Gain truss structures may be required in cases where errors 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, the reinforcement of the rafters becomes acute necessary procedure, which can save your home.
The rafters, which are the basis of any roof, must be periodically checked for any defects or damage caused by the use of the roof. If any are detected, it is necessary to strengthen and strengthen rafter system house, garage, barn, bathhouse or other buildings. Errors during installation and calculations can occur with any type of rafter system, so home craftsmen need the ability to strengthen rafters for each of them.
Strengthening rafters can be done in several ways, the main ones will be discussed in detail below. These methods can be used individually or in combination. In each specific case, homeowners must resolve this issue themselves. But it is best not to save money and take into account that the destruction of the roof above 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, gain load-bearing functions carried out using:
Supports are installed in cases where incorrect calculations of the loads on the rafters have been made, and as a result, an increase in the cross-section of the beams holding the structure of the entire roof is required. It is quite easy to carry out such reinforcement; to do this, you need to install and secure this additional beam between the Mauerlat and the rafter leg. It is fastened either with bolt clamps or with special steel plates with teeth.
The location of the rafter leg on the strut also requires special attention homeowner, since this is where the maximum bending pressure occurs. For clarity, remember how as a child you broke a stick over your knee; it is the knee that plays the role of the brace. To reduce the load and the risk of deformation of continuous rafters in the place where they rest on the strut, we recommend increasing the cross-section of the beam by covering it with overlays from boards. The thickness of the overlays depends on the calculation of the required cross-section for the structure under the planned bending loads. The rafters are connected to reinforcing linings using various fasteners, but more often with nails or special bolts. If at the same time 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 unit.
Sometimes a project may have an error in determining the angle of the roof slope, and 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 make some changes to the design of the rafters. To do this, new parts of the rafters are attached to the old elements using plank walls and nails, due to which the newly formed trusses become more rigid and change the slope of the roof in the desired direction.
This method will allow you to make changes without having to disassemble the entire roof again; however, you won’t be able to make any special changes to the under-roof space, since you won’t be able to either enlarge it or configure it in any way.
The roof truss structure of any building is most vulnerable in its lower part, which is where 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 area of contact between the tree and brickwork Most often, condensation forms and moisture enters if the integrity of the roof is damaged. 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 of high-quality material and ensure reliable hydro- and vapor barrier. The absence or improper functioning of ventilation ducts can also cause moisture accumulation and wood destruction.
In this case, struts are used to strengthen the roof frame. They are attached to the lower end of the rafter leg and rest against the mauerlat or leg. The number of such additional struts depends on your situation. To give additional stability, the struts are attached slightly at an angle, that is, their lower part extends slightly to the sides. It is the support in the bed that will allow you to remove the effect of bending deformation on the span of the rafters in this part.
If you still cannot protect yourself from the destructive effects of rot on wood, you can try to strengthen the damaged areas of the rafters or mauerlat of your house or garage. If we're talking about In one case of damage to the rafters, you can get by with wooden plank overlays. They are fastened with nails or bolts, while the lower part of the board of the lining should rest against the Mauerlat, to ensure additional reliability of fixation, and it is better to attach the linings in this place to the Mauerlat using steel wire.
But if we are talking about massive damage to the rafters, when deformation or rot is found on many rafters, then it is necessary to use a special prosthetic system. These prostheses are made of steel rods and are attached to an undamaged area of the structure, while the deformed part is simply removed. For this operation, it is necessary to fix the rafter with special temporary supports and remove the damaged part (for this you will have to disassemble part of the roof). Then you should cut out a similar size prosthesis from the same wood and install it in place of the removed area, its lower part should rest against the Mauerlat. The steel rods of the prosthesis provide additional fixation of the entire structure.
If fortifications with partial replacement requires not the rafter leg, but the mauerlat, then the following manipulations must be carried out:
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 places where they are fastened.
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 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 connection points. First of all, make sure that the rafters and ridge of your roof are properly secured; problems in this area often arise if you are not careful during installation.
When correcting defects, it is necessary to achieve the tightest possible connection between the rafters and ridge beam, using a special jack can help with this. To qualitatively strengthen this unit, use various techniques. This unit is fastened using either a special steel strip with perforated holes, or various wooden planks, or by placing the rafters on a steel fastening bolt. In each of these methods, several options can be distinguished, for example, wooden overlays can be attached both above and below the ridge beam; there are also several types of metal plates for reliable fixation of rafters and overlays.
There are some secrets when correcting the deflection of rafters. For this purpose on inside beams are securely fastened with special wooden stops, after which the rafters are straightened using a jack, and strong jumper spacers are inserted between them one by one. Such a system will help to resist external pressure on the roof and rafters and stop the deformation of the latter.
When strengthening the legs of the rafters through timber extensions, it is necessary to correctly select its parameters. It should be either equal in width to the rafters or slightly wider. For ease of installation, the timber is secured with self-tapping screws to rafter beam, and then make holes through both elements, after which the entire structure is mounted on special steel bolts or studs.
It is better to drill these holes in a staggered pattern, which increases the structure’s resistance to loads during bending deformation. The diameter of the drill and mounting pins must be equal. Fastening is done with steel studs, self-locking nuts and washers. This design is not only easy to install, but also reliable in operation. It will not come loose and will last as long as the wood can withstand.
A gable roof is one of the most common roofing options in individual construction. It is reliable, and you can arrange it in the most different materials. The roofing pie is a complex system of rafters, layers various materials, but if you want to figure out how to build all this, you can. One of the parts that is almost always included in this design and is irreplaceable is the Mauerlat for gable roof. What is it and how to make it?
Mauerlat is a special connecting element between the walls of the house and the roof itself. The strength and reliability of the entire structure will largely depend on how correctly it is manufactured and secured. That is why the Mauerlat and its creation should be given special attention.
The Mauerlat is a so-called belt, which is mounted along the entire perimeter of the upper part of the walls directly at their end. The rafters are fixed on it during the construction of the roof. Its purpose is a reliable connection between the walls of the building and the roof elements, and it is this element that will allow the load to be evenly distributed roofing pie on the walls and foundation. Also, the Mauerlat allows you to significantly reduce the windage of the roof and will not allow the wind to rip it off the house, that is The resistance of the roof to wind loads thanks to the Mauerlat is significantly increased.
On a note! Sometimes roofs are installed without installing a mauerlat, that is, the rafters are simply fixed to the floor beams. But in this case, the entire load from them falls precisely on the places of support, and not on the entire wall. Because of this, there is a risk of rapid wear and subsequent destruction of the structure.
When building a roof that has two slopes, the Mauerlat is always installed on two parallel walls on which the roof will rest, and not along all the ends of the perimeter of the walls. If the house is built of timber or logs, then this detail is not always necessary - the Mauerlat will cope perfectly with the main tasks top part walls.
Type and specifications the material used to construct the Mauerlat will depend on several factors, including the type of roof, the need to equip the attic, the size of the house and the quality of the walls, the material used to make the entire structure, climatic conditions etc. To create this element, wood, channel, I-beams, and metal can be used.
The most common material for creating this element is ordinary wood. It is easy to process and affordable option, but at the same time characterized by durability and strength. Working with wood is much easier than with others, as it can be easily adjusted to the right sizes, even if errors were made in the preliminary calculations.
Table. What is a wooden mauerlat like?
| Wood type | Peculiarities |
|---|---|
| This is the simplest and convenient option. The timber is already sawn in advance, is quite strong, thick, and reliable. Unlike logs, it will not be able to roll off the end of the walls and fall. Typically, a beam 15-20 cm thick is used to create a Mauerlat. The main parameters of the sections are: 10x10 cm, 15x15 cm, 10x15 cm, 8x18 cm, 20x20 cm. |
| Instead of timber, boards are sometimes used as a mauerlat. However, due to their small thickness, they will have minimal reliability. To improve this quality, several boards are fastened together in single design. This method allows you to save some money spent on construction. The option is suitable for arranging roofs on small country houses, but during major construction it is not recommended to stop there. |
Attention! When purchasing wood, it is important to very carefully evaluate its quality, including examining it for the presence of knots, especially when purchasing timber. Knots should not occupy more than 2/3 of the thickness of the material, as they will not allow the wood to stretch and cracks may appear on the walls of the building in the future due to improperly distributed load.
Wooden Mauerlat can be used in roof construction on both wooden house(in this case, the element is installed extremely rarely), and on one built from aerated concrete or foam concrete. In the latter cases, it is recommended to take care of the construction of a reinforced concrete belt around the perimeter of the building. The wooden Mauerlat is fixed with anchor bolts.
Construction boards
This is peculiar combined option. Here they are used for production metal pipes, which are pulled into pre-made holes in the rafters.
This option will be optimal if the roof rafter system is also made of metal. To Work with metal element more difficult than with wood, but this design will be much more reliable. It is better to use high-quality steel pipes with a small cross-section.
Steel pipe
Fixing the Mauerlat on the walls can be done in different ways. First of all, with and without the installation of an armored belt. This element is necessary if the strength of the material from which the walls are made raises certain doubts - that is, there is a risk of gradual destruction of the structure as a result of the load carried by the roof.
The Mauerlat is attached to the walls in several main ways:
Mauerlat during installation gable roof installed on two walls parallel to each other, on which the roof will rest. If the rafters are mounted using a layered system with a ridge girder having supports, then the Mauerlat can also be installed on load-bearing wall, located in the middle of the structure.
If the house is entirely built of wood, then it does not need a mauerlat. But you can’t do without it when building roofs on brick, foam concrete and other types of houses.
On a note! The more modest the house, the fewer requirements are placed on the reliability of its fixation.
The Mauerlat itself can be fixed so as to be laid along the inner or outer edge of the wall end or in the middle of the end. But the distance from the outer edge of the wall in any case should be at least 5 cm.
If installation is carried out hanging rafters, then the Mauerlat is not installed. The rafters are attached to floor beams laid across the walls. It is the beam here that will provide the rigidity of the rafter system. However, the option of hanging rafters can only be used in the case of buildings with a small span between the walls. In this case, the walls are usually made of logs or timber.
Correct calculation of the materials needed for arranging the Mauerlat will allow you not to buy too much and not spend an excessive amount of money. And knowledge of certain of its parameters (such as weight, volume) will allow you to determine the type of fastening so that the entire system is reliable. To carry out calculations, certain formulas and material parameters are used. First of all, the length and perimeter of the future element are determined. Then the weight of the material used is calculated using the formula M = R x V, where R is the density of the wood used, V is the volume of the entire material. Volume can be calculated using the formula V = S x L, where S is the section (at least 10x10 cm), and L is the length of the beam.
The thickness of the reinforcing belt should be calculated based on the load it will experience under the influence of the rafter system, wind and precipitation. Its width cannot be less than the width of the end of the wall.
To work, you will need to purchase M400 cement. It is poured in one go to make the structure reliable and monolithic. The concrete mixture is made from crushed stone, sand, cement in a ratio of 3:3:1. To improve the properties of the mixture, plasticizers can be added to it. For formwork you can use boards or building blocks, OSB boards and other materials.
The armored belt is made as follows: a wooden formwork is created in the upper part of the wall, reinforcing bars are laid (in parallel, one above the other). Anchor bolts, studs, and staples (diameter about 14 mm) are fixed to these rods with wire. The pitch between individual fasteners should not exceed 100 cm. They are located strictly vertically. The created formwork is poured concrete mixture thickness of at least 5 cm. The formwork can be removed no earlier than 10-12 days after pouring.
It is important to lay waterproofing material between the Mauerlat and the wall of the house or armored belt, as well as take care of additional insulation or sealing of gaps. Otherwise, it is in this place that cold bridges may form. For waterproofing, a strip of roofing material is usually used.
The length and cross-section of the studs or anchors are determined depending on the thickness of the Mauerlat used, the thickness of the waterproofing and thermal insulation materials. The height of the installed stud must exceed the height of the mauerlat beam by at least 3 cm - this is necessary to be able to screw on the nuts and fix the supporting element itself.
Advice! The mounting location for the Mauerlat mounts must be determined in advance.
Let's consider how the process of installing a Mauerlat without installing a reinforcing belt on walls made of aerated concrete blocks occurs.
Step 1. First of all, the end of the wall, which will act as the base for the Mauerlat, is leveled. For this purpose, cement adhesive is used, which was used when laying gas blocks. It is applied to the end of the wall using a trowel and then leveled with a wide spatula.
Step 2. The layer of cement that was used to level the end of the wall is dried. Its evenness is checked using a building level.
Step 3. Next is installation waterproofing material. In this case, its role will be played by roofing material. The material is cut into strips having the same width as the end of the wall. They are laid evenly on the base and straightened out. The individual strips are laid overlapping.
Step 4. The timber used as a mauerlat is laid on the end of the wall on top of the roofing felt. It is aligned along the inside of the wall.
Important! Before laying, the timber is treated with an antiseptic, as well as a composition that protects it from moisture. The element must be thoroughly dried before installation.
Step 5. To ensure that when installing the rafter system, the rafters are not installed on anchor bolts, markings are applied in the places where the rafters themselves will be attached. In this case, the pitch between the rafters is 833 mm.
Step 6. Holes for anchors are made in the Mauerlat using a drill. The dimensions of the anchors used are 12x150 mm. In accordance with them, the length and diameter of the drill are selected.
Step 7 A hammer drill makes holes in the concrete. They are made directly through previously made holes in the Mauerlat.
Step 8 All anchors are fitted with nuts under a washer - they will increase the area of the head of the fixing element and will allow you to better press the Mauerlat to the end of the wall.
Step 9 Anchors are driven into previously prepared holes with a hammer.
Step 10 To ensure they fit securely, they are additionally tightened with a wrench.
Step 11 The gaps between the Mauerlat and the walls of the house are sealed with acrylic sealant.
Mauerlat must be used in the construction of a gable roof if the walls of the house are made of materials such as brick, aerated concrete, etc. It is not so difficult to make, but the presence of a Mauerlat will allow you not to worry about the condition of the walls and the reliability of the roof throughout the entire period of operation.
For increase bearing capacity rafter legs (Fig. 68) in both layered and hanging rafter systems, the installation of unloading beams (supports), double-sided linings and struts is used.
Rice. 68. Strengthening rafter legs with help
As calculations according to the old SNiP “Loads and Impacts” showed, rafters in the span between the mauerlat beam and the rafter leg with section dimensions selected according to strength characteristics often did not pass the deflection calculation and it was necessary to increase their height. You can make a rafter leg of variable cross-section by including an additional wooden beam- help. The support is attached in the span between the mauerlat and the rafter leg; its height is adjusted to the height of the rafter section so that it passes according to the calculation for deflection. The support is secured with bolted clamps or metal toothed plates.
Another dangerous knot in the continuous rafter leg- leaning on a strut. Have you ever broken a stick over your knee? So, in this design scheme, the strut is that same knee; here the largest bending moment occurs, due to which it is necessary to increase the cross-section of the entire rafter leg. There is no deflection in this node, so you can increase not the height of the rafters, but its width, by attaching double-sided board overlays (Fig. 69). The width of the overlays is selected when calculating the rafter section for the maximum bending moment. The linings are fastened with nails, bolts or, as in the previous case, with bolt clamps. If the rafter is already reinforced with help, then it needs to be made longer and the edge should be brought out beyond the support unit on the mow. In this case, two problems are solved at once: strengthening the support unit and the deflection in the span.
rice. 69. Strengthening the support unit by increasing the width of the rafters When reconstructing a roof under a steeper slope, new rafters are installed, merging them with the old ones (if they have not rotted) with a board-and-nail cross wall. New rafters can be introduced either on top of the old rafters or below them. The resulting truss provides not only a new slope, but also increased rigidity of the truss structure (Fig. 70). This method eliminates the need to disassemble old roof and speeds up the work, but does not increase the under-roof space. If the purpose of changing the slope of the slopes was to construct an attic, then the volume of the attic will remain the same.
rice. 70. Reinforcing rafters with a board-and-nail truss Sometimes it happens that the end of the rafter leg rots and the support on the mauerlat becomes unreliable; in this case, additional struts can be attached to the lower end of the rafter leg, which rest against the same mauerlat beam or an additional support (Fig. 71). It is recommended to move the lower ends of the additional struts apart - they provide better stability to the rafters. And struts supported on an additional support can partially reduce the deflection of the rafters in the span between the rafter leg and the mauerlat. Additional struts are secured with nails and supported in the grooves on the rafters.
rice. 71. Strengthening the bottom of the rafter leg by installing additional struts When raw wood (humidity more than 25%) is used in the construction of the roof and there is insufficient ventilation of the cold attic, with high dormer windows, their small area, or in the absence of attic vents, the lower end of the rafter legs or the Mauerlat may rot.
Also, rotting can occur if there is no or damage to the vapor barrier and air vents in the insulated structure mansard roof or clogging their ends. Either when the wood of the rafter legs and mauerlat in roofs of any type is moistened when the roof leaks, or when there is no waterproofing layer between the wood and the masonry of the wall and the wood is moistened from the masonry.
There are several ways to restore and strengthen damaged structures.
1. Use of wooden overlays. They are used for single damage to rafter legs. Reinforcement is carried out by installing reinforcing wooden plates secured with bolts or nails. The support of the linings on the Mauerlat should be the entire end, followed by the installation of twisted wire (Fig. 72).
rice. 72. Repair of the unit supporting the rafters on the Mauerlat with overlays and prostheses 2. Use of rod prostheses. They are used for massive damage to rafter legs. Before work begins, the damaged rafter leg is strengthened on temporary supports, the covering is dismantled and the rotten part of the rafter leg is cut out. The prosthesis is put on the rafter leg and placed on the mauerlat. The sawn end of the rafter leg rests against the support platform of the prosthesis, which prevents it from slipping. The rigidity of the upper compressed belt of the prosthesis is provided by the braced lattice.
3. Use of pads resting on the beam. This option is used if it is necessary to replace a rotten section of the mauerlat and the end of the rafter leg (Fig. 73). Before starting work, the rafter leg is strengthened with temporary supports, the rotten sections of the leg and the mauerlat are cut out, crutches are hammered into the masonry and a beam 1 m long is laid on them. If the design of the walls and ceiling allows, and most often this is the case, then a meter-long beam is laid on the wall or ceiling piece of bed. Two struts rest against this beam, fastened to nails on both sides of the rafter leg. The sheathing is supported by a new elongated fillet.
rice. 73. Repair of the rafter support unit in case of damage to the Mauerlat If there is insufficient air exchange in the attic, and as a result, the development of fungal spores and wood rotting wooden structures roofs carry out a number of measures to restore ventilation (Fig. 74). IN attic you should study the nature of air movement, determine the air temperature at the upper boundary of the insulation (it should not exceed 2°C at any negative temperature outside air) and install additional vents and dormer windows. The cross-sectional area of dormer windows and vents should be 1/300–1/500 of the area attic floor. The width of the vents should be within 2–2.5 cm. It is necessary to measure and, if necessary, increase the thickness of the insulation to the calculated thickness. Caked insulation must be loosened approximately once every five years. For external walls with a width of up to 1 m, its thickness can be increased to 50% higher than the calculated one. The vapor barrier under the insulation layer should be checked and, if necessary, restored.
rice. 74. Arrangement of the normal air exchange process in the attic roof Reinforcements of other wooden structures, walls, floors and foundations can be viewed in a special section of the site.
The Mauerlat has rotted. How to carry out repairs without completely dismantling the roof The Mauerlat serves as a support for the lower ends of the rafters. When the Mauerlat rots, additional struts are installed and the load is transferred to undamaged areas.2015-10-30T10:00:00+03:00
Mauerlat is the most inconspicuous, 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 attached to the unloading belt. In houses made of timber and logs, the functions of the mauerlat are performed by the upper crown of the log house. The Mauerlat is fastened to a brick wall using studs embedded in the masonry. To protect against dampness, roofing material is laid over the unloading belt.
In order for the rafter system to be stable, the end of the rafter must rest on the Mauerlat with its entire plane. For this purpose, the interface unit is carefully adjusted and secured. When the Mauerlat rots, the rafter sags, the plane of the slope is disrupted, and leaks and aesthetic defects in the Onduville roof may occur. Further destruction of the Mauerlat leads to weakening of the rafter system and failure of the roof.
Local repair of the Mauerlat can be performed without complete dismantling roof covering, in most cases it is enough to open the eaves sheathing and remove a few shingles over the damaged area. The main difficulty is to remove the nails without damaging the onduvil. For dismantling bitumen shingles You can use a nail puller, having previously placed a 40x150 mm board or a grinder under the paw, 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, repairs are carried out in the following sequence:
At a distance of ≈ 0.5-1.0 m from the mauerlat, bumpers made of boards with a cross-section of 50x150 mm are installed on the rafters on both sides. The hammers are attached to the rafters with nails;
Two struts are attached to the rafters, one end of which rests against the break, and the other rests on the mauerlat outside the rotten area. The struts are attached to the rafters using nails.
If a significant area is damaged, the struts are supported by an additional beam, installed as close as possible to the damaged mauerlat and secured to the wall or floor beams.
To prevent further rotting of the Mauerlat, it is necessary to remove the rotten wood, thoroughly treat the affected area with an antiseptic composition and eliminate the causes of rotting:
Waterproof the Mauerlat;
Treat the Mauerlat with an antiseptic composition;
Inspect the roof and eliminate leaks;
Provide efficient work roof ventilation systems (clean the supply and exhaust ducts, bring their area into line with the area of the attic, remove foreign objects and ensure the free movement of air masses);
On insulated roofs, you should check the serviceability of the vapor barrier and the efficiency of the ventilation system for the under-roof space.
After completion of the repair, the dismantled section of the roof is restored. The top shingles are carefully placed under the laid shingles and nailed through the old holes. Installation of the onduvilla at the repair site is carried out in accordance with the instructions.
It will be necessary to strengthen the rafter system if during operation it turns out that it is not able to withstand the required load and begins to deform. Below we will talk in detail about how to strengthen the rafter system from the inside in order to eliminate all errors that were made during calculations before installation.
First, it is worth noting that the rafter system of a house, garage, bathhouse and other buildings must be checked in a timely manner for possible damage and deformation. Timely reinforcement of rafters will help prevent possible roof damage and huge repair costs. If the garage roof is damaged, the car may suffer. Rafter reinforcement may be required for any type of rafter system. To do this, expansion beams are often installed - “supports”, struts or double-sided overlays.
If the selection of rafters was carried out taking into account the strength characteristics, then their deflection forces will always correspond to the required indicators, which are regulated by the relevant SNiP “Loads and Impacts”. It turns out that we will need to increase cross section rafter legs. To strengthen thin rafters, wooden supports are used. They are attached to lower belt rafters in the space between the rafters and the mauerlat. As fasteners in in this case steel toothed plates or clamps with bolts protrude.
Particular care must be taken in strengthening the element of support of the continuous rafter leg on the strut. This is because there should be no deflection in such a place, which means that the cross-section of the rafters is increased with the help of overlays that are installed on both sides. The dimensions of the overlays are determined based on the design parameters of the section with the maximum bending moment. Fastening of board overlays is carried out using bolted clamps or nails.
An installed support can also serve as an overlay if its length is increased and it is brought beyond the limit of support on the strut. In this case, it will not only give the span additional rigidity, but will also be able to increase the support capabilities of this unit.
In some cases, to improve performance characteristics roofs, steeper slopes are made for it. In this case, the old frame can not be disassembled, but a new rafter system can be assembled and connected to each other. Such strengthening of the rafter structures will make the new roof more rigid, but the under-roof space, which serves as an attic or uninhabited attic, but it will not increase. The structural elements can be connected to each other using rafter joints on both sides, secured crosswise.
Most often, the mauerlat beams and rafter legs in their lower part are destroyed. This happens as a result of poor waterproofing of the Mauerlat from brick wall due to the leakage of rainfall and melt water through roof covering, or due to the initial installation of insufficiently dried lumber. In addition, moisture ingress into wooden structures may occur due to clogging. ventilation ducts or violation of the integrity of the vapor barrier membrane.
You can reinforce the roof rafters in their lower part using auxiliary struts. These elements are fixed to the lower edge of the rafter leg with an emphasis on an additional leg or mauerlat. You can give the resulting truss additional stability if you slightly move the lower ends of the struts apart. If you place the emphasis of the strut on an auxiliary installed support, you can eliminate the bending forces between the Mauerlat and the rafter elements.
To repair wooden rafters or mauerlat beams, additional pads are usually used. This method is used if single rafters are damaged. Such elements are fixed with nails or bolts, resting the lining with its lower part on the Mauerlat and screwing it with knitting wire.
When deciding how to strengthen the rafter system in the presence of numerous damages, rod prostheses are usually used. Moreover, all deformed and unusable wooden elements needs to be removed. First of all, the rafter is fixed with temporary supports, after which a piece of roofing is dismantled and the damaged area is removed. In its place, a similar element is attached - a “prosthesis” made from fresh wood. For reliability, he must rely on the deer.
If it is necessary to replace individual sections of the Mauerlat, the work is performed in the following sequence:
The question of how to strengthen rafters arises in cases where it is necessary to eliminate defects in wooden structures that appear as a result of natural wear and tear or loss of rigidity wooden frame and damage to its individual elements. As a rule, the rafter legs are the first to undergo deformation and begin to bend. This phenomenon can occur if, during the construction of a house or garage, the installation of gable roof rafters on a log house was not carried out according to all the rules.
The junction of the rafter legs with the roof ridge beam is one of the most important. If the slightest deviations are detected, the roof rafters should be strengthened in this place as quickly as possible. Sometimes a jack is used to tighten the rafters to the purlin or to each other. After this, the joint is properly strengthened with a perforated metal strip or a wooden overlay with a thickness of 2 cm. Such an overlay is installed under the ridge.
At the next stage, they move on to leveling the rafters. A hydraulic cylinder is used for this. Before strengthening the rafters and leveling them, triangular wooden stops are attached to them from the inside with self-tapping screws. After installing them, you can straighten the rafter leg with a hydraulic cylinder and install a spacer, which in the future will protect the roof frame from external loads.
Before strengthening the roof of the house with extensions additional beams, you should purchase material of the required width (it should match or slightly exceed the cross-section of the rafters) and length. First, the prepared timber is attached to the rafter leg using self-tapping screws. After this, a series of holes are drilled through the timber and rafters so that these elements can be secured with studs.
The holes should be drilled with an indentation of 30-50 cm in a checkerboard pattern. Thus, an increase in the resistance of the frame to bending forces is achieved. The cross-section of holes and mounting studs must match. Threaded studs are threaded into the prepared holes, washers are put on and self-tightening nuts are tightened. They will ensure high-quality fastening and operation of the roof without the need to tighten the fasteners. You need to tighten the nut until the characteristic creaking sound of wood appears.
