The need to create an armored belt under the Mauerlat during the construction of the roof is not always obvious to novice builders. They often create a misconception about the reinforced strengthening of the foundation for the construction of the roof as something unnecessary and superfluous. However, the armored belt is an important intermediary that distributes the load of the roof on the walls of the building. Consider why an armored belt is needed under the roof, what functions it performs and how to do it yourself.
In this article
The need for an armored belt
Let's start the consideration of the reinforced base under the roof with its main functions.
Load transformation
The rafter legs transfer the load to the Mauerlat, the main concentration of which is in the places where the rafters rest on the walls of the house. The task of the Mauerlat and armored belt is to transform this load, making it uniform. Mauerlat is affected by two types of loads. This is the weight of the roof itself, the snow accumulated on it, the impact of wind gusts on the roof and other natural phenomena.
Another load is associated with the bursting of the walls of the building by the rafters. With an increase in the weight of the roof, it increases significantly. Modern materials for the construction of buildings, such as expanded clay concrete, aerated concrete, with a number of positive characteristics, are not able to withstand such a bursting load. Before mounting a Mauerlat on them, it is imperative to create a reinforced belt.
Brick walls have greater resistance to point loads, therefore, to mount a Mauerlat on them, it is enough to use anchors or embedded parts. However, experts recommend the use of an armored belt for brick walls if the building is being built in an earthquake-prone region.
Roof fastening to the house
The most important and main task of the Mauerlat is the strong fastening of the roof to the house. Thus, the Mauerlat itself must be securely mounted to the building. 
The main tasks of the reinforced base under the roof can be reduced to the following points:
- Maintaining the strict geometry of the building in all situations: seasonal fluctuations in the soil, earthquakes, shrinkage of the house, etc.;
- Alignment of walls in a horizontal projection, correction of inaccuracies and flaws made during the construction of walls;
- Ensuring the rigidity and stability of the entire structure of the building;
- Uniform and distributed distribution of the load of the roof on the walls of the building;
- The possibility of a strong attachment to the reinforced base of important elements of the roof, primarily the Mauerlat.
Calculation of the reinforced base under the roof
The process of reinforcing the base under the Mauerlat begins with planning and calculations. It is necessary to calculate the dimensions of the armored belt. According to building standards, it should be a width equal to the width of the wall, and not less than 25 cm. The recommended height of the reinforced base is around 30 cm. The armored belt and the Mauerlat laid on it should encircle the entire house.
If the walls are built from aerated concrete, then the top row is made of stone in the form of the letter U, which creates the formwork. It is necessary to lay reinforcing elements in it and pour the entire structure with a cement solution. 
Before starting the actual construction work, it is also necessary to prepare necessary tools and building materials. To create a reinforced base under the roof, you will need:
- Concrete mixer for high-quality mixing of cement mortar;
- A specialized vibrator that disperses the cement mortar in the formwork, preventing the creation of air voids in the structure;
- Materials for the construction of formwork;
- Fittings.
Installation technology
Installation of the armored belt begins after masonry work. It is necessary to wait for the masonry to dry completely.
Creation of formwork and laying of reinforcement
The first stage is the construction of formwork. In buildings made of aerated concrete blocks, the last row of masonry is made from blocks in the form of the letter U. If these are not available, then the outer part of the formwork is created from sawn 100 mm blocks, and the inner part is made from boards. Installation is carried out with strict observance of the horizontal level.
A frame of reinforcement is laid in the formwork. Its longitudinal part is formed from 4 reinforcement bars with a diameter of 12 mm or more. Transverse fasteners are made of rods of 8 mm in diameter, subject to a step of no more than 25 cm. In projection, the frame looks like a square or rectangle. The frame parts are mounted with an overlap of up to 20 cm. The joints are connected with a knitting wire. In solution, such a reinforced frame exists as a monolithic one.
Laying the frame provides for compliance with certain rules:
- The thickness of concrete from the frame to the formwork is not less than 5 cm;
- To comply with this rule, stands made of bars of the desired height are placed under the frame.
An important part of the work is the strengthening of the formwork frame. If this is not done, then it will be crushed by the weight of concrete. This can be done in various ways:
Installing fasteners for Mauerlat
After working with the formwork and laying the reinforcement, you can proceed with the installation of fasteners for the Mauerlat. We recommend using threaded rods. It is convenient to purchase studs with a diameter of 12 mm. The length of the studs is calculated taking into account the fact that their bottom is attached to the frame, and the top protrudes 2-2.5 cm above the Mauerlat.
Installation of studs is carried out taking into account:
- There is at least one hairpin between two rafters;
- The maximum installation step is no more than 1 meter.
Pouring with cement mortar
The main feature of the reinforced base under the Mauerlat is its strength. It can only be reached by pouring concrete mortar at once.
Concrete not less than M200 is used to create a concrete mix. The best mixture for filling the belt is prepared in the following proportions:
- 1 part of cement M400;
- 3 parts of washed sand and the same amount of rubble.
The use of plasticizers will help to increase the strength and hardening rate of the mixture.
Since a lot of mixture is required to create an armored belt at once, it is advisable to use a concrete mixer and a special pump for supplying the solution. In the absence of equipment, the help of several people will be required for the preparation and continuous supply of the finished mixture.
After pouring concrete into the formwork, it is important to expel all air from possible air pockets. For this, a special vibrator device and simple fittings can be used, with which the mixture is pierced around the entire perimeter.
Mauerlat installation
Removal of the formwork from the armo-belt is possible as soon as the concrete hardens sufficiently, and installation on the Mauerlat structure can be started no earlier than 7-10 days after the armo-belt has been poured.
Before laying the Mauerlat parts must be prepared in a special way:
- Mauerlat beam is treated with antiseptics;
- The connections of its individual elements are made by the method of a direct lock or oblique cutting;
- Mauerlat is applied to the armored belt and places for studs are marked. Mounting holes are drilled.
The laying of the mauerlat is preceded by covering the reinforced base with a layer roll waterproofing, as a rule, roofing material is used for these purposes.
Mauerlat is fastened with a large washer and nut; locknuts are used for safety. After tightening all the fasteners, the remaining tops of the studs are cut off with a grinder.
Summing up
A reinforced base under the Mauerlat is more of a necessity than a luxury. Roof structure has a rather large impact on the walls of the house, which, although distributed evenly due to the Mauerlat, can adversely affect the strength of the entire building.
The creation of an armored belt is necessary in buildings made of gas and expanded clay concrete due to the fragility of these materials, in areas with high seismic activity. It is also advisable to strengthen the walls under the Mauerlat when creating heavy roofing structures.
Reinforcement of the upper part of the walls is not hard work requiring the involvement of specialists. Subject to a number of rules and the involvement of assistants, it can be done on its own.
When arranging a roof with one or more slopes, it becomes necessary to install a truss system. However, it is impossible to lay the rafters directly on the walls - for these purposes, a Mauerlat is used, which redistributes the load. If the walls of the building are built from such a porous material as aerated concrete, it is not always possible to lay a reinforcing belt under the Mauerlat. In this article, we will talk about how to fix the Mauerlat to aerated concrete without an armored belt using various methods, we will describe in detail the technology and the subtleties of this process.
What is Mauerlat for?
So, the Mauerlat is a very important structural element, which takes the main weight of the truss system onto itself and evenly distributes it over the entire plane of the bearing walls. As a rule, it is made of a material similar to rafters - most often a wooden bar. However, a steel truss system will require an I-beam or channel Mauerlat.
For the manufacture of Mauerlat, the following materials are used:
- Bars made of wood with a section of 100x100 mm, 150x150 mm, and also 200x300 mm. AT this case you can take a tree hardwood which has undergone antiseptic treatment. The beam is laid around the perimeter of the building. The logs are joined by the locking method or with the help of nails. Wooden frames for roofs erected most often in private construction.
- Rolled profiles- I-beams in the shape of the letter H or channels in the shape of the letter U are used somewhat less frequently. At the same time, the height of steel profiles can vary between 7-12 cm.
Whatever material you choose, it is mounted on the surface of the walls. There can be several ways to attach the Mauerlat to aerated concrete. After fixing given element rafter legs are installed. It is worth noting that the mauerlat not only redistributes the load, but also prevents the truss system from moving in the horizontal plane.
Since aerated concrete is a rather fragile material and does not tolerate increased loads, many craftsmen prefer to pour a reinforcing belt along the upper edge of the walls. At the same time, in order to reduce costs and labor costs, there are some methods for fixing a Mauerlat without an armored belt. It is also worth knowing whether a Mauerlat is needed if there is an armo-belt, what are the advantages and disadvantages.
Please note that there should be at least 30-50 cm from the ceiling to the upper edge of the Mauerlat so that the space under the roof can be well ventilated, and access to load-bearing structures roofs for maintenance and repair.
Methods of fastening to aerated concrete
It is worth noting that laying Mauerlat on aerated concrete is much more difficult than, say, on a brick wall. Usually it is laid indented from the outer edge of the wall by 5 cm.
For laying and fixing the Mauerlat, the following elements can be used:
- steel wire;
- anchor bolts;
- chemical anchors;
- steel pins.
The Mauerlat is fixed on a reinforcing belt or on a brick wall using anchor bolts.
After the beam is installed, the rafter leg is pulled to it and wound with a steel twisted wire with a cross section of 3 mm. 6 cm below the beam, you need to install a shorty, on which the rest of the wire will be fixed. Alternatively, for secure fixing, the wire can be wrapped around the floor slabs.
If we are talking about the roof of a complex structure, then it is recommended to fasten the Mauerlat beam to aerated concrete on a reinforced concrete belt. It will provide not only greater structural reliability, but also allow you to evenly distribute the load.
Between themselves, the Mauerlat bars are fixed with the help of an oblique cut with further fixation on nails or bolts. Staples or steel plates give corner connections extra rigidity.
Fixing Mauerlat using wire
Before fixing the Mauerlat to aerated concrete using steel wire, it must first be fixed in the thickness of the wall. This should be done during the laying of the last rows of gas blocks - the wire is placed under them.
The installation technique in this way looks like this:
- A couple of rows before the end of the masonry, a wire twisted from several thinner wires with a cross section of 6 mm is placed between the blocks.
- In the thickness of the masonry, in this case, the central piece of wire will be placed, and the ends will hang down on both sides of the masonry. The length of the ends is made such that they are enough for a free wrap around the timber.
- There should be enough pieces of wire to tie all the rafter legs.
How to fasten with studs
It would be advisable to fasten the Mauerlat to aerated concrete without an armored belt on studs only in cases where it is planned to use light roofing materials in houses of a small area for overlapping. Therefore, the expected load on the walls will be small.
In addition, in this situation, the Mauerlat beam itself will serve as an armored belt. Although there are conflicting opinions regarding this type of installation of a Mauerlat on aerated concrete, practice nevertheless shows that it has the right to life. This technique provides a sufficient level of reliability and stability of roof structures.
To work, you will need the following components:
- metal studs SRT-12, which are also called " dovetail»;
- a wooden beam with a section of 20 × 30 cm - although the thickness depends on the size of the erected wall of the building.
The sequence of work on laying the Mauerlat on aerated concrete without an armored belt looks like this:
- Along the entire length of the bearing wall, recesses are drilled in its upper part at a distance of 100-150 cm.
- Mauerlat studs are placed in the prepared holes, and fixed with a non-shrinking mortar or cement milk.
- Waterproofing from a double layer of roofing material is laid on the wall of blocks. At the locations of the studs, holes are pierced in the material so that it tightly covers the surface of the metal. This stage allows you to protect the wood from rotting due to moisture.
- Further, in the Mauerlat, recesses are drilled along the diameter of the studs with a step that matches their location.
- Now the Mauerlat beam is put on the studs and fixed with nuts and washers.
- After installing the bars, the joined end parts are pulled together with metal brackets.
- Next, the installation of the rafter legs is carried out directly.
The process of attaching the roof to aerated concrete will look somewhat different if the studs are mounted in a reinforcing belt.
The sequence of actions is as follows:
- Before pouring the cement mixture into the formwork, studs are installed under the armored belt in increments of up to 1 m.
- They are fixed to the frame with knitting wire or plastic ties.
- Align the location of the studs on all axes.
- The formwork with reinforcement and studs is poured with a cement composition.
- After the reinforcing belt has completely solidified, a Mauerlat beam is put on the protruding studs and tightened with nuts.
Application of chemical anchors
Under chemical anchor means a liquid injection mass made on the basis of polymer resin, which quickly hardens and firmly fixes the metal rods in the thickness of the Mauerlat.
advantage this material is the absence of bursting stress, so brittle aerated concrete does not collapse. If mechanical anchors fix the parts by expanding the dowel, then the adhesive composition of the chemical anchor fills the pores of aerated concrete and holds the rod motionless.
The process of attaching liquid dowels looks like this:
- A recess for the anchor is drilled in the gas block. The size of the recess must be larger than for a conventional anchor bolt.
- Remove dust and debris from the hole, for example, with a vacuum cleaner.
- The adhesive is poured into the hole.
- Next, a threaded metal rod is inserted into the glue - a hairpin M 12-14 or a piece of reinforcement.
- Complete crystallization of the polymer composition occurs in 1/3 hour if the temperature of the medium is above 20 ℃.
- As soon as the glue hardens, the hairpin will be securely fixed. It is noteworthy that such fasteners are stronger than mechanical ones.
Installing a Mauerlat for a roof on an aerated concrete wall using liquid dowels has a number of undoubted advantages:
- Fastening does not lose strength for more than 50 years.
- Due to the polymer structure of the adhesive, this method of fixing is widely used at the edges of walls, where there is a risk of splitting the gas block.
- The chemical anchor has good chemical resistance.
- Even wet weather and wet surfaces of the joined elements do not interfere with the installation of these fasteners.
- Installation of the roof mauerlat on aerated concrete blocks can be carried out without pouring the armored belt, since the reliability of fixing a chemical anchor is much higher than that of a mechanical one.
- The chemical composition of the anchor is ideally combined with the porous structure of gas blocks.
- To install liquid dowels, holes of less depth are required than in the case of mechanical anchors - there the depth is 2-3 rows.
Nevertheless, it is impossible to carry out welding work on the anchors installed by this method - overheating of the metal rod will lead to disturbances in the polymer structure of the material, from which it will lose strength.
Fastening on mechanical type anchors without armored belt
Finally, the last way to fix the mauerlat to aerated concrete is to use traditional mechanical anchor bolts.
The anchor consists of:
- threaded inner steel rod;
- the outer case - the spacer part of the mechanism.
The principle of operation of the anchor is to gradually deform the outer body as the nut is tightened on the bolt. In this way, the bolt is firmly fixed in the drilled hole.
Installation of anchor fasteners is as follows:
- On the last row of blocks, bars are laid out along the walls.
- Holes for mounting bolts are made along the entire length of the beam in increments of 1 m. Please note that the anchors must hit the corners of the building and the junction of two pieces of timber.
- With a special drill, a hole is made through the laid Mauerlat in the gas block to the depth of the anchor. In this case, the depth of the hole should be no less than the thickness of 2-3 rows of masonry.
- An anchor bolt is inserted into the recess made. It is advisable to use products with a length of at least 50 cm and thread M 12-14.
- At the end, put a washer on the bolt and tighten the nut as tightly as possible. As a result of compression, the anchor body is compressed and expands the material. So the bolt is securely fixed in the thickness of the wall.
How to fix the Mauerlat to aerated concrete without an armored belt?
On the websites of manufacturers there are conflicting statements regarding the need for the construction of buildings from aerated concrete blocks. Someone claims that they are quite capable of withstanding the expected load. Others, on the contrary, offer to play it safe. However, all manufacturers and builders are confident that porous materials react negatively to point loading. Therefore, it must be evenly distributed. If for some reason the device of the armored belt is not possible, it is necessary to use. This will extend the life of the building.
Mauerlat is most often made from the same material as the rafters - metal (channel, I-beam) or wood (beam)
What is Mauerlat
This is a special design that is used to evenly distribute the weight of the roof over the walls. As a rule, it is made of wooden beams. It is to the Mauerlat that the rafters are attached to make the roof stable. The durability and reliability of the entire structure depends on the quality of installation.
Mauerlat can be metal, but only if steel rafters are used. However, such designs are rare, since the cost of the structure increases significantly. In addition, it is much more difficult to fasten steel parts than wooden ones.
Mauerlat functions:
- even distribution of the weight of the roof along the walls;
- reliable fixation of the truss system;
- protection and prevention of point load on aerated concrete blocks.
The minimum size of a beam used as a Mauerlat should be 10 * 10 cm. However, to ensure best quality clutch, it is desirable to take a material of a larger cross section. It is also permissible to use a log, but it is necessary to chop off the side that will be adjacent to the aerated concrete.
The rafter legs at the points of support transfer the load to the Mauerlat, which, transforming and distributing it, transfers it to the walls
Hardwood timber performs these functions best. In order for it to last longer, it must be treated with antiseptics and impregnations that prevent decay and damage by insects. The bars should completely and evenly cover the walls. Between themselves they are fastened with nails or a direct lock. Due to the fact that the cross section of the wooden material is less than the width of the gas block, the Mauerlat is placed along the inside of the walls. The distance to the outer edge must be at least 5 cm. Laying bricks with outer side building.
There must be a waterproofing layer between the aerated concrete wall and the wooden Mauerlat.
Mauerlat mounting methods
Mauerlat can be attached directly to aerated concrete or using an armored belt. There are ways to connect wooden beam with wall:
- using steel wire;
- using anchors;
- hairpins.
When using any of the listed methods, it is necessary to ensure that the fastening is of high quality and reliable. Also, during installation, structural shifts should be avoided.
In private housing construction, a wooden beam is the main material used to work on a Mauerlat
How to fix the power plate with steel wire
As a rule, a solid reinforced concrete belt is poured under such load-bearing structural elements. However, some amateur builders, apparently for reasons of saving time and materials, are trying to find ways to fix the Mauerlat on aerated concrete without an armored belt. Let's see how this is possible, and whether it is worth resorting to such a solution at all.
A few words about the importance of Mauerlat
What is a Mauerlat and why is it needed? To a person inexperienced in matters of construction, this tricky word often does not say anything at all. Meanwhile, we are talking about one of the most important load-bearing parts of the building structure.
What is the foundation - probably everyone knows. So, in terms of its functionality, the Mauerlat can be compared with a foundation tape. True, she is responsible for the loads transmitted from the entire building as a whole, and the Mauerlat is only for those that are formed during the operation of the entire roof structure - the truss system, roofing, insulating "pie", inner lining stingrays (if any), etc.
And the loads here can be considerable, and what is most dangerous is to have a bursting direction perpendicular to the surfaces of the walls, that is, to work for their destruction. It's all about the angles of the roof slopes - this is what gives such a decomposition of the force application vectors, both from the severity of the roof structure itself, and when external loads- snow and wind.
Such bursting point loads transmitted from the rafter legs, for walls laid out of piece material - brick or masonry blocks (which includes aerated concrete). This means that it is necessary to distribute the drop-down load as evenly as possible along the entire length of the wall. And, again, by analogy with the foundation tape, a powerful wooden beam can cope with this, which rests tightly throughout its entire length against the end of the wall.
The second remarkable quality of the Mauerlat is the significant simplification of installation work when installing the truss system. Agree that attaching each rafter leg to the main wall is much more difficult than, as they say, "tree to tree." With the presence of a Mauerlat, very wide possibilities for using various connection schemes come off, from “deaf” to movable, using a variety of fasteners.
As a Mauerlat, a wooden beam with a cross section of 100 × 100 mm and above is usually used (as a rule, depending on the massiveness of the roof structure, another 100 × 150, 150 × 150, 150 × 200 mm are chosen). Very often they rely on an unspoken, in principle, but effective rule - the thickness of the Mauerlat should be at least two thicknesses of the rafter legs.
Width - depending on the thickness of the wall on which it is installed. At the same time, they try to arrange the beam so that it does not fall flush with the surface of the wall either outside or inside. This will make it easier to protect the wood from negative impact external environment, to carry out the insulation of this rather difficult in terms of ensuring normal thermal insulation of the unit. This rule is not mandatory, but if you read the advice of the masters, then all of them almost unanimously advise leaving at least 50 mm from the edge on each side.
It is possible to make a Mauerlat from a log, but such a solution does not seem to be optimal - the operations of attaching to the wall, and then inserting the rafter legs will become much more difficult and, accordingly, will require increased skills in carpentry.
It is clear that in view of the high responsibility of this element of the roof structure, for such purposes, they try to choose dried wood of the first grade, which does not have curvature, pronounced knotting, cracks, signs of biological decomposition, and other defects.
For Mauerlat, selected hardwood is generally recommended. But finding such material is not easy, therefore, high-quality pine is most often used, but only by exposing it to a very picky choice: saving on quality in this case is completely unacceptable.
By the way, the Mauerlat may not be wooden. For example, if you plan to create a truss system from prefabricated or welded metal trusses, then a steel beam will also be used as a Mauerlat - usually a channel or an I-beam. However, in the practice of private construction, such solutions are rarely resorted to - wood remains a "classic".
Mauerlat may not be used on walls made of timber or logs (its role will be played by the last row - top harness), and on frame houses- for the same reason. Sometimes they refuse the Mauerlat when the walls are built from a material that is durable, resistant to point and bursting loads (for example, concrete), and at the same time the roof structure involves attaching the rafters to the outer extension of the floor beams. For walls made of piece materials, it will not be possible to do without a Mauerlat in any case.
It is clear that in order for the Mauerlat to fully perform its functions, the reliability of its fastening to the wall should not cause any concern. With concrete, stone, brick walls - it's easier, since there are many ways to securely fix the timber at the end of the wall. For example, when laying ceramic or silicate brick bookmarks are made from wooden bars. This makes it possible then to use ordinary steel brackets for fastening the Mauerlat. But to complete such bookmarks with aerated concrete is an absolutely hopeless task, you don’t even have to try, since no reliability will be provided. We have to look for other ways, which will be discussed later in the article.
On aerated concrete walls, Mauerlat is recommended to be performed according to a “closed circuit”, that is, in the form of a frame that completely encircles the entire perimeter of the building - this is how the maximum reliability of the structure is achieved. However, this is not always possible - for example, in the case when gables are laid out from the same foam blocks. This means that the more reliable the fastening of the beam to the end of the wall should be.
How is a gable truss system calculated?
In the course of the presentation, we have already once referred the reader to the size of the rafter leg - the section of the Mauerlat depends on this to a certain extent. But, taking into account the angles of steepness and all the drop-out loads - read in a special publication of our portal.
How can I attach a mauerlat beam to a gas silicate wall without an armored belt?
First of all, a builder who faces such a problem must clearly answer the question for himself - “Is it really not possible for me to pour a reinforced concrete belt so as not to have problems in principle?” Why? - Yes, because any of the options proposed below is not without certain shortcomings. And besides - the very possibility of installing a Mauerlat without an armored belt is rather doubtful, and is accepted with many reservations.
No matter how much you look, it is unlikely that you will be able to find intelligible criteria when experts say unequivocally - yes, you can do without a concrete armored belt on this gas silicate wall. There are only many "ifs" in which, it seems, one can hope for the success of such a montage.
Aerated concrete prices
aerated concrete
- If the house or outbuilding is small (unfortunately, there are no evaluation criteria).
- If the roof has a not too complex and heavy structure (let's say that we are talking about simple ones from, for example, corrugated board or metal tiles - all other roofing materials, together with their crate, will be heavier).
- If a climatic conditions construction regions do not imply a large snow load and wind pressure (and where is the guarantee that a weather anomaly will not happen?).
- If the design of the truss system will minimize bursting loads. This can be provided:
- The use of hanging stops, rigidly tied with horizontal puffs.
- The use of layered rafters, with obligatory support at the point of the ridge connection, if at the point of connection of the rafter legs to each other, a hinge connection is provided on the ridge, and the attachment point to the Mauerlat involves the use of movable, sliding joints.
In a word, the list of conditions in order to try to do without an armored belt (and even then without complete confidence in success) is quite large. And it is necessary, probably, to think ten times before choosing this particular path.
However, the Internet offers several ways to mount a Mauerlat beam directly on a gas silicate wall without pouring an armored belt. Let's try to understand them.
Mauerlat fastening with wire
One of the most simple ways, which is often used in the construction of brick walls. In this case, approximately 4–5 rows before the end of the masonry, bundles of steel wire with a diameter of approximately 3 mm (3–4 cores in a bundle) are laid between rows so that they look out from both the outer and inner sides of the wall. The length of the release of these "pigtails" is made such that it provides coverage for the Mauerlat beam mounted at the end of the masonry and allows for reliable twisting and tightening of the wire loop without any problems. The location step of such leash bookmarks is usually chosen equal to the installation step of the rafters, so that the attachment points of the Mauerlat fall between adjacent rafter pairs.
When the wall is ready, it is laid on its end. Then a bar is installed on top, leveled, and then a wire loop is created and tightened. Tightening is usually carried out with the help of a crowbar (mount), achieving the tightest pressing of the timber against the wall.
It would seem - here it is, the simplest solution. However, take a closer look: all the examples shown are only on a brick wall. They write that this method also works well with gas silicate blocks, only the laying of wire "pigtails" is carried out approximately two rows before the end of the masonry.
They write something, but it was not possible to find a single reliable evidence of the reliability of such a method with gas silicate walls on the Internet.
According to personal feelings - will the wire be under heavy loads, and even more so - with possible vibration, for example, when strong wind, work like " hacksaw blade", gradually biting into gas silicate block(which can be sawed hand saw)? After all, this is a violation of the integrity of the masonry, and a weakening of the fixation of the Mauerlat on the wall, with all the ensuing consequences.
In a word, not everything is so obvious...
Fastening the beam with anchors or dowels
It would seem that the simplest reliable way proven by practice and time. Everything is so, but only if we are not talking about gas silicate. The increased fragility of this material may well give a surprise when a crack or even a chip forms when the anchor is tightened or the dowel is screwed in.
Of course, on sale in our time you can find a considerable range of fasteners designed specifically for aerated concrete walls. But, you see, it is one thing to fix furniture, interior items, or even a frame for wall insulation - and a completely different powerful one, which becomes the basis for the entire roof structure.
Given that the holding properties of gas silicate are small, you will have to purchase anchors maximum length- about 300 ÷ 500 mm, so that, taking into account the thickness of the Mauerlat beam, it would be possible to more or less reliably “hook” on the wall. But the cost of such long powerful anchors is considerable, so this must also be borne in mind.
The work on mounting the Mauerlat on the anchors is carried out approximately in the following sequence:
| Illustration | |
|---|---|
 | First of all, it is necessary to ensure reliable waterproofing between the gas silicate and the stacked timber. Otherwise, at the point of contact of wood with another building material inevitably there will be a center of dampness and, as a result, biological decomposition. |
 | For a waterproofing barrier, a strip of high-quality roofing material is quite suitable - it is laid so that it completely covers the entire end of the wall. If it enters a few on the sides, it’s not scary, since this one is easy to cut off later. The strip can be laid dry, that is, without the use of bituminous mastic. |
 | After that, a Mauerlat is laid on the end of the wall. In this example, a high-quality board 50 × 150 mm is used for it, which, by the way, looks a bit thin in terms of thickness. But the principle of fastening does not change from this. |
 | The beam is laid exactly in its place, as provided by the project, leveled. |
 | The necessary markup is carried out. In principle, in this case, it boils down to marking out the areas for installing the rafter legs - then the Mauerlat fastening anchors can be placed between them - and there will be no mutual interference. |
 | The place of attachment of the rafter leg is outlined. Anchors can be positioned arbitrarily, repeating the step of the rafters. |
 | Here it is, the anchor bolt. Let's make a reservation right away - in this example, an armored belt is still poured on top of the gas silicate wall, so the master uses relatively small anchors, 12 mm in diameter and 150 mm long. In mature concrete, such fastening will provide the required reliability. But if there is no armored belt, you will have to install the longest fasteners - up to half a meter. |
 | Further, a pen-shaped drill bit for wood (in this case, 12 mm in diameter) is installed in the drill, and drilled in the Mauerlat beam through holes up to the end of the wall. It is recommended to immediately sweep away the sawdust so that it does not fall back into the canal. |
 | After that, a puncher with a drill for 12 is used. Directly through a hole in the wood, a channel for the anchor is drilled into the wall material. |
 | After the hole is ready, an anchor is inserted into it. Further, the anchor must be hammered with a hammer for its entire length, until the washer stops under the nut into the wood. |
 | And the last step is to tighten all the anchors using the appropriate key, thereby firmly pressing the Mauerlat beam to the end of the wall. |
Will such a connection be reliable? With concrete, yes. With gas silicate directly - the question is complex, even with a large anchor length. In any case, no studies or results of the study of experience on this issue on the Internet could be found - neither positive nor negative.
Let's focus on one more thing. Often, the length of the timber in order to lay out the Mauerlat along the wall in one piece is not enough, and you have to resort to splicing. Experienced carpenters can make very interesting and reliable interlocks, but for a non-professional, it will be enough to make a half-tree connecting knot. A prerequisite: at this place it will then be necessary to provide for fastening - an anchor or a hairpin in order to tighten the junction.
Prices for corrugated board
corrugated board
A similar approach is also used in the corners where the beams of adjacent walls are joined - a locking connection, followed by tightening with the selected fasteners.
In addition, in order to tie all sides of the Mauerlat into the most rigid frame, reinforcement of the connection with steel brackets is practiced at the corners. One of the diagrams above shows this well.
Another tip - if you have to join two sections of timber on the wall, then you should strive to ensure that they are approximately the same length. For example, on a wall with a length 8,5 meters it is better to use bars not 6 + 2,5 , and, for example, 4,2 + 4,3 m.
Technological innovations - chemical anchors
A dozen years ago, few people heard about these innovative methods of fastening parts in various materials. Today, chemical anchors are widely available for sale, however, it is not yet possible to call them publicly available at a price.
By the way, many of the home craftsmen carried out similar fastening technologies without special chemical anchors - we are talking about those cases when a mixture of epoxy and a hardener was poured into the hole made, and then the part was inserted - a reliable connection was obtained in a day.
The advertising that accompanies such chemical anchors ascribes to them the highest strength properties. True, one can already meet consumer complaints, although, perhaps, they are related to the fact that there are a lot of low-quality fakes of such chemistry on the market. And if we talk about reputable manufacturers of such materials, then we should focus on the brands Sormat, Hilti, Nobex, Fischer, Tox, Tecseal, Tecfix, Technox, KEW and some others.
By themselves, chemical anchors can differ in the principle of their application.
- So, one variety has a capsule (ampoule) layout.
An ampoule is inserted into the hole drilled under the anchor, which contains a one- or two-component composition, which begins to quickly harden after mixing and contact with air.
After laying the ampoule, the anchor (pin) itself is inserted into the hole, and hammered to the required depth. When clogging, the anchor destroys the ampoule, sucking fills the entire space of the channel. Including between the walls and threads of the stud. At normal temperature After 25÷45 minutes of air, the composition completely polymerizes, hardens, provides reliable retention and immobility of the anchor even under considerable load.
- Another type of chemical anchors involves the use of cartridges (tubes) with a polymer composition (usually two-component) and a special dispenser gun. The gun is similar in design to the one we usually use with silicone sealants or " liquid nails". And some types of chemical anchors are directly designed for such simple guns.
In addition, depending on the material of the wall, additional devices can also be used. For example, let's see how a chemical anchor is installed, which is designed specifically for porous concrete.
| Illustration | Brief description of the operation to be performed |
|---|---|
 | The illustration shows the possible components of a set of chemical anchors "Fisher" - these are the cartridges themselves with compositions of different hardening speeds, dosing guns. The channel for any chemical anchor always needs to be thoroughly cleaned of dust - for this there is a special pump for purging and pumping out, brushes of different diameters. A drill with a special nozzle allows you to do tapered holes(just what you need for porous concrete). And, finally, various adapters, guide adapters, mesh bushings for hollow walls, and stud anchors themselves of various lengths. |
 | In this case, we are interested in the topic of the article precisely gas silicate wall- porous concrete. |
 | The drilling of the channel under the anchor begins. For this, a special drill with a round stop-limiter and a spherical nozzle is used. |
 | First, a straight hole is drilled - all the way to the limiter. |
 | The stopper rested against the wall, and thanks to the spherical shape of the nozzle, the hole begins to be conical - as shown in the illustration. |
 | When the channel is ready, the drill is placed straight and carefully so as not to break the accidentally narrowed top of the cone, it is removed from the hole. |
 | After that, they take a hand pump - it is necessary to thoroughly clean the channel from dust. Purge begins with the pump probe fully immersed in the hole. |
 | Then the pump probe is gradually removed from the channel without stopping the purge. If necessary, use a round brush of the appropriate diameter. This purging operation should be repeated at least four times - the presence of dust drastically reduces the reliability of the chemical anchor. Ideally, it is necessary to strive for the channel to be completely clean. |
 | After cleaning, a plastic sleeve is inserted into the hole. It will “ennoble” the edge of the hole and, most importantly, ensure the position of the inserted anchor (stud) perpendicular to the wall surface. |
 | Chemistry is getting ready to work. A cartridge is inserted into the gun, a mixer nozzle is screwed on. A small release of the composition is made on any surface - you need to make sure that all components are completely mixed - this will show an even color of the outgoing mixture. |
 | After that, the spout is inserted into the sleeve that limits the hole, and the filling of the cavity with the composite composition begins. |
 | Typically, the cavity is filled to about ¾ of its volume. |
 | Next, an anchor-stud of the required length is taken and carefully screwed (in the literal sense of the word) into the plastic mass that fills the conical cavity - for this, at this stage, the effort of the fingers is sufficient. It is important to ensure that the stud takes a position perpendicular to the wall - the guide sleeve will help with this, but it still does not interfere with checking. The pin is screwed all the way into the wall. |
 | It remains to wait only 45 minutes - and at normal temperature (about +20 °C) the anchor will be ready for load testing. |
What else is said about the advantages of chemical anchors:
- The fastening is considered high-strength, durable - the service life is estimated at 50 years.
- The used polymer composite is completely inert to atmospheric, biological, chemical influences.
- When installing such an anchor, there are no bursting loads inside porous concrete, that is, the risk of a crack or chip is practically eliminated.
- At the same time, the penetration of the composite into the pores of aerated concrete adjacent to the drilled channel ensures the maximum degree of adhesion of the chemical dowel to the wall material.
Well, now - about the shortcomings. There are not many of them, but judge for yourself:
- The cost of chemical dowels is high, and mounting the Mauerlat will cost a very impressive amount. Moreover, our task requires very deep channels with their complete filling with composite - so a fair amount of cartridges will be required.
- Chemical anchors are not resistant to high temperatures. It is clear that on the Mauerlat, temperatures above 100 degrees, in principle, have nowhere to come from, but nevertheless ...
- No reliable data on the timing and results of the operation of chemical anchors for attaching the Mauerlat to aerated concrete without an armored belt have been identified. That is, there are suggestions that it should seem to work out well - but there are no results of the tests carried out yet. Maybe you want to be the first?
Video: Hilti Chemical Anchor Demonstration
Mauerlat fastening on embedded studs
If, even before attaching the Mauerlat, studs stick out from the end of the wall at the right distance from each other, the installation process is simplified to the limit.
- Marks for the location of the studs are transferred to the beam - for this it is enough to lay the Mauerlat on top and tap a little - the studs will leave marks that will become the centers of drilling holes.
- Further, a waterproofing strip is “pricked” on these studs.
- Then a beam with drilled holes is strung.
- Wide washers are put on the studs, nuts are baited - and a completely understandable procedure for pressing the Mauerlat to the end part of the wall takes place.
Everything is very simple, but except for one thing - how to fix studs into an aerated concrete wall. This is where the difficulties begin.
There are tips like this: aerated concrete masonry a deep hole is drilled, about 500 mm, a hole with a diameter of about 3-4 mm larger than the diameter of the stud. The channel is then filled with masonry adhesive or cement laitance. After that, a hairpin is inserted into it until it stops - and in this form it is left until the solution has completely set.
It would seem easy, but some craftsmen who have tried this method are clearly not enthusiastic about it - solutions can shrink, it is difficult to avoid void areas, and the quality of such a knot is still not the highest. Some fasteners can become loose due to dynamic load or vibration, and this is fraught with a general weakening of the structure, the appearance of cracks on gas silicate blocks - with all the ensuing sad consequences.
Another option for early installation of studs. In this case, they are welded perpendicular to the metal plates, which will be placed in the masonry joint before installing the last row of gas silicate blocks. The shape of the plates does not play a big role - for example, they can be as shown in the illustration.
The main thing is that the plates create a support for the stud and at the same time work against the pulling load. With this approach, holes are drilled in the blocks of the upper row in advance, before they are installed in the masonry, then studs are inserted there, if necessary, the edges of the block are “aligned” so that it does not skew due to the thickness of the plate. After that, masonry is carried out - and when the wall is ready, there is immediately a number of embedded studs for mounting the Mauerlat.
The plates are hidden in the masonry joints, and the studs become a convenient tool for securely fixing the Mauerlat. And yet, the most reliable installation of embedded studs is ensured only when pouring reinforced belt.
Is it reasonable to refuse to fill the armored belt?
And now, on the contrary, a direct question to the reader - how serious are your reasons for refusing this simple, but very reliable, proven, guaranteeing strength created structure the roof of the operation to fill the armored belt? Let's take another look at how simple and clear it all is before making a final decision.
The process of pouring a reinforced belt is nothing complicated!
| Illustration | Brief description of the operation to be performed |
|---|---|
 | If you look at all kinds of instructions and manuals on the construction of houses from aerated concrete blocks, the issue of attaching a Mauerlat beam to the end of the walls without a reinforced concrete belt is not even considered. And only somewhere in the text can there be a modest mention: as an exception, for example, on small outbuildings, with roofs of a small area, if the climatic conditions of the region do not imply a pronounced snow and wind load, etc. In a word, practically at your own peril and risk. Is it really so difficult to fill in the armored belt in order to get away from this dependence - “if” at once? |
 | By the way, there is nothing particularly difficult in this, that is, something that even a novice builder would not be able to do. Manufacturers of aerated concrete building materials have provided in their assortment a special type of blocks designed specifically for the last row of masonry. They have a characteristic shape, for which they received the name U-blocks (for their resemblance to this letter of the Latin alphabet). In fact, this is a non-removable formwork made of aerated concrete in the factory for pouring a reinforced belt. |
 | Look at the illustration - it shows various sizes of aerated concrete U-blocks. The smallest block (200 mm thick) has a symmetrical shape, all the others have one wall thicker than the other. This thickened wall should look towards the street - it is made wider for reasons of maximum preservation of thermal insulation qualities. |
 | The dimensions of the "channel" for the reinforced belt itself are not so large, that is, a lot of concrete is not required, and for country house of medium size it will be easy to make it yourself right at the place of work. Moreover, you still have to fill it manually, since the concrete pump in this case will not be an assistant - the “tape” is too narrow and small. The amount of concrete for this operation will be discussed below. It would seem, why even think about ways to do without an armored belt - isn't it better to start pouring it right away? However, many are stopped by the fact that the U-blocks that it takes less material in production, however, they are significantly more expensive, since they are usually sold individually. But it turns out that such blocks can be made independently, using standard wall blocks, or you can do without them altogether by applying other technical solutions. |
 | So, U-blocks can be cut from standard wall blocks. |
 | To begin with, of course, markup is carried out - the width of the cut fragment ... |
 | ... and its depth. |
 | Lines are drawn along which cuts will be made. In this case, the master decided to cut a “channel” 120 mm wide and 160 mm deep. This will be enough for a reinforced belt. |
 | If walls were built from gas silicate blocks, then the master must have a tool for cutting them. Usually this is a powerful hand saw with a large tooth. They begin to make cuts along the marked lines - to the depth of the “channel” being created. |
 | To achieve evenness of the cut in depth, the block is sawn in turn, achieving the desired immersion of the saw, first with one ... |
 | ... and then on the other side. By the way, we don’t have a picture, but judging by the assurances of the masters, such even and identical cuts in depth can also be made with a circular saw. True, the release of the saw may be insufficient (well, you need at least 100 mm of cutting depth) - finally, you can work with a hand saw. Why not an option? |
 | A block with slots made is placed "on the butt". |
 | Next up is the perforator. A drill is inserted into its cartridge - the diameter is not so important (usually 8 ÷ 12 mm is enough), but it is better to take a longer length, about 400 mm, so that the drilled hole reaches approximately the middle of the block. A series of holes are drilled along the line defining the bottom of the “channel” being created, with a distance between their centers of the order of 15 mm. |
 | Then the block is turned over, and a similar operation is carried out with opposite side. |
 | After that, a light blow with a hammer is usually enough - and the fragment cut from three sides falls out of the block. By the way, these fragments, if they have not split, should not be thrown away - they can still come in handy during construction. |
 | And to fill the reinforced belt, there remains such a home-made U-block. |
 | If necessary, the remaining irregularities can be trimmed with a chisel ... |
 | ... sweep away crumbs and dust ... |
 | …and send finished block to the place of their storage before laying. |
 | After a sufficient number of homemade U-blocks have been prepared, they move on to laying the last row of the wall. Work usually starts from the corner. |
 | Glue for aerated concrete is prepared from a dry mixture. Blocks are laid out sequentially. Everything is as in ordinary masonry - first, glue is applied with a layer of the desired thickness ... |
 | …this layer is then leveled and spread with a notched trowel… |
 | ... and then another gas silicate U-block is installed. Work continues in a similar way until the entire row is laid out - until a “channel” is formed for pouring the armored belt. |
 | Particular attention is paid to the corners and at the junction of the walls - here you will have to think about how to join the U-blocks so that the "channel" for the armored belt is not interrupted. One of the options is shown in the illustration, but other solutions are quite acceptable. |
 | To some, this approach may seem overly time-consuming, and, moreover, accompanied large quantity waste. Well, this is true to a certain extent, and it is quite possible to apply other methods of creating formwork for the armored belt. Here is one of them. To create the walls of this peculiar fixed formwork in this case, gas silicate blocks of smaller thickness are used - they are often called additional ones. For example, you can use blocks with a thickness of 100 mm - to create an external wall. |
 | A number of these blocks are laid on the adhesive along the outer contour of the wall (the illustration shows only an installation example). |
 | Any armored belt, due to the specific thermal properties of concrete, always turns into a powerful "cold bridge". To reduce this disadvantage, it is advisable to immediately provide a layer of insulation - lay along the outer wall of the fixed formwork (if the width allows wall block) extruded polystyrene foam with a thickness of about 50 mm. |
 | On the opposite side, the wall of our "formwork" is formed by a thin block, 50 or 75 mm thick. This row is also installed on gas silicate adhesive. |
 | The result is something like this picture - a channel for further pouring of the reinforced belt (shown in the illustration with the reinforcing cage already laid). By the way, you can slightly reduce the depth of the “channel” if it turns out to be too large. At the bottom, also on glue, you can lay fragments cut out from additional blocks, so that the depth is in the region of 150 ÷ 180 mm - this is quite enough. |
 | There are more options. For example, on the one hand - the same gas silicate block 100 mm and a layer of insulation, and on the other - just a wooden (or OSB) formwork, pressed to the surface or set exactly along the end of the wall. |
 | But the option and generally without the use of gas silicate blocks. Wooden formwork is installed on both sides. Nose outside along the formwork boards, a strip of expanded polystyrene 100 mm thick and a width corresponding to the height of the “channel” created for the armored belt is laid. |
 | Here is this option, so to speak, live - with the insulation laid along the outer perimeter of the formwork. Although the insulation is not mandatory in this case, it should not be neglected - this has already been mentioned above. But on internal walls it is not needed - if it is also planned to pour a reinforced belt there, then only wooden formwork on both sides will be enough. |
 | After the formwork (in any of its versions) is exposed, they proceed to knitting the reinforcing frame. As a rule, too much reinforcement is not required for the armo-belt under the Mauerlat - four rods of a periodic profile are enough ( class A-III) with a diameter of 10 mm. |
 | The spatial position of the reinforcement bars can be provided in various ways. The "classics", of course, are clamps made of smooth or corrugated reinforcement, with a section of 6 or 8 mm. - about the same as on a strip foundation. |
 | But often this scheme is also simplified - it still looks “too heavy” for an armored belt along the top of the wall. If you look at the examples presented, then many masters use very non-standard solutions. This one, for example, cut squares from a ready-made welded reinforcing mesh for a screed - and uses them as a kind of clamp templates. |
 | Binding is done in the usual way - with the help of steel binding wire. |
 | And such a picture is obtained after linking - a neat spatial structure of four rods of longitudinal reinforcement. |
 | And here is another original solution. Apparently, the owner has the opportunity to inexpensively (or even for free) get production waste metal products. One can only envy such creativity! |
 | Be that as it may, no one cancels the rules for knitting reinforcement, especially in areas of reinforcement (longitudinal connection of rods, turns, junction areas). Therefore, appropriate bends, overlaps, clamps, etc. are made. - everything according to the rules strip foundation. By the way, pay attention to an extremely important nuance. The presence of a reinforced belt leaves practically no difficulties for the subsequent fastening of the Mauerlat - matured concrete will perfectly hold even conventional expansion anchors. And yet, before pouring concrete, one more operation can be done - install the studs in advance, linking them to the reinforcement cage. After the belt hardens, the master will immediately have ready-made reliable fasteners for the beam. |
 | There are also several options for installing studs. So, for example, a guide hole is drilled under them in the bottom of the channel, and the stud itself is linked to the lintel of the frame reinforcing structure (as shown in the figure). |
 | The hairpin can also be located with an offset from the center line of the armored belt - it all depends on its width and the planned place for laying the Mauerlat. The figure shows how the embedded stud is tied to the longitudinal reinforcement rods. |
 | This shows how, in order to save cuts threaded studs simply welded to the collars of the transverse reinforcement. True, for this it is already necessary to have a very good command of the skills of electric welding. |
 | If you screw a nut at the bottom of the stud and put on a wide washer, the reliability of the resulting fastening will increase significantly. After the full maturation of the poured concrete belt, it will be almost impossible to pull out such a hairpin. |
 | The step of installing the studs is usually taken the same as the step of the future installation of the rafter legs. At the same time, it is desirable that these Mauerlat attachment points fall between the rafters - so that they do not interfere with further installation operations. |
 | After installing and linking the studs, it is recommended to close the upper threaded part, together with the baited nut, with a stretch film - so that the thread does not clog when pouring concrete. |
 | It is necessary to ensure that the reinforcement rods are located at a certain distance from the walls of the impromptu "formwork" - in order to create protective layer concrete. For these purposes, you can use special liners - they will provide the necessary clearances from both the bottom and the sides. |
 | Concrete is being prepared. As a rule, for such an armo-belt, the M200 concrete grade is sufficient (but not lower). In a medium sized house a large number concrete for these purposes is not required - it is quite possible to do self-manufacturing in a concrete mixer. |
 | Then the finished solution is fed up (by buckets), and gradually the “channel” of the armored belt is filled with it. |
 | It is very important to ensure that when pouring there are no unfilled voids. To do this, the poured concrete is carefully “bayoneted”, that is, it is pierced along the entire length of the filled section with a piece of reinforcement or a pointed wooden lath - this will allow air bubbles to escape. |
 | After “bayoneting”, the solution is compacted as much as possible with a trowel or spatula, while leveling the surface of the created belt. |
 | So they sequentially move on, along the entire length of the created belt. |
 | The belt is filled and aligned. This illustration shows a variant without studs - the owner assumes the use of conventional expansion anchors for mounting the Mauerlat. |
 | But the option - with linked mortgage studs. After pouring the belt and its final maturation, for the masters who will deal with the truss system, there are ready-made fasteners. In any case, the armo-belt must be given time for high-quality maturation - it is advisable to start further robots no earlier than a month after pouring. |
As promised above - a few auxiliary materials:
Reinforcement of the strip foundation - how to do it right?
It has already been mentioned in the table that the principles of spatial reinforcement of the autumn belt are similar to the foundation tape - especially in matters of reinforcement at intersections, junctions and at corners. Details are given in a special publication of our portal. And in another article are given. Plus, in both articles there are convenient calculators for calculating materials.
And finally, a calculator that will help you quickly and accurately determine required amount M200 concrete for pouring the armored belt, and the number of components for its manufacture.
For a user uninitiated in capital construction, it is unlikely that it will be known what a Mauerlat is, what role it plays in building a structure, and so on. Therefore, the question of how the Mauerlat is attached to aerated concrete is generally misunderstood.
However, the use of such technology is a relevant and very effective solution. With it, you can solve a number of significant problems that can reduce the durability and strength of the structure.
More must be mentioned economical option implementation of the specified fastening method. If it is necessary to fasten the Mauerlat to aerated concrete without an armored belt, then in this case it is not a continuous armored belt that is poured, but concrete pillows are made in the right places. Such a mount for foam blocks is also quite reliable.
2.3 Metal studs
In the presence of a small house, as well as a slight pressure of the roof, a lightweight method can be used to fasten the walls of the cinder block with the Mauerlat beam - metal studs embedded in the wall. These are steel fasteners in the form of bolts with a base in the form of a square with sides of more than 5 cm.
If, when laying a cinder block, studs are embedded in the wall, they must be installed one or two rows to the top edge. The length of the stud should be sufficient to pass through the beam.
Subsequent fixation similar to fastening a mauerlat with a cinder block using anchor bolts.
2.4 Waterproofing during installation
Having decided on the method of fastening, it is necessary to calculate the fasteners and their location. If it is necessary to fix the Mauerlat to the gas block without an armored belt, then the first option is suitable - steel wire.
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