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Asymmetrical gable roof. DIY rafters for a gable roof: design and installation. Cuckoo roofs

The rafter system of any object is equivalent to the value of the load-bearing structural elements of the house. The roof plays the role of a node under which the building's stiffening ribs are assembled. Accordingly, when installing a roof with your own hands, you need to pay maximum attention to all structural units, even when using a simple option - a gable roof.

Advantages of gable roofs

There are a lot of options for pitched rafter systems. Among them, the simple symmetrical one is especially popular. Why? Here are its advantages:

• Variations are created on the basis of a gable roof to reflect the special architecture of the building.
• Simple calculations that are easy to understand.
• One-piece design creates favorable conditions for dryness internal space and unimpeded flow of water, snow and ice.
• The maintainability, strength and wear resistance of a gable roof are much higher than other options.

Depending on the size, homeowners always have the opportunity to equip the under-roof space, turn it into a full floor or attic. In a word, a gable roof is the correct and profitable solution for any object, be it a residential building, a summer house or a bathhouse.

Elements of the rafter system

Depending on the type of roof, the structural elements vary. Without knowledge of the purposes of each, it is impossible to arrange reliable coverage for your home. Let's look at it in detail:

Mauerlat

The basis of the rafter system. It is a beam with a cross-section of at least 150 mm, or an I-beam channel if the roof structure is metal. It is located on the load-bearing walls of the facility. Its purpose is to distribute the load of the system evenly throughout the entire structure of the house.

Rafter leg

The structural basic unit of a system. Together with others, it forms a truss system - strengthening the strength of the entire roof. It is made of wooden beams, not inferior in cross-section to the Mauerlat or profile pipes.

Rafter stand

Vertical beam or pipes. Depending on the gable roof option, the racks can be located in the center and/or sides. They take part of the weight of the entire rafter system, which is why the cross-sectional size is 150 mm.

Rafter purlins

Horizontal beams laid on the posts and under the ridge to support the rafter legs. They provide rigidity to the structure and relieve stress on the trusses.

Tightenings and struts

Connecting beam for rafters. The action is similar - relieving the tension of timber or metal and imparting rigidity to the structure.

Lezhny

Installation support for posts and struts. To reliably connect these two elements, a beam is required large section– 150 mm or thick-walled pipe of impressive diameter.

Lathing beam

Elements laid perpendicular to the rafters. Serve to set the selected roofing covering and creating a multi-layer protective cake. The cross section is small - 40–50 mm.

If the intended roof structure is made of wooden beams, you should carefully consider the quality of the wood when purchasing - the timber should not have any knots and be made of soft wood.

Also, the wood must have natural moisture, otherwise it will begin to dry right in the structure of the system, cracking, deforming the roof model, depriving it of reliability and safety.

Calculation of the rafter system

A gable roof is a complex structure. The project takes into account many factors - natural nuances, wind, constant and variable loads. It is extremely difficult to make calculations on your own, without special knowledge about the climate of the area, the characteristics of the material for the manufacture of the system, and the nuances of pressure distribution.

Ideally, the calculations are left to professionals; you can choose only the coating material yourself - the following parameter depends on its type:

Tilt angle

The minimum angle of inclination of the roof relative to the parallel of the ground is 5 degrees. However, its dependence comes from the selected roofing material. For this purpose, traditional slate, corrugated sheets, flexible and metal tiles are used.

They are guided by the following rule: the steeper the slope, the more textured the roof can be.
From 5 degrees for laying rolled protective roof insulation. The number of layers matters - up to 15 degrees three-layer coatings, above - two- and single-layer.

• From 6 – ondulin.
• From 11 – slate.
• From 12 – corrugated sheets.
• From 14 to 20 – metal tiles.
• From 15 to 45 – soft roofing.

Thus, the resulting precipitation - snow, water - will not linger on the surface, although complete cleaning requires your own efforts or the involvement of specialists to install the Anti-Ice system.

Determination of rafter parameters - pitch, length, cross-section

The smaller the step, the more impressive the cross-section of the timber or the diameter of the pipes should be. As a rule, for load-bearing structures this parameter is at least 150 mm, 100 mm for country houses and related construction - gazebos, bathhouses, outbuildings.

Next, you need to set the number of rafters per slope: its length is divided by the installation step, ranging from 60 to 100 cm + 1 outer leg. Multiply the result by 2 to get the total quantity. Depending on the cross-section of the beam, the amount of rafter legs and the installation pitch vary.

The length of the rafters is simply calculated if the school knowledge about the right triangle remains in your luggage. The rafter leg is equal to the hypotenuse of the resulting figure. The calculation is as follows: A² + B² = C², where – A is the height of the roof, B is half the length of the pediment, C is the length of the rafter leg. To the resulting value always add from 30 to 70 cm for the eaves overhangs.

Types of rafter systems

Before getting to work, it is important to choose a rafter system option for a gable roof. There are few of them, each has its own advantages and disadvantages:

Hanging

Only suitable for standard width the roof is 6 m, respectively, this is the length of the rafter leg. Fastening occurs by fixing the ends to the ridge girder and the load-bearing wall. Be sure to install a tightening that levels out the tension and pressure of the structure.

In addition, they will play the role of load-bearing beams. Without them, the structure will corrode under the weight. The advantages of this option are the absolute dryness of the roof surface during the off-season, and less deformation at the time of shrinkage.

Layered

The option is suitable for any roof width. Reliability and stability are ensured by fixing the bed to the Mauerlat. Thus, the pressure is leveled by the stand, causing the tension in the rafter legs to decrease. The advantage of the system is its simplicity, but the design requires large investments– additional lumber is required for arranging the beds.

Hybrid

These systems are typical for multi-slope roofs, where the transitions are accompanied by numerous reinforcements, beams, posts, beams, slopes and other elements for the stability of the entire structure. The device is expensive and complex, so only a professional should be involved in the design and construction. At least supervise it.

Do-it-yourself gable roof installation

So, when the rafter system option has been selected, lumber has been purchased, a roof design has been drawn up, you can begin to work. You cannot deviate from the sequence of stages. This threatens to delay installation and loss of structural reliability.

Mounting the Mauerlat

If the length of the timber for installing the Mauerlat is not enough, extensions are made. The ends are connected using the half-tree cutting method. Additional fasteners are anchor bolts. Do not use screws, dowels or nails - they are unreliable. Mounting to the wall is as follows:

• A distance from the edge of at least 5 cm is maintained.
• Holes are drilled along the wall to insert fasteners. Similar actions are carried out with timber.
• The Mauerlat is attached to the edge using steel pins. The fastening step is often 2 times the distance between the rafter legs. Subsequently, before installing the main units, they are guided by metal marks.

Important - before laying the mauerlat, the edge of the wall is protected with waterproofing. Spread one layer even if the house is made of wood.

Manufacturing and fastening of rafters

Roof trusses are convenient because they can be assembled on the ground in finished design and move it to the roof. This will reduce installation time, however, the model is heavy and lifting equipment will be required, which, naturally, will increase the cost of the project.

For budget construction Another method is suitable:

• A cut is made at the bottom and top of the rafter legs to connect to the mauerlat and ridge girder. This must be done separately with each unit, after first lifting the wood to the top.
• Places for fixing are marked on the Mauerlat and a ridge girder is installed: racks are installed along the gables, on which the timber is placed. If the length is not enough, it is increased, but in a different way, unlike the Mauerlat - a board is screwed onto the joint on both sides.
• Depending on the chosen model of the rafter system - layered, hanging - cuts are made in the ridge beam, mauerlat, or holes are drilled in them for fastening.
• Next, they begin installing the rafter legs from opposite ends of the roof, gradually moving towards the middle. It’s a good idea to pull a cord between the corners of the outer trusses to ensure that the entire horizontal part matches exactly.
• The rafter legs are connected to each other by ties and struts. Under the ridge part, at the angle formed by the rafters, wooden overlays are stuffed, and the ends themselves are tightened with bolts.

More recently, professional builders have begun using sliding fasteners to install roofing. Metal plates reliably hold the load-bearing elements and at the same time move due to shrinkage. This neutralizes its consequences.

The work of fastening the rafters is hard and long. You should calculate the time in advance - you cannot leave the roof unfinished during the rainy season, otherwise the rigidity of the structure will be lost in the future due to absorbed moisture.

Pediments and sheathing

The side parts of the roof - gables, are made in the form of ready-made panels from boards and are completely installed at the top. There shouldn’t be any difficulties - it’s just important to carefully cut them at the required angle. The sheathing should be fastened only after the final type of roofing is known. For example:

• Under corrugated sheeting, the pitch of the sheathing beam will be 440 mm.
• The metal tiles are fixed to the sheathing in increments of 350 mm.
• A soft roof requires a continuous plywood covering.

It is important to mark the passage places chimney– the sheathing should not come into contact with the brick or metal surface. The distance to the hot unit is at least 15 cm. Before installing the sheathing finished roof covered with waterproofing with allowances extending beyond the edges of the walls. Then the timber is installed.

If you decide to make an insulation cake from above, then first strengthen the vapor barrier from the inside, then put the selected material into the boxes formed by the rafter legs. Next, waterproofing and wind protection.

Then you need to again mark the contours of the rafter legs with a 20*20 beam and then fill in a new layer of sheathing, along which the roofing material will be laid - formation ventilation ducts. This method will preserve the capacity of the under-roof space if the owners intend to use it for a specific purpose.

Flooring roofing material

Regardless of the type of roofing material, installation begins from the edges of the roof and goes up, placing one unit on top of another. This way, rain moisture will not get under the material.

The method of fastening depends on the type of material - soft tiles or tiles with a bitumen or polymer base are fused. Solid profiled sheets - ondulin, metal tiles - are fixed into pre-drilled holes to the sheathing, using rubber linings to seal and preserve the anti-corrosion layer.

As a result: a description of the installation of the rafter system and roof is easy only on a screen or paper. In reality, the process is complex and multifaceted. Therefore, if knowledge is not enough, it is better to invite professionals to work - their work is always guaranteed.

Rafters perform a number of significant roofing functions. They set the configuration of the future roof, absorb atmospheric loads, and hold the material. Among the rafter's duties are the formation of smooth planes for laying the covering and providing space for the components of the roofing pie.

In order for such a valuable part of the roof to flawlessly cope with the listed tasks, information is needed about the rules and principles of its design. The information is also useful to those who are constructing rafter system gable roof with their own hands, and for those who decide to resort to the services of a hired team of builders.

In the construction of the rafter frame for pitched roofs, wooden and metal beams. The starting material for the first option is a board, log, timber.

The second is constructed from rolled metal: channel, profile pipe, I-beam, corner. There are combined structures with the most heavily loaded steel parts and wood elements in less critical areas.

In addition to its “iron” strength, metal has many disadvantages. These include thermal qualities that are unsatisfactory to the owners of residential buildings. The need to use welded joints is disappointing. Most often, industrial buildings are equipped with steel rafters, and less often, private cabins assembled from metal modules.

In business self-construction Wood is the priority for rafter structures for private houses. It is not difficult to work with, it is lighter, “warmer”, and more attractive in terms of environmental criteria. In addition, to perform nodal connections you will not need welding machine and welding skills.

Rafters - a fundamental element

The main “player” of the frame for constructing a roof is the rafter, which among roofers is called a rafter leg. Beams, braces, headstocks, purlins, ties, even a Mauerlat may or may not be used depending on the architectural complexity and dimensions of the roof.

Rafters used in the construction of gable roof frames are divided into:

• Layered rafter legs, both heels of which have reliable structural supports under them. The lower edge of the layered rafter rests against the mauerlat or the ceiling crown of the log house. The support for the upper edge can be a mirror analogue of the adjacent rafter or a purlin, which is a beam laid horizontally under the ridge. In the first case, the rafter system is called spacer, in the second, non-spacer.
• Hanging rafters, the top of which rests against each other, and the bottom is based on an additional beam - a tie. The latter connects the two lower heels of adjacent rafter legs, resulting in a triangular module called a rafter truss. Tightening dampens the tensile processes, so that only vertically directed load acts on the walls. Design with hanging rafters Although it is a spacer, the spacer itself does not transfer to the walls.

In accordance with the technological specifics of rafter legs, the structures constructed from them are divided into layered and hanging. For stability, the structures are equipped with struts and additional racks.

To support the top of the layered rafters, planks and purlins are installed. In reality, the rafter structure is much more complex than the elementary templates described.

Note that the formation of the frame of a gable roof can generally be done without a rafter structure. In such situations, the supposed planes of the slopes are formed by slabs - beams laid directly on the load-bearing gables.

However, what interests us now is specifically the structure of the rafter system of a gable roof, and it can involve either hanging or layered rafters, or a combination of both types.

Subtleties of fastening rafter legs

Fastening the rafter system to brick, foam concrete, aerated concrete walls is carried out through the Mauerlat, which in turn is fixed with anchors.

Between the Mauerlat, which is wooden frame, and walls made of the specified materials must be laid with a waterproofing layer of roofing material, waterproofing material, etc.

The top of brick walls is sometimes specially laid out so that along the outer perimeter there is something like a low parapet. This is so that the mauerlat placed inside the parapet and the walls do not push apart the rafter legs.

The rafters of the roof frame of wooden houses rest on the upper crown or on the ceiling beams. The connection in all cases is made by notches and is duplicated with nails, bolts, metal or wooden plates.

How to do without mind-boggling calculations?

It is highly desirable that the cross-section and linear dimensions of wooden beams be determined by the project. The designer will provide clear calculation justification for the geometric parameters of the board or beam, taking into account the entire range of loads and weather conditions. If available home handyman there is no design development, its path lies on the construction site of a house with a similar roofing structure.

You don’t have to pay attention to the number of floors of the building being constructed. It is easier and more correct to find out the required dimensions from the foreman than to find out them from the owners of a shaky self-built building. After all, in the hands of the foreman is documentation with a clear calculation of the loads per 1 m² of roof in a specific region.

The installation pitch of the rafters determines the type and weight of the roofing. The heavier it is, the smaller the distance between the rafter legs should be. For laying clay tiles, e.g. optimal distance between the rafters there will be 0.6-0.7 m, and for corrugated sheets 1.5-2.0 m is acceptable.

However, even if the pitch required for proper installation of the roof is exceeded, there is a way out. This is a reinforcing counter-lattice device. True, it will increase both the weight of the roof and the construction budget. Therefore, it is better to understand the pitch of the rafters before constructing the rafter system.

Craftsmen calculate the pitch of the rafters according to the design features of the building, simply dividing the length of the slope into equal distances. For insulated roofs, the pitch between the rafters is selected based on the width of the insulation slabs.

You can find it on our website, which may also help you a lot during construction.

Rafter structures of layered type

Layered rafter structures are much simpler to construct than their hanging counterparts. A reasonable advantage of the layered scheme is to ensure adequate ventilation, which is directly related to long-term service.

Distinctive design features:

• It is mandatory to have support under the ridge heel of the rafter leg. The role of support can be played by a purlin - a wooden beam resting on posts or on the internal wall of the building, or the upper end of an adjacent rafter.
• Using a Mauerlat to erect a truss structure on walls made of brick or artificial stone.
• The use of additional purlins and racks where the rafter legs, due to the large size of the roof, require additional support points.

The disadvantage of the scheme is the presence of structural elements that affect the layout of the internal space of the attic being used.

If the attic is cold and organization is not expected in it useful premises, then the layered structure of the rafter system for installing a gable roof should be given preference.

Typical sequence work on the construction of a layered truss structure:

• First of all, we measure the heights of the building, the diagonals and horizontality of the upper cut of the frame. When identifying vertical deviations of brick and concrete walls, we eliminate them cement-sand screed. Exceeding the heights of the log house is cut off. By placing wood chips under the mauerlat, vertical flaws can be combated if their size is insignificant.
• The floor surface for laying the bed must also be leveled. It, the Mauerlat and the girder must be clearly horizontal, but the location of the listed elements in the same plane is not necessary.
• We process everything wooden parts structures before installation with fire retardants and antiseptics.
• We lay waterproofing on concrete and brick walls for installation of the Mauerlat.
• We lay the mauerlat beam on the walls and measure its diagonals. If necessary, we slightly move the bars and turn the corners, trying to achieve the ideal geometry. Align the frame horizontally if necessary.
• We mount the Mauerlat frame. The beams are joined into a single frame using oblique notches; the joints are duplicated with bolts.
• We fix the position of the Mauerlat. Fastening is done either with staples to wooden plugs placed in the wall ahead of time, or anchor bolts.
• Mark the position of the prone position. Its axis should recede from the mauerlat bars at equal distances on each side. If the run will rest only on posts without supports, we carry out the marking procedure only for these posts.
• We install the bed on a two-layer waterproofing. We fasten it to the base with anchor bolts, with internal wall we connect with wire twists or staples.
• We mark the installation points of the rafter legs.
• We cut out the racks to uniform sizes, because... Our bench is pointed at the horizon. The height of the racks should take into account the cross-sectional dimensions of the purlin and beam.
• We install racks. If provided by the design, we secure them with spacers.
• We lay the purlin on the racks. We check the geometry again, then install brackets, metal plates, and wooden mounting plates.
• We install a test rafter board and mark the cutting areas on it. If the Mauerlat is set strictly to the horizon, there is no need to adjust the rafters on the roof after the fact. The first board can be used as a template for making the rest.
• We mark the installation points of the rafters. For marking, folk craftsmen usually prepare a pair of slats, the length of which is equal to the clearance between the rafters.
• According to the markings, we install the rafter legs and fasten them first at the bottom to the mauerlat, then at the top to the purlin to each other. Every second rafter is screwed to the Mauerlat with a wire bundle. In wooden houses, the rafters are screwed to the second crown from the top row.

If the rafter system is made flawlessly, the layer boards are installed in any order.

If there is no confidence in the ideal structure, then the outer pairs of rafters are installed first. A control string or fishing line is stretched between them, according to which the position of the newly installed rafters is adjusted.

The installation of the rafter structure is completed by installing fillets, if the length of the rafter legs does not allow forming an overhang of the required length. By the way, for wooden buildings the overhang should extend beyond the contour of the building by 50 cm. If you plan to organize a canopy, separate mini-rafters are installed under it.

Another useful video about building a gable rafter base with your own hands:

Hanging rafter systems

The hanging variety of rafter systems is a triangle. The two upper sides of the triangle are folded by a pair of rafters, and the base is the tie connecting the lower heels.

The use of tightening allows you to neutralize the effect of the thrust, therefore, only the weight of the sheathing, roof, plus, depending on the season, the weight of precipitation, acts on walls with hanging rafter structures.

Specifics of hanging rafter systems

Characteristic features of hanging type rafter structures:

• The obligatory presence of a tie, most often made of wood, less often of metal.
• Possibility to refuse to use the Mauerlat. A timber frame can be successfully replaced by a board laid on double-layer waterproofing.
• Installation of ready-made closed triangles – trusses – on the walls.

The advantages of the hanging scheme include the space under the roof free from racks, which allows you to organize an attic without pillars and partitions. There are disadvantages.

The first of them is restrictions on the steepness of the slopes: their slope angle can be at least 1/6 of the span of a triangular truss; steeper roofs are strongly recommended. The second disadvantage is the need for detailed calculations for the proper installation of cornice units.

Among other things, the angle of the truss will have to be installed from jeweler's precision, because the axes of the connected components of the hanging rafter system must intersect at a point, the projection of which must fall on the central axis of the Mauerlat or the backing board replacing it.

Subtleties of long-span hanging systems

The tie is the longest element of a hanging rafter structure. Over time, as is typical for all lumber, it becomes deformed and sags under the influence of its own weight.

Owners of houses with spans of 3-5 meters are not too concerned about this circumstance, but owners of buildings with spans of 6 meters or more should think about installing additional parts that exclude geometric changes in tightening.

To prevent sagging, there is a very significant component in the installation diagram of the rafter system for a long-span gable roof. This is a pendant called a grandmother.

Most often it is a block attached with wooden pegs to the top of the truss. The headstock should not be confused with the racks, because its lower part should not come into contact with the puff at all. And installation of racks as supports in hanging systems ah does not apply.

The bottom line is that the headstock hangs, as it were, on the ridge assembly, and a tightening is attached to it using bolts or nailed wooden plates. To correct sagging tightening, threaded or collet-type clamps are used.

The tightening position can be adjusted in the area ridge knot, and connect the headstock to it rigidly with a notch. Instead of a block on non-residential attics For the manufacture of the described tension element, reinforcement can be used. It is also recommended to install a headstock or hanger where the tie is assembled from two beams to support the connection area.

In an improved hanging system of this type, the headstock is complemented by strut beams. The tension forces in the resulting rhombus are extinguished spontaneously due to competent arrangement vector loads acting on the system.

As a result, the rafter system is stable with minor and not too expensive modernization.

Hanging type for attics

In order to increase usable space the tightening of the rafter triangles for the attic is moved closer to the ridge. A completely reasonable move has additional advantages: it allows you to use the puffs as a basis for lining the ceiling.

It is connected to the rafters by cutting with a half-pan and duplicating with a bolt. It is protected from sagging by installing a short headstock.

A noticeable disadvantage of the attic hanging structure lies in the need for accurate calculations. It is too difficult to calculate it yourself; it is better to use a ready-made project.

Which design is more cost effective?

Cost is an important argument for an independent builder. Naturally, the price of construction for both types of rafter systems cannot be the same, because:

• In the construction of a layered structure, a board or beam of small cross-section is used to make rafter legs. Because layered rafters have two reliable supports underneath them; the requirements for their power are lower than in the hanging version.
• In the construction of a hanging structure, the rafters are made of thick timber. To make a tightening, a material with a similar cross-section is required. Even taking into account the abandonment of the Mauerlat, the consumption will be significantly higher.

It will not be possible to save on the grade of material. For the load-bearing elements of both systems: rafters, purlins, beams, mauerlat, headstocks, racks, 2nd grade lumber is needed.

For crossbars and tensile ties, grade 1 will be required. In the manufacture of less critical wooden overlays, grade 3 can be used. Without counting, we can say that in the construction of hanging systems, expensive material is used in greater quantities.

Hanging trusses are assembled in an open area next to the facility, then transported, assembled, upstairs. To lift weighty triangular arches from timber, you will need equipment, the rental of which will have to be paid. And the project for complex nodes of the hanging version is also worth something.

Video instruction on the construction of a hanging category truss structure:

There are actually many more methods for constructing rafter systems for roofs with two slopes.

We have described only the basic varieties, which in reality are applicable for small country houses and buildings without architectural tricks. However, the information presented is enough to cope with the construction of a simple truss structure.

Housing construction today is so diverse that sometimes the structures being built take on a completely bizarre, fantastic look. In particular, architects like to experiment with the roof, which is made transparent, and in the form of tree foliage or a flower, and a platform for skateboarding - in general, their imagination is completely limitless. But we are somehow closer to simpler options, for example a gable roof. We’ll talk about what it is and what the rafter system of a gable roof consists of in this article.

It is this type of construction that is most popular in the construction of residential buildings, since with its help it creates sufficient attic space, which does not require additional insulation. In addition, a gable roof is not as difficult to install as, for example, a hip roof, and also does not require huge investments for its installation.

A gable roof is a structure consisting of two rectangular planes connected at the top to each other, and at the bottom to the walls of the house. The end part of such a building is usually built from the same materials as the walls of the building; sometimes the entrance to the attic is built here.

Recently, it has become very popular to build an additional room in the attic space, often used as a summer guest room. Installation of a gable roof rafter system and subsequent insulation of the resulting room allows you to create a full-fledged room in which you can live both in summer and winter.

All the advantages of gable structures

Main components rafter roof are the mauerlat and rafter legs, in addition, various struts, racks, crossbars, stops and battens help make the structure strong and reliable. The drawing of a gable roof also includes a layer of insulation, vapor barrier, waterproofing and the roof itself. Thanks to all these elements, a gable roof has a number of advantages:

• simplicity of technical execution;
• low probability of leaks, since the structure is solid;
• high efficiency, because a relatively small amount of materials is spent on its construction;
• the possibility of arranging a full-fledged living area in the attic;
• ease of repair in case of defects;
• high strength and wear resistance.

The angle of inclination is an important component of a durable roof.

The angle of inclination is determined depending on the weather conditions of the region of residence, the characteristics of building materials and architectural requirements.

For example, in areas where large amounts of precipitation are normal, the roof is always built at a large angle. This is necessary to ensure that snow masses accumulate on its surface as little as possible, which could lead to the collapse of the building. In regions with strong winds, flat roofs are most often built, since the wind pressure on such structures is significantly reduced.

No matter what climate zone the home is located in, the rafter system of a gable roof cannot be built at an angle of less than 5 degrees!

Recommendations for calculating the area of ​​a gable roof

Calculation of roof area - picture

Carrying out the calculation is not as difficult as it might seem at first glance, but this painstaking process requires perseverance - all data must be double-checked at least three times. Agree, no one wants to spend money on completely unnecessary building materials.

In some cases, measuring the roof area may be complicated by certain “obstacles”, for example, the presence of an attic or unusual shape roofing – it’s unlikely to be possible without the help of a specialist. We will consider calculating the area on the classic version of the roof with two slopes:

• First, we determine the length of each slope; it is equal to the distance between the lower edge of the ridge and the extreme point of the cornice;
• We take into account all elements of the roof: parapets, overhangs, firewalls and other structures that create additional volume;
• We decide on the type of roofing material for which we will calculate the area;

It should be taken into account that in the case when the roof is covered with rolled or tiled materials, the length of each slope will be reduced by about 0.7 m.

• We do not take into account elements such as ventilation shafts, windows and chimneys;
• When the area of ​​each slope has been calculated, taking into account all the details, we calculate the slopes: we multiply the elements of the slopes by the cosine of the angle of inclination of the roof, and calculate the area only by overhangs.

For the greatest convenience of calculation and obtaining correct data, it is best to calculate the area of ​​​​each element separately, and then add the resulting numbers.

The roof area has been calculated, the roof has been decided on - all that remains is to understand in detail all the structural elements, such as rafters, mauerlat, side/ridge girders, struts and braces, as well as diagonal braces, after which you can begin to calculate the specific type of rafter system.

Hanging and layered rafters

Of course, such a structure as a do-it-yourself gable roof rafter system appears in the minds of many as something very complex and labor-intensive. But if you carefully consider the construction of such a structure and study in advance required material– the only question will remain in the “number of hands” you will need for the construction process.

Let's start with such a component of the roof as hanging rafters. These beams have only two points of support - the walls, so the main loads acting on them are bending and compression. The weight of the roof, as well as the action of snow and wind, is transferred to the walls through the hanging rafters, so that this pressure is compensated, the rafters are connected with a tie made of metal or wood. It can be placed at any height, but the higher it is, the stronger and more durable it should be.

Layered rafters are beams that have an intermediate support resting on the internal wall of the house. The main effect on such a structure is bending. Basic structure roofing is made only from layered supports, when the distance between them is no more than 6.5 m.

The same roof can consist of layered and hanging rafters at the same time: where there is an intermediate support, layered rafters are erected, and where there is not, hanging rafters are erected.

Mauerlat and purlins

The lower part of the rafters in houses built from timber rests on the upper crown, and in buildings made of brick or foam concrete - on a special beam called a mauerlat. To lay it on the inside of the load-bearing wall, place waterproofing material, on which the Mauerlat rests. The length of the beam can be equal to the length of the building wall, or it can be adjusted to the size of each rafter leg - this is even more economical.

Ridge purlin is a beam to which the upper parts of the rafters are attached. That is, this is the ridge of the roof. Its length depends on the length of the roof, so both a solid mass and several logs are used for its construction.

Side purlins are needed for additional support of the rafters; their emphasis is also placed on the gables of the building. The ends of such purlins are sometimes extended beyond the gables, thus creating unloading consoles, as a result of which the roof pressure on the central part of the purlin is significantly reduced.

If the roof of a building is erected from heavy materials, for example from natural tiles, then the side purlins are made in the form of a rocker arm, for this purpose the logs are slightly hemmed and bent.

A little more about the important elements of the roof

Diagonal overlaps - picture

Additional diagonal ceilings are called braces, with the help of which the rafter system of a gable roof is strengthened and the wind resistance characteristics of the gables are increased. Top part The braces rest against the gables, and the lower one rests against the central ceiling.

Struts are necessary to reduce the load on the rafters; installing them at an angle of 45 degrees or higher can significantly reduce wind loads and the pressure of snow masses on the roof, therefore northern regions countries, such roof elements are simply irreplaceable.

If the roof consists of slopes of different sizes, then their angle of inclination will not be equal. Consequently, for the greatest strength of such a structure, they erect vertical racks, on which the side girders rest. Most often, such structures are built for attic spaces.

In areas characterized by constant strong wind, rafter systems must be strengthened with diagonal ties, which are boards with a thickness of 25 to 50 mm. The lower edge of the board is attached to the heel of the rafter leg, and the upper edge to the middle of the opposite rafters.

Correct calculation of materials for the rafter system of a gable roof

You should not be afraid to make all the necessary calculations yourself, because the dimensions of a gable roof, especially if it has the shape of an isosceles triangle, can be calculated by anyone without deep mathematical knowledge.

So, let's consider the calculation of the rafter system of a gable roof on specific example. The house for which you need to build similar design, has a width (W) of 4 m, a length of 6 m, and the angle of inclination of the rafters (Y) should be equal to 120 degrees. The roof will be constructed from metal tiles, the distance between the rafters is planned to be 1 meter.

First, find the height of the central support (C):

C = 0.5? Width / tgY/2 = 0.5? 4 / 1.73 = 1.2 m

The length of the rafter leg (Ds) is calculated using the following formula:

Ds = 0.5?Wir / sinY/2 + 0.5 = 2.8m

0.5 in this formula is the allowance for the roof canopy, it must be taken into account without fail!

Roof area (Pk) = D? Ds? 2 = 33.6 m2

It turns out that this is exactly the number of sheets of metal tiles you will need for the roof.

Let us conditionally take the distance between each lathing plank (Рп) as 35 cm, which means:

Sheathing length = Ds / Rp? D?2 = 96 linear meters

With a house length of 6m and a distance between the rafters of 1m, we will need 7 rafter legs, which means the amount of timber for them and for the mauerlat is needed no less than:

Length of beam = (2 ? Ds + Width + C) = 75.5 l.m.

The required amount of other materials is calculated in the same way. When all the calculations have been made and the required volume of building materials has been purchased, we proceed to the actual construction of the gable roof.

We build a gable roof with our own hands

So, now we have come close to the moment of installing a gable roof rafter system. This process begins with the construction of beam floors.

There are only two options for their installation:

• If the attic space is not planned to be used as housing, then boards measuring 50? 150 mm.
• To equip the attic you will already need timber with dimensions of 150? 150 mm, and each of them fits exactly on load-bearing walls building. This is the only way to create a truly reliable and durable attic structure, only the cost of its construction will be an order of magnitude more expensive than the construction of a conventional attic. But the living area of ​​the house will increase significantly - decide what is more important to you and think through everything to the smallest detail.

Floor beams are laid across the entire width of the building, leaving 500-600mm per projection from the load-bearing walls - this will protect the wall from water flowing from the roof slopes. Along the entire perimeter of the house, a board is laid on beams, which will become the basis for the wall racks of the second floor - the attic.

For the construction of all roof elements, the following fastening materials are used:

• screws,
• nails,
• screws,
• dowels,
• wire,
• metal squares.

Once the racks are installed, you can begin arranging the rafters.

This do-it-yourself gable roof rafter system is the simplest in technical design. Why? Firstly, because there is no need to calculate the structure of the rafters depending on the material and location of the insulation.

And secondly, we don’t need cross-sectional dimensions either.

The easiest way is to “tame” a gable roof of a regular triangular shape, because all its components will have identical dimensions.

In addition, this system has several more undeniable advantages:

• the cross-section of rafters and beams has a high margin for load-bearing capacity;
• this form is very reliable, since the load on the structure is distributed evenly, and the risk of deformation of the rafter legs disappears;
• the triangular rafter system is an independent structure, so if problems occur in other elements of the building, it remains undamaged;
• the beam, laid with a slight protrusion, also serves as a frame for the entire weight of the roof - and this is additional reliability of the entire building as a whole.

Attic rafter system

We will only talk about a one-level attic, since it is quite possible to build it with your own hands. It is recommended to entrust the construction of more complex structures to experienced specialists, since it is easy to make mistakes in calculations without their help, and the result will be disastrous.

A board is placed on the beam, from which the lower part is sawn off - this is done to ensure that there are no gaps between the beams and rafters.

You need to lay a beam on a board (100 mm) and draw a line where they join. Then the board must be sawn along this line, resulting in a beveled board that will fit snugly against all floor beams.

Again, along this line we make a cut and so on. Completing these steps will ensure tight and precise fastening of the upper part of the rafter system, the installation of which can begin. Using the overlay, secure each row of rafters at the top (on the ridge); finally, fasten the resulting strapping with a special crossbar, which will act as a ceiling for the ceiling.

The rigidity of the structure being built directly depends on how firmly the rafters are fastened to each other. It is best to use special metal linings - this way you can achieve the greatest strength of the roof.

When all the rows of rafters are fixed, you can begin checking the correctness of the creation of the pediments - they must be positioned strictly at right angles. This is where a plumb line comes in handy - an indispensable thing for such situations.

When the correctness of the design is beyond any doubt, you can begin to permanently fasten all the parts together; soft wire, nails or staples will help with this.

Now you need to stretch the twine along the top point of the gables, this will make it more convenient to install the middle rafters at the same level.

To eliminate the possibility of sagging of the rafter system, it is necessary to strengthen the middle rafters with special struts.

Installing struts usually does not cause any difficulties: their lower part is attached to the attic post, and the upper part is attached to the middle of the rafter leg, where you need to cut out a groove of the required depth. To secure the structure, you need to choose nails from 200 mm.

That's all - the do-it-yourself gable roof rafter system is ready! All that remains is to build the sheathing and cover the roof with a roof, but these are completely different technologies, which will be discussed in the next article.

Roof installation is a complex multi-step process. To independently assemble and install a rafter system, you need to carefully study the methods of connecting elements, calculate the length of the rafters and the slope angle, and select the appropriate materials. If not the necessary experience, take on complex designs not worth it. The best option for a small residential building - a do-it-yourself gable roof.

A standard roof of this type consists of the following elements:

Mauerlat is a timber laid on top of the walls along the perimeter of the building. It is secured using threaded steel rods embedded in the wall or anchor bolts. The timber must be made of coniferous wood and have square section 100x100 mm or 150x150 mm. The Mauerlat takes on the load from the rafters and transfers it to the external walls.

Rafter legs- these are long boards with a cross section of 50x150 mm or 100x150 mm. They are attached to each other at an angle and give the roof triangular shape. The structure of their two rafter legs is called a truss. The number of trusses depends on the length of the house and the type of roofing. The minimum distance between them is 60 cm, the maximum is 120 cm. When calculating the pitch of the rafter legs, you should take into account not only the weight of the covering, but also the wind load, as well as the amount of snow in winter.

It is located at the highest point of the roof and most often represents a longitudinal beam connecting both slopes. The beam is supported from below by vertical posts, and the ends of the rafters are attached to the sides. Sometimes the ridge consists of two boards that are nailed to the top of the rafters on both sides and connected at a certain angle.

Racks are vertical beams with a cross section of 100x100 mm, located inside each truss and used to transfer the load from the ridge run to the load-bearing walls inside the house.

The struts are made from scraps of timber and installed at an angle between the posts and rafters. The side edges of the truss are strengthened with struts and the load-bearing capacity of the structure is increased.

Tie - a beam connecting the lower parts of the rafters, the base of the truss triangle. Together with the struts, such a beam serves to strengthen the truss and increase its resistance to loads.

A log is a long beam with a cross-section of 100x100 mm, laid along the central load-bearing wall, on which vertical posts rest. Lezhen is used when installing layered rafters when the run between the outer walls is more than 10 m.

The sheathing consists of boards or timber placed on the rafters. The sheathing can be continuous or with gaps, depending on the type of roof. It is always attached perpendicular to the direction of the rafters, most often horizontally.

If there is no more than 10 m between the external walls and there is no load-bearing wall in the middle, arrange hanging rafter system. With this system, the upper ends of adjacent rafters are sawn at an angle and connected to each other using nails, excluding the installation of racks and ridge beams. The lower ends of the rafter legs rest on the external walls. Due to the absence of racks, the attic space can be used for arranging an attic. Very often, the function of tightening is performed by floor beams. To strengthen the structure, it is recommended to install the top tie at a distance of 50 cm from the ridge.

If there is a central supporting wall, the arrangement is more justified layered rafter system. A bench is placed on the wall and attached to it support posts, and a ridge beam is nailed to the posts. This installation method is quite economical and easier to implement. If the ceilings are interior spaces are designed on different levels, racks are replaced brick wall, dividing the attic into two halves.

The roof installation process includes several stages: attaching the Mauerlat to the walls, assembling the trusses, installing the rafters on the floors, installing the ridge, and attaching the sheathing. All wooden elements Before assembly begins, they are thoroughly treated with any antiseptic composition and dried in air.

To work you will need:

• timber 100x10 mm and 150x150 mm;
• boards 50x150 mm;
• boards 30 mm thick for lathing;
• roofing felt;
• metal studs;
• jigsaw and hacksaw;
• hammer;
• nails and screws;
• square and building level.

In wooden houses The functions of the mauerlat are performed by the logs of the last row, which significantly simplifies the work process. To install the rafters, just cut inside log grooves of the appropriate size.

IN brick houses or buildings made of blocks, installation of the Mauerlat occurs as follows:

The Mauerlat bars must form a regular rectangle and be in one horizontal plane. This will facilitate further installation of the roof and provide the structure with the necessary stability. Finally, markings are made on the beams for the rafters and grooves are cut along the thickness of the beam.

When choosing a hanging rafter system, it is necessary to assemble the trusses on the ground and then install them above the floors. First you need to draw up a drawing and calculate the length of the rafter legs and the angle of their connection. Typically, the roof slope is 35-40 degrees, but in open, heavily blown areas it is reduced to 15-20 degrees. To find out at what angle to connect the rafters, you should multiply the angle of the roof by 2.

Knowing the length of the purlin between the external walls and the angle of connection of the rafters, you can calculate the length of the rafter legs. Most often it is 4-6 m, taking into account eaves overhang 50-60 cm wide.

The upper ends of the rafters can be fastened in several ways: overlapping, end-to-end and “into the paw”, that is, with grooves cut out. Metal plates or bolts are used for fixation. Next, the lower and upper ties are installed, and then the finished trusses are lifted up and installed above the floors.

The outer trusses are attached first: using a plumb line, the rafters are aligned vertically, the length of the overhang is adjusted and attached to the mauerlat with bolts or steel plates. To prevent the truss from moving during installation, it is reinforced with temporary beams made of timber. After installing the outer rafters, the rest are set, keeping the same distance between them. When all the trusses are secured, take a board with a cross-section of 50x150 mm, the length of which is 20-30 cm longer than the length of the cornice, and nail it along the upper edge of the slope. The same is done on the other side of the roof.

The first option: a rectangular groove is cut out on the rafter leg at the point where it contacts the mauerlat, 1/3 of the width of the beam. Stepping back 15 cm from the top of the box, a steel spike is driven into the wall. The rafter is leveled, the grooves are aligned, then a wire clamp is placed on top and the beam is pulled close to the wall. The ends of the wire are securely fastened to the crutch. The lower edges of the rafters are carefully cut off circular saw, leaving an overhang of 50 cm.

Second option: the upper rows of walls are laid out with a stepped cornice of bricks, and the mauerlat is placed flush with inner surface walls and cut a groove in it for the rafter. The edge of the rafter leg is cut to the level of the upper corner of the cornice. This method is simpler than others, but the overhang is too narrow.

Third option: beams ceilings are released over the edge outer wall by 40-50 cm, and the trusses are installed on the beams. The ends of the rafter legs are cut at an angle and rest against the beams, secured with metal plates and bolts. This method allows you to slightly increase the width of the attic space.

Installation of layered rafters

Figure 1 shows the cutting of rafter struts into a beam laid on intermediate supports, and Fig. 2 - resting the rafter leg on the mauerlat

The procedure for installing a layered rafter system:

When the main elements are fixed, the surface of the rafters is treated with fire retardants. Now you can start making the sheathing.

For the sheathing, timber 50x50 mm is suitable, as well as boards 3-4 cm thick and 12 cm wide. Waterproofing material is usually laid under the sheathing to protect the rafter system from getting wet. The waterproofing film is laid in horizontal stripes from the eaves to the roof ridge. The material is spread with an overlap of 10-15 cm, after which the joints are secured with tape. The lower edges of the film should completely cover the ends of the rafters.

It is necessary to leave a ventilation gap between the boards and the film, so first stuff them onto the film. wooden slats 3-4 cm thick, placing them along the rafters.

The next stage is covering the rafter system with boards; they are stuffed perpendicular to the slats, starting from the roof eaves. The pitch of the sheathing is influenced not only by the type of roofing, but also by the angle of inclination of the slopes: what larger angle, the greater the distance between the boards.

After completing the installation of the sheathing, they begin cladding the gables and overhangs. You can cover the gables with boards, plastic panels, clapboard, waterproof plywood or corrugated sheeting - it all depends on your financial capabilities and personal preferences. The sheathing is attached to the side of the rafters; nails or screws are used as fasteners. Overhangs are also hemmed various materials– from wood to siding.

Video - DIY gable roof

Each roof is based on a large number of beams, rafters, posts and purlins, which are collectively called the rafter system. Over the centuries-old history, many types and methods of its organization have accumulated, and each has its own characteristics in the construction of nodes and cuts. Let's talk in more detail about what the rafter system of a gable roof can be and how the rafters and other elements of the system should be attached.

Design of a gable roof truss system

In cross-section, a gable roof is a triangle. It consists of two rectangular inclined planes. These two planes meet at the highest point at unified system ridge beam (purlin).

Now about the components of the system and their purpose:

• Mauerlat is a beam that connects the roof and walls of a building, serves as a support for rafter legs and other elements of the system.
• Rafter legs - they form the inclined planes of the roof and are the support for the sheathing under roofing material.
• Ridge purlin (bead or ridge) - combines two roof planes.
• A tie is a transverse part that connects opposite rafter legs. Serves to increase structural rigidity and compensate for thrust loads.
• Lezhny - bars located along the mauerlat. Redistribute the load from the roof.
• Side purlins - support the rafter legs.
• Racks - transfer the load from the purlins to the beams.

There may still be fillies in the system. These are boards that extend the rafter legs to form an overhang. The fact is that to protect the walls and foundation of the house from precipitation, it is desirable that the roof ends as far as possible from the walls. To do this, you can take long rafter legs. But standard length 6 meters of lumber is often not enough for this. Ordering non-standard is very expensive. Therefore, the rafters are simply extended, and the boards with which this is done are called “fillies”.

There are quite a lot of designs of rafter systems. First of all, they are divided into two groups - with layered and hanging rafters.

With hanging rafters

These are systems in which the rafter legs rest only on the external walls without intermediate supports(load-bearing walls). For gable roofs, the maximum span is 9 meters. When installing a vertical support and a strut system, it can be increased to 14 meters.

Hanging type The good thing about the rafter system of a gable roof is that in most cases there is no need to install a mauerlat, and this makes the installation of rafter legs easier: there is no need to make cuts, just bevel the boards. To connect the walls and rafters, a lining is used - a wide board, which is attached to studs, nails, bolts, crossbars. With this structure, most of the thrust loads are compensated, the impact on the walls is directed vertically downwards.

Types of rafter systems with hanging rafters for different spans between load-bearing walls

Gable roof rafter system for small houses

There is a cheap version of the rafter system when it is a triangle (photo below). Such a structure is possible if the distance between the external walls is no more than 6 meters. For such a rafter system, you can not make a calculation based on the angle of inclination: the ridge must be raised above the tie to a height of at least 1/6 of the span length.

But with this construction, the rafters experience significant bending loads. To compensate for them, either rafters of a larger cross-section are taken or the ridge part is cut in such a way as to partially neutralize them. To give greater rigidity, wooden or metal plates are nailed on both sides at the top, which securely fasten the top of the triangle (also see the picture).

The photo also shows how to extend rafter legs to create a roof overhang. A notch is made, which should extend beyond the line drawn from the inner wall upward. This is necessary to shift the location of the cut and reduce the likelihood of the rafter breaking.

Ridge knot and fastening of rafter legs to the backing board when simple version systems

For mansard roofs

Option with installing a crossbar - used when. In this case, it serves as the basis for lining the ceiling of the room below. For reliable operation of a system of this type, the crossbar cut must be hingeless (rigid). The best option is in a semi-frying pan (see picture below). Otherwise, the roof will become unstable to loads.

Please note that in this scheme there is a Mauerlat, and the rafter legs must extend beyond the walls to increase the stability of the structure. To secure them and dock them with the Mauerlat, a notch is made in the form of a triangle. In this case, with an uneven load on the slopes, the roof will be more stable.

With this scheme, almost the entire load falls on the rafters, so they need to be taken with a larger cross-section. Sometimes the raised puff is reinforced with a pendant. This is necessary to prevent it from sagging if it serves as a support for ceiling cladding materials. If the tie is short, it can be secured in the center on both sides with boards nailed to the nails. With a significant load and length, there may be several such belays. In this case, too, boards and nails are enough.

For large houses

If there is a significant distance between the two outer walls, a headstock and struts are installed. This design has high rigidity, since the loads are compensated.

With such a long span (up to 14 meters), it is difficult and expensive to make the tie in one piece, so it is made from two beams. It is connected by a straight or oblique cut (picture below).

For reliable joining, the connection point is reinforced with a steel plate mounted on bolts. Its dimensions should be more sizes notches - the outermost bolts are screwed into solid wood at a distance of at least 5 cm from the edge of the notch.

In order for the circuit to work properly, it is necessary to make the struts correctly. They transfer and distribute part of the load from the rafter legs to the tie and provide structural rigidity. Metal pads are used to strengthen connections

When assembling a gable roof with hanging rafters, the cross-section of lumber is always larger than in systems with layered rafters: there are fewer load transfer points, therefore each element bears a greater load.

With layered rafters

In gable roofs with layered rafters, the ends rest on the walls, and the middle part rests on load-bearing walls or columns. Some schemes push through the walls, some don't. In any case, the presence of a Mauerlat is mandatory.

Non-thrust schemes and notch units

Houses made of logs or timber do not respond well to thrust loads. For them they are critical: the wall may fall apart. For wooden houses, the rafter system of a gable roof must be non-thrust. Let's talk about the types of such systems in more detail.

The simplest non-thrust rafter system diagram is shown in the photo below. In it, the rafter leg rests on the mauerlat. In this version, it bends without pushing the wall.

Pay attention to the options for attaching the rafter legs to the Mauerlat. In the first, the support area is usually beveled, its length being no more than the section of the beam. The depth of the cut is no more than 0.25 of its height.

The top of the rafter legs is laid on the ridge beam, without fastening it to the opposite rafter. The structure results in two pitched roofs, which in the upper part are adjacent (but not connected) to one another.

The option with rafter legs fastened at the ridge part is much easier to assemble. They almost never push against the walls.

To operate this scheme, the rafter legs at the bottom are attached using a movable connection. To secure the rafter leg to the mauerlat, one nail is driven from above or a flexible steel plate is placed from below. See the photo for options for attaching rafter legs to the ridge girder.

If you plan to use heavy roofing material, it is necessary to increase the load-bearing capacity. This is achieved by increasing the cross-section of the rafter system elements and strengthening the ridge assembly. It is shown in the photo below.

Reinforcing the ridge assembly for heavy roofing material or for significant snow loads

All of the above gable roof schemes are stable in the presence of uniform loads. But in practice this practically never happens. There are two ways to prevent the roof from sliding towards a higher load: by installing a screed at a height of about 2 meters or by struts.

Options for rafter systems with contractions

Installing contractions increases the reliability of the structure. In order for it to work properly, it needs to be secured to them with nails at the places where it intersects with the drains. The cross-section of the timber for the scrum is the same as for the rafters.

They are attached to the rafter legs with bots or nails. Can be installed on one or both sides. See the figure below for attaching the screed to the rafters and ridge girder.

In order for the system to be rigid and not “creep” even under emergency loads, it is enough in this option to ensure rigid fastening of the ridge beam. In the absence of the possibility of its horizontal displacement, the roof will withstand even significant loads.

Layered rafter systems with struts

In these options, for greater rigidity, rafter legs, also called struts, are added. They are installed at an angle of 45° relative to the horizon. Their installation allows you to increase the span length (up to 14 meters) or reduce the cross-section of beams (rafters).

The brace is simply placed at the required angle to the beams and nailed on the sides and bottom. An important requirement: the strut must be cut accurately and fit tightly to the posts and rafter leg, eliminating the possibility of it bending.

Systems with rafter legs. The top is a spacer system, the bottom is a non-spacer system. The correct cutting nodes for each are located nearby. At the bottom - possible schemes strut fastenings

But not in all houses the average load-bearing wall is located in the middle. In this case, it is possible to install struts with an angle of inclination relative to the horizon of 45-53°.

Systems with struts are necessary if significant uneven shrinkage of the foundation or walls is possible. Walls can settle differently on wooden houses, and foundations can settle on layered or heaving soils. In all these cases, consider installing rafter systems of this type.

System for houses with two internal load-bearing walls

If the house has two load-bearing walls, install two rafter beams, which are located above each of the walls. The beams are laid on the intermediate load-bearing walls, the load from the rafter beams is transferred to the beams through the racks.

In these systems, a ridge run is not installed: it provides expansion forces. The rafters in the upper part are connected to one another (cut and joined without gaps), the joints are reinforced with steel or wooden overlays which are nailed down.

In the upper non-thrust system, the pushing force is neutralized by the tightening. Please note that the tightening is placed under the purlin. Then it works effectively (top diagram in the figure). Stability can be provided by racks, or joints - beams installed diagonally. In the spacer system (in the picture it is below) the crossbar is a crossbar. It is installed above the purlin.

There is a version of the system with racks, but without rafter beams. Then a stand is nailed to each rafter leg, the other end of which rests on the intermediate load-bearing wall.

Fastening the rack and tightening in the rafter system without a rafter purlin

To fasten the racks, 150 mm long nails and 12 mm bolts are used. Dimensions and distances in the figure are indicated in millimeters.