Method of assembling rafters for the roof. The process of installing the rafter system. Roof frame with hanging rafters

Installation of rafters is one of the key stages of roof construction. To ensure that the rafter system does not deform during operation and does not collapse under high loads, the rafters must be properly secured.

Calculation of rafter pitch

When designing a rafter system, this issue is given Special attention. The strength characteristics of the roofing system depend on the cross-section of the rafters and the pitch of their installation.

The rafter pitch is the distance between adjacent rafter legs. The minimum pitch of the rafters is 60 cm, the maximum is more than 1 meter. A simplified version of calculating rafter pitch involves using the table:

The length of the eaves slope must be divided by the rafter pitch selected in the table, then add one to the resulting value and round up to a whole number. The resulting result means required amount rafter legs per slope. Then the length of the slope along the eaves should be divided by the calculated number of rafter legs - the final number corresponds to the value of the center distance between the rafters.

This calculation method is general, it does not take into account the specifics of roofing coverings and the type of insulation used. If you intend to lay a roll or slab insulator, it is recommended to adjust the pitch of the rafters to the size of the material. It should be taken into account that the width of the cotton insulation should be 1-1.5 cm greater than the span between the rafters.

When determining at what distance to install the rafters, you should also pay attention to the recommendations for installing the selected roofing covering.

Preparation of material

Installing rafters with your own hands requires not only knowledge of the process technology, but also proper preparation wooden elements systems for installation. The rafters are made from edged boards or timber, the cross-section of the lumber is selected at the roof design stage. The tree should not have cracks, wormholes or other damage.

Rafter legs should be made of well-dried wood coniferous species to prevent their deformation.

Wooden elements must be treated with fire retardant and bioprotective compounds. Before you begin installation, you need to decide on the method of attaching the rafters to the mauerlat or beams, and the type of ridge connection. In accordance with the project, metal and wooden fasteners are selected, including:

• plates (made of metal or wood);
• bolts or studs with nuts and wide washers;
• nails, screws, staples, etc.;
• wire rod.

Types of rafters and features of their installation

When constructing the roof of a house, hanging or layered rafters are used. In some cases, a combination of both may be used. Hanging ones rest only on the walls of the building, and layered ones require the installation of additional supporting structures, so this option is primarily used if there is a middle load-bearing wall or support pillars inside the building box.

The lower part of the layered rafters rests against the mauerlat; accordingly, the walls of the structure must have sufficient width for the installation of a special supporting structure made of timber with a section of 150×150 mm. Top part layered rafters rests on ridge run. Thus, installation requires the installation of a purlin, for which racks should be mounted on the middle wall or pillars.

Hanging rafters rest only on the walls. This design can be mounted both on the Mauerlat and on thin walls without laying the Mauerlat. In this case, the support for the lower part of the legs is provided by floor beams protruding beyond the plane of the wall on both sides of the building. Hanging rafters are connected by a jumper (tightening, crossbar) which relieves the pushing forces. When covering large purlins roof trusses are intensifying additional elements to enhance the rigidity of the structure. When installing hanging rafters on a mauerlat, a low-lying tie can serve as a floor beam.

Before installing the rafters, it is necessary to mount the scaffolding. This makes it possible to provide necessary security and ease of use.

Installation of the upper ends of the rafters

When choosing how to install rafters, it is important to evaluate the complexity of the work and weight truss structures. If the assembled truss has a relatively light weight, or it is possible to use lifting equipment, then it is easier to assemble the structures on the ground, and then lift and install them on the roof. If the system elements are heavy and have to be lifted manually, then the trusses are assembled on the roof. The technology for installing roof trusses is described in the video instructions.

Compound upper ends rafters can be performed different ways. First of all, this is a butt mount. On the opposing rafter legs, cuts are made at the desired angle. Then the rafters are joined with the resulting ends and attached to two nails. The connection is further reinforced with a wooden or metal overlay.

Attaching the rafter legs with an overlap is done using bolts or studs with wide washers and nuts. In this case, the rafters are in contact with the planes.

If the rafter system is mounted on a wooden house with gables made of timber or logs, it is necessary to install the rafters on the walls using sliding fasteners to avoid deformation of the roof during shrinkage of the structure. Accordingly, in the ridge part the rafters must be connected in a special way: rafter legs must be positioned with a gap, and they are fastened using a special movable metal connecting element.

In the presence of ridge beam installation of rafter trusses on the ground is not required - the rafter legs are installed one at a time and attached to the ridge girder.

The ridge run must be positioned strictly horizontally so that the rafter system evenly distributes the load experienced by the roof.

Methods for installing rafters on walls

The lower ends of the rafters are attached to beams or mauerlats. The hanging rafter trusses, assembled according to a template, rise to the roof. The outer trusses are installed first. It is necessary to make two or three holes in the tightening to attach the rafters to the beams laid on the upper crown of the frame.

If hanging rafters are mounted on a stone building, it is necessary to use special fasteners - the so-called “ruff”, made of durable steel. This fastener is driven into every fourth row brickwork. Using the loops extending from the ruff, you can secure the beams. It is recommended to use a strong beam as a mauerlat - in this case the load will be evenly transferred to the walls.

On buildings made of brick or other material that is not prone to shrinkage, the rafters should be firmly secured. To do this, a cutout is made in the rafter leg, the lower part of which should lie firmly on the Mauerlat. The rafter is fixed with three nails (two are driven in on both sides at an angle, and the third vertically from above) and tied with wire. A connection using corners and a support bar can also be used to prevent the rafters from shifting.

Proper installation of rafters involves making a fire break in the place where the roof passes chimney. If its arrangement involves the installation of a special rafter system, this should be taken into account when installing a shortened rafter leg (from the Mauerlat to the chimney structure). The distance between the structural elements and the pipe must be at least 130 mm.

Erection of the roof is one of the most critical stages of construction. From the reliability of the “umbrella” from above, from its resistance to precipitation and any external influences, the durability of the building itself and the level of comfort of living in it directly depend.

Of all the variety of roof designs, the gable roof can be considered one of the most popular, simply due to the relative ease of its construction. However, even behind this “simplicity” lies a lot various nuances, the need to carry out certain calculations and follow technological rules. However, this publication has main task: show that installation of rafters gable roof with your own hands is a completely doable task, even for a novice builder.

Let's go through all the stages of the process of installing rafters for such a roof, from the basics of preliminary design to an example of practical implementation.

General structure of a gable roof

Basic Concepts

Structural elements of a gable roof truss system

Let us immediately make a reservation that this diagram, of course, cannot reflect the entire possible variety of designs, but the main parts and assemblies are shown quite clearly on it.

1 - Mauerlat. This is a board or beam that is rigidly attached to the upper end of the external load-bearing walls of the building. Its purpose is to uniformly distribute the load from the entire roof system onto the walls of the house, creating conditions for reliable fastening of the rafter legs at their lower support point.

2 – rafter legs installed in pairs. They become the main load-bearing parts of the entire roof system - it is the rafters that determine the steepness of the slopes, will be the basis for attaching the sheathing, roofing, and if the roof is planned to be insulated, then also the entire thermal insulation “pie”.

For the manufacture of rafter legs they are used quality boards or timber, you can also use round timber. The cross-section of lumber, which will be sufficient to guarantee withstand all possible loads, will be discussed below.

The rafters can end at the mauerlat, but more often they extend beyond the perimeter of the walls of the house, forming a cornice overhang. However, lighter parts can also be used for this - the so-called “fillies”, which are used to extend the rafter legs to the required overhang width.

3 - ridge run. It could be a beam, a board, or even a composite structure. The purlin runs along the entire line of the ridge and serves to reliably connect the upper points of paired rafter legs, connecting all rafter pairs in order to impart overall rigidity to the entire roof structure. In various roof options, this purlin can be rigidly supported by racks, or linked only to the connection node of the rafter legs.

4 – tightening (contracts, crossbars). Horizontal reinforcement parts of the system, additionally connecting paired rafter legs to each other. Several puffs located at different heights can be used.

5 – floor beams, which will serve as the basis for installing the floor in the attic and the ceiling on the side of the room.

6 - and this beam simultaneously serves as a bench. This is a beam that runs along the entire length of the roof, which is a support for the installation additional details strengthening the rafter system. The beam can be installed as shown in the figure (like a floor beam), or it can be rigidly laid on a permanent partition inside the building.

7 – racks (headstocks) – additional vertical supports of the rafter legs, preventing them from bending under the influence of external loads. The racks at the top can rest against the rafters themselves, or into an additional purlin that longitudinally connects the rafter legs at a certain height.

8 – struts. Often, when the rafter legs are long, their load-bearing capacity is not enough, and reinforcement with racks alone does not provide the necessary strength. In these cases, diagonal reinforcing elements are used, resting on the bottom of the beam, creating an additional support point for the rafters. The number of struts and their installation location may vary on roofs varying degrees difficulties.

Some differences between the hanging and layered gable roof systems

Gable roofs can be divided into two types of structures - with layered and hanging rafters. In addition, combined systems are widely used, in which both construction principles are combined. What is the fundamental difference?

Layered rafter system

This rafter system design is characterized by the presence of support on the internal main partition in the building. At the upper end of this partition, a bench is mounted on which the drains supporting the ridge girder rest. Thus, the rafter legs are “leaned” onto a vertical support, which makes the entire system as strong as possible.

This type of scheme is the most popular because of its reliability and relative ease of implementation. If it is possible to create an additional point of support in the center, then why not take advantage of it? True, if you plan to place living space in the attic, then vertical racks can sometimes become a hindrance. However, their presence is also sometimes “played up”, using, for example, to install an internal light partition.

Depending on quantity and placement internal partitions, the design of the layered rafter system may vary. Some examples are shown in the illustration below:

Fragment “a” shows the simplest option, which, by the way, on short rafter lengths (up to 5 meters) may not even have the shown struts - a row is enough B-pillars under the ridge girder

As the width of the building increases, the system naturally becomes more complex, and additional reinforcing elements appear - tie rods and struts (fragment “b”).

Fragment “c” clearly demonstrates that the internal main wall does not have to be located exactly in the center, under the ridge. An option as shown in the illustration is also quite possible, but with the condition that the displacement of the bed relative to the ridge does not exceed one meter.

Finally, fragment "d" shows how the rafter system in a building can be supported big size, but having two capital partitions inside. The distance between such parallel beams can reach up to a third of the width of the building.

Hanging rafter system

Graphically, this roof diagram can be depicted something like this:

It is immediately noticeable that the rafters rest only on the lower part, and then are connected to each other at the ridge. There is no additional support in the center, that is, the rafter legs seem to “hang”, which determines the name of such a system. This feature imposes certain restrictions on the use of hanging rafters - usually this scheme is practiced when the distance between the load-bearing walls to which the Mauerlat is attached is no more than 7 meters. The installed puffs only partially relieve the load from the external walls.

The illustration below shows several options for a hanging system. However, some of them can rather be classified as combined.

Fragment “d” - hanging rafters are connected to each other by a tie at the level of the mauerlat or fixed to a powerful floor beam, forming a triangle with it. There are no other reinforcing parts. A similar scheme is acceptable with a distance between walls of up to 6 meters.

Option “w” is for a house of the same size (up to 6 meters). The tie (bolt) in this case is shifted upward, and is often used for lining the ceiling attic space.

Options “e” and “z” are designed for a span between walls of up to 9 meters. Multiple tie-downs may be used (or a top tie-down in combination with a bottom joist). Another approach is to install racks under the ridge girder, similar to the layered system. Only, as the lower point of support, it is not the support on the main partition that is used, but the racks are supported by a tie or a floor beam. It is already difficult to call this option purely “hanging”, since here it is clearly a combination of parts from both designs.

To an even greater extent, this combination of two schemes is expressed in the “and” option, which is designed for large spans, from 9 to 14 meters. Here, in addition to the headstock, diagonal struts are also used. Often such trusses are assembled on the ground, and only then they are lifted and installed in place, connected to each other, thereby forming the entire roof frame.

So, when preparing for the construction of a gable roof, it is necessary to study the principles of the design of a particular system, evaluate their advantages and disadvantages, choose the optimal one for your conditions and draw up a graphical working diagram. You will also need it when purchasing required material, and for the production themselves installation work. However, drawing up a drawing must still be preceded by some calculations.

Calculation of the basic parameters of a gable roof rafter system

Let's take another look at the schematic diagram of a gable roof to highlight the parameters that will need to be calculated.

So, in the calculation process we will need to decide on the following values.

The initial data is the length of the side of the house along the gable part (highlighted in blue - F), and the length of the house along the ridge ( purple– D). It is assumed that the owners have already decided in advance on the type of roofing - since there will be certain restrictions on the steepness of the roof slopes. (angle a).

• The height of the ridge above the plane of the Mauerlat (H – green color), or, conversely, decide on the angle of the slope, starting from the planned height of the ridge.
• Length of rafter leg ( Blue colour– L), and, if necessary, extending the rafters to form a cornice overhang of the required width (l).
• Calculate total loads falling on the rafter system to determine optimal cross section lumber for making rafters, the step of their installation (red color - S) and permissible length spans between support points. All these parameters are closely interconnected.
• Once you have these calculated values ​​in hand, it is no longer difficult to draw up a graphical diagram, determine the need and optimal location of reinforcement elements, and calculate the amount of material for their manufacture.

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We calculate the steepness of the slope and the height of the ridge

The angle of steepness of the slopes can be determined by the owners according to various criteria ratings:

• For purely aesthetic reasons - when “at the forefront” becomes appearance buildings. Many people like roofs with a high ridge, but we must not forget that the cost of such a roof sharply increases wind load. And there will be immeasurably more materials needed to make a high roof. At the same time, on steep slopes it decreases to almost zero snow load– it is possible that for “snowy” regions this assessment parameter may become decisive.
• For reasons of beneficial use of the attic space. With a gable roof scheme, in order to achieve the maximum area of ​​the attic, it is necessary to build slopes with a very large steepness, that is, with the same consequences as mentioned above.

• Finally, there may be a completely opposite approach - for reasons of economy, make a roof structure with minimum height in a skate. But in this case, you will have to focus on the minimum permissible slope angles for a specific type of roofing. Reducing the slope below the values ​​recommended by the manufacturer means “planting a bomb” in your roof, both for reasons of its strength and durability, and from the standpoint of the waterproofing qualities of the coating.

Calculating the height of the ridge above the plane of the ceiling (mauerlat) is not difficult. The vast majority of components of any roofing system are based on a triangle, which, in turn, obeys strict geometric (more precisely, trigonometric) laws.

So, in our case, the width of the roof along the gable line is known. If the roof is symmetrical, then the ridge will be placed exactly in the middle, and for calculations you can simply divide the width F by two (the base of the triangle f =F/2). For asymmetrical slopes, you will have to project the top of the ridge onto line F, and measure the distances f1 and f2 from it to the edge of the triangle (to the Mauerlat) on each side. Naturally, in this case the slope of the slopes will be different.

N =f×tga

In order not to force the reader to look for tangent values ​​and carry out calculations manually, below is a calculator in which the necessary tabular values ​​have already been entered.

Roof installation is difficult technological process, which includes the stages of design, frame assembly, laying roofing material and installation of auxiliary elements. Although it is not easy to design a roof correctly to reduce the cost roofing works, if you have basic construction skills and tools, you can make them yourself. In this article we will describe in detail the sequence of actions necessary to independently install the roof truss system of a private house.

The roof truss frame is a collection of wooden elements that form a kind of “skeleton” of the structure, supporting the roof slopes, giving them the necessary shape. If desired, you can make a rafter system with your own hands; the main thing is to correctly calculate the loads and determine the composition of the structure. The functions of the roof frame are:

1. Roof slope support. Rafter legs give the surface of the roof slopes the slope necessary so that melted or melted water is effectively removed from them. rainwater, the snow masses melted away on their own.
2. Roof weight distribution. Properly designed frame design distributes weight evenly roofing pie on load-bearing walls and the foundation of the structure, preventing deformation and subsidence of supports.
3. Place for fixing roofing material. Those who have at least once covered a roof with their own hands know that the sheathing of the frame serves as the basis for fixing the waterproofing coating.

Note! The rafter frame is made of wood or galvanized metal. The cost of roofing work, service life and load bearing capacity roofs. Experienced craftsmen believe: if the length of the slope does not exceed 6 meters, it is much more rational to make these elements from wood.

Creating a Project

Before you make rafters for the roof of a private house with your own hands, you need to create a working design of the structure, taking into account the climatic conditions in the area where construction is taking place, the method of using the attic space, as well as the type of roofing. All these factors are taken into account when calculating the loads affecting the roof frame. To determine the required load-bearing capacity and create a roof design, you need to determine:

• The total load on the rafters. For this permanent loads(the weight of the rafter system itself, insulation, roofing material and waterproofing) is summed up with temporary loads (snow, wind and natural loads). The total weight of the roofing pie when using thermal insulation can reach up to 700 kg.
• The height of the roof ridge. This indicator is calculated based on the desired slope of the slopes and the width of the structure to be covered. The height of the ridge is also influenced by the way the attic is used: if it is equipped with a residential attic, the ridge should be located at least 250 cm from the ceiling.
• The slope of the slopes. The angle of inclination of the roof slopes is calculated as the quotient of the height of the ridge and half of the base of the roof. This factor depends on the climatic conditions in the region of construction, as well as the characteristics of the roofing material.

Important! The result of calculating the total loads, ridge height and slope slope is a correctly designed, detailed diagram rafter frame, which will make it easier to make the structure yourself and also reduce the risk of errors.

Selection and preparation of material

To make a strong and durable rafter frame for the roof of a private house, use hardwood or metal profiles. The final cost, weight, service life and load-bearing capacity of the finished structure depend on the choice of material. For DIY work, experienced craftsmen recommend choosing wood. In order for the rafters to last a long time, it is necessary to check the compliance of the lumber with the standard:

1. The moisture content of lumber used to make rafters with your own hands should not exceed 19-21%. During the drying process, wet wood can crack and warp, causing deformations and distortions in the roof.
2. The tree must be in healthy condition. That is, it must have light color, characteristic of the breed, do not have areas of rot, mold, darkening or traces of pest activity.
3. For the manufacture of rafters, it is recommended to choose straight, even boards without large quantity knots, as they reduce the strength of the supports.

Please note that in order for the wooden rafter frame to last a long time, before starting work on assembling the structure with your own hands, they will treat the components with an antiseptic deep penetration, and to reduce the risk of fire, impregnation with a fire-retarding compound is carried out.

Laying the Mauerlat

Installation of the rafter system of a low-rise building begins with laying the mauerlat. This term refers to a support beam that is mounted on top harness load-bearing walls where the roof slope rests on them. The number of mauerlat bars involved in the design always coincides with the number of slopes. Mauerlat is made from thick wooden beam 10-15 cm thick. The laying of this frame element is carried out in accordance with the following rules:

• The Mauerlat is installed only if the frame of the house is made of brick, concrete, gas silicate, or foam block. In wooden buildings, the role of the mauerlat is played by the upper crowns of the frame, firmly fixed with metal brackets or dowels.
• Some types of layered rafter systems do not provide for the installation of a Mauerlat, since they do not exert a bursting load on the walls of the structure.
• Strong waterproofing is always laid between the wall of the house and the mauerlat to prevent condensation from settling or rotting of the wood. For these purposes, use glassine, roofing felt or roofing felt.
• It is not allowed to make a tie-in under the rafter legs in the mauerlat, since each violation of the integrity reduces the strength of the beam.
• The Mauerlat beam is fastened using studs embedded in the wall of the house, or long anchor bolts.

Do not forget that before installation it is advisable to treat the Mauerlat with a deep penetration antiseptic to prevent wood rotting, and also impregnate it with a fire retardant to protect the roof frame from fire.

Assembly technology

The degree of complexity and sequence of assembly of the roof rafter frame depends primarily on the design and type of rafters. To do the installation yourself, it is better to choose simpler ones. gable structures. If load-bearing walls are provided inside the house, then a layered rafter system can be used. Assembly of the frame occurs in several stages:

1. Laying the mauerlat and bed. At this stage, it is important to firmly fix the support beams along the load-bearing walls with metal studs or anchors.
2. Vertical racks are installed on the bench laid on the internal load-bearing wall in increments of 1.2-1.5 meters. To keep them vertical, temporary supports are installed.
3. A ridge girder is placed on top of the posts. It pulls together the vertical supports and serves as the basis for installing the rafter legs.
4. Mount the rafter legs. One end of the rafter is attached to the mauerlat, and the other to the ridge girder.
5. A sheathing is nailed perpendicular to the rafters, on which the roofing covering is laid.

Remember that overlap wooden house You can do it yourself only after the box has completely shrunk. To compensate for changes in roof geometry, movable fasteners are used that adapt to the size of the house.

Video instruction

The rafter system of a gable roof is a simple design that can be installed with your own hands even by a novice developer. You just need to make preliminary calculations, familiarize yourself with the details and stages of roof construction, and calculate the materials needed for installation. When making calculations, it should be taken into account that the load-bearing capacity of a gable roof depends on the influence of loads from wind, snow, and the weight of materials on it.

To make the process of building a gable roof truss system as easy as possible for you, detailed information is presented below. step-by-step instruction for installing a rafter system with your own hands.

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Requirements for building materials

For the installation of a rafter system the best option There will be the use of lumber from coniferous wood - pine, spruce or larch, grades I - III.

The material for the rafters is taken at least grade II, the mauerlat is made from boards or timber of grade II, material of grade II is taken for racks and purlins, the sheathing is made from lumber of grades II-III, it depends on the roof. Crossbars and tie-downs are made of Grade I material. Grade III material can be used on linings and linings.

Note! The lumber must be dry with a moisture content of no more than 20%. It should be treated before installation fire retardant compounds and antiseptics against fungal diseases.

Lumber should be stored under a canopy, providing protection from the sun and moisture. Level the storage area and cover the lumber with pads for ventilation.

For installation you will need fastening elements: ties, plates, studs, bolts with washers and nuts, self-tapping screws with EPDM gaskets, 2.8 mm thick, mounting tape, galvanized brackets.

Brackets are used when attaching the Mauerlat; they are secured with nails or self-tapping screws.

KR corners serve to attach the rafters to the mauerlat and prevent the rafters from moving.

All fastening material must be made of high quality material and have corrosion protection.

Tools for constructing a rafter system

To install a gable roof rafter system, you will need the following set of tools:

• tape measures of different lengths 5, 10, 20 meters;
• markers, pencils;
• cord for tensioning;
• hammers, for various purposes, nail puller;
• scissors, for cutting;
• roofing knife;
• putty knife;
• scotch;
• hacksaws, electric saw, electric drill with various drills and attachments;
• screwdriver with attachments;
• markings, horizontal and vertical levels;
• slats, rulers;
• polyurethane foam;
• safety belt and rope - for safe work.

Keep all tools on the roof in a tool bag for safety reasons.

Types of rafter systems for a gable roof

Sent rafters

They rest on the mauerlat and racks installed on the internal wall, with a pitch equal to the rafters. To provide rigidity for spans of 6 m, additional struts are installed.

Scheme of layered rafters of a gable roof

Hanging rafters

If the building is small in width, you can arrange a rafter system where the rafters rest on the mauerlat or walls, without intermediate supports. The maximum span is 9 meters. Such roofs can sometimes be installed without a Mauerlat. The rafters are installed on the wall using spacers; in this embodiment, a bending moment acts on the rafters.

To unload, wooden or metal linings. They securely strengthen the corner. For hanging rafters of a larger span, a headstock and struts are installed. For hanging systems, the rafters are arranged with a larger cross-section, and lumber is chosen not lower than grade I-II.

Scheme of hanging rafters of a gable roof

Calculation of the rafter system

You can determine the cross-section of a gable roof beam required in a rafter system by collecting all the loads acting on it: the weight of the covering, sheathing, snow, wind pressure, precipitation.

Constant loads can be determined by the weight of 1 m 2 of roofing and sheathing. It is important that the weight per 1 m 2 of roofing be in the range of 40-45 kg.

Variable loads from snow and wind are calculated using tabular values ​​of SNiP normative documents, depending on the height of the building and temperature zone. The load from snow is equal to its weight multiplied by a coefficient depending on the slope of the slope. All these calculations are performed during the project.

What if there is no project and the roof is being erected on a small building? You need to look at the construction of a house in the neighborhood, which is being carried out according to a design whose roof area is the same as your building. The gable roof rafter system will serve as a model.

Dimensions of timber for rafters

At the top point a ridge is laid that connects the rafters. The height of the ridge depends on the slope of the roof. The slope is affected by the choice of coating material. Minimum dimensions are:

• For tiled roofs, slate 22 gr.;
• for metal tiles - 14 g;
• ondulin - 6 g;
• corrugated sheeting - 12 gr.

The optimal angle is 35-45 degrees. tilt, ensures rapid discharge of water and snow. In regions with strong winds, the roofs are made flat and then the angle of inclination is within 20-45 degrees.

The height can be determined using the formula: H=1/2Lpr*tgA. Where A is the angle of inclination, L is the width of the building.

The task is simplified when using a ready-made table. The coefficient depends on the width of the building and the angle of inclination. Multiply the coefficient by 1⁄2 the width of the building.

The rafters are made from pine or spruce bars, with a section of 50x100 mm, 50x150 mm.

The size of the rafters depends on the pitch. The pitch of the rafters is smaller, a larger number is installed, and the cross-section will decrease. The distance between the rafters on a gable roof ranges from 600 mm to 1800 mm, it all depends on the design of the roof and the materials used for its construction.

The roof does not end at the level of the walls; it is extended outward by 500 mm. The rafter leg can protrude, or a board or block can be built up. In this case, moisture does not get on the wall and the foundation is not poured.

Step-by-step installation of a gable roof truss system

The rafter system of a gable roof consists of the following elements:

1. Mauerlat.
2. Lay down.
3. Racks.
4. Rafters.
5. Struts.
6. Puffs.
7. Lathing.

Mauerlat installation

Fastening the Mauerlat to a monolithic reinforced concrete belt

Mauerlat evenly distributes the load on the walls of the building; its installation can be done in several ways:

• attached to the wall through a reinforced concrete belt with studs;
• studs are inserted into the masonry;
• a simple and common method for simple roofs, fastening with wire rod.

For it, take timber with a cross section of 100×100 mm, 150×150 mm or 200×200 mm. Which section to choose depends on the size of the roof and its covering. The Mauerlat is joined along its length; to do this, make 100 mm cuts, 500 mm long, fold the bars and fasten them with pins.

In the corners, the mauerlat is tied with notches into the floor of the timber, fastened with staples or bolts. For wooden buildings, the Mauerlat is the last crown. On brick walls, make a monolithic reinforced concrete belt with a cross-section of 400×300 mm. Along the belt, place threaded pins 12 mm in diameter, every 120 mm, for fastening.

Drill holes with a diameter of 12 mm in the Mauerlat, lay them so that the pins go into the holes. Tighten the top with nuts. First, we lay two layers of roofing felt or roofing felt under the block. WITH outside brick the walls and mauerlat. Lay the Mauerlat on a horizontally and vertically level base. You need to check with a level that the surface is horizontal. Check diagonals. If necessary, level with pads.

Installation instructions for beds, racks, rafters, struts and tie rods

The installation of a gable roof rafter system with your own hands is carried out in the following order:

1. Install the beam with the rafters in place.
2. Mark the installation step of the rafter legs.
3. Prepare according to the size of the rack.
4. Install them, if necessary, with spacers.
5. Lay the purlin. Check geometry. Install fasteners.
6. Try on the first rafter leg and mark the cutting areas.
7. Mark the points and install the rafters at the beginning and end of the roof, stretch the cord between them in order to align the remaining elements along it.
8. Having installed the rafter leg, we first attach it to the mauerlat, then to the ridge purlin, to each other.
9. Screw each second leg to the Mauerlat with wire.

The rafters are fastened to the mauerlat using notches, stop corners and a hemmed support bar. Secure with nails or staples.

Methods for attaching rafters to the Mauerlat

Install the support posts on the beds or pads and overlays. A log is a beam 50×100 mm or 50×150 mm, laid on the middle wall along a layer of roofing felt. Place brick pillars under the linings, 2 bricks high.

The rafter legs are connected to each other at the ridge. Let's consider the common connection nodes of the rafter system:

1. They make cuts at one leg and cut down at the other. Insert one leg into the cut of the other and fasten with a bolt.
2. Install overlays, wooden or metal.
3. Using notches in the purlin, they are secured with nails or bolts.

Methods for connecting rafters on a ridge

To ensure the roof's resistance to wind loads, tie rods, struts and purlins are installed. The tightening is a 100×150 mm block, purlins and struts are made from a 50×150 mm or 100×150 mm block.

With the installation of contractions, the reliability of the rafter structure increases. The sections of the timber are the same as the rafters. They are attached to the legs with bolts or nails. The device of struts adds rigidity to the structure. They are installed tightly to the surface of the rafters

Lumber has standard length 6 m. Rafters can be longer. Then you need to dock them. There are several connection methods:

1. Fasten by placing bars on both sides at the junction, connecting them with nails checkerboard pattern.
2. Connect with an overlap, one part of the rafters to another, at a distance of 1 meter, fasten with nails in an alternating order.
3. Make a cut obliquely, cut out part of the rafter legs, connect them, strengthening them with bolts.

Sheathing device

Lathing is installed along the roof rafters. It serves to distribute the load from roofing material and snow onto the rafters. Acting air gap between the roof and the rafter system.

The design of the sheathing depends on the roofing material used:

• under soft tiles make the sheathing continuous, lay an anti-condensation film on the rafters, press it on top with a counter batten, nail the sheathing onto it, then OSB boards and underlay carpet, lay tiles on top.
• Under the roof made of corrugated sheets, the sheathing should be sparse. The pitch of the sheathing depends on the brand of corrugated sheeting, its thickness and the angle of inclination of the roof.
• lathing under standard slate make in increments of 500 mm from a bar of 75×75 mm or 50×50, as well as boards from 30×100 mm. The design features of the roof should be taken into account when making the final choice of the appropriate option.

The lumber from which the sheathing is made is first or second grade pine. It is advisable to take the width no more than 14 cm. With a wider width, the boards may warp and damage the roofing. The length of the nails should be three times the thickness of the sheathing. Lay the boards along the ridge. Install the first board of greater thickness to the height of the roofing.

Install continuous sheathing along the roof slope.

The first layer is to place a board along the ridge from it at a distance of 500-1000 mm to the next one and so on. Lay the second layer of sheathing in the direction along the rafters. Place the joint between the boards only on the rafters at intervals. Sink the nail, head and all, into the flesh of the wood.

Cornice overhangs

They are installed to protect from precipitation and play an aesthetic role. Eaves overhangs are arranged tightly without gaps. The final stage of installing the roof.

Diagram of the eaves overhang of a gable roof

Gable

The gable roof has two gables. They have the shape of a triangle, with the apex at the ridge and the sides coincide with the slopes of the roof. The gables support the rafters and enclose the attic space. They protect from wind and precipitation and provide stability to the roof.

IN wooden buildings the pediment is made frame. IN brick buildings, frame or brick. Gables made of brick or gas block are erected before the roofing is installed. They require very precise execution.

Frame pediments fit into the finished opening when the rafter system is already assembled.

The frame is made of bars or boards. The frame elements are connected on tenons or in the wood floor, all fastened with nails. They are sheathed by nailing boards, lining or siding, maintaining the color scheme in the decoration of the building facade. To construct a window opening, an additional frame is made under it according to the size of the window. If the attic is insulated, then the gable also needs to be insulated. The insulation is placed in the middle of the frame. Mineral wool insulation with reduced flammability is used. From the outside, the frame is covered with a hydro-windproof film or windproof membrane, With inside under finishing material nail a vapor-proof film or a vapor-proof membrane.

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Arranging a gable roof is considered very practical and the right decision during the construction of a residential or commercial building. This option combines relative simplicity of execution and reliability, ease of maintenance and long service life. IN this material we will talk about how to install a gable roof rafter system with your own hands, what its varieties are, and how to calculate the dimensions of its individual elements. Our step-by-step instructions will help you deal with any complications that may arise during the work process.

A roof with two slopes has a whole list of advantages:

• ease of calculations;
• various options execution;
• saving materials;
• possibility of natural outflow of water;
• low probability of water leakage due to the integrity of the structure;
• the possibility of arranging an attic or attic;
• reliability and long service life;
• convenience of preventive repairs.

Types of gable roofs

Let's consider the main types of roofs with two slopes, the rafter system in which will differ slightly in design.

Symmetrical gable roof

This is the simplest gable roof, however, the most reliable and in demand. Symmetrical slopes allow you to distribute the load on the mauerlat and load-bearing walls evenly. IN in this case the type and thickness of the insulating layer do not affect the choice of roofing material. Thick rafter beams have a sufficient margin of safety, so they will not sag. In addition, spacers can be installed at your discretion.

Among the disadvantages this option can only be noted too sharp corner slopes, which makes it difficult to use the attic floor and creates “dead” areas that have no use.

Roof with two asymmetric slopes

If the angle of inclination of the slopes is made more than 45º, you can use some unused areas of space. It will even be possible to arrange a living space in the attic. However, some additional calculations will be required, since the load on the walls will become uneven.

Broken roof with external or internal fracture

This configuration makes it possible to place a spacious attic or attic under the roof. However, in this case, more complex engineering calculations will be required.

The design of rafters for arranging a roof with two slopes

The design of the gable roof truss system assumes the presence of the following components:

• Mauerlat. It is a durable beam made of oak, pine, larch or other strong wood, which is laid along the perimeter on the load-bearing walls of the building. The purpose of the Mauerlat is to evenly distribute the load. The cross-section of the bars is chosen based on their structure - solid or glued, as well as on the age of the building. The most commonly used beams are 100×100 or 150×150 mm.
• Rafters. The entire structure is created from such elements (read also: " "). Connecting at the top point, two rafters form a truss. They are made from logs or strong bars.
• Puff. This part serves to connect the rafters and ensure their rigidity.
• Runs. In those places where the rafter legs are joined, a ridge purlin is attached, onto which the ridge will subsequently be mounted. And with the help of side girders, the rafter frame is given additional strength. The expected load determines the size and number of such elements.
• Rafter stand. This vertical beam, which partially takes over the weight of the roof. If the design of a gable roof is simple, then one such beam is placed in the center. A long span may require three bars - one in the center and two on the sides. If an asymmetrical roof is being erected, then the location of such a beam is determined by the length of the rafter legs. Under the rafters for sloping roof racks are placed on the sides to free up space for movement. Beams are placed in the center and sides if there are two rooms.
• Struts. These are the supports for the rack. If significant winds and precipitation are expected in winter period, install longitudinal as well as diagonal racks.
• Sill. The rafter stand rests on it, and the struts are also attached.

• Lathing. The selected roofing material, and you can also move along it while working. Fix the sheathing perpendicular to the rafters. Please note that the lathing allows you to evenly distribute the mass of roofing material throughout the rafter system.

The installation diagram of the gable roof rafter system will greatly facilitate everything. construction works. How such a roof scheme will look depends on the type of roof.

Please note that the material for the rafter system must be of the highest quality, treated with fire retardants and antiseptics. There should be no knots or cracks on the beams for rafters, mauerlat and racks. Only a small number of knots firmly seated in the wood are allowed on the sheathing.

Calculation of frame elements for a gable roof

Laying Mauerlat on walls

This element is attached to load-bearing wall along its entire length. If we are talking about log house, then the upper crown can serve as the Mauerlat. For buildings made of aerated concrete or brick, you will need a Mauerlat equal to the length of the wall. Sometimes this part can be laid between the rafters.

If there is insufficient length of material for the Mauerlat, several pieces can be spliced ​​together. In this case, the edges are filed at 90º and joined using bolts - wire, dowels or nails are not suitable.

There are two ways to lay a mauerlat on top of a load-bearing wall:

• symmetrical in the center;
• with a shift in the desired direction.

Installation of the Mauerlat is carried out on a pre-laid waterproofing layer from roofing felt. This will protect the wood from rotting.

It is worth taking the process of attaching the Mauerlat responsibly, since in strong winds it must withstand a particularly large load.

The following consumables can be used as fastenings for the Mauerlat:

• Anchors that are indispensable for monolithic materials.
• Wooden dowels. These parts are used in houses made of timber and logs, although they require additional fastenings.
• Staples.
• Reinforcement or special studs. This option is preferable for buildings made of foam or aerated concrete.
• Knitting or steel wire is an auxiliary fastener, which is almost always used.

Assembling trusses or rafter pairs

Trusses can be assembled using one of the following methods:

• The beams for the rafters are assembled and attached directly to the roof of the building. This process is quite labor-intensive, since all measurements, trimming and coupling of beams will have to be done at height. However, you can do it on your own, without the involvement of technology.
• Trusses or rafter pairs can be fixed to the ground, and then ready-made elements lift to the roof of the building. On the one hand, this simplifies the process of installing the rafters, and on the other, due to the large weight of the structure, lifting it to the top will require special equipment.

Please note that you should start assembling rafter pairs only after marking has been applied. And if you make a template in advance, for which you take two boards, equal to length rafters, and connect them together, then all pairs will turn out exactly the same.

Installation of rafters

After assembly and lifting to a height, the gable roof rafters are installed wooden house. To fix them on the Mauerlat, cuts are made at the bottom of the rafters. The first to install are two trusses at opposite ends of the roof.

After this, a rope is pulled between the starting pairs, along which all other trusses will be aligned and the ridge will be installed.

Now you can mount the remaining pairs, observing the calculated step between them. In cases where the pairs are assembled directly on the roof, a ridge girder is attached between the two end trusses. The rafters are subsequently installed on it.

The procedure for installing rafter halves may differ according to the opinions of professionals. Some people prefer to lay the beams in a checkerboard pattern so as not to overload the foundation and walls during work. Others are inclined to install pairs of rafters in series. Be that as it may, rafter legs may need supports and posts - it all depends on the size of the roof and the shape of the trusses.

Skate attachment

A ridge is an element that is formed by attaching rafters at the top point. As soon as all the details of the rafter system are gable roof will be installed, it is necessary to carry out major consolidation of all structural elements.

Installation of sheathing

The presence of sheathing is mandatory when constructing any roof. It not only supports the roofing material and allows it to be securely fastened, but also makes it possible to move along the roof while working.

The distance between individual boards is selected based on the type of roofing material:

• soft roofing is laid on a continuous sheathing without gaps;
• for metal tiles you need lathing in increments of 35 cm (between the two bottom rows - 30 cm);
• slate and corrugated sheeting can be laid on the sheathing in increments of 44 cm.

Results

Thus, in order to assemble a rafter system for a roof with two slopes, many nuances should be taken into account and any possible complications should be provided for. We hope that our tips will help you cope with this difficult task and create a high-quality and durable roof for your home.