The rafter system is the frame of the roof of the house, which bears and evenly distributes the weight of the roofing pie, sometimes reaching up to 500 kg / m2. The reliability of this kind of skeleton depends on three factors: the accuracy of the calculation, on the basis of which the number and cross section of the supporting elements are selected, the material from which it is made, and also on the correct fastening technology. Knowing how to properly fix the rafters, you can significantly increase the bearing capacity of the frame, making it more durable and reliable. Installation errors, on the contrary, lead to noticeable strength losses and roof deformations. In this article we will talk about the main types and methods of fastening, with which you can install the rafters with your own hands.

The truss frame of the roof of the house is a system of interconnected supporting elements made of wood or metal, which give the structure a shape, slope, and evenly distribute its weight between the bearing walls. Its main component is the rafter legs, which are angled beams that are connected in pairs along the slope, forming a ridge at the top of their connection. There are two main types of rafters:

• Layered. Rafters are called supporting elements, which in the roof structure have two points of support - on the ridge run and the Mauerlat. This type of rafter system is used in structures that have one or more load-bearing walls inside, on which the rafters can be “leaned”. This fastening of the rafters allows you to unload them through the use of additional vertical supports.
• Hanging. Hanging elements are called elements that have only one point of support, located where the rafters are attached to the wall or Mauerlat. The hanging type truss system experiences a load not only in bending, but also in bursting, so it is reinforced by horizontal compensating elements (crossbars, puffs, contractions).

Note! In most of the most popular truss systems, the rafters are attached to the Mauerlat. Mauerlat is a massive bar or beam with a section of 150x150 mm or 200x200 mm, laid along the load-bearing walls of the structure, on which the rafter legs will subsequently rest. It softens the pressure on the walls of the house, and also evenly distributes the weight of the roofing cake. You can attach the Mauerlat to the upper belt of the walls using anchor bolts or embedded metal studs.

Main connecting nodes

The rafter frame is called a system, because all its elements are closely interconnected and fixed, as a result of which the roof structure acquires a stable shape, rigidity and high bearing capacity. Each connecting node between its parts is a weak point that can easily be deformed under load, so all fastenings must be carried out strictly according to the technology. Experienced craftsmen distinguish types of connections in the roof structure:

1. Fastening rafters to the ridge beam. This connecting node is typical only for layered truss systems, in which the upper part of the rafter leg rests on a ridge run, mounted on vertical posts. The rafters can be fastened to it with the help of metal plates, nails or sliding sliders.
2. Fastening rafters to the Mauerlat. The most important fastening unit of the truss frame is the junction of the Mauerlat beam with the rafter legs. You can fix the rafters on it with the help of nails, metal corners or wooden blocks.
3. The connection of the rafters to each other. To lengthen the rafter legs, if the length of the slope exceeds the standard length of lumber, they are assembled from several elements interconnected with nails, glue or metal linings.
4. Connection of rafter legs with auxiliary supporting elements. In the design of the truss frame, the rafters can be connected to a puff, crossbar or struts to increase rigidity, strength and bearing capacity.

Please note that any cuts made to attach the rafters to beams, mauerlat or other structural elements of the frame lead to a decrease in their strength, so experienced craftsmen recommend connecting them together using corners and overlays.

Fixation methods

When deciding how to attach the rafters to the Mauerlat or ridge run, it is necessary to choose the right mounting hardware. The modern construction market has a huge assortment of fasteners of various designs and sizes. The main criteria for choosing fasteners are the material used to make the rafters, their cross section, as well as the type of load to which they are subjected. There are the following ways of fastening rafters:

Experienced craftsmen believe that the most reliable way to fix the rafters is to use metal corners that firmly connect the wooden elements to each other, rigidly fixing the angle between them. The corner that overlaps the joint between the rafter leg and the ridge beam or Mauerlat serves as a kind of spacer between them.

Varieties of fasteners

Wood is a natural material that, in the process of leveling moisture and drying, shrinks significantly, due to which the linear dimensions of the structure change. That is why experienced craftsmen recommend building a roof for timber and log houses, a year after construction, when the shrinkage process passes from an active to a passive phase. If you fix the wooden elements of the frame rigidly, then after drying the roof of the house may be deformed. Therefore, the following types of fasteners are used to connect the rafters:

Interestingly, there are several options for combinations of movable and fixed connecting nodes. The most common are truss systems with one rigid and two sliding fasteners, which provide sufficient mobility with high strength and rigidity of the structure.

Types of fasteners

Among experienced roofers, disputes do not subside, the more efficient it is to fasten rafters to floor beams and Mauerlat. However, in most cases, the catch is that in these conditions it is more practical to use nails or self-tapping screws. Both of these fasteners have their own advantages and disadvantages:

• Nails are good because only a hammer is needed to drive them, which is in every household. However, some masters complain that scoring them by hand is too long. It is worth recalling that special serrated nails are used to fix the rafters, which securely adhere to the wood.
• To assemble the rafter frame, galvanized self-tapping screws are used, which are not afraid of corrosion. Due to the thread, they are firmly screwed into the thickness of the wood, securely fixing the elements together. Screw them quickly and conveniently with a portable screwdriver. The disadvantage of this type of fastener is that during dismantling, removing self-tapping screws from wood is long and dreary.

Most experienced roofers agree that it is better to use galvanized ruff nails to fix the rafter legs, the length of which is 5-3 mm longer than the thickness of the lumber. Properly selected fasteners are the key to high-quality and long-term fixation of the roof frame, which will not be afraid of either mechanical stress or wind load.

Video instruction

Anyone who decides to build a house on their own needs, among other things, to figure out how to fix roof rafters to mauerlat. This is one of the most important connections, the correct execution and reliability of which directly affects the life of the roof structure and, of course, the safety of people staying in the house. That is why it is important to thoroughly understand all the nuances of connecting rafter legs with other elements of the roof in order to avoid tragic consequences.

The method of articulation of the rafters with the Mauerlat is selected taking into account the characteristics of a particular system. The most important thing is to ensure the optimal distribution of the incoming load from the weight of the roof structure as a whole and directly from the rafters to the walls of the building.

There are several main connection points, the main ones being, first of all, the connection of the rafter legs with the Mauerlat, as well as the fastening of the beams to additional structural elements with the aim of increasing the rigidity and overall strength of the roof.

Mauerlat itself is a relatively thick beam, fixed along the upper part of the outer wall of the house parallel to the roof ridge. As a rule, a beam with a section of 150x150 mm is used for the Mauerlat device. Fastening the support system to the wall is usually done using galvanized studs.

The need to install beams on the Mauerlat arises in the process of arranging non-spacer and spacer structures. Hanging and layered rafters are installed on the support system using a sliding or rigid joint. A suitable connection method is selected taking into account the features of a particular design.

The notch for the connection must be made directly in the rafter. The creation of a notch in the support system is undesirable for the reason that it can reduce the bearing capacity of the support beam and, in general, contribute to a decrease in the reliability of the system.

With a rigid connection, the possibility of displacement of structural elements in any direction is completely excluded. To achieve the required rigidity, fastening is carried out using metal corners. This can also be done by creating special cutouts in the rafter legs. These cutouts in the rafters are additionally fixed with brackets or self-tapping screws, you can also use bolts and other fasteners.

When arranging the roofing systems of wooden buildings, it is quite often performed sliding connection rafters with Mauerlat. To create it, the so-called. "sled". This is a special fastener that connects the elements of the system in such a way that the rafter legs have a certain freedom, thanks to which in the future it is possible to prevent the occurrence of all kinds of deformations of the roof during the natural shrinkage of the structure made of natural wood.

Using a corner to connect structural elements

When choosing a method for attaching roof rafters to the Mauerlat, you need to focus on the features of a particular roof. In the case of wooden buildings, a sliding joint is usually used, in all other situations, the joint is made rigid.

If preference is given to a connection using special cutouts, work must begin directly with their preparation. Make the cutouts so that the rafter can be installed with its horizontal section on the Mauerlat without any problems, and the angle of inclination of the timber corresponds to the slope of the roof slope. To fix one bar, three nails will be enough, two of which should be driven in on both sides of the rafter at an angle. Drive the last nail in a vertical direction from above. Use wire to reinforce the connection. As a result, you will get the most durable and rigid connection.

The most common method of connecting rafters with Mauerlat is a method involving the use of a hemmed beam and a corner. In this case, work begins with the fact that the rafter is cut at the required angle. The angle is selected in accordance with the slope of the roof slope, fixed in the project.

Next, it is necessary to install a hemming beam about 100 cm long along the edge of the support beam. The rafter will firmly rest against this beam along the pressure line. The design of the system under consideration is such that the connection will be as rigid as possible, without shifts and other disturbances. Lateral fastening of the rafter leg to the support system is carried out with metal corners. Such fasteners help prevent lateral displacement of the rafters. Additionally, experts recommend reinforcing the attachment points with a special wire.

There are several types of corners that can be used to articulate the rafters with the Mauerlat. The most common are the corners of the brands KR11 and KR21. Such products have oval holes for the anchor, due to which the probability of fastener breakage under the influence of loads or during the settlement of the structure is significantly reduced. With the help of a corner of the brand KP5, it is possible to fasten structural elements with a large value of bearing capacity. Corner brand KP6 has a reinforced structure and is used to fix heavy elements.

Additionally, corners of the KM brand are used, for the manufacture of which perforated steel is traditionally used. With their help, the main load-bearing and various additional elements of the truss system are fixed. Among the advantages of such fasteners, it should be noted the possibility of using traditional screws and self-tapping screws, as well as the absence of the need to involve special equipment in the installation work.

Reinforced corners of the KMRP brand are also available for sale. They are designed to fix structural elements at a right angle. Such products provide high-quality fixation of rafters. Such corners can be adjusted, which makes the work as convenient as possible.

How to make a hard join

Fastening, as already noted, can be carried out using rigid and sliding technologies.

Rigid articulation is traditionally used for fixing layer-type rafters. Such work requires ensuring the most durable landing of the rafters on the support beam. The rigid connection must not be subjected to any force. To obtain the desired rigidity, you can use the method of cutting and patching.

When fastening with notches, first of all, it is necessary to prepare notches on each individual rafter. The height of such a recess should be no more than 1/3 of the height of the beam. Each rafter must be rested against the Mauerlat with prepared recesses and secured with two nails driven into the sides of the rafter board. For additional fixation, you need to hammer in the third nail, only vertically. This method is the most widely used and is traditionally used in the arrangement of roofing systems of any level of complexity.

Remember that cutting can only be done in rafters. It is impossible to create such “saddles” in the Mauerlat, because. because of this, its bearing capacity will decrease.

In accordance with the second method of fixing the rafters to the Mauerlat (the stripe method), additional bars 1 m long must first be prepared. They will be hemmed to the rafters, and directly the wooden bars will rest against the surface of the Mauerlat. The bars are fixed using the previously discussed corners.

If one end of the rafter is fixed using the rigid joint method, the other end must be fixed "sliding". The properties of wood are such that it tends to change its volume depending on the weather. And in the event that both ends of the timber are rigidly fixed, this will inevitably provoke an increase in the level of loads on the walls and rather quickly lead to a violation of their strength and, in general, deformation.

Sliding connection features

Such a joint, as already noted, is used in the arrangement of roofing systems for houses built of wood (beams, log cabins, etc.). A rigid joint is forbidden to use because of all the same properties of wood.

After the construction is completed, the material will change in size for a couple more years, i.e. shrink. The truss elements will also move, so there can be no talk of any rigid connections, because. because of them, the walls of the house are simply deformed.

It is important to give the rafter legs a little freedom of movement. This is done with the help of the already mentioned "sled". Also, installation can be carried out using special corners with an elongated mounting hole.

Spacers, struts and stocks are attached to the rafters by clamps and brackets. In addition, the rafters must be fastened to the walls of the building using wire twists. Thanks to them, the risk of failure of the roofing system in strong winds will be significantly reduced.

What other fasteners are used for connection?

Each existing method of fastening involves the use of appropriate fasteners. For example, you are already familiar with steel corners and thick wires. Additionally, a variety of reinforced corners, a special tape, all kinds of bolts, nuts and self-tapping screws, special-purpose fasteners, etc. are used.

If the installation will be carried out using brackets, tie-ins in the rafter legs are not made. That is, this method allows you to get the most reliable and efficient connection.

Instructions for attaching rafters to beams

It is important to know not only the order of connection of the rafters with the Mauerlat, but also features of fastening these elements with other parts of the roof structure. One of these moments is the connection of rafters with beams. The latter rest on the walls of the house and are located in the same plane with the rafters.

To make such a connection, it is necessary to cut special recesses at the ends of the floor beams, into which the rafters will be inserted in the future. To ensure the most even laying of the transverse beams, you can pull a string on the extreme bars and navigate along it.

At this point, the articulation is usually performed using the "butt" method. To do this, first of all, cut the upper edge of the rafters at an angle. The cutting angle must be the same as the angle of the roof slope. To facilitate the work, it is recommended to make a template and cut all the rafter legs along it. The fastening of the rafters under the ridge is carried out with the help of two nails, which are hammered at an angle.

Additionally, the joint can be strengthened with a wooden or metal plate, attracted with nails or bolts, respectively. The rafters are fastened with a ridge beam. This technology is quite difficult to implement, which is why it is almost never used in private housing construction.

The most favorite and popular mounting option among builders in this case is the overlap joint. The rafters are fastened with their side parts and pulled together with nails or a bolt. Special galvanized studs are also suitable for connection. This method is particularly easy to perform, which is why it is so popular.

In the process of connecting the Mauerlat and rafter legs, it often becomes necessary to lengthen the latter. The standard lumber length is 6 meters. If it is necessary to obtain longer beams, they have to be increased. There are three main ways to lengthen the rafters.

If nuts and bolts are used to make connections, special washers or plates must be used. Without them, nuts can simply "drown" in the material. Among all existing connection options, fasteners using nails are the least reliable, so it is recommended to use it only in extreme cases.

The service life, quality and reliability of the roof directly depend on how correctly the connection of the beam with the Mauerlat is performed. Regardless of the chosen connection method, you must adhere to the basic rules. First of all, the planes of the elements should fit as closely as possible to each other. This can only be achieved by precise and accurate execution of all recesses and cuts.

The rafter system is the basis, the “skeleton” of any roof, so its arrangement must be approached with skill. The service life and main operational characteristics directly depend on the correct installation and fixation of the main structural elements. Therefore, be careful, follow the recommendations received at each stage of installation and everything will work out. Successful work!

Video - How to attach the rafters to the Mauerlat

Rafters are the most essential part of the roofing skeleton. The legs of the rafters transmit thrust to the Mauerlat and the load-bearing walls of the house. What determines the quality of the entire rafter system and the roof as a whole? Experts remind that the reliability of any roof structure will depend, first of all, on the quality of fastening the rafters to the Mauerlat. What principles and features of this process every novice builder should know and how to fix the rafters to the Mauerlat with your own hands, you will learn right now.

Fastening rafters to the Mauerlat: a little "materiel"

To begin with, we propose to consider an illustration that shows two types of truss systems:

The place of attachment of the rafter leg with the base is called the support node. There are many such nodes in the system, but we will touch in detail on the lower fasteners of the frame with rafters. Mauerlat and rafter legs are almost always made of wood, less often of metal. It is more profitable and convenient to use wood, as this material is light in weight, easy to install and durable with proper installation and operation.

Types of support nodes according to the level of rigidity

Support nodes - places where the rafters are attached to the roof elements:

In the case of iron joints, the nodes are fixed, rigid (welds or bolts). Wood is a softer and more dynamic material that can swell, dry out and deform. In this regard, experts recommend performing support nodes, adjusted for possible changes in the shape of the wood. Such nodes can have different degrees of mobility:

• Zero Mobility Node- rigid fastening with corners on both sides, in which the fastening of the rafters to the Mauerlat remains motionless.
• Connection of the first degree of mobility- the beam can rotate in a circle.
• Connection of the second degree of mobility- circular rotation with offset, the installation of special sliders or sleds is provided.
• Movable connection of the third degree– the possibility of horizontal, vertical and circular movement.

For any node, whether it is movable or not, at least two types of fixation should be used. For example, notched planks are additionally fixed from the inside with a support beam, while dynamic connections are strengthened with bolts and special steel angles.

About the types of fasteners for rafters to the base

Let's talk about modern fasteners. For the strength and durability of the support units, a variety of metal fasteners are used: beam holders, equilateral, fastening, anchor, reinforced corners, plates, supports, profiles, connectors, anchors, etc. All these spare parts are made of high-quality metal. For dynamic nodes (types 1, 2 and 3), sliders, corners and perforated plates are used. For rigid fastening, stationary connectors, anchors and corners are used.

Such fasteners for the truss system are most often used:

For self-assembly, more than others, perforated mounts are suitable, as they have many holes for self-tapping screws and bolts.

Rigid or movable connections: what to choose

So, we noted that the support nodes connecting the Mauerlat with the boards can be of varying degrees of mobility: from "0" to "3". Zero degree - these are rigid fasteners that exclude any changes in the position of the beams.

Rigid connections: when you need them

Mauerlat is installed when it is necessary to transfer the spacer load from the rafters to the load-bearing walls. This is done mainly in houses made of bricks, panels and blocks. In this case, they try to exclude deformation and shrinkage of the roof in order to prevent changes in the load on the supporting walls. This is where the need for a fixed connection of the truss system with the Mauerlat appears.

Fixed knots fixed with gash

Many experts recommend making appropriate cuts at the point where the rafters are attached to the floor beams for greater strength and immobility of the connecting nodes. These cuts should fit snugly with the Mauerlat. Additionally, such nodes are strengthened with bolts, anchors and metal plates:

Or with long screws:

And one more important point: the size of the washed down bar should not exceed 1/3 of its section. Otherwise, the rafter system may lose its bearing capacity:

Rigid knots without notching rafters

The fastening method using a hemmed bar is used in layered truss systems. The rafter is cut according to the template and beveled (to give the roof the desired slope) at the point of contact with the Mauerlat. From the inside, such rafters are reinforced with supporting bars and reinforced with corners on both sides to the base frame:

Another option for a non-butt joint is a rigid fastening of the rafters, reinforced with overlay bars on both sides. Two boards at least a meter long border each rafter leg. One end of such supports is cut at an angle that corresponds to the slope of the roof slope (including rafters). The boards are fastened with a cut to the Mauerlat using long bolts and reinforced steel corners. The bars are attached to pre-marked places, first one at a time. Then, close to the overlays on one side, the rafters themselves are mounted, which are immediately reinforced with the same overlay on the other side. There is an option to install two overlay bars at once, and after that, rafters, but this method is used less often, since it requires more accurate calculations.

When do you need to make mobile connections?

So we come to dynamic reference nodes - connections that can change their position. What is it for? We recall the physical properties of materials - many of them shrink or swell. First of all, this applies to buildings made of pure wood - timber, log house, etc. Natural wood necessarily shrinks, due to which your roof can not only be deformed, but also completely destroyed. To avoid such fatal consequences, the masters recommend performing sliding fastenings of the rafter legs with a Mauerlat (or the upper crown of the log house).

A prerequisite for the installation of sliding nodes is the support of the truss frame on a strong ridge beam. Since the supporting lower nodes are dynamic, the maximum rigidity must be achieved at the roof ridge. The upper edges of the rafters are sawn for a tight connection between themselves and the ridge beam, connected and reinforced with crossbars, metal tapes, plates and corners. It is better to connect a truss element already fixed in the ridge with the crown of the log house.

What is a sliding mount?

The movable connection is carried out by establishing sliding fasteners, called "sleds" or "sliders". Such a node provides for a certain freedom of the rafter legs, which helps prevent the deformation of the roofing system after the natural shrinkage of wooden structures:

Here are the types of sliding supports:

Do I wash down on the rafters if the house is made of timber: an alternative expert opinion

I propose to still file down, but not the rafters, but the upper crown. Firstly, in this case, the risk of curvature of the rafters is reduced, secondly, the “cold bridge” decreases, thirdly, the tangential pressure on the Mauerlat (the upper beam of the log house) decreases, and fourthly, roof insulation is simplified in the future. The disadvantage of this method is that when the upper crown of the beam is cut down, the height of the ridge decreases, therefore, if in the future it is planned to raise the height of the ceiling, one more crown should be provided. But! Such schemes are only suitable for wooden houses, since in brick and concrete buildings the mauerlat must be intact in order to maintain load-bearing qualities.

How to fix the rafters to the beams?

In simple houses, mostly frame houses, the Mauerlat can be abolished. In this case, the rafters are attached to the floor beams. The most reliable option for assembling such a system is the preparation of roof trusses. Each truss consists of two rafter legs, a connecting crossbar and a lower puff. For strength, the trusses are reinforced with central beams and struts:

Floor beams are laid in such a direction that the roof trusses cross them perpendicularly in different planes. The puff performs the main load-bearing functions, is attached to the floor beams with anchors, through bolts, studs and is reinforced with plates and metal corners.

It is possible to attach the rafter legs directly to the beam, which will additionally perform the functions of tightening. To create high-quality support nodes in such a system, two methods of fastening are recommended:

1. The connection of the rafters with the beam with a double tooth - the cuts are made on the beam and the bevel of the rafter leg (two butt notches on each).
2. Bolt and clamp fastening. Through fastening may be provided, but if the boards have a large cross section, cuts are made and the parts are connected with long bolts.

Fastening the rafter to the Mauerlat: a step-by-step description

For example, we will describe the process of rigidly attaching rafter joints to the Mauerlat on a simple gable roof.

I. Preparation of the Mauerlat and rafters for work

At this stage, it is necessary to cut out the rafter legs of a given length and mark their step on the basis. The optimal step length of the rafter legs is 60-200 cm. You should also accurately determine the angle of inclination of the rafters.

Mauerlat installation master class:

II. Creating a gash

We carry out washed down on each rafter leg for a tight connection with the base. To enhance strength, you can provide an additional notch on the frame or rafter and install a thrust beam under each rafter leg.

III. Installation of rafters on the Mauerlat

It is necessary to impose rafters carefully so as not to damage other elements of the building (windows, walls, etc.). We start the boards with a cut on the beams and rest them on the ridge beam. First, we install the extreme rafter legs, between which you need to stretch the thread to align all the other rafters.

IV. Fastening each rafter to the Mauerlat

Now that all the trusses are in place, you need to firmly fix the support nodes. We use several of the mounts proposed above for this:

• Nails+ steel corners on the left and right side of the joints between the board and the base.
• Through bolts or studs+ support bar for cutting the rafters.
• Anchors or bolts+ corners or steel plates, etc.

Two overhead boards on both sides of the rafter leg, installed on pre-marked places of the Mauerlat, will help to strengthen the fastening. You can also use wire fastening as a reinforcement of the strength of the connections. To do this, you need to prepare a steel wire twist of 2-3 wires. Its length should be enough to wrap around the rafter leg at the junction with the Mauerlat and fix the ends of the twist on a metal crutch. As a crutch, you can take a long steel bolt, which is mounted into the wall 30-40 cm below the Mauerlat, strictly under the support node.

We will also consider one of the old-fashioned ways - fastening with brackets:

And finally, we invite you to watch the video:

What is the secret of the quality of the truss system: the three main rules of the master

• High-quality lumber is half the battle on the way to successful construction. Mauerlat and rafters should not have cracks, wormholes and knots.
• The accuracy of measurements, cuts and the uniformity of the position of the fasteners is no less important. If all rafter legs are of the same length and section, then it is better to prepare a template for making cuts and notches.
• Washed down on the Mauerlat - loss of the supporting functions of the base by 50% or more. The percentage of strength reduction depends on the depth of the notches.

When the rafter system is ready, it is the turn of the installation of the crate, insulation and flooring of the roofing material. But this is another interesting topic, which we will definitely cover in the next article. In the meantime, we wish you good materials, easy work and good helpers!

We have already talked about the hip roof on the site. There was described the design of the roof with the support of the rafters on the Mauerlat. After the publication of the article, I received many requests to show how to make a hip roof with rafters resting on floor beams, and also to answer the question of whether it is possible to make a hip roof with different slope angles.

Thus, I wanted to “kill two birds with one stone” with one example. Now we will consider the construction of a hip roof with rafters resting on floor beams and with different slope angles.

So, let's say we have a house box of 8.4x10.8 meters.

STEP 1: Install the Mauerlat (see Fig. 1):

Picture 1

STEP 2: We install long floor beams with a section of 100x200 cm in increments of 0.6 meters (see Fig. 2). I won't dwell on it anymore.

Figure 2

The very first we put beams that run strictly in the middle of the house. We will navigate along them by installing a ridge beam. Then we put the rest with a certain step. For example, we have a step of 0.6 meters, but we see that 0.9 meters are left to the wall, and one more beam could fit, but it does not. We leave such a span especially for "removals". Its width should not be made less than 80-100 cm.

STEP 3: Installing takeaway. Their step is determined when calculating the rafters, about which a little later (see Fig. 3):

Figure 3

For now, we only put the extension corresponding to the length of the skate, which will be equal to 5 meters. The length of the ridge is greater than the difference between the length and width of the house, which is 2.4 meters. What does this lead to? This leads to the fact that the corner rafter will not be located at an angle of 45 ° in plan (in the top view), and the angle of inclination of the slopes and hips will be different. For slopes, the slope will be more gentle.

It is enough to fix the removal on the Mauerlat with nails. We attach them to a long floor beam, for example, like this (Fig. 4):

Figure 4

There is no need to make any cuts in this knot. Any washed down will weaken the floor beam. Here we use two LK-type metal rafters on the sides and one large nail (250 mm) driven through the beam into the end of the stem. We hammer the nail with the very last one, when the stem is already fastened to the Mauerlat.

STEP 4: We install the ridge beam (see Fig. 5):

Figure 5

All elements of this design, except for the struts, are made of timber 100x150 mm. Struts from a board 50x150 mm. The angle between them and the overlap is at least 45°. We see that under the extreme racks there are bars resting immediately on five floor beams. We do this to distribute the load. Also, to reduce the load on the floor beams and transfer part of it to the load-bearing partition, struts were installed.

We determine the installation height of the ridge beam and its length for our house ourselves, making a preliminary sketch on paper.

STEP 5: We manufacture and install rafters.

First of all, we make a template for the rafters of the slopes. To do this, we take a board of the desired section that is suitable in length, apply it, as shown in Figure 6, and make markings using a small level (blue lines):

Figure 6

The height of the bar, which we put on the takeaway for marking the lower gash, is equal to the depth of the upper gash. We made it 5 cm.

According to the template obtained, we make all the rafters of the slopes, based on the ridge beam, and fix them (see Fig. 7):

Figure 7

In such structures, where the rafters do not rest on long floor beams, but on short extensions, we always put small supports under the rafters above the Mauerlat, forming, as it were, a small triangle and unloading the attachment point of the extension to the beam (see Fig. 8):

Figure 8

It is not necessary to bring these supports further inside the roof, and even more so to put them at the junction of the removal with the beam. Most of the load from the roof is transmitted through them (this can be seen in the calculation program) and the floor beam may simply not withstand.

Now a little about the calculations. When choosing a section of rafters for a given roof, we calculate only one rafter - this is the rafter of the slope. It is the longest here and its angle of inclination is less than the angle of inclination of the hip rafters (explanation - we call a roof slope in the form of a trapezoid a slope, a hip - a roof slope in the form of a triangle) Example results in Figure 9:

Figure 9

Yes, I forgot to say. Who has already downloaded this calculation program from my website before December 1, 2013. There is no ʺSling.3ʺ tab. To download the updated version of the program, go to the article again at the link:

This article has also been slightly corrected due to feedback from some readers, for which special thanks to them.

STEP 6: We add the takeaway and fasten the wind boards (see Fig. 10). We add enough offsets so that there is room for attaching the corner offset. Wind boards at the corners are just stitched together, controlling their straightness. Check visually for sagging corners. If so, put temporary props under them directly from the ground. After installing the corner offsets, these supports are removed.

Figure 10

STEP 7: We mark and set the corner offset.

To begin with, we need to pull the cord along the top of the floor beams, as shown in Fig. 11

Figure 11

Now we take a beam of a suitable length (the cross section is the same as for all extensions) and put it on top of the corner so that the lace is in the middle of it. From below on this bar with a pencil we mark the lines of cuts. (see fig. 12):

Figure 12

We remove the lace and install the timber sawn off along the marked lines (see Fig. 13):

Figure 13

We attach the corner offset to the Mauerlat with the help of two roofing corners. We fasten it to the floor beam with a 135 ° corner and a large nail (250-300 mm). Corner 135 °, if necessary, bend with a hammer.

Thus, we put all four corner offsets.

STEP 8: We manufacture and install corner rafters.

At the hip roof, which I described earlier, the angles of inclination of the slopes and hips were the same. Here, these angles are different and therefore the corner rafter will have its own characteristics. We also make it from two boards of the same section as the rafters. But we sew these boards together not quite usually. One will be slightly lower than the other (about 1 cm, depending on the difference in the angles of the slopes and hips).

So, first of all, we pull 3 laces on each side of the roof. Two along the corner rafters, one along the middle hip rafter (see Fig. 14):

We measure the angle between the lace and the angular offset - the bottom washed down. Let's call it "α" (see Fig. 15):

Figure 15

We also mark the point "B"

We calculate the angle of the upper gash β = 90°- α

In our example, α = 22° and β = 68°.

Now we take a small piece of board with a rafter section and saw down one end on it at an angle β. We apply the resulting blank to the ridge, combining one edge with the lace, as shown in Fig. 16:

Figure 16

On the workpiece, a line was drawn parallel to the side plane of the adjacent slope rafter. On it, we will make another gash and get a template for the upper gash of our corner rafter.

Also, when we apply the workpiece, it is necessary to mark point “A” on the rafter of the slope (see Fig. 17):

Figure 17

Now we make the first half of the corner rafter. To do this, take a board of suitable length. If one board is not enough, we sew two boards. You can temporarily sew it by trimming an inch about a meter long into self-tapping screws. We make the upper washed down according to the template. We measure the distance between points "A" and "B". We transfer it to the rafters and make the lower washed down at an angle "α".

We install the resulting rafter and fix it (see Fig. 18):

Figure 18

Most likely, due to its length, the first half of the corner rafter will sag. It is necessary to put a temporary stand under it approximately in the middle. It is not shown in my drawings.

Now we make the second half of the corner rafter. To do this, we measure the size between the points "C" and "D" (see Fig. 19):

Figure 19

We take a board of suitable length, make the top cut at an angle β, measure the distance "C-D", make the bottom cut at an angle α. We install the second half of the corner rafter and sew it with the first nails (100 mm). We drive the nails into a run-up after about 40-50 cm. The result is shown in Fig. 20:

Figure 20

The upper end of the second half of the corner rafter must be cut down again. We do this with a chainsaw right in place (Fig. 21):

Figure 21

In the same way, we make and install the three remaining corner rafters.

STEP 9: We install racks under the corner rafters. First of all, it is imperative to put a rack resting against the junction of the corner offset with the floor beam (see Fig. 22):

Figure 22

If the length of the span covered by the corner rafter (its horizontal projection) is more than 7.5 meters, we put more racks at a distance of about ¼ of the span from the top point of the corner rafter. If the span is more than 9 meters, add racks in the middle of the corner rafters. In our example, this span is 5.2 meters.

STEP 10: We install two central rafters of the hips. At the beginning of the 8th step, we already pulled the laces to measure them.

We make the rafters in this way - we measure the angle of the lower gash "γ" with a small one, we calculate the angle of the upper gash "δ":

δ = 90° - γ

We measure the distance between the points "K-L" and make a rafter along it. We cut the ends at the corners we have determined. After that, the upper end must be sawed again (sharpened) taking into account the angle "φ", which is also measured using a bevel (see Fig. 23):

Figure 23

STEP 11: Adding takeaway to the corners. We make the most extreme extensions, which do not reach the Mauerlat, lightweight, from a board 50x200 mm (see Fig. 24):

Figure 24

STEP 12: We install the guards. How to make sprigs, I described in detail in the first article about. Here the principle is absolutely the same, so I will not repeat myself (see Fig. 25):

Figure 25

We fasten the sprigs to the corner rafter using a 135 ° metal corner, bending it if necessary.

After installing all the sprigs, it remains for us to hem the cornices from below and make a crate. We have already talked about this many times.

The layered rafter system can be a spacer or non-spacer structure. It depends on the correct choice of the support nodes and the articulation of the rafter legs whether the rafters will burst the walls or not, it is necessary to provide for various measures under them to intercept the thrust or not.

On the design diagrams in the nodes of the structures, circles are drawn, indicating a hinged connection. The hinges are connected by paws to conditional supports, which can be used to visually represent the degree of freedom of the assembly.

A hinge with two paws embedded in the support assumes that the node is stationary, but the beam can rotate in the hinge, that is, the node has one degree of freedom - rotation. A hinge with paws standing on a sliding support or slide shows that the assembly has two degrees of freedom - the possibility of beam rotation and horizontal displacement.

The three degrees of freedom of the knot allow horizontal, vertical displacement and rotation, such a knot is simply drawn as a circle and can be cut into a bar representing a beam. If the node is cut into the beam, then it is called a split one, that is, the beams located to the left and right of the hinge, with some assumptions, can be considered as separate elements.

If a circle (hinge) is drawn under a beam, then the beam lying on it is called continuous. The 3-DOF hinge embedded in the beam, in many cases, makes it an instantaneous system, i.e. a rather unstable structure. A node with a zero degree of freedom means a rigid pinching of the end of the beam and prohibits it from any displacement: horizontal, vertical and rotation (Fig. 19).

Rice. 19. Examples of a schematic representation of nodes

In the design schemes, other schematic representations of nodes can also be used, but they are all generally understandable, and if ambiguities suddenly arise, you just need to mentally imagine in which direction the node can “go” when a load is applied to it. The transverse dimensions of the beams relative to their length are small, so the beams (rafters, etc.) are drawn as rods, and the load in them is distributed, as it were, only along the longitudinal axis of the element, and the calculation of the entire structure is carried out for the rod scheme.

It should be noted that the words: horizontal displacement and rotation do not mean at all that, for example, a slider - a node with two degrees of freedom moves arbitrarily in a horizontal direction.

In fact, this node is quite well fixed, but allows the possibility of moving the end of the beam from the load, temperature and humidity changes without excessive development of internal stresses in it. This node simply does not transmit thrust, and rotation when bending the beam is possible only within the normative limits. In fact, the crawler will crawl (sorry for the tautology) only when loads exceed the maximum allowable. The word "hinge" also does not need to be taken literally.

Yes, the ends of the beams can be connected with a bolt or a real specially designed hinge, but, most often, this is a simple nail connection. For example, you can take a board and nail it at one end with 3-4 nails, let's say, to a wooden wall. Nothing prevents us from taking it by the other end and calmly turning it around a certain angle.

In this case, the nail fastening acts as a hinge. However, if the number of nails is increased and calculated for a load that does not allow shear (bending), then rotation becomes impossible, here we get a beam with a pinched end, but when the load exceeds the calculated one, the node again becomes a hinge.

Therefore, it is very important to initially determine the load under which the system will work. Since the excess of the actual load in excess of the calculated one, leads to a change in the scheme of operation of the nodes and the destruction of the entire structure. The joints of the layered rafters related to various schematic representations of the nodes are shown in Figure 20.

Rice. 20.1. Support nodes for rafters on the run and Mauerlat. One degree of freedom hinge (pivot only)
Rice. 20.2. Support nodes for rafters on the run and Mauerlat. Slider - hinge with two degrees of freedom (rotation and shear)
Rice. 20.3. Knot supporting the rafters on the run. Hard pinching

Depending on the problem being solved, when designing the roof, the nodal joints of the rafters may be different from those shown in Figure 20. The main thing is to design in nodes with two degrees of freedom: a turn arising from the bending of the rafters and a shift in the horizontal direction. And in nodes with one degree of freedom - the rotation of the rafters. As a rule, the shift of the top or bottom of the rafters is provided by horizontal cuts, and the shift is limited by the emphasis of the rafters into each other and / or into the joined element: Mauerlat or run.

It is likely that for people who are not related to engineering professions, but who remember the principle of decomposing the inclined force vector into a horizontal and vertical axis from a school physics course, it is difficult to understand where the horizontal component goes in the lower part of the rafter leg. Let's try to explain the principle of a non-thrust system using an example. We can all easily imagine an ordinary ladder. The ladder is like a ladder, nothing special, two poles (strings) and transverse sticks-steps.

Let's mentally attach such a ladder to the wall, and for the purity of the experiment, we will pour oil on the floor and wall. What happens if you load the ladder - climb on it? The stairs will collapse. It has two degrees of freedom in the lower and upper supports. At the bottom it has a rotation and a horizontal offset, at the top it has a rotation and a vertical offset.

What needs to be done in order for the ladder to become stable in this oil-drenched environment and hold the load - the weight of a person? And you just need to deprive it of one (out of four) degrees of freedom: horizontal in the lower or vertical in the upper support. In other words, you need to fix the bottom or top of the stairs. When fixing the top of the ladder, the expansion from the expansion of the inclined force acting along the longitudinal axis of the ladder remains at the top and acts on the wall, but it is not at the bottom.

If we put the same ladder on the other side of the wall and load it with the same weight, we will get a thrust in the upper part equal to the thrust from the first ladder, but directed in the opposite direction. These horizontal forces cancel each other out. We get a stable and stable system.

You can think of a thought experiment with a ladder in oil by putting it in different situations, for example, if the ladder is long and rests on the wall from above with bowstrings with horizontal cuts or without cuts. How will she behave?

It is quite interesting to make such a brainstorming session, which helps in understanding the operation of layered rafters with various support methods, in which it is not at all necessary to imagine the force vectors and degrees of freedom of the nodes, but simply to predict whether the staircase will roll along a horizontal plane or remain motionless due to the absence of a horizontal component of the force.