.
Rafter with tightening
They are used for spans up to 15 m. in special puffs. They are mounted at the height of the building between two rafters and tied. And longitudinal struts will prevent lateral bending.
Roof rafter tightening All structures with retaining wooden beams must be assembled in the form of truss structures reinforced with special props, which will be based on cross beams and all load-bearing walls, as well as in the form of trussed systems. The concept of sprengel is structural element by the type of an open triangular rod system, which is attached to the main truss supporting structures.
The structural rigidity of this roof is given by a longitudinal brace or strut. The use of struts reduces the overall load on the entire structure. Vertical struts are usually attached to or uprights using notches, trunnions, steel plates.
Truss hanging wooden truss systems
Sprengel The entire load from the rafter legs goes to the racks, which transfer it further to the main carriers. With this design, the load will be distributed between all load-bearing walls. Racks are attached at the heads of the main bearing walls. The lower ends of all racks are fixed with suspension trunnions.
Sprengel beams are produced from solid solid wood or glued plank array. Usually, they are of small height. A good and high-quality bearing capacity of trussed beams is carried out using a trussed system and wooden beams supporting it.
Schrengel beams can cover huge spans. Sometimes they are completed with steel belts.
Complex structures of the truss system
Produced by the type of truss trusses. Lattice trusses are divided into types according to the shape of their gaps: triangular, trapezoidal or parallel belts. Usually, lattice trusses are produced symmetrically, but other options are possible, for example,. A common lattice truss includes top and bottom chords, racks and braces. 
Reliable and high-quality carrier connection wooden structures with central supports in one common system called a frame. Racks and beams connected in a frame are necessarily fastened or included in each other. To date, there are two main types of frames - two-hinged and three-hinged. Double-hinged frames are equipped with a crossbar that runs across the entire width of the finished frame. Frame data the best way suitable for structures with a small angle of inclination. Three-hinged frames consist of two equal halves, which support each other in the region of the roof ridge. Three-hinged frames are used where a more significant angle of inclination is needed.
Calculation of truss structures and the final selection of their elements and parts trust specialists. On act huge loads. In addition to its own weight, it is affected by wind loads, heavy rains, hail, snow and ice. The roof quite often undergoes various
A number of interior styles, including those related to minimalism, allow or even welcome open rafter systems into the attic space. These elements make the architecture of the ceiling more interesting and decorate the interior.
If the owners decide to leave the rafters and beams open, then at the design stage they must decide how much these elements should protrude towards the room. The fact is that their cross section will depend on this, which the designer must specify in the project.
The cross-sectional dimensions of the rafters cannot be arbitrary. On the one hand, it is about bearing capacity elements, and on the other hand, the possibility of laying thermal insulation of sufficient thickness between them. If desired, of course, you can build up rafters with inside, but this approach, in principle, is not the most rational.
The attic roof is a standard building envelope. Building codes for such a design impose appropriate requirements for resistance to heat transfer - R mansard roof must be at least 4.95 m² C/W. In this regard, the thermal insulation layer in the structure of the roofing pie should be at least 20-22 cm. This is somewhat larger than the cross-sectional height of conventional rafters, which is 18-20 cm. That missing part of the thermal insulation is either not provided at all, or is laid between the battens frames that are installed for fastening plasterboard sheathing. Both solutions from the point of view of engineering and economic feasibility, as already mentioned, are not rational. It is necessary to look for other solutions.
wooden rafters
The disadvantage of solid wood rafters, which are supposed to be left in plain sight as decoration of the attic ceiling, is that they have insufficient cross-sectional height. Standard wood rafters allow only a few centimeters to be visible, since the maximum sectional height of finished lumber is limited to 24 cm. Thicker rafters must be specially ordered, which will increase their cost dramatically.
If the owners are satisfied with a slightly protruding part of the rafters, then they can choose maximum size solid wood products. Most often, rafters are made of pine or spruce. In the case of use in the interior, such materials are planed on four sides, and also polished. Sanded wood has a higher fire resistance. The absence of roughness and notches does not allow the flame to “catch” easily. Wood treated in this way is also less susceptible to insect infestation, as the latter are more difficult to penetrate through smoothly polished surfaces.
For open ceiling beams lumber impregnated with green impregnation should not be used. Impregnation penetrates deep into the wood and planing cannot fix this. It is unlikely that green beams will suit their appearance; therefore, it is better to buy natural-colored wood treated with colorless bioprotective preparations.
Glued timber rafters
Glued wood is made from individual small-section lamellas, so that products from it can have large section and unlimited length. Today, glued beams with a cross-section height of up to 60 mm are available. However, glued wood is much more expensive than solid wood. Each additional centimeter of section is reflected in its price.
The lamellas from which the beams are glued can have a thickness of 18 to 45 mm. Between themselves, they are firmly fastened with melamine resin or resorcinol glue. White glue lines indicate the use of melamine resin, and if dark, then resorcinol glue is used. The material of the lamellas is pine, spruce or larch wood. There are also imported glued products from exotic breeds which have high strength and durability.
In length, the lamellas are built up “by the mustache”, i.e. with a wedge connection. On sale there are tinted and varnished products.
For strength and other performance characteristics glued beams are superior to solid wood beams of the same section. In particular, in terms of strength, they are 2 times superior to products made from solid coniferous wood. The undoubted advantage of glued timber is the unlimited length of products, which allows you to design a truss structure without support posts.
I-rafters
The I-beam has a section in the form of two oppositely connected letters T. This type of profile gives the products rigidity in two directions, with minimum area sections. Today, I-beams made of solid or laminated wood with an intermediate post made of OSB have become popular. Along with them there are beams made according to the same principle, but completely from glued wood.
The advantage of I-beam rafters is their low weight. Such beams are easy to mount. But in our case, they are not very suitable, since their end part has a small height - 38-48 mm. Accordingly, it is precisely such a visible protrusion of the beam that can be counted on, and no more. In addition, I-beams in the truss structure, due to their bearing parameters, are installed with a smaller step than usual - namely, every 50-70 cm.
A wider bar at the end (89 mm) has I-beams for floors. This makes them more visible on the ceiling. Due to this, when choosing an I-beam option, such beams are more in demand.
Thermally insulated feet
You can get a large protrusion of the rafters into the attic room by placing thermal insulation not directly between them, but on top of them. To cope with this task is possible only with the help of rigid board insulation with low water absorption, for example, such as extruded polystyrene foam or foam glass. Laying thermal insulation on top of the rafters also significantly increases the resistance of the attic roof structure by creating a continuous thermal insulation layer where the rafters are not cold bridges. In this case, a solid hard flooring is constructed over the rafters, which is covered with a layer of roofing material or roofing film.
Insulation plates are laid on top of the flooring prepared in the described way. They are attached to the rafters with the help of counter-battens and long nails that pierce the insulation through and through. It is important to make fasteners in such a way that the counter rails cannot move down under the weight of the roof. To do this, you can drive nails at an angle of about 67 ° with respect to the slope; or screw the beam eaves overhang to the rafters, thus insuring the counter-battens.
For insulation over the rafters, it is desirable to use plates with profiled edges, which make the mating more dense.
Imitation of rafters
There are several ways to simulate exposed rafters while keeping the actual truss elements completely hidden in the structure of the roofing pie. Imitation can be achieved in several ways. The first one involves nailing bars of the required section to the rafters, possibly even exceeding the width of the true beam. The protruding part can be made of more expensive and noble wood. This solution is primarily suitable for roof structures made of I-rafters. False beams are glued to the rafters, since it is impossible to fasten through fasteners - the screw heads will be visible. Disguising these hats is quite problematic. If you cover them with wood putty and open them with stain on top, then the attachment points will most likely darken. The rhythm and symmetry of such dark dots will by no means give an imitation of veracity.
In the second case, polyurethane imitations of beams are used, which look almost identical to natural ones. Their only drawback is their high price. Otherwise, polyurethane beams in the form of boxes are a very convenient interior solution for attic ceiling slopes. These boxes are pretty light. They can be attached directly to the attic sheathing using wooden bars nailed in advance, or you can simply glue them. In the latter case, it is necessary to press the polyurethane beams tightly during the setting of the glue, for which you can use props. Wooden false beams, when glued, sit on a spike, so they do not need support.
On sale today there are polyurethane imitations with various types of finishes. Standard length polyurethane beams is 3 m and 4.5 m, and the cross-sectional dimensions are 120 × 60 or 160 × 100 m.
False beams can also be made in the form of wooden boxes U-shaped. However, their price can exceed solid wood false beams, so the expediency of hollow wooden boxes is due only to their relatively low weight.
