Ridge run. Splicing rafters in the ridge area: splice rafters along the length and installation methods in the ridge area

When building a house, there are practically no elements or connecting nodes that would not be particularly important, since the overall reliability of the structure in one or another of its areas depends on each of them. . Splicing the rafters in the ridge area is enough difficult task which can be done different ways... The master usually chooses the most reliable of them, applicable for a particular structure.

It should always be remembered that any mistakes made during installation work during the construction of the roof structure, ranging from rafter system and ending with roofing material, sooner or later will negatively affect the quality of the entire building. Therefore, when drawing up a house project, it is imperative to think over the connection of each of the nodes. And it is especially important to choose a reliable fastening of the rafter legs when forming the ridge.

A few words about the basic design of the rafter system

First of all, a few minutes of attention should be paid to general structure rafter system in order to remember what its main elements are called, since in the further description of installation work they will be encountered quite often.

Mauerlat - This is a bar fixed to the load-bearing wall. It serves to secure the lower side of the rafter leg on it, and for uniform distribution loads from the entire roofing system to the walls.

Mauerlat - a reliable basis for the rafter system

This element of the rafter system must be correctly selected and fixed on the wall, since the reliability of the installation of all other load-bearing parts depends on this. How to install - described in detail in the corresponding publication of our portal.

Rafter legs or just rafters - they form the frame of the slope, fixed on the Mauerlat in the lower part, and on top - on the ridge run or between themselves, forming a ridge.
Ridge run fixed on a rack supported by struts. It is designed to rigidly attach the rafters.
Tightening Is a horizontal bar that additionally connects a pair of rafter legs, giving the structure additional rigidity. Tightenings are of particular importance in hanging truss systems, when it is impossible to create intermediate supports on the main walls. Ties placed between two Mauerlat beams are often used as beams attic floor... Installed closer to the ridge - they can serve as the basis for filing the ceiling of the attic.
Braces and help - These are reinforcing elements designed to give the truss of the truss system additional rigidity and strength. Usually used in cases where it is required long length rafter legs, more than 5 ÷ 6 meters.

Rack It is used as a support for a ridge run and is most often installed in each of the trusses if a layered rafter system is being erected, which has additional supports in the form of capital intra-house partitions.
Lezhen - This is a beam that is laid on the load-bearing partitions of a house and is designed to secure racks or struts on it.

The importance of the correct fastening of the rafters on the ridge

An element such as a ridge is present in the design of most types of roofs. He is not in the tent, vaulted and

rafter mount

The ridge is the highest point of the roof, at which the elements that form the slopes - the rafters - are connected. Therefore, the main mission of the ridge knot is to give the entire rafter system strength and rigidity. From how correctly the fastening is made, the operation of the roof structure will become longer without the need for repairs.

The main methods of installing rafters

Installation on load-bearing walls structures can be produced in various ways, which you need to be aware of before choosing the type of connections for the bearing elements of the slopes on the ridge:

The rafters and the brace are connected in a triangle on the ground, and then rise to the box of the house in finished form, where they are fixed on the Mauerlat laid on the walls. Installed trusses are interconnected by side slopes or a ridge run.

On the ground, two extreme triangular trusses are assembled, which will go to the end, pediment sides of the structure. Then they go up and are fixed on the Mauerlat. The upper ridge corners of two opposite trusses are connected by a stretched cord, which becomes a kind of level along which the rest, middle rafter pairs, assembled already in place, will be exposed. After that harvested farms connected by a ridge run.

All elements are individually lifted onto the floor and assembled at the place of their installation. In this case, on end walls, centered, installed vertical posts defining the height of the skate. Then the racks are connected to each other by a ridge run, on which the rafter legs are fastened.

If the rafters are connected on a run, then they do not require control with a pull cord. Therefore, the racks and the girder must be set very carefully, in level and plumb line, at right angles to each other.

Varieties of rafter joints on the ridge

As mentioned above, there are several ways to mate the rafters when forming a ridge, and different fasteners are used for this purpose.

The main options in private housing construction include three types of connections:

A cut "in half a tree", when half of its thickness is selected at the edges of the rafter bar. These selected sections are superimposed on each other and fastened with one of the fasteners suitable for this case, for example, twisted with a bolt passed through.

Overlap - the ends of the rafters are superimposed on each other and fixed to each other by a through fastening element.

By trimming the end sides of the rafters - this method of joining is performed most often. It is carried out by overlapping the rafters, then they are trimmed at the same time. This is how even cut two rafters at the same angle in the mirror image, so they fit perfectly together.

It should be noted that there are other ways of joining, for example, "tongue-groove" or butt to the ridge girder, possibly with fastening to the girder for additional strength between the rafters of additional bars or boards.

Often one of the sides of the rafter leg, top or bottom, is fixed on movable mounts, hinged (top) or sliding (bottom). This is important to provide in cases where the roof is installed on a newly built, new house, especially - log cabin... This approach is due to the fact that in the first years of operation, the structure usually shrinks, and if a rigid fastening is applied, then the roofing structure can be damaged, deformed, as the "geometry" of the system will change, and the distribution of loads will be disturbed.

Read the advice of professionals, which one is better to choose, in our new article on our portal.

Elements for fastening rafters on the ridge

There are many options for fastening rafters to each other or on a ridge run - they can be rigid or hinged. To determine their choice, you need to know what they are and which rafter connections are suitable.

To fix the rafters in the ridge area, they use fasteners such as overlays made of metal or wooden plates, timber, metal corners of various configurations, staples, movable fasteners, wooden wedges, nail plates. These fasteners are held in place with self-tapping screws, screws, bolts and nails. The choice of fasteners mainly depends on the chosen connection design.

Bolt fixing

Fixing the rafters on the ridge with one bolt allows them to move to one side or the other relative to the axis when the structure shrinks. If such a mount is applied in the upper part, the lower side of the rafter leg must be rigidly mounted on the Mauerlat.

In the above diagram, under the first number, the connection of the rafters by the "groove-thorn" method and fastened with a bolt is shown, allowing them a small play relative to each other when the building shrinks.

It should be especially noted that this way will fit for light cold roofs, which will not be weighed down by a large load, since the rafters in the fastening unit are somewhat weakened by the cutouts for the groove-tenon connection and the through hole drilled in them.

The sixth figure of the diagram also shows the fastening of the rafters with a bolt, but in this case they are installed with each other "overlapping", and on the run - by the cut-in method. This method of bonding gives a smaller offset range, but it is still possible within certain limits. In this version, the rafters are less weakened, since they do not have cutouts for the connection and can withstand a large one. Nevertheless, it is still not recommended to use such a connection technology for roofs with large area stingrays.

If you plan to make a rigid fastening of the rafter legs fitted in the end part with bolts in the ridge part, then two fasteners are used, installed in through holes, through two metal plates that are mounted on both sides of the connection.

If you want to make the connection of the overlapping rafters and fixed with one bolt rigid, additional fasteners are used - metal corners fixed to the ridge girder.

Fastening rafters with plates

The above diagram, numbered two and three, shows options for rigid fastening using metal plates and wooden plates. In this case, it is very important correct location additional elements. A similar method of fastening is used when the rafters are joined end-to-end by trimming and fitting their edges, as well as when installing the rafters on a ridge girder.

Perforated metal plates are fixed to the rafters with nails, screws or bolts. For rigidity of the connection, the rafters can be additionally attached to the purlin using metal corners. This type of fixation is strong enough and can be easily used for the installation of roofs with a large area and load.
Wooden linings are more reliable, since they work not only as fasteners, but also as tightening the rafters together.

If it is supposed to make a reinforced version of fastening, for roofing, having a lot of weight, the rafters are fastened with two rows of linings, between which the ridge girder is pinched. This method of fixing rigidly holds the rafters in the area of the ridge, but in this case, a sliding connection must be installed on the Mauerlat, which will avoid deformation of the system when the structure shrinks.

wood screws

A separate line can be used to highlight the fastening of the rafters on the ridge with a triangular overlay that repeats.

This fixation method gives high degree fastening rigidity, but if the slopes have large area, then additionally the rafter legs are connected with puffs. They are located below the ridge connection, and they are designed not only to stiffen the structure, but also to remove part of the expanding load from the rafter system from the bearing walls.

These elements can also act as a frame for ceiling sheathing if it is planned to equip a living or utility room in the attic.

The pads and braces can be fixed to the rafters with nails or self-tapping screws.

Fastening the rafters with a cut

This method of securing is shown in the diagram above with the fourth and fifth numbers. With this approach, cuts are made on the rafters to fit the width of the ridge run. The cutouts are made 5 ÷ 7 mm wider than the purlin width, since it is necessary to provide a distance for temperature and humidity expansion. The cut can be used in combination with other fasteners, for example, "overlap", "groove-thorn", overlays and metal corners.

Hinged rafters

This method of connecting rafters is rarely used in construction, although it is quite convenient in installation and allows you to balance the rafter system when the load-bearing walls shrink. In this method, you do not have to adjust the angle of the rafter legs, since it can be formed using a hinged mount. It is fixed between the rafters at the required distance, which will depend on the slope angle of the roof slopes. The bolt acts as a hinge, which fasten the rafters after installing them on the girder at the desired angle.

Fastening rafters with nail plates

In addition to the elements mentioned above, nail plates are used to fasten the rafters to the ridge connection.

However, they can only be used when the trusses are assembled in a lying position on the ground, and are already ready-made installed on the Mauerlat, since this type of plates is fixed on the rafter legs using a special press. This process is almost impossible to carry out by weight, in an upright position.

Using this bonding method wooden parts, you can significantly speed up the installation process, but for this you will have to purchase or rent a special press.

screwdriver

In this way, not only the rafter legs are fastened, but also other structural elements. Nail plates help to significantly save money on screws, bolts or nails, since a lot of these fasteners will have to be purchased, given the number of connecting nodes in the rafter system.

In addition to these fasteners, metal corners and brackets are used as auxiliary the right size, driven into both rafters at once on their ridge part. However, it is necessary to work with brackets extremely carefully, since they can easily split the rafter beam.

Splicing rafters on different types of roofs

Now, having familiarized yourself with the main methods of connecting and fastening rafter legs on the ridge, then you should consider what types of them are used for the installation of various rafter systems.

Gable roof system

Splicing rafter legs in a gable roof system can be done:

- Butt, that is, they abut against each other, and in this case, their ends are adjusted using trimming;

- Fixed on a ridge run on both sides.

If the rafters are connected end-to-end, then they are usually fixed together with overlays, which are screwed with self-tapping screws or bolts.

If the rafters are fixed on a ridge run, then they are fixed on it with metal corners, corner brackets or overlays screwed using self-tapping screws.

This diagram shows a design with two purlins:

1 - Rafter legs.

2 - Racks.

3 - Tightens (crossbars).

4 - Runs.

5 - Mauerlat.

6 - Beds.

The rafter legs of the gable rafter system can be supported by two girders fixed on racks that are installed and fixed on the racks. For the spacer effect of the structure, tightenings (crossbars) are also applied. All these elements firmly hold the rafter legs, removing the main load from the ridge, so the rafters can be overlapped or with a tongue-and-groove connection.
If the rafter system is assembled without using a girder, only by joining the butt ends of the rafter legs, then in addition they must be supplied with one or two pairs of pads, which are fixed to the rafters with nails, screws or bolts.
To fasten the rafter leg with the crossbar, when installing it end-to-end, side wooden or metal strips are used, and nail plates can also be used if the truss is assembled in advance.

If the rafter legs are made of logs, then they are fastened to the crossbar without the use of overlays. For connection at the ends of the crossbar, recesses are made by ½ of their thickness, then they are pressed against the rafters and fixed with nails or self-tapping screws. Additionally, such rafter legs are reinforced with struts. This is especially important to take into account if the distance between the load-bearing walls is more than 7000 mm.
Corner brackets are used for more reliable fixation of rafter legs on a ridge run in buildings located in regions with strong winds. The brackets will help prevent possible displacement and deformation of the elements of the rafter system.

Rafters from logs are made only with reliably reinforced, having a large thickness of load-bearing walls, since the entire rafter system from them will turn out to be quite massive. If it is planned to use this particular material for the structure, then it is recommended to make accurate calculations the bearing capacity of the walls and the system itself, and it would be best to entrust them to specialists.

Another point that must be taken into account when drawing up a roof project and during its installation is that the steeper the roof slopes, the stronger the horizontal reinforcing elements of the structure should be. And, conversely, if the roof slopes are at a slight angle, then special attention should be paid to the strength of the vertical retaining elements of the rafter system.

Hip and half hip roof

There are two similar designs - this is a half-hip rafter system. They differ in the configuration of the end slopes: if the first one is equipped with two full hip slopes, from the ridge to the level of the cornice, then in the second the slope ends above the level of the cornice or is crowned on top with a small triangular vertical pediment.

The fastening of rafters in the ridge girder in both structures has its own characteristics, somewhat different from the usual gable roof. Complicate the installation of these truss systems additional elements forming the hips - slant legs or diagonal rafters. In addition, in addition to the usual rafter legs, which in this design are called central and intermediate, shortened ones (napkins) are installed parallel to them.

If a hip roof is selected, the ridge size will be less than the length of the building. According to the "classical" scheme, with equal angles of steepness of the side and hip slopes, the length of the ridge will decrease by the width of the building. The eaves side of the side slopes will be equal to the length of the wall, excluding the overhangs. Thus, the side ramps will have a trapezoidal shape, and the end hips will be triangular.

In such roofs, the installation of a ridge girder (console) differs from the standard design, since the load on it will be much higher than in a conventional rafter system with two slopes.

The support racks, on which the purlin will be fixed, must be installed on a bed, laid and fixed on a capital internal partition or on powerful floor beams. The rafter leg extreme to the hip in this design is fixed on the girder, with an indent from the edge of 150 ÷ 200 mm. This distance will depend on the width of the diagonal rafters, which must be attached to this section of the purlin end-to-end with the extreme rafters of the trapezoidal part of the roof. Like connector knot- is rather difficult to self-adjust, and the corners of the elements converging on it must be carefully calculated and adjusted by trimming.

The Mauerlat in the hip and half-hip roof structure is necessarily laid along the entire perimeter of the building box, representing a single, rigidly connected frame, since this is necessary to fix the hip elements and evenly distribute all loads on the walls.

Diagonal (oblique) rafters that form the edges of the hip should have a notch in the form of a step along their entire length on both sides, or mounted cranial bars. This is necessary to simplify the fastening of the shortened rafter legs of the hip - Since the diagonal rafters are of a greater length than the central ones, and the maximum load falls on them, they are often made of two boards, fastening them together. Skull bars on diagonal rafters are fixed with nails or self-tapping screws.

Work on the installation of hip elements is carried out in the following order:

The finished diagonal rafters are installed and fixed by the cutting method on the edge of the ridge girder and to the central rafters of the gable part of the structure. The underside of the rafters is fixed exactly at the corner of the building on the Mauerlat. Fastening can be done with metal corners and angle brackets.

The next step can be the installation of two struts, which are fixed on the rack of the main rafter system with one edge, and on inner sides diagonal rafters, at a level of approximately ⅓ of the length from the upper attachment - different. Fastening is carried out using metal corners or pads and self-tapping screws (nails).

Further, if there is a need for this, the diagonal slant rafters should be reinforced from below with supports-supports fixed to the sprengel. A sprengel is a beam that is installed diagonally at the corners of the Mauerlat frame, on which the rack rests, supporting the slant rafters. These elements can be held together with metal corners or brackets.

The upper edge of the racks is cut off at an angle equal to the slope of the diagonal rafters, and fixed to them with self-tapping screws. If necessary, the rack can be additionally reinforced with struts fixed on it and on the sprengel.

Then, depending on the slope of the diagonal rafters, they are marked on them and fixed by cutting them onto the cranial bars. In the lower part of the structure, the handcuffs are fixed on the Mauerlat.

Calculation and installation of a hip roof is not an easy task!

If it is decided to build just such a roof, then you will have to work well both on the calculations and on the preparation of the necessary structural elements... Read more about it in a special publication of our portal.

The installation of any truss system is an extremely responsible event, since the durability of the entire structure as a whole depends on the quality of its installation. Therefore, if it is decided to do this work independently, then it is recommended to invite to assistants experienced master, which will not make gross mistakes that beginners often make.

At the end of the publication - a short video that shows the process of fitting and installing rafter legs.

Video: installing rafters on a gable roof structure

At the heart of each roof is a large number of beams, rafters, uprights and purlins, which are collectively referred to as the rafter system. Over the centuries-old history of species and methods of its organization, a lot has accumulated, and each has its own characteristics in the construction of nodes and cuts. More about what a rafter system can be gable roof and how the rafters and other elements of the system should be attached in more detail.

The structure of the gable roof truss system

In section, the gable roof is a triangle. It consists of two rectangular inclined planes. These two planes are connected at the highest point into a single system by a ridge bar (run).

Now about the components of the system and their purpose:

Mauerlat - a beam that connects the roof and walls of the building, serves as a support for the rafter legs and other elements of the system.
Rafter legs - they form the inclined planes of the roof and are a support for the lathing under roofing material.
Ridge girder (bead or ridge) - unites two roof planes.
Tightening is a transverse piece that connects opposing rafter legs. Serves to increase the rigidity of the structure and compensate for bursting loads.
Beds are bars located along the Mauerlat. Redistribute the load from the roof.
Side Girders - Supports the rafter legs.
Racks - transfer the load from the girders to the benches.

Filly may still be present in the system. These are boards that lengthen the rafter legs to form an overhang. The fact is that to protect the walls and foundations of the house from precipitation, it is desirable that the roof ends as far as possible from the walls. To do this, you can take long rafter legs. But standard length lumber of 6 meters is often not enough for this. Ordering a non-standard is very expensive. Therefore, the rafters are simply grown, and the boards with which they do it are called "filly".

There are quite a few constructions of truss systems. First of all, they are divided into two groups - with layered and hanging rafters.

With hanging rafters

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

The hanging type of gable roof rafter system is good because in most cases there is no need to install a Mauerlat, and this makes the installation of rafter legs easier: you do not need to make cuts, it is enough to mow the boards. To connect the walls and rafters, a lining is used - a wide board, which is attached to studs, nails, bolts, and crossbars. With such a structure, most of the bursting loads are compensated, the impact on the walls is directed vertically downward.

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

Gable roof rafter system for small houses

Exists cheap option rafter system when it is a triangle (photo below). Such a structure is possible if the distance between the outer walls is no more than 6 meters. For such a rafter system, you can not do the calculation by the angle of inclination: the ridge must be raised above the puff to a height of at least 1/6 of the span length.

But with this construction, the rafters experience significant bending loads. To compensate for them, either rafters of a larger section are taken or the cut of the ridge part is made so as to partially neutralize them. To give greater rigidity in the upper part, wooden or metal strips are nailed on both sides, which securely fasten the top of the triangle (also see not the picture).

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

The ridge knot and the fastening of the rafter legs to the underlay board when simple version systems

For mansard roofs

The option with the installation of the crossbar is used for. In this case, it is the basis for filing the ceiling of the room below. For reliable work systems of this type, the crossbar cut must be non-hinged (rigid). The best way- semi-oily (see the figure below). Otherwise, the roof will become unstable to loads.

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

With such a scheme, almost all the load falls on the rafters, therefore they must be taken of a larger section. Sometimes the raised tie is reinforced with a suspension bracket. This is to prevent it from bending if it supports the ceiling sheathing materials. If the tightening is short, it can be secured in the center on both sides with boards nailed to the nails. With a significant load and length, there may be several such belayings. In this case, too, planks and nails are enough.

For large houses

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

With such a long span (up to 14 meters), it is difficult and expensive to make an integral tightening, therefore it is made of two beams. It is connected with a straight or oblique cut (figure below).

For a secure fit, the joint is reinforced with a bolted steel plate. Its dimensions should be larger than the dimensions of the cut - the extreme bolts are screwed into solid wood at a distance of at least 5 cm from the edge of the cut.

In order for the circuit to work normally, it is necessary to make the braces correctly. They transmit and distribute part of the load from the rafter legs to the tightening and ensure the rigidity of the structure. Metal pads are used to reinforce the connections.

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

With layered rafters

In gable roofs with layered rafters, their ends rest on the walls, and in the middle part they rest on load-bearing walls or columns. Some schemes burst the walls, some don't. In any case, the presence of a Mauerlat is required.

Spreader-free schemes and cutting units

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

The simplest spreader-free diagram of the rafter system is shown in the photo below. In it, the rafter leg rests on the Mauerlat. In this version, it works in bending without bursting the wall.

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

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

It is much easier to assemble the version with rafter legs fastened in the ridge part. They almost never give space to the walls.

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

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

Reinforcement of the ridge knot for heavy roofing material or with significant snow loads

All of the above gable roof schemes are stable in the presence of uniform loads. But in practice, this practically does not happen. There are two ways to prevent the roof from sliding towards a higher load: by installing a scrum at a height of about 2 meters or with struts.

Variants of rafter systems with scrapes

Installation of scrapes increases the reliability of the structure. In order for it to work normally, in the places where it intersects with the drains, you need to fasten it to them with nails. The cross-section of the timber for the fight is used the same as for the rafters.

Attached to the rafter legs with bots or nails. Can be installed on one or two sides. See the figure below for attaching the scrum to the rafters and ridge girder.

In order for the system to be rigid and not "crawl" even under emergency loads, it is sufficient in this version to provide a rigid fastening of the ridge bar. In the absence of the possibility of its displacement horizontally, the roof will withstand even significant loads.

Systems of layered rafters with struts

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

The brace is simply placed at the required angle to the beams and nailed from the sides and bottom. An important requirement: the brace must be cut accurately and fit snugly against the uprights and rafter leg, excluding the possibility of its deflection.

Systems with rafter legs. Above the spacer system, from the bottom - non-spacer. The nodes of the correct felling for each are located next to each other. At the bottom - possible schemes strut mounts

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

Strut systems are necessary if significant uneven shrinkage of the foundation or walls is possible. Walls can sit in different ways on wooden houses, and foundations - on layered or heaving soils. In all these cases, consider the device of this type of rafter system.

System for houses with two internal load-bearing walls

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

In these systems, the ridge girder is not installed: it provides thrust forces. The rafters in the upper part are connected to one another (cut and docked without gaps), the joints are reinforced with steel or wooden lining, which are nailed.

In the upper non-thrust system, the tightening force is neutralized by the tightening. Please note that the tightening is placed under the purlin. Then it works efficiently (top diagram in the figure). Stability can be provided by uprights, or jointing - beams installed obliquely. In the spacer system (in the picture it is at the bottom), the cross member is the crossbar. It is installed over the purlin.

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

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

For fastening the uprights, 150 mm nails and 12 mm bolts are used. Dimensions and distances in the figure are in millimeters.

A special "ridge" in the skill of builders can be considered the installation of a ridge beam - an upper crossbar designed for fastening rafters in some roof models. Often, the timber itself requires the installation of additional supports, especially when the ridge part of the attic has an estimated length of more than 4.5 meters.

Nevertheless, with any design of a ridge bar, it remains important for him to solve problems:

evenly distribute the total weight of the roof to the gables;
evenly distribute the area and force of pressure along the lateral perimeter;
to give rigidity to the structure of the rafter system.

For the ridge beam, it is also important to maintain the geometry of the roof, especially with a length of more than 4.5 meters, in order to be able to mount the rafters without using a template. The rafters lie with their upper part on the ridge beam, and bottom- on the Mauerlat.

Ridge wood

The construction of wooden houses from profiled timber provides for the use of a rafter system in accordance with design features building. Taking into account the fact that the ridge beam carries a large operational load, it is made from reliable sawn timber. The weight of the ridge bar should not increase the total weight of the roof, but in terms of strength it should be such that for many years of operation it will flawlessly perform the functions assigned to it. Therefore, for the ridge beam, as well as for the entire rafter system, pine lumber is selected so that the beam comes out with a cross section of at least 20x20 cm.

At the top roof structure any roof is fitted with a ridge girder

For the construction of a residential building 8x8 from a bar, whose roof will be covered with slate or shingles, all components of the truss system, including the ridge girder, are made of well dried pine wood. In the construction of a bath, where hot steam can damage wooden structure, larch timber is used for the rafters. In addition, the sauna requires a heavy roof that retains heat optimally. Light pine is not suitable here, a stronger and heavier larch is needed.

Larch for the production of a ridge girder is also used when residential building a heavy tiled roof is planned, under which it is required to build a very strong and equally heavy rafter frame... Here calculations take into account that the load from total weight the roofs held up the walls of the house.

The choice of materials used in the construction of the truss system depends on the structure of the building. Therefore, only professionals can make a qualified decision.

Ridge run in the rafter system

When the rafters require a center support, a ridge girder setup is used. It rests on two sides against parallel load-bearing walls.

The installation height of the ridge bar is determined by:

the design width of the house;
the average annual amount of winter precipitation;
the presence of strong winds.

The peculiarity of the installation of the ridge bar is to exclude its drilling and hammering of nails. This is necessary for:

preventing the formation of cracks;
preserving the integrity of the timber;
ensuring the reliability of the rafter system.

The design of a gable roof requires the installation of a ridge girder. In the future, it serves as a ridge of the roof. When building a house from a 6 by 6 bar, the ridge run is prepared from a solid bar or log, which structurally rests on two gables, without the use of additional supports. If the projected length of the house is more than 6 meters, a compound ridge girder and construction trusses are used. Regardless of the design length of the house, the length of the ridge bar is determined in such a way that it lies exactly on the ledges of the outer gables.

warm corner dovetail

The construction of wooden houses involves the use of several types of joining joists. Modern construction goes to high level environmental friendliness and reliability of housing, when even the joints between the beams in the structure of the house are practical and durable. Their task is to make the house warm.

The rafter structure is the basis of any roof. Therefore, its creation must be treated with special attention... When installing a roof, most people turn to professionals, fearing that they will not cope with the task on their own.

The rafter structure is the basis for the pitched roof.

But if the total area of the building does not exceed 100 m 2, then the roof frame can be made independently.

The main difficulty that novice craftsmen face is the fastening of the rafters and the ridge girder. But if you choose the right ridge beam and plan all stages of work in advance, then usually there are no difficulties during installation.

Preparatory stage of work

A ridge run is called a horizontal beam, which is located in the upper part of the roof at the junction of 2 slopes. Usually, a ridge bar is used as a beam. This type of lumber is specially designed for heavy loads. But before purchasing the material, it is necessary to calculate the slope angles of the roof slopes. It is generally accepted that the smaller this angle, the cheaper it will cost to build a roof. The calculations should not be based on economic benefits, but specifications... Consideration must be given to the load on the rafters and the expected weight of precipitation (especially in winter). That is why in middle lane Russian rafter mounts are positioned so that the ramps are at an angle of 45 °. It is this roof that is considered optimal.

Next, you should select the required construction material... Really reliable roof can only provide an easy one, but enough robust construction... Therefore, it is wiser to opt for lumber made from pine. For the roof frame, a board is usually used, the dimensions of which do not exceed 20x5x600 cm.In addition, it is necessary to purchase a ridge beam with a section of 20x20 cm.

Figure 1. Diagram of the roof ridge.

When choosing materials, it is necessary to consider not only their size. You also need to pay attention to quality. Never buy undried lumber. After some time, the rafter mount, assembled from such boards, will certainly lead. Accordingly, the entire roof is deformed. Remember that wood is considered ideal if its moisture content does not exceed 20%.

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Installation of a roof ridge

Before starting work, draw up a scheme for fixing all roof elements. An example of such a scheme is shown in Fig. 1.

Only with the help of such a drawing can you correctly determine required dimensions and think over the rafter fastening, which will be most effective for the selected roofing material.

The ridge bar is usually a crossbar located at the top roof structure... It is necessary in order to evenly redistribute the roof pressure on the walls of the house. Self-installation such a bar is not the most simple job... And it is necessary to approach it with all responsibility.

First of all, you need to calculate the length of the timber that you need. Usually, during the construction of houses traditional for Russia, there are small protrusions on the sides of the roof. As a rule, their width does not exceed 1.5 m. The entire structure must be calculated so that the ridge bar is fastened to the entire length of the canopies.

Waterproofing is laid on the base of the roof (usually roofing material is used for it) and the edges of the insulation are folded around the timber. Further, the structure is strengthened with reinforcement. To do this, take 2 rods of 40 cm each and fix them on the sides of the beam. It is wiser not to drill the timber itself, otherwise cracks may appear on it.

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Elongation of the ridge bar

For further work you need the following tools:

a saw (if the lumber you have chosen has a significant thickness, then it is wiser to use an electric or gasoline-powered tool);
electric planer;
puncher;
hammer;
building level and plumb line.

Installation of the roofing Mauerlat is carried out on anchor bolts.

Sometimes it is necessary to build up the timber, since the ridge of the roof of the standard 6 m is not enough. This procedure is more convenient to carry out directly on construction site, because the extended structure can be quite difficult to transport to the roof.

The place where the seam for securing the timber will pass must be chosen so that it lies on the ceiling (for example, a wall). Remember that the long beam needs extra support.

To provide vertical support, a sufficiently thick board is taken, to which 2 pieces of timber are attached from the sides. As a result, you should have an open frame, in which the bars will serve as vertical supports for the beam. The junction of the 2 bars on the ridge should fall on this frame.

Sections of the timber, which will form the ridge, are fastened together with rather long (at least 2 m) boards. To do this, the ends of the beam are laid in the place provided for them, their correct location is checked using a level and sewn with boards on the sides. With this method of fastening, the dimensions of the ridge beam are unimportant. The whole design is quite reliable.

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The scheme of preparation of the rafter structure and counter-lattice.

Mauerlat is called a roof element that is necessary to connect the rafters with load-bearing wall buildings and the correct redistribution of the total load. To form such a structure, it is necessary to choose flat boards, since they must fit snugly against the wall surface. Therefore, all bumps on the lumber must be removed in advance.

The installation of the Mauerlat begins with a waterproofing layer. All nodes are secured with anchor bolts with a length of at least 20 cm. The nests for them must be formed in advance, having calculated their location so that the bolt heads are between the rafter fastening elements and do not interfere with further installation. Sometimes the standard length of the boards for the Mauerlat is not enough. But they can also be increased.

Next, proceed to the installation of rafters. But first you need to define required amount frame ribs. For this count total length roof and divide it by 1.3 (approximate distance between rafters). The length of the roof is divided by the resulting number and the number of rafters is determined. For example:

8 m / 1.3 = 6 pcs.

When calculating, the fractional number must be rounded up. Thus, you need 12 ribs (6 on each side). After the required number of rafters is determined, you can get Exact size between them:

The rafters should be fastened at 2 levels: on the ridge beam and the Mauerlat.

If you follow the wording, then a run is load-bearing beam, which rests on the wall with two ends. In most cases, the ridge rests on two pediments, but sometimes this formulation is not entirely true. So, in hip roofs the skate does not rest on the walls. The simplest option is a beam laid on gables without the use of props. In any case, it is necessary to correctly determine the cross-section of the ridge run.

To calculate the cross-section of the ridge run, it is necessary to sum up the loads from half of the roof, or rather, from its horizontal projection. The dimensions of the purlin depend on its length and the dimensions of the building. In a large building, the run will turn out to be so powerful and heavy that you will need to use a crane for installation. However, it is very difficult to find an even solid timber more than 6 meters long, therefore, for the manufacture of such a ridge, it is better to take an ordinary log or a glued beam.

In this case, the ends of the ridge element, which will rest on the wall and are actually walled up in it, must be treated with antiseptics and wrapped in tar paper or roofing felt to protect against decay. If a solid wood beam is used, then its end must be cut at an angle of 60 degrees and left open, that is, this end should not come into contact with the wall material. Such a measure is needed in order to increase the end area, which will improve the moisture exchange in the wood.

If the ridge run will pass through the entire wall, then that part of it that is in contact with the wall should also be treated with an antiseptic and wrapped around roll material... This overhang of the ridge outside the wall makes it possible to form an unloading console. If, in the middle of the ridge, the load from the roof tries to bend the beam down, then on the consoles, the pressing force promotes the deflection in the opposite direction, thereby reducing the deflection of the girder in the middle part.

Important: even if the cross-section of a long solid wood girder is selected correctly, and it is suitable for its deflection strength, the beam can bend under its own weight. Therefore, instead of such a long wooden ridge, it is better to use a construction truss.

Section calculation

To select the cross-section of the ridge beam, it is necessary to carry out a calculation according to two indicators:

deflection;
and calculate the breaking strength.

First, you need to determine the internal stress that occurs in the beam when bending under the action of an external load. This value should not be more than the calculated bending resistance of the material, which can be found from the table or in SNiP number II-25-80. The internal stress is found by the formula: Σ = M: W, where:

Σ - the required value, which is determined in kg per cm²;
M - ultimate bending moment (kg X m);
W is the moment of resistance to deflection at the selected section of the rafters (found by the formula bh²: 6).

The deflection of the run must be compared with the normalized value, which is equal to L / 200. It should not exceed it. The deflection of the beam is found by the formula f = 5qL³L: 384EJ, where:

J is the moment of inertia, which is determined by the formula bh³: 12, where h and b are the dimensions of the section of the run;
E - the value of the modulus of elasticity (for coniferous wood it is equal to 100 thousand kg / cm²).

First you need to calculate the bending moment. If there are several of them on the beam diagram, then after the calculation the largest is selected. Further, to determine the dimensions of the beam section, we can arbitrarily set the beam width parameter and then determine its required height by the formula: h = √¯ (6W: b), where:

b is the value of the beam width specified by us in cm;
W is the bending resistance of the run, the value is determined by the formula: W = M / 130, where M is the largest bending moment.

You can do the opposite, set an arbitrary width of the purlin and calculate its height using the formula b = 6W: h². After you calculate the dimensions of the cross-section of the purlin, it must be checked for deflection using the formula from paragraph 2.

Attention! It is better to add a small margin of safety to the calculated value of the deflection.

When the ridge bar is designed for deflection, it is necessary to compare this value with the L: 200 value. If the deflection in the longest section does not exceed this value, then the section of the beam is left as it turned out. Otherwise, it is necessary to increase the height of the purlin or use additional supports from below. In the latter case, the resulting section must be rechecked by again performing the calculation taking into account the supports used.

The obtained values for the width and height of the ridge must be rounded up. In principle, this calculation is not difficult. The most important thing is to indicate the values in the desired units of measurement, that is, do not get confused by converting meters to centimeters and vice versa.