Proper installation of rafters with your own hands. How to properly install gable roof rafters How to build a roof truss system

During the construction of private houses, the roof is most often made gable. There are reasons for this. First, it is reliable. Handles wind and snow loads well. The second - it is compatible with any roofing. The third is relatively inexpensive. The fourth is a simple design that is difficult to spoil. Fifth - it looks attractive. All this, and also the fact that a do-it-yourself gable roof is built without special knowledge, determines its popularity.

Do-it-yourself assembled gable roof ready for installation of roofing

Step-by-step installation of a gable roof

As you saw above, there are a lot of truss systems. Accordingly, when assembling each has its own characteristics, but in general the order is the same. It is necessary to say about the general step: pre-drying and processing of wood. This step is required if you bought fresh lumber, not dried.

The use of raw wood of natural moisture in the construction of the roof will lead to problems: the beams will bend, they will dry out, the geometry will change. All this will lead to the emergence of stress points and at the slightest sign of overload (a lot of snow, strong wind or rain), negative processes will begin. Their elimination is a complex and costly undertaking. Therefore, either buy dry wood (no more than 20%, ideally chamber drying 8-12%), or buy material a couple of months in advance, put it in ventilated piles. After that, treat with the necessary impregnations (from fungal attack and to reduce flammability) and only after that use it in the installation of the truss system.

Timber must be dried in ventilated stacks. To do this, they are laid in short pieces of boards. They are placed a meter from the edges and further through the meter. Spacers must be installed under the bottom

We will talk about the main stages of assembly, about how to make a gable roof with your own hands in this section.

Mauerlat

The assembly of the gable roof truss system begins with the installation of the Mauerlat. It must be set strictly horizontally, therefore, before starting installation, the horizontalness of the wall to which it is attached is carefully checked, if necessary, it is leveled with cement mortar. You can continue work after the solution gains 50% strength.

Depending on the system, this is a beam with a section of 150 * 150 mm or a board with dimensions of 50 * 150 mm. It is attached to the top row of masonry walls. If the house is wooden, its role is played by the upper crown. If the walls are made of light building blocks - foam concrete or aerated concrete and others - their rigidity is not enough to redistribute the load. In this case, a reinforced concrete belt is made over the last row of masonry, into which embedded fasteners are embedded - wire or studs. A bar or board is then mounted on them.

There are several ways to connect walls and Mauerlat:

• In the masonry (in the reinforced concrete belt) a smooth rolled wire of large diameter is fixed (two ends stick up). Holes are then made in the board in the necessary places, into which the wire is threaded. She then twists and bends.
• Studs with a diameter of at least 12 mm are immured in the wall. Under them, holes are made in the Mauerlat, a beam / board is placed) and tightened with nuts with wide washers.
• Having aligned the beam or board along the outer or inner edge of the wall, take a drill with a diameter of 12 mm and make holes for the anchor bolts. They (the same diameter of 12 mm) are hammered to the very hat, then tightened with a key.

The distance between the studs (wire) should not be more than 120 cm. Cut-off waterproofing must be laid on the wall (belt) under the Mauerlat. It can be rolled roofing felt or waterproofing in two layers, it can be smeared with bituminous mastic.

Rafter installation

There are more than a dozen types of gable roof truss systems. First of all, you need to choose what yours will look like. Further, in order to make it easier to work, a template is made from thin boards for all cuts, cuts and other similar details. To do this, you may need to assemble the first form on the roof, and then make templates for the finished one.

The assembly order depends on the type of truss system. If the rafters are layered, they are installed gradually, assembling from the elements directly on the roof. In this case, it is convenient if the beams of the ceiling are laid and, if possible, the draft flooring of the attic or attic.

In systems with hanging rafters, a farm is assembled on the ground - a ready-made triangle of puffs and rafter legs with all the required struts, racks. The required number of farms is assembled at once. Then they are lifted to the roof, placed vertically there and attached to the Mauerlat.

On the one hand, this is convenient - it is easier to work on the ground, with a high assembly speed, the accuracy is high: one farm is not much different from the other, which simplifies the procedure. But it can be difficult to raise finished trusses, especially for large buildings. To make this easier, two inclined boards are installed, which at one end rest against the ground, and the other sticks out a little above the wall. Farms are brought closer to this “lift”, one by one they are installed below, ropes are tied and tightened along the boards to the roof. In the absence of a winch or crane, this is the most acceptable method.

The assembly of rafters requires certain knowledge: how and in what order to mount them, how to mark and make cuts. See the video for the assembly of one of the schemes with a headstock.

Assembly order of the truss system

Everything, the do-it-yourself gable roof is assembled and ready for installation of roofing material.

The process of installing the rafters itself raises enough questions, but there are many ways and it is impossible to tell about them all. See one of them in the video. The system is large and went up to the roof in parts, and there it was already assembled into a single structure. It is convenient for large houses.

Features of the installation of the truss system of a wooden house

The difference between wooden houses is that the log house shrinks, and this leads to a change in the geometry of the truss system. If the elements are fixed rigidly, the roof may fall apart. Therefore, the mounts are made floating. There are special sliding fasteners, which in this case attach the rafters to the upper crown and to the girders, if any (see photo).

In order for the rafter to move freely during shrinkage, its long part is fixed strictly parallel to its edge, and the support is placed strictly perpendicular. If necessary, a platform is cut out under it. Mark the mount so that the hook is in the lowest position or near it. They are mounted on special self-tapping screws that come with the kit (ordinary ones do not fit). If the installation is done on a log, so that the rafter leg does not slip along it, a semicircular hole is cut out in the lower part, on which it will rest.

Such fasteners are sold on any construction market, it is called "slippery". How to attach the slippery to the beam, see the video.

Video on assembling and installing a gable roof truss system

It is not easy to build a gable roof with your own hands: there are a lot of subtleties and nuances, there are different ways of fastening, building up. Describing them in words is a thankless job. This is the case when it is better to see. Below is a selection of videos that you may find useful.

Video report on how a gable roof is made

The story of the owner of the house about the stages of construction. There are interesting technical points that may be useful.

Two types of rafter connection: rigid and sliding

Video about the two most problematic types of connections.

How to determine the angle of the rafters

Full video report on the assembly of the truss system

This movie is just under an hour long, but the entire process is shown from start to finish with plenty of detail. The roof is placed on, but when installed on buildings of a different type (except for wooden houses), there is no difference.

Photo
In order for the roof to serve as long as possible and to fully fulfill all the duties assigned to it, it is necessary, among other things, to properly assemble the truss system. This can be done by hand. However, before starting the main stage of work, it is necessary to determine the type of roof and the rafter system itself, select a suitable and high-quality material, and also draw up a plan in accordance with which the rafter system will be built.

Types of roof truss systems.

The type of system depends on the shape of the roof of the house. At the design stage, in general, the features of the entire system and the design of the roof in particular should be taken into account. After preparing and fixing the individual elements, the truss system is mounted directly. This work involves the implementation of many technological stages. Doing everything according to the instructions, you will not encounter any significant problems, and the finished rafter system for the roof of your house will be of the highest quality.

Drafting a truss system

When drawing up a project, it is necessary to take into account the type of roof of the house. For the roof of each individual type, an individual truss system is prepared. For example, a rafter system for a mansard roof will be completely different from a system for a hip roof. Therefore, when performing work independently, it is necessary to take into account these factors.

However, there are a number of requirements that are universal for any type of roof. When designing the truss system and the roof itself, consider the following important points:

Scheme of the hip roof truss system.

1. If the roof is to be insulated, then all installation work must be thought out so that they can be performed as conveniently, easily and quickly as possible.
2. When installing the insulation, you need to consider the further arrangement of the rafter legs.
3. It is important to take into account the weight of the roof structure and calculate the power of the rafter leg in accordance with this parameter.

The rafter system should be assembled from high-quality and durable wood. It is important that the harvesting, drying and storage of the material is carried out in accordance with the rules. It is best to use resinous bars. Resin is a natural antiseptic, so the wood will be under additional protection, and the finished truss system will last as long as possible.

If the roof of your house is hip, the rafters should have a different section. The strongest rafters should be installed where several bars are connected. When choosing the material for the valley rafters, you need to be especially careful. The joint between the planes quite often becomes one of the main problem areas. Such areas are characterized by the lowest strength in the entire system and can leak.

Timber preparation before work

Rafter attachment points.

To build a reliable truss system, you need to use a fairly thick beam. Suitable material with a section of 10x20 cm, 10x10 cm, 20x20 cm, etc. Where the rafters must have particularly high strength, for example, if the design provides for the presence of slanted rafters, the beams need to be spliced. It is best to use a beam 400-600 cm long. An already aged beam is best suited for rafters. This ensures that the wood does not change in size after the roof is erected.

Before proceeding with the installation of rafters and waterproofing, be sure to consider such points as protecting wood from fire and pests. First, the beam should be impregnated with antipyretics. Such processing leads to a decrease in the combustibility of wood. Secondly, the material is necessarily processed with antiseptic compounds, due to which its decay will be prevented.

These measures must be taken long before the final installation of the truss system. In this way, you can consistently process each element of the structure, paying special attention to those that may be damaged in the future. Pay special attention to the seams. Protective compounds are most conveniently applied with a brush. Use a fairly wide tool with a long pile. Don't forget personal protection. Be sure to wear gloves, a respirator and goggles.

Protective compounds are recommended to be applied in a double layer. The wood must be dry before processing. You can, of course, not wait for complete drying. But if you want the material to be as saturated as possible and serve as long as possible, take your time and let it dry completely before applying the next layer. You can start installing the roof truss system only after the protective agents are well absorbed and the material is completely dry.

System diagrams for gable roofs.

In the process of doing this work, you will need a few simple tools that do not require special skills and training, namely:

1. Axe.
2. Hammer.
3. Chainsaw or wood saw.
4. Yardstick.
5. Building level.
6. Electric drill.
7. Metal staples from 20 cm.
8. Nails 8-20 cm long.
9. Nail puller.
10. Pencil.

Step-by-step instructions for installing rafters

The procedure for installing a truss system for a house with your own hands is as follows. First, the mauerlat is laid. It is a bar that serves as the basis for the truss system. Lay the Mauerlat on top of the walls around the perimeter of the building. Special fasteners are used. They must be installed in increments of up to 1-1.2 m. To further increase the moisture-proof properties, a roofing material must be placed under the Mauerlat. You can use other waterproofing materials that are convenient for you.

The beam is laid next to the studs. Places for creating holes are marked. After all the necessary holes have been drilled, the studs should be threaded into the Mauerlat. This must be done in such a way that the studs protrude slightly. You do not need to make a large protrusion, a few millimeters will suffice. Mauerlat is additionally fixed with washers and nuts. After completing the fixing of the Mauerlat, you can proceed to the next stage of work, in which you have to fasten the rafters with the mounted Mauerlat.

Scheme of hanging truss systems with a raised puff.

The rafter leg is set in a suitable position and fixed to the Mauerlat. For this, galvanized steel brackets are used. Additionally, prepare mounting brackets and screws.

The bracket will prevent the rafters located along the Mauerlat from moving. The bracket is also designed to prevent their displacement. By the same principle, using brackets, the rafters are mounted to the ridge part of the roof. For the purpose of additional reinforcement and fastening of the ridge part of the roof, a rail can be used. It should be connected to opposite rafters in the form of the letter "A".

For the most reliable connection of the rafters with each other, you can also use studs. For this work, studs of at least 8 mm are suitable, if ondulin and other lightweight roofing materials are used for the roof. If you choose ceramic tiles and other heavy materials, you should use longer studs, from 10-12 mm.

So that the rafters do not move, it is better to use 2 studs at once for one attachment point.

In some cases, it becomes necessary to lengthen the beam. In the event of such a situation, overlap the bars using high-strength studs and a diameter of at least 1 cm.

Recommendations for fastening the truss system with Mauerlat

The scheme of fastening the rafters to the Mauerlat.

Sometimes situations arise when the length of the rafters is not enough. This usually happens when building a T-shaped roof. But it can also happen under other circumstances.

In such cases, in order to prevent or even completely eliminate the sagging of the roofing along the length under its own weight or the weight of precipitation, it is necessary to thoroughly work on strengthening the roof. It is better to do everything right and “on conscience” right away. The intention to fix defects “sometimes later” in the future can lead to problems that require a much more significant investment of time, money and effort.

To resolve this issue, you can use one of the two available methods. In accordance with the first of them, a run is installed in the middle of the truss system, thanks to which the load will be evenly distributed. Or you can resort to another method. In accordance with it, additional transverse beams are installed and spacers are installed. Thanks to such a system, the entire incoming load will be distributed quite efficiently.

The second method of load distribution is more practical and efficient. It is he who is most often used in the construction of mansard roofs.

After completing the installation work, cut off all the rafters on the roof. Cut them to the level of the eaves. After that, if there is such a need, it will be possible to carry out waterproofing work.

Thus, there are no special problems in the independent arrangement of the truss system. By doing everything yourself, you get a great experience and save a lot of money on the services of third-party craftsmen. You just need to follow the instructions in everything, strictly follow the established requirements and rules, and you will definitely be able to create a durable and reliable truss system. Successful work!

The truss system is the basis of the roof, the reliability and strength of the roof, its ability to withstand precipitation and wind depends on it. The design of the truss system is determined by the shape of the roof and the features of the layout of the house, as well as the materials used. A do-it-yourself truss system is usually made of wood, but other materials, such as a metal profile, can also be used.

Types of rafters and their application

The choice of a truss system is a crucial step that requires knowledge of the design of each type of roof. Rafters can be:

1. Laminated rafters based on a ridge run and Mauerlat. They are used in the construction of a single-pitched, simple gable roof, as well as one of the elements of a hip and sloping mansard roof.
2. Sliding rafters - a type of layered rafters used for wooden buildings that give a lot of shrinkage. Their difference is the sliding fastening of the rafters to the Mauerlat, which allows you to compensate for the shrinkage of the walls without deformation of the roof.
3. Hanging rafters - a system of rafters tied with crossbars or puffs, usually used in the construction of a simple gable roof, as well as the upper rafters of a mansard roof. In the hanging rafter system, there is no ridge run, and in the upper part the symmetrical rafter legs rest directly on each other.
4. Sloping rafters, otherwise called angular or diagonal. They are used to make a three-pitched or four-pitched roof, as well as for roofs with complex geometry.

Elements of the truss system

Any rafters are designed to distribute and transfer the load of the roof to the walls of the house. The main elements on which the rafters rely are:

• Mauerlat - a beam fixed on the upper plane of the walls around the perimeter of the whole house;
• Beds - support bars laid on internal load-bearing partitions or columns;
• Beams of the ceiling of the upper floor;
• Racks and supports;
• Runs - horizontal support elements laid along the roof axis on racks.

The truss truss consists of the following elements:

• Rafter legs - boards or beams that form the contour of the roof and are laid with a certain step;
• Puffs or crossbars - horizontal elements that pull paired rafter legs together;
• Struts - supports set at an angle and supporting the rafter legs;
• Filly - boards fixed at the lower end of the rafters and forming roof overhangs;

Narozhniki - short rafters resting on diagonal rafters in a hip roof.

All these elements in private construction are usually made of wood - timber or coniferous boards, naturally dried. The tree is impregnated with an antiseptic, which allows you to extend its service life. The thickness and section of the elements is determined by calculation.

Laminated rafter technology

1. Before construction begins, it is necessary to sketch the roof and calculate its dimensions. The cross section and pitch of the rafters, as well as the need to install additional supports and struts, are also determined by calculation.
2. Support elements are laid and exposed: mauerlat, beds and floor beams, racks, ridge and intermediate runs. These operations are described in detail in articles on various types of roofs:
3. Make a rafter template. To do this, take a board with a width corresponding to the estimated length of the rafters, with the same width, but with a smaller thickness - it is lighter and easier to fit exactly in place. The board is applied to the installation site of the extreme rafter with one end to the ridge run, the other to the Mauerlat.
4. At the top of the template mark the top gash. The shape of the cut should be such that the board lies on the ridge run and at the same time fits snugly against the opposite rafter. The depth of the cut should be no more than 1/3 of the width of the board.
5. After sawing out the upper cut, the template is once again applied in place and the lower cut is marked out - it should rest on the Mauerlat, without leaving large gaps. The end of the template is filed at an angle so that the cut is in a vertical plane.

   

6. The resulting template is applied at the installation site of all rafter legs, checking whether it will be necessary to fit in place. If the template fits perfectly (which rarely happens), you can immediately make the required number of rafter legs. If adjustment of the lower notch is needed, then only the upper part of each rafter is cut out according to the templates, and the lower notch is done in place each time.
7. The rafters are placed with the established step calculation. Usually it is from 50 to 120 cm and depends on the type of roofing, namely on its severity, and on the expected snow load. The heaviest coatings are slate and ceramic tiles, but they are rarely used today. More often, the choice is made in favor of more modern, light and reliable materials: metal tiles, ondulin, soft roofing. For them, the pitch of the rafters can be chosen about 100 cm without performing complex calculations.
8. First, rafters are installed from the side of the gables. The rafter leg is supported on the ridge run and the Mauerlat and fixed on two nails 100-150 mm in each attachment point. Having installed the rafter pair, they additionally fasten it: in the upper part with the help of metal plates and self-tapping screws on one side and corners with a stiffener on the other, in the lower part - with brackets or also on the corners.

   

9. After installing the rafters from both gables of the roof, a twine is pulled between them and the rest of the rafters are aligned along it. Rafters are fastened in the same way.

   

10. Install struts, if required by the results of the calculation. The struts are made from the same material as the rafters. A board of suitable length is applied at the desired angle to the rafter and the bottom cut is marked. It is important to consider what the brace will rely on: on the floor beam or on the bed, the shape of the lower gash depends on this. After completing the lower cut, the brace is put in place and the cut line along the rafters is marked. The prepared brace is placed at a distance between the beams and rafters and secured with metal plates or corners.

Roof strut installation

Technology for the implementation of hip diagonal rafters

1. Since the rafters for the hip roof are installed diagonally, the usual methods of attaching them are not suitable. In addition, the load on diagonal rafters is much higher than on layered or hanging ones, so the material for their implementation must have a larger cross section. You can use a beam with a thickness of 100 mm or more, but practice shows that it is more convenient to make these rafters from two folded and fastened boards of standard thickness.
2. The diagonal rafters are supported by the upper end on the racks, the lower end - on the Mauerlat bars converging at right angles. They are marked in place, and their main feature is that the cuts are not made perpendicular to the plane of the board, but at an angle of 45 degrees. When making rafters from spliced ​​boards, first one side is performed with oblique cuts, then the second, in a mirror image.
3. The boards are pulled together with screws, nails or studs. The hip rafters are fixed with overlays and self-tapping screws.

A video will help you better understand the basic techniques for building a truss system with your own hands.

When doing any truss system with your own hands, it is important to carefully secure all knots and connections and remember that the roof is the main protection of your house from bad weather. Therefore, it is important not only to make a high-quality frame, but also to choose the right one, for example, corrugated board, and lay it correctly.

Installation of rafters is one of the key stages in the construction of the roof. To prevent the rafter system from deforming and collapsing under high loads during operation, the rafters must be properly fixed.

Calculation of the pitch of the rafters

How far apart are the rafters? When designing the truss system, special attention is paid to this issue. The strength characteristics of the roofing system depend on the section of the rafters and the step of their installation.

The pitch of the rafters is the distance between adjacent rafters. The minimum pitch of the rafters is 60 cm, the maximum is more than 1 meter. A simplified version of the calculation of the pitch of the rafters involves the use of a table:

The length of the slope along the eaves must be divided by the rafter step selected in the table, then add one to the resulting value and round up to an integer. The resulting result indicates the required number of 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 and the type of insulation used. If it is planned to lay a roll or slab heat insulator, it is recommended to adjust the pitch of the rafters to the size of the material. It should be noted that the width of the cotton insulation should be 1-1.5 cm more than the span between the rafters.

When determining how far to put the rafters, you should also pay attention to the recommendations for installing the selected roofing.

Material preparation

Do-it-yourself installation of rafters requires not only knowledge of the process technology, but also the correct preparation of the wooden elements of the system for installation. Rafters are made of edged boards or timber, the section of lumber is selected at the design stage of the roof. The tree should not have cracks, wormholes or other damage.

Rafter legs should be made of well-dried softwood to prevent their deformation.

Wooden elements must be treated with fire retardant and bioprotective compounds. Before proceeding with the installation, it is necessary to decide on the method of attaching the rafters to the Mauerlat or beams, with 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, self-tapping screws, staples, etc.;
• wire rod.

Types of rafters and features of their installation

When erecting the roof of a house, hanging or layered rafters are used. In some cases, a combination of both may be used. Hanging ones rely 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 an average load-bearing wall or supporting pillars inside the building box.

The lower part of the rafters abuts against the Mauerlat, respectively, 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. The upper part of the layered rafters rests on the ridge run. Thus, the installation of roof rafters requires the installation of a run, 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 floor beams protruding beyond the plane of the wall on both sides of the building serve as a support for the lower part of the legs. Hanging rafters are connected by a jumper (puff, crossbar) which relieves bursting forces. When covering large runs, truss trusses are reinforced with additional elements to enhance the rigidity of the structure. When installing hanging rafters on a Mauerlat, a low puff can serve as a floor beam.

Before you put the rafters, you need to mount the scaffolding. This makes it possible to provide the necessary safety and convenience of work.

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 the weight of the truss structures. If the assembled truss has a relatively low weight, or it is possible to use lifting equipment, then it is easier to assemble the structures on the ground, and then lift and mount on the roof. If the elements of the system are heavy and have to be lifted manually, then the trusses are assembled on the roof.

The connection of the upper ends of the rafters can be performed in different ways. First of all, this is a butt mount. On the opposite rafter legs, cuts are made at the desired angle. Then the rafters are docked with the resulting ends and fastened to two nails. The connection is additionally reinforced with a wooden or metal lining.

The overlap of the rafter legs is carried out using bolts or studs with wide washers and nuts. In this case, the rafters are in contact with planes.

If the rafter system is mounted on a wooden house with gables made of timber or logs, it is required to install the rafters on the walls using sliding fasteners in order 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: the rafter legs must be located with a gap, and they are fastened with a special movable metal connecting element.

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

The ridge run must be located 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. Hanging rafter trusses mounted according to the template rise to the roof. First of all, extreme farms are installed. In the tightening, two or three holes are required to attach the rafters to the beams laid on the upper crown of the log house.

If hanging rafters are mounted on a stone building, it is required to use special fasteners - the so-called "ruff", made of durable steel. This fastener is driven into every fourth row of brickwork. With the help of loops extending from the ruff, you can fix the beams. It is recommended to use a solid 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 fixed rigidly. To do this, a cutout is made in the rafter leg, the lower part of which must 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 is vertically on top) and tied with wire. A connection can also be used with the help of corners and a support bar that prevents the rafters from shifting.

Proper installation of rafters involves making a fire break at the point where the chimney passes through the roof. If, during its arrangement, the installation of a special rafter system is provided, 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.

If the rafter leg rests on the Mauerlat without an overhang, then special boards - fillies - should be installed to create a roof overhang.

The installation of rafters during the installation of a broken mansard roof has its own characteristics. In this case, first of all, a rectangular frame of racks and girders is mounted. Then, hanging truss trusses with a crossbar strut are attached to the girders, mounted on racks. Next, each rack is connected by a short rafter to the Mauerlat.

Do-it-yourself installation of rafters: how to set it correctly and over what distance

Installation of rafters: the specifics of sawing and the rules for installing the truss system

The truss frame sets the geometric and operational parameters of the pitched roof. Due to violations in the installation technology, due to flaws in the manufacture of its elements, distortions of the system, traditional leaks, holes in the coating appear, threatening emergency situations. In order to build a reliable and stable roof structure, you need to clearly know how the sawing and installation of rafters is performed, followed by fixation to the supporting elements.

Classification of rafter legs

Rafters, or rafter legs, are wooden or metal beams installed on the house box at a given angle. They determine the configuration of the roof structure, take on and steadfastly resist the sum of permanent and temporary loads acting on the upper enclosing system of the building.

The structural simplicity of the rafter legs is extremely deceptive. In fact, these are quite complex elements that require careful marking and accurate cutting. Inconsistencies in the connections of the rafter legs with the Mauerlat, with each other and other components of the system lead to a change in the shape of the slopes, a violation of the integrity of the coating and the destruction of nodes.

On the other hand, the competent installation of rafter legs can correct some errors in the construction of the house box, and not aggravate the situation by clearly repeating and increasing the wall height differences. True, in such situations, the frame elements are made individually and scrupulously adjusted in fact directly at the facility.

However, before dealing with the specifics of installation, you need to find out what their design differences are, according to which the rafter legs are divided into two groups, these are:

• Hanging. Type of rafters that do not have an upper support. At the top of the roof, the rafter legs rest against each other with their ends. So that under the weight of the components of the roofing cake and snow, such a design does not burst the Mauerlat beam, the hanging rafters are connected with a horizontally installed puff.
• Layered. A kind of rafter legs, stacked on two supports of different heights. At the top, they most often rely on a ridge run installed in the cross to the rafters, less often they rest against each other, cut down at an angle. The bottom rests on the Mauerlat beam or rests against it.

The scope of their application and installation technology depend on which group the rafter legs belong to. The hanging variety is collected on the ground, and the trusses, made in the form of peculiar triangles, are raised to the roof and mounted in a form completely prepared for installation.

The advantage of building a truss frame using hanging technology lies in the safety of work and the ability to perform nodal connections as accurately as possible. If the simplest version of a hanging truss with a puff at the bottom is used in the construction of the roof, you can abandon the Mauerlat device, in place of which a narrow leveling board is quite suitable.

The disadvantages of hanging technology are accompanied by advantages. For example, a truss assembled on the ground is much more difficult to transport to the installation site than boards and timber for layered rafters. There are restrictions on the spans to be covered: the limit is 14 m, above which it is unreasonable to install wooden beams prone to sagging without intermediate supports.

The rafter legs of the layered group both top and bottom are based on independent structures. The top of them is laid on a purlin structure, which is mounted on the floor beams or on the bed, replacing the Mauerlat on the inner wall. The bottom is either installed on the Mauerlat, or rests against it, catching on the bar with a tooth or a support bar sewn instead of a tooth.

The advantage of layered systems is rightfully recognized as the possibility of overlapping almost any span in size. It’s just that with an increase in the overlapped space, the design becomes more complicated: it is supplemented with struts for a couple with racks, additional runs, coupled with beds, fights.

The layered structure is assembled and mounted longer, because. it is built not from farms, but from individual elements. However, just this scheme has more opportunities to correct the shortcomings of a box or an unevenly settled log house. Because rafters of the layered type are stacked individually, it is possible to slightly change the position and size of the node in order to eventually form an immaculately leveled slope plane.

The specifics of the manufacture and installation of rafters

It is clear that for the construction of the truss system, lumber will be needed - long-length products of timber processing enterprises with clear geometric parameters. You will need a board or timber, on which, of course, there are no mounting cuts and cuts for installation.

Why are cuts and cuts needed? The fact is that when placed on an edge, boards and beams have too little support area. They are in contact with the Mauerlat with only one vestma in a thin line, because of which, at the slightest load from above, they can tritely “move out” from their position and drag the entire structure with them.

In order to increase the area of ​​\u200b\u200bsupport in the junction of the rafter and the Mauerlat, or it and the additional run, a corner cut is selected in the beam or board, a tooth is cut out or a support bar is sewn on. If the top of the rafter is paired with a mirror-opposite counterpart, then for a reliable stop, you will need a gash, the plane of which must be clearly perpendicular to the horizon.

The basic rule in the construction of truss frames is that the support sites selected in the lumber are strictly horizontal and vertical. At the slightest violation of horizontality with verticality, stability is lost, structural parts are displaced under their own weight and load, up to the complete destruction of the system.

Note that the nodes of the truss systems are entrusted with the obligation to ensure the possibility of a slight displacement and rotation when the load is exceeded. These movements are necessary in order for the structure to bend slightly, move slightly, but not collapse and maintain stability.

These subtleties should be known both to the master who decided to do the manufacture and installation of rafters with his own hands, and to the owner of the house under construction, who does not want to pay for the poor-quality labor efforts of the builders' team. Let's analyze the common options to understand the essence of the process.

Hanging roof frame construction

Consider an example of the construction of a truss system over a log cabin of a bath. The span between the walls is small, it is easier and more reasonable to block it with a hanging structure, the installation of which will be carried out on the bypasses of the ceiling beams - matrices.

The log base is an almost ideal option for installing hanging systems, because. it is easiest to cut it into the horizon, eliminating the need to adjust the rafters in case of a violation of the geometry of the foot. There is no need for a Mauerlat device. However, the puff will have to be moved up in order to bypass the upper crown of the log house and form a useful attic space.

Before performing the installation of the rafters, a phased preparation of the log house is carried out. On both sides of the foot, we align the bypasses according to the lace tied to the nails hammered into the two extreme beams. On top of the bypasses, we cut off the slab so that the edge of each beam ends with a flat horizontal platform.

The surface formed after squeezing the upper bulge of the log along the edges of the beams is aligned to the horizon according to the level. We apply the specified control tool to three or more beams at the same time. If the level is not long enough to carry out such a check, use a long rail or board instead.

After squeezing all the excess, we mark the nests for the rafter tooth. To do this, we again use nails and lace. Note that it is possible to draw nest sampling sites on the bypasses both before the construction of hanging trusses and after. However, it is much more convenient to make nests before making rafters. They will help to carry out the fitting with higher accuracy.

To facilitate your work, it is advisable to find the center of the log house from the side of future tongs. At these points, it is recommended to nail along the control rail, one of the edges of which will indicate the axis of symmetry. You can do without rails if you already have some experience in the construction of roofs.

• We sew two inch boards 10–15 cm longer than the designed length of the rafters at the top with a nail or bolt so that they can rotate around this connecting point.
• On the rail installed in the center of the future tongs, we mark the design height of the truss system. We put one more mark above it - this is the height of the tooth, more precisely, the length of the vertical laid off from the base of the tooth to its top.
• We set the boards sewn at one point to the extreme bypasses so that the corner of each board rests against the future socket under the tooth.
• We combine the connection point of the boards with the upper mark on the rail, which determines the length of the rafters with the tooth.
• From the lower corner of both rafters, we set aside the height of the tooth, return with the template blank to the ground and cut out the tooth according to the markup.
• We return the template blank to its place, install it by inserting the teeth into the sockets intended for them. It may happen that after installation, the top of the workpiece does not match the directions of the rail. Then you need to pull out the nail and adjust the position of the top, be sure to mark a new point.
• After fitting the top, we draw a vertical line of their upcoming joint on both boards, measure the size of the crossbar and mark on the trimmings of the board the shape of the overlays for the upper joint of the rafters.

If everything turned out exactly and no more adjustments are required, the template is ready. We return with him to the ground. We disassemble the workpiece and make cuts along the marked lines. The parts obtained as a result of fitting and fitting will serve as a standard for the practically in-line production of roof trusses in the required quantity.

We will assemble hanging farms on the ground. Their installation, as well as fitting, should be carried out by at least two people. One master simply can not cope with such work. The performer at the top will install the truss, and the second one will change its position according to the plumb line. The position of each leveled and installed truss should be fixed with temporary struts.

To increase the stability of the system, we will install racks under the rafters:

• Let's mark the matrices under the place of installation of additional supports in an already proven way: we will hammer in a nail from opposite sides and pull the cord.
• We will hollow out nests in the logs according to the markings.
• Let's try a piece of bar to the installation site. We mark on it the line washed down, taking into account the height of the spike.
• Let's make a rack and two pads for attaching it to the rafter.
• Install the support made and fix the position of the truss truss on the other side in the same way. According to the verified scheme, we continue to work until we equip each rafter with an additional support.

To ensure the rigidity of the hanging system, the truss trusses are connected by wind ties - boards, poles or slats nailed from the inside of the structure. On the outside of the truss frame, rigidity will increase due to the construction of the crate.

The rafter legs are attached to the matrices with 200 mm nails or angle brackets. In this regard, metal corners and plates with perforation for fasteners significantly lose to traditional methods. To the sidewalls of the rafters we nail fillies made of a board, the width of which is half the material used in the manufacture of the rafters.

The length of the filly should be 70 - 80 cm more than the designed width of the overhang. This distance is necessary for their reliable connection with the rafter legs. The fillies can be cut in advance, or without preliminary cuts, you can nail the trimmings of a narrow board to the rafters, and then draw up the line of the eaves. However, the first option is more convenient and economical.

In most cases, as in the example above, fillies must be partially buried in the mats bypass, for this:

• We note in fact the width of the filly at the bypass.
• We make two cuts with a saw according to the markup for 2/3 of the thickness of the filly. We also saw the log between the extreme cuts with a saw. We refine the recess with a chisel, accompanied by a hammer.
• We install the fillies in the formed recesses, sew them with rafters with nails 100 mm long.

Upon completion of the installation of all fillies in the last ones, we hammer in a nail. We pull the control cord and mark where to saw off the excess.

The device of the layered roof frame

In the construction of a truss frame using layered technology, there is much in common with the installation of a hanging structure. The fitting is carried out in almost the same sequence, so it makes no sense to describe the actions twice. The main difference is in the methods of forming the upper node, because the tops of the layered rafters have a support - a ridge run.

If at the top the layered rafters are tritely based on a ridge run, they are laid either with a run, i.e. parallel to each other, or with a strictly vertical joint, similar to the docking of hanging legs. However, in most cases, they try to fix the upper part with a notch or a vertical cut with a tight fit to the ridge beam.

There are schemes according to which the layered rafters are based not on the ridge, but on the side run. In such situations, the top is formed according to the hanging principle, and the point of support on the girder is made out with a corner cut.

Let us analyze the most popular option in private construction for the construction of rafter legs with support on the lower corner cut and on the ridge run through a vertical gash. Note that the maximum depth of the cut should not exceed 1/3 of the width of the board.

Option for marking with a construction square:

• On the square, we mark the height of the roof and half the span on a scale. These values ​​reflect the slope of the slopes and set the main angles. The proportions must be exactly maintained.
• If further use of the square is not planned, then the delayed points can be marked with screwed bosses or short screws with screws, if planned, it is better with paint that is removed with a solvent.
• We apply a square to the board laid flat with the side on which the height of the roof is marked. We draw a line according to the indications of the square - this is the line of the upper cut of the rafter - the section of its interface with the ridge run.
• Cut along the marked line with a circular saw. Lay the board for sawing flat, as it should be when cutting in width. Longitudinal cuts are made with setting on the edge.
• From the top of the formed angle, we set aside the length of the so-called diagonal. This is the distance from the junction point with the run to the outer edge of the Mauerlat or the upper trim, if a frame house is being equipped.
• We move the square to this point. We draw a line parallel to the first.
• We turn the square over, move it along the workpiece so that 2/3 of the total distance is on the left, and 1/3 on the right. In the picture, these are 8ʺ and 4ʺ.
• The line of a smaller segment will just designate a cut for us.

At the end, we draw the outline of the eaves overhang on the board, cut it along the outlined lines and use the rafter blank made by ourselves to saw the rest of the roof elements.

You can apply the described method without a building square and marking the parameters of the roof on it. It is enough to imagine the process in order to set aside the necessary distances with a conventional drawing tool. However, without experience, you can get confused in the calculations of angles and segments.

To help novice builders, a template has been developed with options for forming corner cuts. It will help you navigate the manufacture of rafter legs from the most common lumber in this area.

In cases of laying rafter legs with notches in the upper and lower parts, it should be remembered that the depth of both notches must be the same so that the roof slope does not change during construction work. Usually, for the device of two equal cuts, an auxiliary bar is used, the thickness of which is not more than 1/3 of the thickness of the board.

The rafter blank is then installed with an edge on the Mauerlat and on the run. The bar is applied on the side in the area of ​​​​the lower and upper nodes to outline the cut.

If the cut is needed only in the lower part of the rafter, and the top will be based on the run with a cut, the board is installed at the bottom on the Mauerlat, and at the top on the run and the bar, so that as a result of cutting, the slope of the slope does not change. At the bottom, a second bar of the same size is applied to the future node and the outline of the future cutting is outlined with it.

The same methods are used to form cuts with a tooth. The difference is only in the form washed down.

The installation of layered rafters begins with the installation of two extreme trusses. The elements are mounted one at a time, their position is carefully checked using a plumb line. Most often, extreme farms are arranged from paired boards, because. they carry more load. They are fixed with temporary spacers, then connected with a cord or rail to indicate the plane of the ramp.

Ordinary rafters located between the extreme load-bearing trusses are installed according to the instructions of the laces. If necessary, correct the position of the legs according to the actual situation.

Installation of rafters: how to make and lay rafters for the roof with your own hands

Do-it-yourself rafters and installing them on the roof

The truss system is the basis of the roof. Therefore, the installation of rafters with your own hands must be approached with a great deal of responsibility. The durability of the roof will depend on how well you perform the calculation and assembly of the rafters.

Rafters take on all the loads: from the roof, snow, wind. Therefore, it is important that the wood for them is ideal. There should be no chips, cracks on it, there should be no knots, traces of rot and other flaws.

Types of truss systems

There are hanging and layered rafters.

The slopes form the slopes of the roof. Supports for them are internal and external walls. Rafters are used mainly for roofing with one slope.

For a gable roof, they are used only when there is an additional supporting wall in the house structure.

Hanging rafters are good because they can be used for large spans without additional supports. Additionally, crossbars are mounted, which reduce the load on the roof from snow.

Do-it-yourself hanging rafters on the roof are installed if the span is not more than seven meters.

For larger values, it is necessary to additionally mount a vertical spacer (headstock). With a distance between spans of more than nine meters, struts are nailed to the rafter legs at an angle.

It is impossible to imagine a roof truss without additional spacers. Keep this in mind when installing a truss system with your own hands. For example, tightening prevents the rafter legs from spreading, which can occur due to pressure exerted on the roof. But one puff is not enough. The bars under load will begin to sag and may break. To avoid this, crossbars are installed, as well as "grandmothers".

And these conditions apply to the construction of any roof. Even the roof of a frame house built with your own hands needs various reinforcements, despite the fact that the construction of such a roof is one of the lightest.

But before proceeding to the construction of the roof, it is necessary to build a house. You can read about how to build a frame house here. Houses using this technology quickly became popular not only in our country. They are built in a short time, do not require huge cash costs, have good performance characteristics, and are environmentally friendly.

The main thing that you should pay special attention to when assembling rafters yourself is the quality of the connections. Let's talk about this in more detail.

Hard connection

To join the rafter legs with the Mauerlat, a rigid connection is often used. Its essence is that at the end of the rafter leg, a cutting is made at an angle of 90 degrees. With this part, the leg rests securely on the Mauerlat.

For a stronger connection, the rafter is fixed to a horizontal beam with a metal corner or three nails: two at an angle, one on top.

sliding joint

With a sliding joint in the Mauerlat, a groove is made into which the rafter leg is inserted. Fastening is carried out using a "sled" with self-tapping screws or nails.

Connecting rafters to each other

You can attach the rafters to each other at the top in several ways. 1 way - butt fastening. To do this, the ends of the rafter legs are overlapped on top of each other. Next is a vertical cut. After that, the rafters are applied end-to-end to each other and fixed with two nails at an angle. Additionally, you can use a metal plate, which is mounted between the rafter legs at the top.

Building rafters: timber

You can build up rafters from a bar by cutting down. To do this, cuts are made at the ends of the bars, with a length equal to twice the height of the section. The height of the cuts should be equal to 1/5 of the height of the timber.

After joining the bars, a bolt hole is drilled in them, the bars are connected.

Rafter extension: board

There are more connection options here. You can overlap the boards. The length of the overlap is approximately the same as half the length of the board.

A secure connection is made using ten nails driven in at a 45 degree angle.

You can join the boards end-to-end, and nail a board on the seam on both sides.

When installing rafters with your own hands, you must constantly ensure that they are located exactly on the same level. It is better to collect farms directly in the attic, as they are very heavy, and it is rather difficult to lift them without special equipment. The dimensions and shape of the rafters are also acquired already at the top.

Before proceeding with the construction of the roof, it is necessary to separate the floor with a ceiling. Ceilings in a house made of foam blocks are part of the overall design of the house, which is not inferior in importance to the foundation and roof.

If you have already made ceilings, then think about it, maybe you want to make a roof under the room. Houses in which part of the volume under the roof is equipped as a living space are called houses with an attic.

Features of the construction of the roof of the house from foam blocks are described in this article. When erecting a roof, it is necessary to strive to reduce its weight so that the load on the walls is small. However, if the house has a reinforced concrete frame, then this recommendation can be deviated from.

Self-installation of the truss system

Installing a truss system is a simple process. First, you need to assemble a farm on the roof. You can do this in any way, depending on its type.

It is convenient to make a truss with a puff at the bottom.

First, a timber or board of the required length is cut off. They will play the role of a puff. To do this, the distance between the walls of the house is measured with a call to the walls themselves. Next, a vertical beam (board) is prepared, which will stand between the puff and the rafter legs. Its length must be adjusted so that when the rafter legs are connected to it at the top point, the necessary slope of the slopes is obtained. Make calculations taking into account the fact that the roof should hang at least half a meter over the eaves.

The first farm should be used as a template. A second farm is immediately made on it. All calculations must be recorded. After you have built the rafters with your own hands, you need to install the assembled structures along the edges of the roof and pull the rope between them. When installing intermediate trusses, it is necessary to control their height on it.

Before installing intermediate trusses, it is necessary to make markings along the perimeter of the roof in order to accurately maintain the step between the rafters during installation. When all the roof trusses are mounted, you can proceed with the installation of the battens, counter battens, lay the roofing material and insulate the roof.

Do-it-yourself construction of rafters and the process of installing them on the roof of your house

How to put rafters on a gable roof: expert advice

If a decision is made to build a house or a small outbuilding, then it is necessary to protect the building from moisture, and for this you need to make a roof. The roof in its design can be different, but in most cases a gable roof is used. Proven for centuries, it is easy to install and compatible with any type of roofing. Its installation is carried out on the crate, and it is stuffed on the rafters. In order for the roof to last for a long time, you need to know exactly how to properly put the rafters on the roof.

The most actively used material from which rafters are made is wood. Coniferous blanks are usually used, since the structure impregnated with resin allows the wood to retain its qualities for a long time and has a low weight. When choosing a material, it is desirable to avoid boards with knots and large cracks. It is not recommended to use freshly sawn boards and beams for the manufacture of a truss frame, the tree should be dried.

The rafters need to be assembled into a triangular truss, this design allows for optimal rigidity, and it affects the bearing capacity of the entire building.

Components of the roof structure

Rafter systems are divided into two types:

1. Hanging. They are used if the width of the wall along the pediment does not reach 10 m. When using a hanging system, the rafters are leaned on the side walls, and to equalize the load, they are connected by tightening.
2. Layered. They are used in the presence of load-bearing walls, if the width of the wall along the pediment is greater than 10 m. In order to strengthen the rafter system, a vertical beam is placed in the middle, through which the entire load is distributed on the walls, as well as the bed.

The installation of the truss system must begin with the Mauerlat. The place for its installation is planned in the process of building the walls. To do this, you need to lay out a ledge on the outside of the wall, and lay the Mauerlat at the inner edge. For its fastening use:

• binding wire;
• anchor bolts;
• corks made of wood;
• rebar cut into pieces.

The intended place for laying the Mauerlat must be waterproofed, and the beam must be treated with an antiseptic. To reduce the number of joints, the beam must be chosen to the maximum length. If suddenly the length of the beam turned out to be small, you need to make an oblique washed down, and then connect the two parts using self-tapping screws, nails and staples. The length of the cut should be up to 1 meter.

For the manufacture of rafter legs, you need to cut the boards of the required length. A 50 × 20 beam is well suited for this. The connection should not be located in the middle, the required offset is 1/3 of the entire length of the rafters.

For small buildings, truss trusses are easier to assemble on the ground and then lift to the roof.

You need to start putting rafters from the extreme gable trusses. The building level controls the verticality of their installation. And for the precise installation of intermediate trusses, it is desirable to pull the cord from above and below.

The rafter legs are installed in increments of 0.6 to 1.2 m, and the trusses are fixed to each other with a temporary fixator.

After installing all the trusses, they are fastened with a board in the upper belt, and the latches are removed.

If the span is more than 6 m, and there is a load-bearing wall in the center of the house, then the rafters must be installed differently. Supports are installed in the center, and a ridge beam is mounted on them. Rafters are alternately attached to it. Installation, as usual, begins with the extreme supports. Between them it is necessary to pull the cord to install the remaining rafters in the same plane. An additional beam can be installed between the internal supports, it will reinforce the ridge beam.

Having decided on the angle of inclination and the height of the roof, a template can be made to facilitate marking work. All rafters are of the same length, so you can wash down on the ground, and assemble the prepared structure at the top.

If the rafters are placed without a central run, then they can be overlapped between themselves. The upper points must be fixed rigidly, and a bolt should be installed below.

Having familiarized yourself with how to install rafters, on a small building you can properly do this work yourself.

How to put rafters on a gable roof: expert advice

Do-it-yourself gable roof truss system - device instructions

A gable roof or gable roof is a roof with two slopes, i.e. having 2 inclined surfaces (slopes) of a rectangular shape.

The gable roof frame, due to its design features, ideally combines ease of installation and maintenance with reliability and durability. These and many other parameters make the construction of a gable roof a practical and rational solution for private and commercial housing construction.

In this article, we will consider how to make a gable roof truss system with your own hands. For effective perception of the material, it is presented in the form of a step-by-step instruction from A to Z, from selection and calculations, to installation of a Mauerlat and a crate under the roof. Each stage is accompanied by tables, diagrams, drawings, drawings and photos.

The popularity of the roof with a house is due to a number of advantages:

• design variability;
• simplicity in calculations;
• natural flow of water;
• the integrity of the design reduces the likelihood of leaks;
• profitability;
• preservation of the useful area of ​​​​the attic or the possibility of arranging an attic;
• high maintainability;
• strength and wear resistance.

Types of gable roof

The installation of a gable roof truss system depends primarily on its design.

There are several options for gable roofs (types, types):

1. Simple gable roof - symmetrical

Simple gable roof - symmetrical The most common version of the roof device due to its simplicity and reliability. Due to the symmetry, a uniform distribution of loads on the load-bearing walls and the Mauerlat is achieved. The type and thickness of the insulation do not affect the choice of material.

The cross section of the beam makes it possible to provide a margin of bearing capacity. There is no possibility of bending the rafters. Supports and spacers can be placed almost anywhere.

A clear drawback is the impossibility of arranging a full-fledged attic floor. Due to sharp corners, “blind” zones appear that are unsuitable for use.

2. Simple asymmetrical gable roof

Simple asymmetric gable roof The construction of one angle greater than 45° leads to a reduction in the amount of unused area. There is an opportunity to make living rooms under the roof. At the same time, the requirements for the calculation are increasing, because. the load on the walls and foundation will be distributed unevenly.

3. Broken gable roof, with external and / or internal fracture

Broken gable roof, with an external and / or internal fracture This roof design allows you to equip a full-fledged second floor under the roof.

Naturally, a simple gable truss roof differs from a broken one, not only visually. The main difficulty lies in the complexity of the calculations.

The design of the gable roof truss system

Building a roof of any complexity with your own hands involves knowledge of the purpose of the main structural elements.

The locations of the elements are shown in the photo.

Elements of the truss system of a gable roof Elements of the gable roof truss system - scheme 2
Elements of the gable roof truss system - scheme 3

• Mauerlat. Designed to distribute the load from the truss system to the load-bearing walls of the building. For the arrangement of the Mauerlat, a beam of durable wood is selected. Preferably larch, pine, oak. The cross section of the beam depends on its type - solid or glued, as well as on the estimated century of construction. The most popular sizes are 100x100, 150x150 mm.

The silhouette of the roof truss determines the appearance of the structure. Examples of farms in the photo.

Roof truss options

Rafter parameters are important. They will be discussed below.

• puff- connects the rafter legs and gives them rigidity.

• Run:

• • Skate run, mounted at the junction of one rafter to another. In the future, a roof ridge will be installed on it.

• • Side runs, they provide the truss with additional rigidity. Their number and size depend on the load on the system.

• Rafter rack- a vertically located beam. It also takes on part of the load from the weight of the roof. In a simple gable roof, it is usually located in the center. With a significant span width - in the center and on the sides. In an asymmetrical gable roof - the installation location depends on the length of the rafters. With a sloping roof and the arrangement of one room in the attic attic, the racks are located on the sides, leaving free space for movement. If there are supposed to be two rooms, the racks are located in the center and on the sides.

The location of the rack depending on the length of the roof is shown in the figure.

Location of the rack depending on the length of the roof

In regions with a significant wind and snow load, not only longitudinal struts (located in the same plane with the rafter pair) are installed, but also diagonal ones.

• Sill. Its purpose is to serve as a support for the rack and a place for attaching the strut.

• crate. It is intended for movement during construction works and fixing of roofing material. It is installed perpendicular to the rafter legs.

The presence of a drawing and a diagram indicating the location of all the listed structural elements will help in the work.

The choice of material for rafters

When calculating the material for a gable roof, you need to choose high-quality wood without damage and wormholes. The presence of knots for beams, Mauerlat and rafters is not allowed.

For boards, there should be a minimum of knots, and they should not fall out. Wood must be durable and treated with the necessary preparations that will enhance its properties.

Calculation of the truss system of a gable roof

The calculation of material parameters is an important stage, so we present the calculation algorithm step by step.

Calculation of the truss system It is important to know: the entire truss system consists of many triangles, as the most rigid element. In turn, if the slopes have a different shape, i.e. are an irregular rectangle, then you need to divide it into separate components and calculate the load and the amount of materials for each. After calculations, summarize the data.

1. Calculation of the load on the truss system

The load on the rafters can be of three types:

• Permanent loads. Their action will always be felt by the truss system. Such loads include the weight of the roof, lathing, insulation, films, additional elements of the roof, finishing materials for the attic floor. The weight of the roof is the sum of the weight of all its constituent elements, it is easier to take into account such a load. On average, the value of the constant load on the rafters is 40-45 kg / sq.m.

For reference: The weight of some roofing materials per 1 sq.m. presented in the table

• Variable loads. They operate at different times and with different strengths. Such loads include: wind load and its strength, snow load, precipitation intensity.

In fact, the roof slope is like a sail and, given the wind load, the entire roof structure can be destroyed.

Wind load on the roof

The calculation is carried out according to the formula: wind load is equal to the indicator for the region, multiplied by the correction factor. These indicators are contained in the SNiP "Loads and Impacts" and are determined not only by the region, but also by the location of the house. For example, a private house surrounded by high-rise buildings has fewer loads. A detached country house or cottage is experiencing increased wind loads.

2. Calculation of the snow load on the roof

The calculation of the roof for snow load is carried out according to the formula:

The total snow load is equal to the weight of the snow multiplied by the correction factor. The coefficient takes into account wind pressure and aerodynamic influence.

The weight of snow, which falls on 1 sq.m. roof area (according to SNiP 2.01.07-85) is in the range of 80-320 kg / sq.m.

The coefficients showing the dependence on the slope angle are shown in the photo.

The scheme for calculating the snow load on the roof

• Special loads. Accounting for such loads is carried out in places with high seismic activity, tornadoes, storm winds. For our latitudes, it is enough to make a safety margin.

Assessment of the condition and bearing capacity of walls and foundations

It should be borne in mind that the roof has a significant weight that can harm the rest of the building.

Determination of the roof configuration:

• simple symmetrical;
• simple asymmetric;
• broken line.

The more complex the shape of the roof, the greater the number of roof trusses and sub-rafter elements is needed to create the necessary margin of safety.

3. Calculation of the angle of the roof

The angle of inclination of a gable roof is determined primarily by the roofing material. After all, each of them puts forward their own requirements.

It should be noted that increasing the angle increases the area of ​​\u200b\u200bthe space under the roof, but also the amount of material. What affects the overall cost of work.

Calculation of the angle of the roof

5. Calculation of the pitch of the rafters

The pitch of the rafters of a gable roof for residential buildings can be from 60 to 100 cm. The choice depends on the roofing material and the weight of the roof structure. Then the number of rafter legs is calculated by dividing the length of the slope by the distance between the rafter pairs plus 1. The resulting number determines the number of legs per slope. For the second number, you need to multiply by 2.

6. Calculation of the length of the roof rafters

The length of the rafters for the attic roof is calculated using the Pythagorean theorem.

Parameter "a"(roof height) is set independently. Its value determines the possibility of arranging a dwelling under the roof, the convenience of being in the attic, the consumption of material for the construction of the roof.

Parameter "b" equal to half the width of the building.

Parameter "c" is the hypotenuse of the triangle.

It should be noted that the maximum length of the beam is 6 r.m. Therefore, if necessary, the timber for the rafters can be spliced ​​(building, joining, joining).

The method of splicing the rafters along the length is shown in the photo.

Methods for splicing rafters along the length

The width of the rafters for the roof depends on the distance between opposite load-bearing walls.

7. Calculation of the section of the rafters

The cross section of the gable roof rafters depends on several factors:

• load, we already wrote about it;

• type of material used. For example, a log can withstand one load, a beam - another, a glued beam - a third;

• rafter leg length;

• type of wood used in construction;

• distance between rafters (rafter pitch).

You can determine the cross section of the beam for the rafters, knowing the distance between the rafters and the length of the rafters, using the data below.

Rafter cross section - table

Dimensions of lumber (beams and boards) for a gable truss system:

• thickness (section) of the Mauerlat - 10x10 or 15x15 cm;

• the thickness of the rafter leg and puffs is 10x15 or 10x20 cm. Sometimes a beam of 5x15 or 5x20 cm is used;

• run and strut - 5x15 or 5x20. Depending on the width of the leg;

• rack - 10x10 or 10x15;

• lying down - 5x10 or 5x15 (depending on the width of the rack);

• thickness (section) of the roof lathing - 2x10, 2.5x15 (depending on the roofing material).

Types of gable roof truss system

For the considered roof structure, there are 2 options: layered and hanging rafters.

Types of roof system: with layered and hanging rafters

Consider each type in detail in order to make an informed choice.

hanging rafters

They are used with a roof width of not more than 6 r.m. The installation of hanging rafters is carried out by attaching the legs to the load-bearing wall and the ridge run. The design of hanging rafters is special in that the rafter legs are under the influence of a bursting force. Hanging rafters with a puff installed between the legs can reduce its influence. The puff in the truss system can be wooden or metal. Often puffs are placed at the bottom, then they play the role of load-bearing beams. It is important to ensure that the puff is securely fastened to the rafter leg. Because a bursting force is also transmitted to it.

The higher the puff is located, the greater the strength it should have.

If the puff is not installed, the load-bearing walls can simply “disperse” from the pressure created by the truss system.

Rafters

They are used in the arrangement of roofs of any size. The design of the layered rafters provides for the presence of a bed and a rack. Lying lying parallel to the Mauerlat takes on part of the load. Thus, the rafter legs seem to be inclined towards each other and are supported by the rack. The rafter legs of the layered system work only for bending. And the ease of installation also tips the scales in their favor. The only downside is the stand.

Combined

Due to the fact that modern roofs are distinguished by a large variety of shapes and complexity of configurations, a combined type of truss system is used.

Combined view of the truss system

After choosing the type of truss system, you can accurately calculate the amount of materials. Record the calculation results. At the same time, professionals recommend drawing up drawings for each element of the roof.

Installation of a gable roof truss system

After the gable roof rafters are calculated, installation can begin. We break the process into stages and give a description of each of them. You will get a kind of step-by-step instruction containing additional information on each stage.

1. Attaching the Mauerlat to the wall

The beam is installed along the length of the wall on which the rafters will rest.

In log cabins, the role of the Mauerlat is played by the upper crown. In buildings built from porous material (aerated concrete, foam concrete) or brick, the Mauerlat is installed along the entire length of the load-bearing wall. In other cases, it can be installed between the rafter legs.

Splicing Mauerlat to each other (straight lock with bolts) Since the length of the Mauerlat exceeds the standard dimensions of lumber, it has to be spliced.

The connection of the Mauerlat with each other is done as shown in the figure.

How to connect the Mauerlat?

Washed down the bars is made only at an angle of 90 °. Connections are made using bolts. Nails, wire, wooden dowels are not used.

How to fix the Mauerlat?

The Mauerlat is installed on top of the wall. Mounting technology provides for several ways to mount the Mauerlat:

• strictly in the center of the bearing wall;
• offset to one side.

Mauerlat cannot be placed closer than 5 cm to the outer edge of the wall.

To protect the timber for the Mauerlat from damage, it is laid on a layer of waterproofing material, which most often acts as an ordinary roofing material.

The reliability of fastening the Mauerlat is an important aspect of construction. This is due to the fact that the roof slope is like a sail. That is, it experiences a strong wind load. Therefore, the Mauerlat must be firmly fixed to the wall.

Methods for attaching the Mauerlat to the wall and rafters

Mauerlat fastenings with anchors Anchor bolts. Ideal for monolithic construction.

Mauerlat fastenings with wooden dowels Wooden dowels. Are used for fellings from a log and a bar. But, they are always used with additional fasteners.

Mauerlat fastenings with brackets Staples.

Mauerlat mounts on studs or fittings Stud or fittings. It is used if the cottage is built of porous materials (aerated concrete, foam concrete).

Mauerlat mounts with a sliding mount Sliding mount (hinged). The bundle in this way allows you to ensure the displacement of the rafter legs when the house shrinks.

Mauerlat fastenings with wire Annealed wire (knitting, steel). Used as an additional mount in most cases.

2. Production of roof trusses or pairs

Installation is carried out in two ways:

• installation of bars directly on the roof. It is not used often, since it is problematic to perform all the work, measurements, trimming at a height. But it allows you to completely do the installation yourself;

• assembly on the ground. That is, individual elements (triangles or pairs) for the truss system can be assembled at the bottom, and then raised to the roof. The advantage of such a system is faster work at height. And the disadvantage is that the weight of the assembled roof truss structure can be significant. To lift it, you need special equipment.

3. Installation of rafter legs

The collected pairs rise up and are installed on the Mauerlat. To do this, at the bottom of the rafter legs, you need to make a drink.

Methods for attaching the rafter leg are shown in the figure.

Methods for attaching the rafter leg

You need to start installing rafter pairs from opposite ends of the roof.

A twine is stretched between the rafter pairs A twine is stretched between the fixed pairs. It will simplify the installation of subsequent rafter pairs. And also, will indicate the level of the skate.

If the rafter system is mounted directly on the roof of the house, then after installing the two extreme rafter legs, the ridge support is installed. Further, half of the rafter pairs are attached to it.

It is worth noting that the opinions of professionals differ on this issue. Some advise using a staggered mounting order, which will evenly distribute the increasing load on the walls and foundation more evenly. This order involves the installation of one rafter in a checkerboard pattern. After part of the rafter legs is installed, the missing parts of the pair are mounted. Others insist that you need to do a consistent installation of each pair. Depending on the size of the structure and the configuration of the truss, the reinforcement of the rafter legs is carried out with props and racks.

Fixing with rafter brackets Nuance. Additional structural elements are connected by cutting. It is preferable to fix them with building brackets.

If necessary, you can lengthen the rafter leg.

Methods for splicing rafter legs are shown in the photo.

Methods for splicing rafter legs

4. Installing the gable roof ridge

The ridge knot of the roof is made by connecting the rafter legs at the top.

Roof ridge device:

• Method without using a support bar (see fig.).

Installation of the roof ridge without the use of a support beam

• A method using a rafter bar. Timber is needed for large roofs. In the future, it can become a support for the rack.

• The method of laying on the beam.

Installation of the roof ridge by laying on the beam Installation of the roof ridge by laying on the beam

• A more modern version of the manufacture of the ridge knot can be considered the method shown in the photo.

Method for making a ridge knot

• Cutting method.

Installation of the roof ridge by cutting

After the truss system is installed, we make a major fixing of all structural elements.

5. Mounting the roof sheathing

The crate is mounted in any case, and is designed for more convenient movement along the roof during work, as well as for fixing roofing material.

The step of the lathing depends on the type of roofing material, for example:

• under the metal tile - 350 mm (the distance between the two lower boards of the crate should be 300 mm).
• under corrugated board and slate - 440 mm.
• under the soft roof we lay a continuous crate.

Conclusion

As you can see, despite the seeming simplicity, the installation of a gable roof truss system contains many pitfalls. But, based on the above recommendations, you can easily build a reliable structure with your own hands.

Gable roof truss system - calculation, installation, do-it-yourself installation of rafters