How to make a roof of a house. Strengthening and repair of roof structures Video - Mauerlat for a gable roof

Gain rafter system usually required if the roof does not withstand the load and deforms during operation. This is usually the result of calculation or installation errors.

Increasing the bearing capacity of the rafter legs

The rafter system of the house, garage, bathhouse and other buildings should be regularly checked for damage and deformation. Timely reinforcement of the rafters will avoid roof destruction and costly repairs. In the case of a garage, the car could be damaged as well, resulting in serious financial damage. Strengthening the bearing capacity of the rafters may be required in any type of rafter system. For this purpose, the most common practice is the installation of unloading beams ("help"), the installation of struts or double-sided linings.

If the rafters are selected according to their strength characteristics, they do not always have the necessary deflection indicators corresponding to SNiPu "Loads and Impacts". Thus, it is required to increase the area cross section rafters. Reinforcement of thin wooden rafters of the roof of a garage or other building is carried out using additional wooden beams - help. The beam is attached to the lower chord of the rafter in the span between the rafter leg and the Mauerlat. A toothed metal plate or bolt clamps can be used as a fastening element.

Particular attention should be paid to reinforcing the support unit with a continuous rafter leg on the brace.

At the point where the continuous rafters of the roof of a house or garage are supported on the brace, a maximum bending moment occurs. It is necessary to avoid deflection in this node, for which it is required to increase the cross-section of the rafter leg with overlays installed on both sides. The dimensions of the plank plates are selected based on the design parameters of the section at the maximum bending moment. Reinforcement of the rafter leg with plank pads is performed using bolt clamps or nails. If you increase the length of the support and bring it beyond the edge of the support on the brace, then this beam will at the same time perform the function of an overlay, strengthening the support node, in addition to increasing the rigidity of the span.

When renovating a roof, a steeper roof slope is often required. In order not to completely replace the rafter system of a garage, bathhouse or residential building, new rafters are mounted, fastening them to the old ones. Splice wooden elements performed using a cross-plank-nail wall. The resulting truss has a predetermined slope and provides increased structural rigidity. It should be borne in mind that this approach does not allow you to increase the space of the attic or attic when remodeling the roof.

Reinforcement of the lower part of the truss structures

To the most vulnerable parts roof structures garage, house or other buildings, include the lower parts of the rafter legs, resting on the Mauerlat, and the Mauerlat beams themselves. If raw lumber was used during the construction of structures, or the wood is moistened due to roof leaks or insufficient waterproofing between the Mauerlat and the brickwork of the garage or house, decay of wooden elements and a decrease in the strength of the structures occurs. Moisture ingress or condensation can also be caused by damage to the vapor barrier, blockage or damage to the ventilation ducts.

To strengthen the roof frame, additional struts are installed. Such a brace is attached to the lower part of the rafter and abuts against the Mauerlat beam or an additional bed. To increase the stability of the truss structures, it is advisable to slightly push the lower ends of the braces installed additionally. By resting the struts against the additional bed, you can remove the bending moment from the span between the rafter leg and the Mauerlat.

Strengthening the damaged truss system

If you need to replace the rotted part of the Mauerlat or sections of the rafters of the roof of a garage or other building, additional overlays are used. Reinforcement with wooden lining is performed with single damage to single rafters. The pads are fastened with bolts or nails, while the bottom end of the patch should rest on the Mauerlat beam and additionally be fixed on it using a twisted of rolled wire.

Reinforcement of structures with bar prostheses is used for massive damage to wooden rafters. In this case, reinforcement implies the dismantling of damaged parts of structures. The damaged rafter leg is fixed on temporary supports, then part roofing disassembled, and the rotten section of the rafter is cut out. A "prosthesis" is made from the new timber - an element whose dimensions correspond to the cut-out piece of rafter. The prosthesis is installed in place of the removed fragment with support on the Mauerlat.

If the reinforcement of structures requires a partial replacement of the Mauerlat, the roof frame is reinforced using the following technology. The rafter legs are fixed on temporary supports, the decayed fragment of the Mauerlat is dismantled. On crutches hammered into the masonry, it is necessary to lay a beam of a suitable section, the length of which should be about 1 meter. A piece of wood of the same length is placed on the ceiling or wall. Then the rafter leg needs to be strengthened with two struts resting against the new beam.

Reinforcement of structures pitched roof implies a set of works aimed at correcting damage to wooden elements that have undergone biological destruction, or at eliminating deformations of rafters and attachment points. Most often, you can encounter such a problem as the deflection of the rafter legs during the operation of the roof, but you should also carefully consider the quality of the rafter fastening even at the stage of erecting the roof of the garage or other buildings.

One of the fundamentally important nodes is the place where the rafters are attached to the ridge of the roof. If there are discrepancies, it is necessary to promptly correct this defect.... The technology of work may require the use of a jack in order to ensure a snug fit of the rafter leg in the ridge part. The place where the rafters are joined must be qualitatively strengthened. Reinforcement is carried out using a metal perforated strip, or a wooden lining made of a board with a thickness of at least 2 cm. The lining is mounted directly under the ridge.

Next, you should eliminate the deflection of the rafters. For this purpose, a hydraulic cylinder is activated. Using self-tapping screws, it is recommended to fasten wooden triangular stops on the inside of the rafter. After that, the rafter is straightened using a hydraulic cylinder and a rigid expanding bulkhead is installed, which prevents deformation of the roof truss under external loads.

To reinforce wooden rafter legs by building up a beam, it is necessary to prepare a beam of the required width - it must correspond to the dimensions of the rafter, or slightly exceed them. Before performing a reliable fixation of the reinforcing bar, this element is best fixed to the rafter using self-tapping screws. Next, you should perform several through holes through the rafter leg and a reinforcing bar for attaching the elements with pins.

The holes should be staggered, with a pitch of about 30-50 cm. This fastening principle makes it possible to increase the resistance of the structure under bending loads. The diameter of the holes must exactly match the diameter of the fasteners. Threaded rods are inserted into the prepared holes, wide washers are put on their ends and self-locking nuts are screwed on - this allows you to create reliable fasteners that will not loosen during the operation of the rafter system. The nuts are tightened until the sound of crackling wood is heard.

In order to increase bearing capacity rafter legs in all types of rafter systems, it is necessary to reinforce the rafters. To do this, use the installation of unloading beams, or, as they are also called, help, and double-sided pads and struts.

The main types of roofs. There is a rafter system for all types of roofs.

As practice has shown, rafters selected for strength characteristics are not always confirmed by calculations for deflection according to SNiP "Loads and Impacts", and therefore it is necessary to increase their cross-sectional area. It is very simple to reinforce the rafter legs: just turn on the additional wooden beam- I will help. The help is attached to the lower belt of the rafter leg in the span between the Mauerlat and the rafter leg. The rafter reinforcement is fastened with metal toothed plates or bolt clamps.

There is another dangerous knot in the continuous rafter leg - leaning on the brace.

A simple example: if you break a stick over the knee, it turns out that in this case the knee is the brace. Therefore, the largest bending moment occurs at this point. Since there can be no deflection in this node, it is possible to increase the cross-section along the entire rafter leg with the help of reinforcing double-sided plank pads. In other words, you need to increase its width, not its height. The sizes of the overlays are selected based on required section, which is determined by calculations for the maximum bending moment.

The pads are secured with bolts, bolt clamps or regular nails. If it is already reinforced with help, then you just need to make it longer and bring it over the edge of the support on the brace. In this case, we solve two problems: we achieve the deflection indices in the span that are satisfactory for us and we strengthen the support node.

Sometimes during reconstruction it is necessary to choose a steeper roof slope. In this case, the old and new rafter elements are spliced ​​using a plank-nail cross-wall. In this case, new rafters can be installed both below and above the old rafters. The truss formed as a result of these actions provides increased rigidity and a new slope. This method allows you not to dismantle the existing truss structure, which allows you to significantly speed up the work, but it does not increase the under-roof space. If this is done under the attic device, then you should know that the volume of the attic will not increase.

Scroll necessary tools and materials:

• axe;
• hammer;
• nail puller;
• a hacksaw for wood or a hand-held circular saw;
• square;
• building level;
• pencil;
• roulette;
• drill;
• drills d = 4-10 mm;
• timber (section is the same as that of existing rafters);
• board 25-40 mm (determined by calculations);
• fastening material: nails, staples, clamps, screws.

Reinforcement of the lower part of the board-nail truss

Often the most vulnerable part of the rafter structures are the lower parts of the rafter legs, which rot over time, or the Mauerlat itself. In this case, the problem can be solved with the help of additional struts. Additional struts attached to the lower end of the rafter leg, which, in turn, abut against an additional bed or Mauerlat beam, make the support unit more reliable. To ensure better stability of the truss structures, it is recommended to slightly move the lower ends of the additional struts. In order to partially reduce the deflection in the span between the Mauerlat and the rafter leg, you can support the struts on an additional bed.

If you use raw wood during the construction of the roof (humidity above 25%) and if there is insufficient ventilation in the attic, the Mauerlat and the lower ends of the rafter structures can rot over time. Decay can occur in any type of roof when the wood of the Mauerlat or rafter legs is moistened, when the wood is moistened from the masonry, or in the absence of a waterproofing layer between the masonry of the wall and the wood. In addition, this may be the result of damage to the air vents, vapor barrier or clogging of their ends in the structure of the insulated attic roof.

Ways to restore and strengthen damaged structures

There are several ways to strengthen and restore damaged structures:

1. Installation of wooden linings. They are used when single rafter legs are damaged. Wooden strips are fixed with nails or bolts. Thus, with their help, the damaged section of the roof is reinforced. The pads should rest on the Mauerlat with their entire end and are attached to it with a wire twist.
2. Installation of bar prostheses. This method is used for massive damage to roof structures. First, with the help of temporary supports, the damaged rafter leg is fixed. After that, the cover is disassembled and the rotten part of the rafter leg is cut out. Then exactly the same element is prepared from a new bar (the so-called "prosthesis"), which is inserted into the place of the decayed one and rests on the Mauerlat.
3. Application of overlays supported by a beam. This way will fit when replacing a rotted section of the end of a rafter leg or a section of a Mauerlat. Areas of rotten structures are cut out, having previously strengthened the rafter leg with temporary supports, and a beam about 1 meter long is laid on crutches hammered into the masonry. Then a piece of the same length is laid on the ceiling or wall. After that, two struts, fixed with nails on both sides of the rafter leg, abut against the new beam.

Attic ventilation

Strengthening the rafter system is an important, but not the only part. For its long-term operation, there must be sufficient air exchange in the attic. With insufficient air exchange in the attic, with rotting wood and the development of fungal spores on wooden structures the roof must be carried out to restore ventilation. In the attic, they additionally arrange airflows and dormer windows... Cross-sectional area to area ratio attic floor should be 1: 300 - 1: 500.

It is also necessary to find out what the air temperature is at the upper border of the insulation (at any negative outside air temperature, it should not exceed 2 ° C), to study the nature of air movement. Caked insulation, about once every five years, must be loosened. With the thickness of the outer walls up to 1 meter, it is better to increase its actual thickness by 50%, since over time it thermal insulation properties are getting worse. The width of the vents should be within 2 - 2.5 cm. It is also necessary to check and restore, if necessary, the vapor barrier under the insulation layer.

Reinforcement of truss structures may be required in cases where mistakes were made at the design or construction stage of the structure. Incorrectly calculated loads or material properties can lead to partial deformation of the roof, or even to its complete destruction. In this case, strengthening the rafters becomes an urgently needed procedure that can save your home.

The rafters, which are the backbone of any roof, should be periodically checked for any defects or damage resulting from the operation of the roof. If such are found, it is necessary to strengthen and strengthen the rafter system of the house, garage, barn, bathhouse or other buildings. Errors in installation and calculations can occur with any type of rafter system, so home craftsmen need the ability to strengthen the rafters for each of them.

Strengthening the rafter legs

Strengthening the rafters can be carried out in several ways, the main ones will be discussed in detail below. These methods can be used both individually and in their entirety. It is up to the homeowners to decide on a case-by-case basis. But it is best not to save money and take into account that the destruction of the roof over the same garage can damage the car and cause significant material damage, not to mention the danger of deformation of the roof structure of the house.

So, the strengthening of the bearing functions is carried out using:

• "Help", beams that take on some of the loads on the rafter structure;
• installation of struts;
• double-sided overlays.

Bolsters are installed in cases where incorrect calculations of the loads on the rafters were carried out, and as a result, an increase in the cross-section of the beams that hold the entire roof structure is required. It is quite easy to carry out such reinforcement, for this you need to install and fix this additional beam between the Mauerlat and the rafter leg. It is fastened either with bolted clamps or with special steel plates with teeth.

The place where the rafter leg is placed on the brace also requires special attention homeowner, since this is where the maximum bending pressure occurs. For clarity, remember how you broke a stick through your knee in childhood, it is the role of the knee that performs the brace. To reduce the load and the risk of deformation of the continuous rafters in the place where they rest on the brace, we advise you to increase the cross-section of the timber by sheathing it with overlays from the boards. The thickness of the overlays depends on the calculation of the required section for the structure under the planned bending loads. The rafters are connected with reinforcing linings using various fasteners, but more often with nails or special bolts. If, in this case, the length of the support is extended beyond the fulcrum, then it is possible to increase not only the strength of the beam, but also the entire connecting node.

Sometimes in the project there may be an error in determining the angle of the roof slope, and the operation reveals this miscalculation. For example, if the slope is not steep enough, snow accumulates, which can damage the roof. In this case, it becomes necessary to introduce some changes in the design of the rafters. To do this, new parts of the rafters are attached to the old elements with the help of plank walls and nails, due to which the newly formed trusses become more rigid and change the slope of the roof in the right direction.

This method will allow you to make changes in and at the same time not to disassemble the entire roof again, however, and special changes in the under-roof space will not be possible, since it will not be possible to enlarge or somehow configure it.

Strengthening the lower parts of the rafters

The roof rafter structure of any structure is most vulnerable in its lower part, it is there that it most often requires reinforcement - this is the bottom of the rafter legs and the Mauerlat beam. The reason for this vulnerability is that it is in the contact zone of the tree and brickwork most often condensation forms and moisture penetrates in the event of a violation of the integrity of the roof. Another reason is the use of low-quality wood, which was either raw or dried in violation of technology. All this leads to the formation of putrefactive processes in the wood and its destruction. Therefore, during construction, it is important to pay attention to the choice quality material and provide reliable hydro and vapor barrier. The absence or malfunctioning of the ventilation ducts can also cause the accumulation of moisture and the destruction of wood.

In this case, struts are used to strengthen the roof frame. They are attached to the lower end of the rafter leg and abut against the Mauerlat or the bed. The number of these additional braces depends on your situation. To give additional stability, the struts are attached slightly at an angle, that is, their lower part is slightly distributed to the sides. It is the emphasis on the bed that will remove the effect of bending deformation on the span of the rafters in this part.

Strengthening rotten parts of the rafter system

If you still cannot protect yourself from the destructive effects of rot on the wood, you can try to strengthen the damaged sections of the rafters or Mauerlat in your home or garage. If it comes about one case of damage to the rafters, then you can get by with wooden plank plates. They are fastened with nails or bolts, while their lower part of the board should rest against the Mauerlat to ensure additional reliability of fixation, while the linings in this place are best attached to the Mauerlat using steel wire.

But if we are already talking about massive damage to the rafters, when deformation or rot is found on many rafters, then it is necessary to use a special system of prostheses. These prostheses are made from steel rods and are attached to the intact part of the structure, while the deformed part is simply removed. For this operation, it is necessary to fix the rafter with special temporary stands and remove the damaged part (for this you will have to disassemble part of the roof). Then you should cut a prosthesis of a similar size from the same tree and install it in the place of the removed site, with its lower part resting on the Mauerlat. Steel rods of the prosthesis provide additional fixation of the entire structure.

If reinforcement with partial replacement requires not the rafter leg, but the Mauerlat, then the following manipulations must be carried out:

• fixed with temporary supports of the roof frame rafters;
• the rotten section of the Mauerlat is cut out and removed;
• steel crutches are driven into the masonry, on which a bar of the desired section is placed, at least one meter long;
• a piece of bedding with a length equal to the bar is installed on the ceiling;
• then the rafter leg is fixed on both sides with struts, which rest on the newly installed beam.

Work to strengthen the rafters of any roof is a whole complex of works, which includes various operations to correct the deformation and destruction of the wooden elements themselves or the place of their fastening.

Deformations are most often expressed through curvature and the formation of cracks in the beams and boards of rafters and other wooden roof elements, but sometimes intervention is required and when it is necessary to correct poor-quality fastening of parts of the system to each other.

In the latter case, it is worth paying attention to the key junctions. First of all, make sure that the rafters and the ridge of your roof are properly secured, this node very often causes problems with insufficient care during installation.

When correcting defects, it is necessary to achieve the most tight joining of the rafters and the ridge beam; the use of a special jack can help in this. For high-quality strengthening of this node, use various techniques... This unit is fastened using either a special steel strip with perforated holes, or various wooden plank plates, or by placing the rafters on a steel fastening bolt. In each of these methods, several options can be distinguished, for example, wooden linings can be attached both above and below the ridge beam, there are several types of metal plates for securely fixing rafters and linings.

There are some secrets to fixing rafter deflection. For this on inside special wooden stops are securely attached to the beams, after which, with the help of a jack, the rafters are straightened, and strong jumpers-spacers are alternately inserted between them. Such a system will help withstand external pressure on the roof and rafters and stop the deformation of the latter.

When strengthening the legs of the rafters through building with a bar, it is necessary to correctly select its parameters. In width, it should be either equal to the rafter, or slightly wider. For ease of installation, the timber is attached with self-tapping screws to the rafter beam, and then holes are made through both elements, after which the entire structure is pushed onto special steel bolts or studs.

It is better to drill these holes in a staggered manner, which increases the resistance of the structure to loads during bending deformation. The diameter of the drill and the fastening pins must be the same. Fasteners are made with steel studs, self-locking nuts and washers. This design is not only easy to install, but also reliable in operation. It will not loosen up and will last as long as the wood will.

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Mauerlat is the most invisible, but very important element roofs. It is the foundation on which the rafter system rests and distributes the weight of the roof over the entire surface of the wall. The Mauerlat is made of timber and is attached to the unloading belt. In houses made of timber and logs, the upper crown of the log house performs the functions of the Mauerlat. Mounting the Mauerlat on brick wall performed with studs embedded in the masonry. To protect against moisture, roofing material is laid on top of the unloading belt.

In order for the rafter system to be stable, the end of the rafter must rest on the Mauerlat with the entire plane. For this purpose, the interface is carefully adjusted and secured. When the Mauerlat decays, the rafter sags, the slope plane is disturbed, and leaks and aesthetic defects in the Onduvilla roof may appear. Further destruction of the Mauerlat leads to a weakening of the rafter system and the failure of the roof.

Local repair of the Mauerlat can be performed without completely dismantling the roofing; in most cases, it is enough to open the cornice lining and remove several shingles of the shingles over the damaged area. The main difficulty is to remove the nails without damaging the onduvilla. For dismantling bituminous shingles you can use a nailer, after placing a 40x150 mm board under the paw, or a "grinder", carefully cutting off the heads of the nails. The second method is much easier, but requires some skill.

If the size of the affected area of ​​the Mauerlat is small, repair is made in the following sequence:

At a distance of ≈ 0.5-1.0 m from the Mauerlat on the rafter, on both sides, wears are installed, made of a board with a section of 50x150 mm. The beads are fastened to the rafters with a nail fight;

Two struts are attached to the rafter, which abut against the sink at one end, and with the other rest on the Mauerlat outside the rotted area. The braces are attached to the rafters with a nail break.

When a significant area is damaged, the struts rest on additional bar, installed as close as possible to the damaged Mauerlat and fixed to the wall or floor joists.

To prevent further decay of the Mauerlat, it is necessary to remove the decayed wood, carefully treat the affected area with an antiseptic composition and eliminate the causes of decay:

Perform waterproofing of the Mauerlat;

Treat the Mauerlat with an antiseptic composition;

Inspect the roof and eliminate leaks;

Provide effective work roof ventilation systems (clean the supply and exhaust air vents, bring their area in line with the area of ​​the attic, remove foreign objects and ensure the free movement of air masses);

On insulated roofs, the serviceability of the vapor barrier and the efficiency of the ventilation system of the under-roof space should be checked.

After the completion of the repair, the dismantled section of the roof is restored. The upper shingles are wound neatly under the installed shingles and nailed through the old holes. Installation of onduvilla at the repair site is carried out in accordance with the instructions.