Construction of the roof truss system, what material to choose. Roof rafter system: elements, types, fastenings, calculation Correctly constructed rafter system

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 useful both for those who are constructing a gable roof truss system with their own hands, and for those who decide to resort to the services of a hired team of builders.

In device 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 the matter of independent construction of rafter structures for private houses, wood is a priority. It is not difficult to work with, it is lighter, “warmer”, and more attractive in terms of environmental criteria. In addition, to make nodal connections you will not need a welding machine or welder 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. Although a structure with hanging rafters is braced, the bracing itself does not transmit 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 a gable roof frame can generally be done without truss 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 design 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 a wooden frame, and the walls made of the specified materials, a waterproofing layer made of roofing felt, waterproofing material, etc. is required.

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 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 step of the rafters determines the type and weight roofing. The heavier it is, the smaller the distance between the rafter legs should be. For styling clay tiles, for example, the optimal distance between the rafters 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 the run - wooden beam, resting on racks 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 rafter legs are required due to the large size of the roof additional points supports.

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

If the attic is cold and it is not intended to organize useful rooms, then the layered structure of the rafter system for installing a gable roof should be given preference.

Typical sequence of work for 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 remove them with a 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.
On concrete and brick walls We lay waterproofing under the 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 installed in advance in the wall, or with 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 bed is exposed to 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” 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 with pinpoint 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 the installation of racks as supports in hanging systems is not used.

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 of the ridge assembly, and the headstock can be rigidly connected to it by 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 stress forces in the resulting rhombus are extinguished spontaneously due to the proper placement of 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 the 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 hanging attic structure is 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 installation 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.

Installation of a gable roof is actively practiced in private construction, since it is the simplest and affordable way construction of a reliable roof for the house. This article describes the main stages of installation, which can be performed independently, with a certain skill in roofing work.

Functional features of a gable roof

The structure of a gable roof consists of load-bearing elements (mauerlat, rafter system) and enclosing elements (roof). A gable roof (gable) has two roofing surfaces located at a certain slope to the outer walls of the building, which ensures natural drainage of moisture from melted snow and rainwater. According to SNiP, the angle of inclination of such a roof should be more than 5°.

The choice of roof slope angle is influenced by:

type of finishing material;
architectural features of the building;
climatic conditions of the construction area.

The construction of a gable roof with a large angle of inclination is usually practiced when relatively lightweight roofing materials are used and in regions without large wind loads, since the pitched roof of a building is a sail. In addition, a steep pitched roof is a practical option for areas with high rainfall - rain moisture is quickly and successfully removed from it, and accumulated snow slides down under its own weight.

Low-slope roofs experience minimal wind loads, but are very sensitive to snow loads. To avoid destruction of the structure under load from snow masses, in winter period The roof should be cleaned regularly.

In private construction, gable roofs are most often erected with an angle of inclination from 35 to 60°. This is the best option in terms of the ratio of roof resistance to atmospheric loads and reasonable costs for materials for installing the rafter system, as well as arranging the roofing pie.

Installation of a gable roof begins with the installation of a mauerlat or floor beams, depending on the type of rafter system chosen. Mauerlat acts as a foundation for roofing structure. It is this that allows you to evenly distribute the load (the weight of the rafter system itself, snow and wind loads, the weight of people servicing the roof), transferring it to building construction structures.

Mauerlat is a beam made of coniferous wood with a cross-section of 150×150 mm (most often). When erecting a gable roof, it is mounted on two parallel walls. If the project provides for the installation of layered rafters with a ridge girder on supports, then the Mauerlat beam should also be laid on the middle load-bearing wall.

When building wooden houses, the mauerlat is not mounted - it is an element for laying on building structures made of brick, foam concrete blocks and other materials. On small buildings, the Mauerlat can be attached to the walls using forged wire embedded in the masonry. When building a house, it is practiced to install a monolithic beam with installed fasteners.

To make a beam at the top of the walls, it is mounted wooden formwork, metal reinforcement bars are attached (at least 2 pairs of parallel lines, one above the other). Using wire, studs or anchors are attached to the reinforcement. It is important to install them in increments of no more than 1 meter, strictly vertically. The prepared formwork is poured with concrete.

The length of the stud with a diameter of about 14 mm is determined based on the thickness of the monolithic beam, the thickness of the Mauerlat beam plus one or two layers of roofing felt waterproofing. In this case, when laying the Mauerlat, the studs must be at least 3 cm above its surface so that it is possible to secure the beam using nuts with wide washers.

When preparing to install a monolithic beam, you should determine in advance the installation location of the fasteners for the Mauerlat. The beam can be laid strictly along the axis of the beam or with a shift to the inner or outer side of the wall. To secure the Mauerlat, you need to make holes for the studs.

The Mauerlat is mounted at least 5 cm from the outer edge of the wall.

If the roof frame is planned to be made of metal elements, a channel or I-beam metal profile can act as a Mauerlat.

A rafter system with hanging rafters can be installed without a Mauerlat. In this case, the lower parts of the rafter legs are attached to the floor beam, which is laid across the walls. The beam acts as a tie and provides rigidity to the truss. Construction of a gable roof using this principle is usually used when constructing buildings with a small span, most often from timber or logs. It is not recommended to install support beams on walls made of piece materials, since a point load can destroy building structures.

Gable roof rafter system

The rafter system includes the rafters themselves (rafter legs), as well as a number of other elements, the installation of which is necessary to ensure structural rigidity:

crossbars;
runs (including ridge runs);
racks;
lying down;
spacers;
struts, etc.

Rafter systems can be mounted from wood or metal, or a combination of both types of materials.

Rafter system design – important stage preparation for construction. Errors in the design can lead to the roof collapsing over time under the influence of operational loads. On the other hand, having designed an excessive safety margin for the roof frame, you will have to spend extra money on its construction.

The design of the gable roof rafter system is based on the most stable and rigid geometric figure- triangle. When installing rafter systems of simple design, the rafters are made of timber with a cross-section from 40×150 mm to 100×250 mm. The choice of a specific value depends on the following factors:

installation step;
rafter leg length;
calculated load value.

In turn, the installation step of the rafter legs is influenced by the type of roofing pie - if installation is planned warm roof, then this parameter is selected taking into account the width of the roll or sheet insulation.

Types of rafter structures

When considering how to build a gable roof, it is necessary to pay attention to the specifics of constructing rafter systems of various designs - with hanging and layered rafters. Rafter legs are the main element of the frame of a gable roof. They serve as a support for the roofing pie. Hanging rafters do not have intermediate supports and rest only on the walls of the building. Layered rafters have additional support points.

A truss, assembled from two rafter legs and a lower tie or an upper crossbar, is a structure that works in compression and bending. The bursting effect from the rafter legs mounted at an angle is compensated by the horizontal lintel. The higher the tie is mounted, the stronger and more rigidly one should be secured. This design allows you to cover even wide spans.

The upper part of the hanging rafters can be attached in various ways. The rigid fastening of the upper ends of the rafter legs is reinforced with the help of overhead elements made of wood or metal. When attaching the rafter legs to the mauerlat, a cutout (saddle) is made on the lower part of the rafter, after which the element is rigidly secured with nails and twisted wire. If rafters are installed on a floor beam, a stop is cut into the beam to prevent movement, and a single or double tooth is cut into the rafter. Installation is carried out using various metal fasteners.

There is no cutout in the Mauerlat timber so as not to weaken the load-bearing capacity of the roof support.

A roof frame with layered rafters is installed if the building has a middle load-bearing wall or columnar supports. The span between the supports should be no more than 6.5-7 meters. The width of the floor can be increased by installing additional supports: up to 11.5-12 meters with one additional support and up to 15-15.5 meters with two. To increase the rigidity of the rafter system and expand the opening between the supports, you should install a rack with struts under the ridge girder. The load on the roof is transferred by the middle part of the rafters to the internal supports, and by the lower ends to the external walls.

Installation of a rafter system with layered rafters is somewhat simpler than assembling and installing roof trusses. After installing the ridge girder on the gables of the building or special racks, the rafters are attached to it with the upper part.

In some cases, it is advisable to use both layered and hanging rafters when installing the roof frame.

The construction of the rafter system should be carried out using quality material to ensure the longevity of the roof. Lumber must have strict geometric shape, wood defects are not allowed. To prevent wooden elements from warping after installation, the material must be well dried. Before installation, it is necessary to treat the prepared parts with a fire-retardant agent.

Roofing pie device

The question of how to properly build a gable roof, in particular, is related to the competent execution of the roofing pie. The functionality of the design, its ability to provide reliable protection buildings from external influences.

When installing the roof, it is important to follow the designed pitch of the sheathing, having previously installed a counter-lattice to create a ventilation gap for the roofing pie. To ensure the necessary air circulation in the under-roof space, install ventilation duct in the ridge part, are provided ventilation holes in the filing of eaves overhangs.

Particular attention is paid reliable waterproofing roofs, otherwise moisture condensed on wooden elements can cause rotting of the structures. If the attic of a gable roof is intended to be used as a living space, it is necessary to provide reliable insulation and vapor barrier for the roof.

To ensure the strength and durability of a gable roof, you should carefully approach the development of the project, the choice of materials and compliance with the work technology.

Installation of a gable roof, how to build it correctly, construction

We learn how to install a gable roof with our own hands. In this article you will learn how to properly build a gable roof and where its construction begins.

How the design of the rafter system works, which one is better to choose

The roof structure is considered the most complex component of a residential building in terms of design and installation. The roof is exposed to wind, precipitation and cold, therefore it must be airtight and durable to create comfortable living conditions. The main part of the roof is the rafter system, with the help of which the shape of the structure is created, the optimal angle of inclination is set and secured waterproofing material. The number of elements of the rafter system, as well as their location, is determined by the configuration of the roof.

Purpose of the rafter system

The rafter system is a certain number of supporting elements that create the geometry of the roof and frame, which gives rigidity to the roof structure and required slope. The main parameters of the components of the rafter system and their location are determined taking into account permanent and temporary loads.

In general, the rafter system is assigned the following tasks:

Creating the shape and angle of inclination. The location of the rafter legs determines the shape of the roof, hence the number of gables and slopes. In addition, with the help of these elements, the angle of inclination of the slopes is formed for the rapid removal of snow, melt and rain water.
Uniform distribution of the roof load on the load-bearing walls of the house. The rafters of the system are interconnected and distributed in the structure so that the weight of the roofing and snow mass is evenly transferred to the building frame, without skewing or deformation of the structure.
Creating conditions for normal ventilation and protection from moisture. The roof frame is assembled in such a way that air circulates freely in the under-roof space, and the material itself is reliably protected from condensation accumulation.

In addition, the rafter system serves as the basis on which the waterproofing material and lathing for the finishing coating are attached.

At correct drafting rafter system diagrams, the roof will be reliable and durable and will last for a long time. According to experts, a high-quality constructed frame has higher value Therefore, there is no need to save at this stage. Therefore, it is best to entrust the design of the roof and its installation to professional craftsmen.

Features of choice

The rafter system of a building consists of a certain set of additional elements and has its own level of installation complexity. The number of auxiliary parts is determined taking into account the loads from roofing material and some environmental factors.

When choosing the type of rafter system, you should pay attention to the following factors:

Features of the climate of the area where construction is planned. It is possible to protect the roof from destruction during snowfalls or heavy rainfall only if the average annual amount of precipitation is correctly calculated. The optimal roof option in snowy regions is a steep slope.
Wind load. The optimal design option is selected based on the wind rose at the construction site and the average speed of air gusts. In windy regions, slopes are made flatter.
Usage attic space. Creating a living space under the roof is of great importance when choosing the shape of the rafter system.
Finish used. In order for the roofing covering to perform its functions to the maximum, you need to choose the right angle of inclination of the slope, taking into account the shape and method of fastening the material.
Financial opportunities. Installation of a roof structure requires large financial investments, therefore, you need to choose the type of roof in accordance with the construction budget.

Types of rafter construction

No roof is complete without a rafter system. The quality of the roof structure largely depends on what is included in the roof truss system. Vertical supports, horizontal ties and rafter legs provide a reliable foundation and support for the roofing. To make the frame, it is necessary to use lightweight materials that do not load the frame at home. They must be durable, with high load-bearing capacity and good resistance to negative natural phenomena.

The most common options are:

Wooden frame. This rafter system has low weight and good strength, and the natural origin of the material ensures the safety of residents and environment. The frame is assembled from bars with a cross-section of 10*10 cm or 15*15 cm or boards 5*15 cm. Among the disadvantages of wood, poor resistance to moisture can be noted. Besides long length products contributes to their bending under their own weight.
Metal rafter system has a high cost, but during installation large area slopes and the use of heavy roofing materials, it becomes indispensable. The metal profile has a high load-bearing capacity, which allows you to increase the distance between structural elements without reducing the strength characteristics. The only drawback of the metal is its poor corrosion resistance. To solve the problem in this case, metals that are resistant to this phenomenon are used.

Structural elements and details

All elements of the rafter system are interconnected. Thanks to this, the structure has rigidity and the necessary strength, and the weight from the roofing is evenly distributed across the load-bearing walls and partitions. The presence of certain structural elements, their cross-section and location depend on the selected roofing material, the angle of inclination of the slopes and the purpose of the attic space.

The main details of the rafter system are the following:

Mauerlat. This element is a rafter beam located on the top row or crown load-bearing walls Houses. For its manufacture, coniferous wood is used, which is hard and durable. The Mauerlat is fastened with metal pins or anchor bolts.
Sill. This element, made of timber, is located on the internal load-bearing partitions. The bench serves as a support for the posts, which are necessary to support the skate.
Racks- these are supports located vertically along the entire length of the bench and supporting the ridge or central part truss truss.
Rafters located at a certain angle to the base of the roof. The support for the rafter legs is the mauerlat and ridge beam.
Bolt and tightening– necessary horizontal elements for paired connection of rafter legs. The crossbar tightens the rafters directly under the ridge girder, the tie rods are slightly lower.
Struts. These elements are placed at an angle to the rafter leg to prevent deflection. The upper edge of the brace rests against the rafter, the lower edge against the rack or tie.

To construct a simple rafter system design, it is enough to use a mauerlat, ridge beam and rafters. Increasing the level of complexity leads to the use of additional elements that make the structure more durable and resistant to deflections.

Types of rafter system

The architectural features of the structure have a great influence on the configuration of the roof, since the load from the roof structure must be evenly distributed between all load-bearing walls and partitions.

In this regard, the following types of rafter system are distinguished:

Layered rafter system. In this design, the roof frame rests directly on the load-bearing walls outside and inside the building. Supports on the internal load-bearing partitions are necessary to support the ridge girder. Layered rafters allow you to cover a large area while maintaining strength characteristics.
Hanging rafter system involves the support of the rafter legs only on the mauerlat. In the upper part, the rafters rest against each other without a ridge. These types of rafters are used when covering structures that do not have internal load-bearing partitions. The truss in this case has the shape of an equilateral triangle, therefore, stabilizing elements are not required.

The result of choosing the types of rafter system and their structural elements can be a simple roof with one or two slopes, or a more complex one - hip and hip.

Construction of the rafter system: types of rafters, structural elements, roof details, what is included, parts

Construction and installation of a wooden rafter system

The roof of the building protects it from cold, rain and wind. This is as important an element as the outer walls and foundation. The rafter system is load-bearing frame roofs. It takes on all the loads: from structures, from snow and wind. To avoid problems during operation, the roof structure of the house must be strong and reliable. Do-it-yourself installation of a rafter system should only be done after careful preparation and study of all the necessary information.

Roof and roofing

Before you start installing the roof of a private house, you need to distinguish between two concepts. Non-professionals are often confused, but builders clearly distinguish between the definitions of roof and roofing. The roof is the entire structure that separates the building from the street above. The roof structure of a private house includes rafters, all other load-bearing elements, thermal insulation material, roofing.

Rafters - load-bearing roof structures

The roof is the top part of the roof. It is also a roof covering. The installation of a roof requires careful selection of materials. After all, the reliability of waterproofing and comfort of living will depend on it.

System requirements

To properly install a rafter system with your own hands, you must take into account a certain set of rules. Without taking them into account, the structure will not be able to effectively resist negative impacts from outside.

First of all, it is worth considering strength. All elements must withstand the load without destruction. The design of the roof truss system involves a preliminary calculation of the load-bearing structures according to the first limit state. It is he who checks the elements of the rafter system for strength.

The rafter system must be strong and rigid

The second requirement is rigidity. The maximum deflection is taken into account here. Roof structure wooden house or any other should not sag too much. The permissible deformations in the middle of the span are equal to the length of this span divided by 200. Before construction begins, the structure of the rafter system must be calculated according to the second group of limit states - for rigidity.

Do-it-yourself roof raftering is done taking into account that the structure is light in weight. Otherwise, the load on the walls and foundations increases greatly. It is for this reason that wood has become widespread as a base material. The wooden rafter system has sufficient strength, but weighs relatively little. Attention should be paid not only to the roof structure, but also to choosing the right roofing material. It shouldn't be too heavy. Ceramic tiles have lost their popularity not only because of the cost, but also because the roof of the house, its walls and foundations must be reinforced to accommodate it.

The weight of the roofing material for a wooden rafter structure should not be too large

Special requirements are placed on the quality of the material. Manufacturing wooden elements should be made only from good raw materials. It is worth considering the following recommendations:

For the main elements, grade 1 or 2 wood is used. Grade 3 can only be used for sheathing and other small parts.
It is recommended to make rafter structures for pitched roofs from coniferous trees. They are more resistant to rot and other problems because they contain resin. With the same cross-section, the permissible span for hardwood will be less.
Before starting work, all elements must be treated with an antiseptic. This stage of preparation allows you to prevent many troubles in the future. You can also treat the wood with fire retardants if desired. This will increase fire resistance.
It is better to purchase wood from the northern regions, which is harvested in winter. This material is of the highest quality.

Parts of the structure

The rafter system diagram includes many elements. To understand drawings and correctly perceive information, you need to know at least the basic ones. So, what is the roof made of?

Ridge, cornice and slopes - the main part of the roof

First of all, these are the ridge, cornice and slopes. These elements are the main parts. The ridge is the topmost part of the structure. Cornice or overhang - bottom. Slopes are inclined surfaces that are located between the ridge and the cornice.

The construction of a rafter system requires knowledge of load-bearing elements. These include:

Mauerlat - timber that is laid along the edge of the walls of a building. The Mauerlat is needed to evenly transfer the load from the rafter legs, which are supported pointwise. Typically, timber with dimensions of 150x150 mm or 200x200 mm (for large buildings) is used for its manufacture.
Rafter legs are inclined beams that transfer the load from the roof's own weight, snow and wind to the mauerlat. Such beams are usually installed from the ridge to the eaves. But when constructing a hip roof, elements appear that have only one of the specified points. They are supported on a ridge or on a cornice. Such details are called spigots. They usually have the same cross-section as the rafters. In fact, sprigs are rafter legs cut off on one side.
Purlin - a beam on which roof elements rest. The purlin can be installed under the racks. Another option is a ridge girder (crossbar). The rafters rest on it at the top point. The cross-section of the purlin depends on its span, usually 200x200 mm.
Sloping legs are only needed for hip roofs. They are diagonal rafters resting on the Mauerlat at the corners. The cross-section is assumed to be enlarged, usually 150x200 or 100x200 mm.
The design of a wooden roof requires the presence of puffs, struts and racks. They are designed to reduce the load on the main elements. When building a house with your own hands, it is important to remember that the racks cannot be rested on the floor span. Installation is only possible on underlying walls or on purlins spanned between walls. Such elements can be mounted on the ceiling only if it is designed for such a load and reinforced in the required area.
The lathing is needed to make a base for the covering. For metal tiles and seam roofing, the lathing can be sparsely made of boards 32-40 mm thick. For bitumen shingles, you need a solid base made of boards 25-32 mm thick or moisture-resistant plywood.
In order to make the cornice overhang, install fillies. They become an extension of the rafters. The filly is attached to the rafters for a length of at least 1 m. The cross-section of the element is usually taken to be 50x100 mm.

Load-bearing elements of a hip roof

Another element of the rafter system is a truss. This is a one-piece structure that consists of rafters, tie rods, struts and racks, rigidly connected to each other. The truss has a triangular shape, and inside it is divided into several smaller triangles, which provides it with good stability.

Roof shapes

Pitched roofs come in different shapes. It is worth highlighting here:

single-pitched;
gable;
hipped (tent and hip);
broken

The most common are gable and hip roofs

The most common option is a gable or hipped hip roof. The first requires the construction of pediments. Broken lines are relevant when constructing an attic. At first the rafters go at a steep angle, and then at a smaller one. This technology allows you to raise the ceiling of the attic room. We also recommend reading about the rafter system for a half-hip roof.

Types of rafters

There are two designs:

with layered rafters;
with hanging rafters.

Installing a roof on a wooden house is only possible using the former. This is caused by two rules:

hanging rafters must be firmly attached to the mauerlat;
in a wooden house, the rafters must be hinged to the mauerlat.

These two statements contradict each other, so the rafter system of a wooden house can only contain layered elements.

Only layered rafters are installed in a wooden house

Layered beams are elements that rest on the Mauerlat at the lowest point and on the ridge girder at the top. This allows you to reduce the horizontal thrust that acts on the walls when the rafters try to move apart and take a horizontal position. Elements can be reinforced with racks or struts. In this case, contractions can be placed through one pair of legs.

Hanging tanks are supported only at the lowest point on the Mauerlat. At the top they just rest against each other. To prevent the system of wooden elements from moving apart, tightening must be done. It is better to install them on each pair of legs. This option is characterized by a strong thrust effect on the external walls, but it allows you to get more free space inside the attic.

Connections

Before you make a rafter system with your own hands, you need to carefully study the nodes. To build your home, you shouldn't save time or money. Only in this case the result will please you for many years.

Main rafter connection units

Mounting points for the roof truss system that deserve special attention, are represented by the following:

fastening the Mauerlat to the wall;
fastening the rafters to the mauerlat;
fastening the rafters at the top point;
splicing rafters along the length.

Mauerlat to the wall

This node can be performed in several ways. The choice largely depends on the wall material. The construction of a building made of brick, block or concrete allows the use of the following methods:

on the wire;
on staples;
on stiletto heels;
on the anchor with the device monolithic belt along the edge of the wall.

The connection of the Mauerlat to the wall during the construction of brick buildings is carried out using anchors

In wooden construction, the upper crown of the wall acts as a mauerlat. It is connected to the previous ones using a dowel. IN frame house Mauerlat is top harness walls It is fixed to the frame posts using a notch and metal corners with holes for self-tapping screws. Read more about attaching the Mauerlat to the wall.

Rafters to the mauerlat

Fastening is carried out in two ways:

rigid for buildings made of brick, concrete or concrete blocks;
hinged for wooden houses.

Rigid fastening can be with or without a notch. It is recommended to do the cutting on the rafters, and not on the mauerlat, since this weakens it. In both cases, the leg is rigidly fixed with nails, screws, staples or metal corners.

With rigid fastening, it is better to make a notch on the rafters and fix the structure with fasteners

For hinged fastening, a special part is used - a slide.. They allow the beam to move without obstacles when the walls of the building shrink.

The hinged connection allows the beam to move

Additionally, the rafter legs are attached to the wall. This is necessary to prevent the roof from being blown off by the wind. For fastening, use a twist of two wires with a diameter of 4 mm, fixed to the wall with an anchor or a ruff. In a wooden house, twisting can be replaced with staples. Fastening is carried out on each beam or through one.

At the ridge level

The layered elements rest on a ridge girder with a notch. Additionally, a board overlay is made on both sides. An overlay is also needed for hanging elements. It can be wooden or metal with holes for screws.

The ridge girder and rafters are connected using a notch

Splicing rafters

There are several methods for splicing roof rafters with your own hands. The choice between them largely depends on the experience of the master. The splice point is located at a distance of 0.15 span lengths from the support. In this case, not only the ridge girder and the Mauerlat are considered supports, but also the struts and racks.

Splicing rafters along the length

There are five ways:

To build quality roof, you need to carefully study the technology, choose the right type of rafters and methods of connecting elements at important nodes. This is especially important when building a rafter system with your own hands.

Roof truss system for a private house: design and installation

How to do it right wooden roof private house. Rafter system: structural elements, rafters, fastening points and do-it-yourself installation.

Types of gable roof truss system: for small and large houses

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 are connected at the highest point into a single system by a ridge beam (purlin).

Scheme gable roof

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 provide support for the sheathing under the roofing material.
Ridge purlin (bead or ridge) - combines two roof planes.
The tie is a transverse part that connects opposite rafter legs. Serves to increase structural rigidity and compensate for thrust loads.
The beds are 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 from the walls as possible. 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 few designs of rafter systems. First of all, they are divided into two groups - with layered and hanging rafters.

The difference in the design of 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.

The good thing about the hanging type of gable roof rafter system 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 such a structure most of bursting 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 calculate 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 with a simple version of the system

For mansard roofs

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

Rafter system of a gable roof with a raised tightening and a crossbar insertion unit

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.

Gable roof rafter system for long span and ridge and rafter cutting units

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).

Straight and oblique cut for connecting the tie

For reliable joining, the connection point is reinforced with a steel plate mounted on bolts. Its dimensions must be larger than the dimensions of the notch - 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

Fastening struts for a rafter system with hanging rafters

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.

The simplest version of layered rafters

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.

A simple non-braced gable roof system with layered rafters

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.

Option for attaching rafters without bracing to 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, you need to increase 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.

Schemes of rafter systems for gable roofs with contractions

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.

Attaching the screed to the rafters and ridge beams

In order for the system to be rigid and not “creep” even under emergency loads, it is enough to ensure rigid mount 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. There is a spacer system on top, a non-spacer system on the bottom. The correct cutting nodes for each are located nearby. Below - possible strut mounting schemes

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°.

Rafter system with off-center vertical girder

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.

Systems with rafter beams

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 plates, which are nailed.

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.

Gable roof rafter system: device, components

A significant part of private houses are covered with a gable roof. To support it, you need a correctly selected rafter system and well-executed components.

In order for a constructed building to last for more than one year, it needs both reliable foundation, so strong system roofs that can withstand the vicissitudes of the weather. The roof must withstand heavy loads with dignity: heavy snowfalls, sharp gusts of wind, heavy downpours. The roof truss system is best suited for this.

Roof trusses and its types

The rafter system is the basis of the roof, which focuses on the load-bearing elements of the structure and also serves as a frame for various types roofing materials: insulation, waterproofing, various coatings.

The dimensions and design of the rafters depend on:

purchased material;
size of the building;
house dimensions;
building materials for rafters;
individual customer preferences;
roof loads relevant for a particular region.

The rafter system has:

sheathing - beams laid perpendicularly on the rafter legs;
ties that absorb tensile forces;
wooden racks located in a vertical position;
mauerlat - a beam, the installation of which is carried out along the wall, the rafters rest on it;
rafter legs are a kind of wooden beams that bear the main load of the roof.

Each of the above factors is very important, since it is necessary to understand what type of rafter system will be optimally suited for a particular situation.

When it comes to low-rise buildings, wood structures are the most common. In many cases, three types of roof trusses are used: hanging rafters, layered rafters and mixed system rafters

Characteristics of hanging rafters

Hanging rafters are the most elementary type of rafter systems, their characteristics:

If the roof of the house complex design, types of rafters can be alternated. For example, if there are supports or a middle main wall, layered rafters are installed, and if there are no such elements, hanging rafters are installed.

Features of layered rafters

For a layered rafter system, the house must be additionally equipped with a load-bearing wall located in the middle. Layered rafters are distinguished according to the following characteristics:

The design of the combined system is the most complex, since it includes parts of two other types of rafters - hanging and layered. It is used for mansard roof. The walls of the rooms located on the second floor are formed by vertical supports; these supports also serve as intermediate supports for the rafter beams.

The part of the rafters that connect one end of the racks functions as a crossbar for the slopes located on the side, and for the upper part of the structure they are a tie.

At the same time, the horizontal beams perform the following functions: for the upper slopes - the Mauerlat, for the side slopes - the ridge beam. To increase the strength of the roof, struts are installed that connect the side slopes and vertical racks.

The combined sling system is the most complex and time-consuming to manufacture, but these shortcomings are fully compensated by the increase in the load-bearing qualities of the roof in the absence of unnecessary supports, especially when there is a need to cover significant spans in the building.

You can increase the load-bearing qualities of the roof using a mixed rafter system

Roof trusses for various roof types

When constructing a certain building, rafter systems of one type or another are necessarily used, and the type of roof will completely depend on the design of the future structure.

Rafter truss for gable roof

A gable roof is normal construction roofs for residential buildings that have no more than three floors. Preference is given to this design due to technical characteristics the inclined shape of the rafter system, and also due to the fact that installation work is carried out easily and simply.

The rafter system of a gable roof includes two rectangular inclined planes. The upper part of the building from the end side resembles a triangle. The main components of a gable roof are the mauerlat and rafter legs. In order to properly distribute the load across the rafters and walls, struts, crossbars and racks are installed, thanks to which you can create a durable, rigid, elementary and lightweight structure for installing a structure for a gable roof.

A gable roof is considered the simplest roofing system; it is used for residential buildings of no more than three floors

You can install sparse or solid sheathing on top of the rafters, and then attach bitumen coating, tiles or some other type of material to it. The rafters and the sheathing itself are usually made of beams or boards, which are fastened with nails, bolts or metal fasteners. Metal profiles can be used as rafters, thereby covering significant spans. There is no need to use extra racks and struts.

The installation of a rafter system for a gable roof allows you to evenly distribute the entire existing load along the perimeter of the building. The lower ends of the system focus on the Mauerlat. They are fixed with fasteners or metal brackets. By the angle of inclination of the rafter bars, you can determine at what angle the roof slopes will be inclined.

The rafter system for a gable roof allows you to evenly distribute the load from the roof along the perimeter of the building

Rafter system for hip roof

When arranging a system for a hip roof, installation will be required different types rafters:

narozhniki (short);
lateral;
hip main;
obliques (diagonal elements that form a slope in the shape of a triangle).

The rafter legs, located on the side, are made of boards, and they are mounted identically to the parts of a traditional pitched roof with a pitched or hanging structure. Hip main rafters are layered parts. For splices, boards or bars are used, attached not only to the Mauerlat, but also to the diagonal beams.

To install this type of structure, the angle of inclination, as well as the cross-section of the slanting beams, are accurately calculated. The dimensions of the parts also depend on the span length.

To prevent the hip roof from deforming from heavy loads, you should accurately calculate the angle of inclination of the diagonal beams for the rafters

Maintain symmetry when installing diagonal beams for rafters, otherwise the roof will deform under significant load.

Rafter system for a sloping roof

A broken roof is a structure with rafters that consist of several individual elements. Moreover, they should be located at different angles relative to the horizon. And since the lower rafter part is almost vertical, the attic space of the building receives additional space, thanks to which it can be used as a living space. The installation of this type of roof is carried out during the construction of a four- or gable rafter structure.

Professionals need to calculate a hipped rafter system, but you can make a gable sloping roof yourself, since its installation is very simple. To do this, it is necessary to install a support frame, which should consist of purlins and racks. Horizontal parts are fixed with hanging rafters. But the supports of the sloping roof are secured to the mauerlat with the shortened legs of the rafters.

The assembly of rafters for a sloping gable roof can also be carried out by non-professionals, since the installation of such a roof is very simple

"Cuckoo" in a roof truss

The so-called cuckoo on the roof is a small ledge that is located on the attic floor. Here is a window for better lighting attic room. The installation of the “cuckoo” is carried out carefully, while monitoring the parameters of the entire structure: depth of cut, angle of inclination and other factors. However, before this they produce necessary measurements.

The first stage of work begins with the installation of the Mauerlat (beam with a cross-section of 10x10 cm, which is needed to support the slings). The rafter system acts as a skeleton for the roofing material. To impart rigidity to the structure, spacers are used, which are mounted between the two legs of the rafters.

After the installation of the roof truss is completed, sheathing is laid, the type of which depends on the roof covering purchased. Installation of the sheathing is done continuously or with a certain step. Boards, OSB and plywood sheets are usually used for it. In addition, the installation of roofing material must be identical throughout the entire roof.

The main difficulty when installing such a rafter system is the location of the internal corners. Snow can accumulate in these places, which means the load will increase, which is why a continuous sheathing is made.

A “cuckoo” on the roof is a small protrusion on the attic floor, under which there is an additional window.

Chalet roof rafter truss

The peculiarity of this design is that the canopies and overhangs are moved outside the house. In addition, there must be rafters and roof beams extending up to three meters on the sides of the building. Each of these elements is secured with a bracket to the wall of the building in the lower part. Next, tie the edges of the beams. They serve as a support for covering the roof of the building.

But when creating large overhangs, it is necessary to install the reinforced belt in parallel with the installation of studs for the Mauerlat. It is necessary to make anchors that help secure the consoles. In this case, the rafters will be perfectly fixed with anchors and, in addition, with mortises.

To carry out the side cornices, a ridge beam is made, after which beams are placed at the level of the mauerlat, which must be identical to the length of the ridge. The truss, and subsequently the building materials for the roof, rest on these structural details.

When designing a building, the angle of the chalet roof is calculated based on the characteristics of the local climate and other factors. With a slope angle of about 45°, the load from snow is not taken into account, since with this option it will not linger on the roof. At the same time, the flat roof will withstand the load from snow, but it is necessary to install a reinforced roof truss. Before installing the chalet roof, a building design is prepared, because the originality of the roof itself, as well as the long eaves and overhangs, oblige this.

A chalet-style roof is characterized by canopies placed several meters outside the house

Rafter truss designed for soft roofing

Soft roofing is made in various ways, but there are technological methods its construction general characteristics. Initially, you need to prepare. When arranging a roof for a house made of foam concrete or other material, first install a mauerlat, then in the upper crowns of the building they make cuts for the ceiling beams in increments of up to one meter. The distance between the boards is calculated based on the type of rafter structure.

Install individual parts of the rafter system. To completely eliminate the risk, the rafter boards are attached to the ground with screws. After the roof truss is created, it is raised to the top of the building.
All elements of the rafters are secured to the ceiling, internal boards, jibs, and crossbars. Further, this base for the roof will become a single whole structure.
The next stage is the sheathing, which is under soft roof installed with small or no gaps. Gaps of no more than 1 cm are allowed. Quite often, leveling plywood is installed on top of the boards. Its sheets are laid using the bricklaying method. The resulting joints are not aligned with the gaps between the plywood and the board.

If the length of the sheathing boards is not enough, then the joints of the parts must be placed in various places. In this way, you can correctly distribute areas that have been weakened.

Self-production of the rafter system

Before the installation of the rafter system begins, the mauerlat must be secured to the longitudinal walls with anchors. Next you need to decide on the required leg section for the rafters, depending on the distance and their length. If there is a need to increase the length of the rafters, then connect them with various fasteners.

When using different insulation, you need to choose the ideal distance between rafter elements in order to reduce the number of thermal insulation scraps.

Installation of the rafter system must be done in the following order:

A template is made according to which the truss is assembled. Take 2 boards corresponding to the length of the rafters and connect them together at just one edge with a nail.

A template for rafters called “scissors” will help you quickly assemble the entire roof rafter system
The result is a design called “scissors”. Its free edges are placed on supports at the points of contact between the rafter legs. The result should be the final angle, that is, the angle at which the roof slope will be inclined. It is fixed with several long nails and transverse boards.
A second template is made, thanks to which the cuts are installed on the rafters. It is made from plywood.
Special mounting cuts are cut on the rafters (a prepared template is used for these purposes) and connected at an angle of inclination of the slope. You should end up with a triangle going up the stairs to the roof. Next, it must be attached to the Mauerlat.
Initially, two side gable rafters are installed. Their correct installation in the vertical and horizontal planes occurs due to temporary struts attached to the rafters.

For proper installation of the entire rafter system, the first pair of rafters is installed on the roof
A cord is stretched between these tops of the rafters. It will indicate the future ridge and the level of other rafters located in the gap.
Raise and install the remaining rafters at the initially calculated distance, which should be at least 60 cm from each other.
If a bulky rafter structure is envisaged, then it is additionally strengthened with struts, supports, and so on.

The bulky structure of the rafters is additionally strengthened with struts and supports
A ridge beam is installed on special supports, to which not only short, but also diagonal and intermediate elements of the rafters are attached.

Correct fastening ridge beam ensures the reliability of the entire rafter system

Typical components of a standard rafter system

The strength of the rafter structure depends on the ideally selected section of the boards, as well as on the high quality of the rafter assemblies. The connection of parts for the roof structure is done according to established rules.

The main typical units in the rafter system:

rafter support assembly on the mauerlat;
ridge;
unit for combining the top ties and the entire rafter system;
securing the strut, rack, as well as rafters and beams.

After the design of the rafter system has been chosen, it is necessary to draw up a plan in which to highlight all the nodes. They are made differently in each design as it depends on different nuances: type of roof, its size, angle of inclination.

Rafters made from a profile pipe are a metal structure that is assembled using lattice rods. The production of such farms itself is a very labor-intensive process, but also more economical. To make rafters, paired material is used, and gussets are connecting elements. The structure of the rafters from profile pipes is assembled on the ground, using riveting or welding.

Thanks to such systems, any spans are blocked, but the correct calculation must be made. Provided that all welding work is done efficiently, in the future all that remains is to transfer the structural elements to the top of the building and assemble them. Load-bearing rafters made from profile pipes have many advantages, such as:

Crossbar in the rafter system

Crossbar is a fairly broad concept, but in the case of roofs it has a certain meaning. The crossbar is a horizontal beam that connects the rafters. This element prevents the roof from “expanding.” It is made of wood, reinforced concrete, and also metal - it all depends on the type of structure. And the crossbar serves to distribute the load exerted by the rafter system.

It can be fixed in various places between the legs of the slings. There is a direct pattern here - if the crossbar is fixed higher, then the timber for its installation must be selected with a large cross-section.

There are many ways to fix the crossbar to the rafter system:

bolts;
nuts;
studs with washers;
special fasteners;
nails;
mixed fastenings when used in parallel different types fasteners

The fastening is available with a mortise or overhead. In general, the crossbar is a design unit, as is the entire system of roof slings.

The crossbar in the rafter system is designed to strengthen the roof structure

Fastening the rafter system

To ensure the reliability of the rafter system, you must first find out how they are attached to the supporting roof and ridge. If a fastening is made to prevent deformation of the roof when the house shrinks, then the rafters are secured on top with a hinge plate or a nut and bolt, and below with a sliding support.

Hanging rafters need a tighter and more reliable fastening in the ridge, so in this case you can use:

metal overhead or wooden plates;
cutting method;
connection using long nails.

In the layered system, the rafter legs are not connected to each other, since they are attached to the ridge girder.

The rafters are attached to the mauerlat using the cutting method, which is made in the rafter leg. Thanks to this fastening method, the roof support will not weaken. Cutting is also done when installing rafters on floor beams. In this case, a cut is also made in the support beam.

Video: how to make rafters with your own hands

Thus, an ideally selected rafter system and their design characteristics will help create the basis for a reliable roof for your home.