Fastening the rafter leg to aerated concrete. We attach the Mauerlat to the aerated concrete wall, all methods

The question of how to fix the Mauerlat to aerated concrete without an armored belt is quite rare, because such a connection is rather nonsense in construction. To understand this, you need to figure out what the armopoyas is for, and what the Mauerlat is and its purpose.

Is aerated concrete?

But first of all, let us designate that the construction of houses from aerated concrete is at the peak of popularity, and the demand for this building material growing. This means that many are faced with it when building their own houses. What you need to know about aerated concrete:

belongs to the category of porous materials;
good thermal insulation qualities;
not the lowest moisture absorption;
good bearing capacity;
low strength.

It is the last characteristic that determines the possibility or impossibility of laying the Mauerlat on aerated concrete. Because the porous structure of the material does not allow it to be heavily loaded, especially pointwise.

As for the Mauerlat itself, this is a structure that is laid on the upper surfaces of the walls. In fact, it performs the functions of a strip foundation, evenly distributing the loads from the roof to the walls of the house. They are made mainly of wooden beams with a minimum section of 100x100 mm. It should be added that this roof element simplifies the fastening of the rafter system to the walls.

Armopoyas: design features

Now about the armopoyas. Its main task is to mount the Mauerlat. And if it is not in the structure of the house being erected, then certain problems arise related precisely to the fastening of the Mauerlat bar. There are several ways of fastening. They are excellently used by builders if houses are built from more durable materials: brick, stone, concrete blocks.

Mounting methods

So, we are familiar with the main elements, indicated by the question of how to attach the Mauerlat to aerated concrete. It remains to figure out the ways and understand one important idea. And the thought is that the proposed fastener options should be taken with big amount reservations. Because installing a Mauerlat on aerated concrete blocks without pouring a reinforcing belt is a rather dubious event.

And no matter how much you look for technologies, they all turn out to be, at least, of little use. And with each option, there is a huge number of contraindications. And although there is a lot of information on some portals that it is possible to lay the Mauerlat on aerated concrete and fix it, everyone unanimously assures that there are certain criteria that must be taken into account.

For example:

you can use this method (without an armored belt) if the building being constructed is small in size;
if the roof is a simple structure covered with light roofing materials;
if hanging rafters are used in the construction of the rafter system, which are tightened together with reliable puffs;
if layered rafter legs are installed, propped along the axis of the ridge beam.

By the way, last option best suited to this situation. Because part of the load from the roof will fall precisely on the supports under the ridge, this will reduce the load on the walls. And yet, before attaching the Mauerlat to aerated concrete, you need to think carefully about whether this process is worth carrying out without pouring the armored belt.

Option number 1

Fastening the Mauerlat to aerated concrete without an armored belt is best done using steel wire 4–5 mm in diameter, which is twisted into 2–4 layers. This method is often used when a Mauerlat bar is laid on brickwork. How this process is carried out. There are several strict requirements:

the wire must be laid in the masonry of aerated concrete stones in the third or fourth row before the end of the masonry, that is, 3-4 rows of blocks must be laid above the wire;
the length of the twist should be such that from both sides it reaches the laid Mauerlat, overlaps it and twists, creating a mount;
the step of laying the wire twists is equal to the step of installing the rafter legs.

An example of fastening a Mauerlat bar with a wire

Before laying the Mauerlat without an armored belt on the walls of aerated concrete, the ends of the walls must be waterproofed. The easiest way is to spread the roofing material in two layers. Then the timber itself is laid. It must be aligned either on the outer surface of the wall, or on the inside. Horizontal alignment is mandatory. After that, the wire braids are tightened using a pry bar. The main thing is that the screed is strong and tight.

Example of Correctly Tightened Wire Braids Using a Pry Bar

It seems that this is the solution to the problem. But let's think sensibly. Strong tightening of gas silicate blocks can lead to cracking of the material, especially this will be seen during the operation of the roof, when wind loads will act on it. From them, the wire will work like a saw. But it is with this tool that blocks are trimmed when it is necessary to adjust them to the required dimensions.

That is, this option, with the seeming correct use, raises great doubts. And the more the Mauerlat is tightened with the wire, the faster it will cut the blocks.

Option number 2

Installation of a Mauerlat bar without an armored belt using anchors and dowels. For fastening, it is proposed to use an anchor with a length of at least 30 cm, preferably 50. Appearance they have this:

How this process is carried out:

After waterproofing their upper ends, a Mauerlat is laid on the walls.
Through every 1-1.2 m in it, as well as simultaneously in aerated concrete blocks, holes are made with a drill and a drill, the diameter of which is matched to the diameter of the dowel for the anchor.
Dowels are clogged.
Anchor bolts are screwed into them.

To attach the Mauerlat to aerated concrete without an armored belt, it is better to use an anchor with a diameter of at least 12 mm. And one more thing - pick up a washer of a larger diameter under the nut.

So, is this method really reliable? If it concerned a reinforcing belt made of concrete mortar, then there was no doubt. This is one hundred percent reliable mount. With aerated concrete, even if long anchors are used, there is no certainty that this type of fastening will be able to withstand the serious loads emanating from the roof structure. It is one thing to fix a shelf, cabinet or TV on aerated concrete, another thing when the loads from the roof are not one ton of different materials.

Option number 3

Mounting the Mauerlat to aerated concrete wall with studs. Here, a hairpin with a diameter of at least 12 mm is used. It is laid across the wall in a masonry of blocks 2-3 blocks below the last row. It turns out that the threaded ends of the stud will stick out from the wall on both sides. Therefore, its length is chosen according to the width of the aerated concrete wall.

In this case, the Mauerlat is laid on aerated concrete in the same way as in previous cases. But the fastening is made by wire twisting. At the ends of the steel "pigtail" loops are made, which are put on the ends of the hairpin. That is:

first one loop is put on, for example, on the outer end of the fastener;
it is tightened with an M12 nut with a wide washer laid under it;
the twisted wire is thrown over the wall, respectively, and the Mauerlat;
a free loop at the opposite end is inserted into the free end of the hairpin;
tightening with a nut and washer;
a pry bar is required, which twists the twist over the Mauerlat bar, that is, the latter is pulled to the wall.

We must pay tribute to this method of attaching the Mauerlat to the wall erected from gas blocks. In many respects, it is more reliable. First, the wire does not come into contact with the aerated concrete material. This means that from its twisting there is no load that could cut it. Secondly, the hairpin is laid without violating the integrity of the blocks, which is very important for aerated concrete material. But even this option does not guarantee one hundred percent reliability of the fasteners.

Option number 4

Today we need to talk about innovative methods of fastening, because scientific and technological progress does not stand still and offers us new materials that increase the strength of the fastening. These are the so-called chemical anchors. In fact, this is all the same metal fixture that is inserted into the wall. But instead of a metal dowel, a two-component adhesive is poured into the hole made, which, in contact with air, quickly polymerizes, forming a strong connection. A steel anchor is inserted into it while the material has not yet become solid.

Today manufacturers offer two types of chemical dowels:

A ready-made two-component composition in a can, on which a pistol nozzle is put on for the convenience of feeding the mixture.
The composition is in a glass capsule, which must be inserted into the prepared hole. Then an anchor is inserted into it, which itself breaks the capsule, thus mixing the two components with each other and creating conditions for their contact with air.

The process of fixing the Mauerlat in this way exactly repeats the technology with conventional anchors and metal dowels, which was considered in option No. 2. Only instead of a steel dowel, either a capsule is inserted into the prepared hole, or the composition is poured from a can. The most important thing in the latter case is to insert the anchor immediately after filling the mounting hole with a two-component chemical compound.

It should be added that manufacturers of chemical anchors today offer varieties specifically for aerated concrete materials. It is them that must be used for fastening.

Now, with regard to the reliability of the fasteners. This is one of the most reliable options. But there is no information that someone has already used it. Therefore, one can only speculate. Although, in theory, everything should work.

Option number 5

All the same studs are used here, only they will be installed vertically and serve as anchors. Steel strips 5 mm thick, 50 mm wide, with a length equal to the width of the wall are welded to them. The device is installed at the stage of wall construction below the upper plane of the butt end by 2-3 blocks. Therefore, it is important to accurately determine the length of the stud. The reference point for the installation is a strip across the wall. It is better to use the option if the walls rise from two blocks, so the pins will be between the blocks, without violating their integrity.

Not a bad mounting option, one of the best, but on one condition - the mass of the roof should not be large. The load on the walls in this case is oblique, so the fasteners work in bending. The wider the strip in the fastening structure, the better.

Generalization on the topic

Several options for attaching the Mauerlat without filling the armopoyas have been proposed. It is difficult to say how the whole structure will behave, whether the fasteners will be reliable. Therefore, you should not take risks and avoid expenses. Fill the armopoyas and all your problems will be solved at once.

In the construction of a small house made of aerated concrete blocks with a simple sloping roof, there is no particular need to cast a reinforcing tape, it is much cheaper and faster to fix the Mauerlat to aerated concrete without an armored belt. The technology reduces the time spent, construction is faster, but does not make the work easier, since this method of attaching the Mauerlat bar directly to the walls requires accuracy and precision.

Features of fastening the Mauerlat to aerated concrete without an armored belt

Simply put, without knowing the technological techniques correct installation, it is better not to risk it and use in the classic way, with the laying of reinforcement and concreting of the tape. On the other hand, the problem lies only in adherence to technology, there are no secrets in this, and with proper patience and accuracy, it will not be difficult to fix a wooden beam without an armored belt.

First of all, you need to know the conditions under which you can attach the Mauerlat to aerated concrete without an armored belt:

In the construction of the roof frame, the rafters should not create an additional expanding load on the upper edge of the walls;
The building and the roof are primarily oriented to the terrain so that the wind flows create minimum pressure on roof slopes;
The slope of the roof is chosen large enough so that in winter, heavy snow cover squeezes the rafters and Mauerlat beyond the upper edge of the walls.

Advice! The way to fix the Mauerlat without an armored belt must be chosen before the walls are laid. A decision must be made before the last three rows of blocks are laid out. It is at the level of the third from the top of the rows that the penultimate layer of wall reinforcement is laid, which is convenient to use in order to fix the beam directly on the aerated concrete wall.

The rafter situation becomes clearer if you look at the diagram below.

Hanging roof beams after installation and alignment on the ridge and Mauerlat, they must be connected and pulled together with horizontal bar ties.

If the layered beam is placed on a ridge run using a hinge, then the heel of the rafter, with which it rests on the surface of the Mauerlat, must be fixed to a sliding joint. Otherwise, the weight of the roof will tear the timber off the surface.

Weighty arguments against the armopoyas

Most of the craftsmen engaged in the construction of buildings from aerated concrete are confident that the arrangement of an armored belt can solve all problems with the installation of a Mauerlat and a roof. In fact, this is not entirely true, for one simple reason - the future house is being built from extremely weak aerated concrete. Therefore, it is impossible to transfer the techniques and technologies of the armopoyas, which successfully work on brick, block and concrete buildings, to aerated concrete walls.

There are only two fundamental objections to the armopoyas:

First of all, with any manufacturing scheme, the armopoyas can be fixed only to the upper row of aerated concrete, so the roof has to be done with restrictions too, as in the case when this belt is not there. The concrete frame redistributes the spreading load well, but all the efforts from the armored belt fall only on the upper row of aerated concrete, hence the appearance of cracks along the upper edge of the walls;
Fixing the Mauerlat on the armored belt means creating huge problems with the cold bridge in that part of the roof where the aerated concrete is least ventilated. Even the laying of a layer of insulation from EPSP does not help much, you have to look for ways to arrange air vents to remove condensate from the armopoyas.

The third argument against concreting has to do with costs. The arrangement of the reinforcing tape will take an amount of approximately the third part of the estimate for the arrangement of the foundation. For a 4x8 m house, this is about 60-100 thousand rubles. It is clear that it is much easier to fix the Mauerlat and the roof frame on the Mauerlat rigidly connected to the concrete armored belt. Sometimes the masters - roofers even refuse to put a roof on aerated concrete without an armored belt, but technologically it is quite possible.

How to attach a Mauerlat to aerated concrete without an armored belt

There are several reliable and proven ways to securely fix the Mauerlat beam on aerated concrete walls. Recommended options include:

Use of studs with embedded elements;
Laying of timber using annealed steel wire;
Schemes that allow you to fix the timber using chemistry;
Use of dowels.

For your information! In addition to the listed options, the Mauerlat can be fixed using anchor bolts.

Fastening the Mauerlat to aerated concrete without an armored belt with anchors

This is the only way that you need to immediately and without a doubt refuse to use it, it is better not to risk it without an armored belt.

The anchorage works great on an armored belt made of concrete, brick, cinder block, but due to the small area of the contact surface of the support sleeve, the fastener can pull out the aerated concrete from the body of the first strong wind.

In order to secure the Mauerlat with anchors, three times as many attachment points will be required, each of which will have to be glued in with an expensive adhesive. The cost of such a fastener will be no less than the cost of a traditional armored belt, and there are practically no advantages over concrete.

Fastening with pins

The easiest way when building a building made of aerated concrete without a reinforcing belt is to fix a wooden beam using embedded element and studs with a thread of at least M16. The method is very similar to the version with an anchor, but differs in the depth and diameter of the threaded rod, which will need to be fixed in the aerated concrete block.

There is one nuance in this mounting method. Before laying the last three rows of box blocks, it is necessary to mark the planned installation lines for the future Mauerlat threaded fasteners. Usually they just draw vertical lines on the walls. Further, embedded elements are placed under the laid steel reinforcement, most often these are steel plates, 5 mm thick, with a welded M16 nut. The remaining rows of aerated concrete are laid out on the walls in the usual manner.

In order to fix the studs in the wall, you will need:

Drill a vertical hole with a diameter of 20-25 mm to the level of the plate embedded in the aerated concrete, usually you have to drill with a drill to a meter depth;
Screw the threaded rod into the nut with the plate;
To properly secure the pin, it will need to be leveled and wedged in the hole;
After it was possible to align and fix all the rods, the free space is poured with a concrete or adhesive mixture.

After a day, you can put the Mauerlat directly on the aerated concrete. This is the only way to fix the Mauerlat on the wall with minimal cost and the maximum degree of reliability. Another option for installing a Mauerlat on aerated concrete without an armored belt is shown in the video

Mounting the Mauerlat on pins

It is clear that it is not always possible to prudently lay the plates into the walls of aerated concrete, and there is simply no way to punch horizontal pits under the fasteners. If the aerated concrete box is small, then you can fix the Mauerlat without an armored belt in a carpentry way, using pins.

The technology practically does not differ from the previous method. Initially, centering holes are drilled in the Mauerlat laid on aerated concrete, the timber is adhered to the surface of the walls with ordinary self-tapping screws. This allows you to correctly align and splice the Mauerlat until the final fastening.

Waterproofing is successively applied under the timber, roofing material is laid, after which holes of 25-30 mm can be drilled under oak pins to a depth of 70-80 cm. It remains to fill in the glue and fix the rods. The tops of the rods are sawn off, a carpentry screw is screwed inside, allowing the dowel to be wedged, and thereby rigidly fix the Mauerlat. At first glance, this method creates the impression of the most unreliable, but the practice of installing the Mauerlat suggests the opposite. Especially if you remember that most log houses are assembled using dowels.

Fastening with chemical anchors

Relatively new way allows you to fix a beam or a board almost anywhere on the aerated concrete wall. To hold the Mauerlat, threaded anchors are used, but they are not wrapped in the body of aerated concrete, but in a special cavity filled with quick-hardening resin.

A preliminary marking is carried out on the walls of the points at which it is planned to fix the timber. Further, the Mauerlat boards are dismantled, and holes are drilled in the aerated concrete for arranging chemical plugs. In order for the anchor bolt to firmly hold in the thickness of aerated concrete, it is necessary that the diameter of the plug cavity is at least 35 mm.

The cavity for pouring the self-hardening resin is cut out using a special tool. An oblique cutter is a drill with a cutting edge bent at an angle of 15 °. The nozzle is installed on a drill and sequentially, in several passes, a cavity is drilled in aerated concrete for a conical plug.

Before fixing the anchor, the hole is blown with air. A hand-held tire inflator or similar device can be used. Next, it is necessary to fix a plastic nozzle on the hole, through which the resin mixed with the hardener is squeezed with a syringe.

After 10 minutes, the anchor bolt must be screwed in, vertically aligned and temporarily fastened until the plastic is completely cured. Before installation, the anchor must be thoroughly cleaned of dust and degreased with a solvent. After another hour, the Mauerlat can be fixed on aerated concrete. The advantage of chemical anchors is simple technology and high reliability of fasteners, without the use of an armored belt. The downside is the high cost of self-hardening resin and the inability to fix the Mauerlat at temperatures below 15 ° C.

Fastening the Mauerlat to aerated concrete with wire

In order to fix the Mauerlat on aerated concrete walls, you do not need any expensive materials or special tools. It is enough to have at hand an electric drill with a long drill with a nozzle, wire scissors and a construction rod with a diameter of 5 mm. Sometimes, additionally, a 2 mm thick wire is used to tie the reinforcement.

Advice! If the walls of aerated concrete were laid by other craftsmen, and the location of the reinforcement is unknown, then it will also be useful to use a hand-held device to find hidden wiring.

The advantage this method is the exceptional simplicity of the process. In order to fix the Mauerlat beam on the wall, it is enough to tie a wire loop and pull the wood to the supporting surface, as in the video

Before proceeding with the installation, two problems will need to be solved. Firstly, you will need to immediately install a thick and very heavy beam on the walls and splice the individual parts of the Mauerlat in one run.

Secondly, you will need to select the line and locations for drilling through holes. The best option is to drill holes below the level of the last reinforcement layer. The sections of the walls above the window and door openings are definitely not suitable.

Before fixing the Mauerlat, the wire is cut and annealed to make it softer and more flexible. The material is passed through the hole and wrapped on the corner edge of the Mauerlat using a pry bar, the remaining mustache is cut off with scissors.

Some craftsmen, before fixing the timber, put on the wire a spiral spring wound from pieces of wire rod 2 mm thick. An improvised tube is inserted into a drilled hole in aerated concrete to avoid cutting the wall material when the fasteners are under strong tension. The method does not guarantee the absolute safety of aerated concrete in case of improper balancing of the rafters, but does not allow the wire pigtail to cut the wall, like a hacksaw, in case of gusts of wind.

Since there is no durable under the Mauerlat concrete armopoyas, then special attention must be paid to the correct and even tightening of the nuts on the studs or anchors. Typically, the fasteners are wrapped with a wrench, following the diagonal rule. That is, each next point for the nut must be located on the opposite side of the wall from the previous nut.

Conclusion

The choice of how exactly to fix the Mauerlat to aerated concrete without an armored belt has to be done taking into account the thickness of the walls, the size of the building and the structure of the roof. For a bath the best option there will be wire fasteners, for a small cottage in the country you can use a chimanker or hairpins. It is better to build two-story buildings with a reinforcing armored belt made of rolled steel.

When arranging a pitched roof, the installation of a rafter system cannot be performed directly on the walls of a building. An additional element that absorbs the loads from the rafters and transfers them to the walls will be the Mauerlat. Usually this is a special bar that fits along the perimeter of the walls. Since it takes up a serious load from the roof, it is very important to securely fix the Mauerlat to the wall. In the case of brick or concrete walls everything is simple and clear. But how is the Mauerlat fastening to aerated concrete carried out without an armored belt, because the gas block itself is rather loose and porous, therefore it cannot provide a strong fixation of the fastener? This is what we will talk about in our article.

The functional purpose of the Mauerlat

Usually, the same material is used for the manufacture of the Mauerlat as for the rafter system. Most often it is made from a wooden bar. However, if the rafter system is made of metal, then this structural detail can be made of channel or I-beam.

Usually this element is made from the following materials:

Wooden beams with a section of 100x100 mm, 150x150 mm or 200x300 mm. The timber is made of hardwood and undergoes mandatory antiseptic treatment. The product is laid along the perimeter on the walls of the structure. The joints are fixed with nails or a straight lock. In private construction, a wooden roof structure is most often used.
Less commonly, rolled profiles are used for these purposes - a channel with a U-shaped section or an I-beam with an H-shaped section. The height of the profile is determined by calculation and can be in the range of 70-120 mm.

A timber or steel beam is attached to the walls. In this case, different ways fastening. Further, the rafter legs rest on the Mauerlat. They exert a load on this element, which, in turn, evenly distributes it, transfers it to the walls of the building. In addition, this bar keeps the rafter system from shifting.

Important: since aerated concrete does not tolerate long-term point loads, it gradually collapses, it is recommended to erect a monolithic reinforced belt along the top of the walls before laying the Mauerlat.

However, there are ways of laying this structural element on aerated concrete walls without an armored belt. It is also worth remembering that the upper edge of the Mauerlat should be located at a height of at least 30-50 cm from the floor surface. This will ensure effective ventilation of the under-roof space and facilitate inspection and repair of roof structures.

Mounting methods

Fastening the Mauerlat to aerated concrete is much more difficult than to a brick wall

Fastening the Mauerlat to aerated concrete is much more difficult than to a brick wall. As a rule, this product is installed at a distance of 50 mm from the outer edge of the wall. The following fasteners can be used to mount the Mauerlat:

steel wire;
anchor fasteners embedded in the masonry;
special chemical anchors;
steel studs.

Important: for attaching a support bar to a reinforced belt or brick walls anchors are used.

After installing the timber, the rafter leg is attracted to the wall using a twist made of twisted metal wire with a diameter of 3 mm. To fix the wire, a steel shorty is mounted 6 cm below the bar. Instead, the wire can be fixed to the floor slabs. When installing a complex roof, it is recommended to carry out a reinforced concrete belt, which will give the building additional rigidity and more evenly distribute the load from the roof to the walls of the house.

To tie the individual parts of the Mauerlat into a single structure, an oblique cut is used, followed by fastening with nails, screws or bolts. Steel plates and brackets are used to reinforce the corner parts of the structure.

Using wire to fasten the timber

If wire is used to fasten the Mauerlat, then this must be taken care of even at the stage of laying the walls. The wire must be laid in the tub of the walls when performing the last few rows. At the same time, they adhere to the following sequence of actions:

During the laying of aerated concrete blocks, two or three rows before the end of the walls, a steel wire with a cross section of 6 mm is laid between the elements, which consists of several thinner wires twisted together.
In this case, the middle part of the fasteners is inserted into the masonry. Its ends should protrude from the walls. The length of these ends should be such that the wire can be freely wrapped around the timber to be laid.
The number of wires used should be equal to the number of rafters to be installed.

Fixation with studs

Fastening the Mauerlat to the aerated concrete wall with pins is allowed when installing lightweight roofs on small houses... The materials used to form the roofing cake should be as light as possible and not transfer significant loads to the rest of the structural parts of the building.

This technique is the best suited in the case when it is impossible to equip the armopoyas. In such a situation, the beam itself will serve as a reinforcing belt. This method causes rather controversial reviews of experts, but in practice it has proven itself very well, providing high reliability and stability of the roof.

To fix the timber to aerated concrete, you will need the following elements:

pins of the CPT-12 marking, called "dovetail";
a wooden beam with a section of 20x30 cm (the dimensions of this element depend on the thickness of the outer walls).

We carry out the work in the following order:

We drill holes in the walls from the gas block with a step of 100-150 cm.
We insert pins into the holes and fix them with cement milk or non-shrinking mortar.
Next, you need to perform waterproofing. For this, two layers of roofing material are laid on the walls. At the location of the pins in the material, holes must be pierced to ensure its snug fit to the walls. Waterproofing will protect the timber from moisture saturation and subsequent rot that can come from the walls.
With the same step as the studs were installed, holes of a suitable diameter for the studs are drilled in the Mauerlat.
Then the bar is pushed onto the studs over the waterproofing, washers are installed and tightened with nuts.
After the installation of the bar, the ends, in which the individual fragments of the bar are joined, are pulled together with forged steel brackets.
Now you can start installing the rafter system.

If the pins are mounted in the armopoyas, then we work like this:

Before the start of filling the armopoyas, studs are placed in it with a step of no more than 100 cm.
They are attached with a knitting wire to the belt's reinforcement cage. Plastic ties can be used instead of wire to secure the studs.
The accuracy of the installation of the studs horizontally and vertically is checked.
Concrete is poured into the formwork of the armopoyas.
After it has solidified, the prepared bar is put on with holes on the protruding ends of the studs and attracted by nuts to the surface.

Chemical anchor

This product is also called a liquid dowel, injection mass or glued in anchor. In fact, this is a glue with high adhesion characteristics, which is made on the basis of a synthetic polymer resin. Thanks to the chemical anchor, it is possible to firmly fasten the metal rod and the base.

Important: unlike others fasteners the liquid dowel does not create expansion stresses in the material, which is especially dangerous for fragile aerated concrete at the edges of the walls.

Unlike mechanical anchors, the fixation of which is based on the use of frictional forces and expansion of a polymer dowel, a chemical anchor is fixed due to the fact that the glue penetrates into the pores of aerated concrete to a considerable depth and firmly fixes the rod in the wall.

The installation of a chemical anchor is carried out in the following sequence:

First, a hole is drilled along the anchor. However, the size should be slightly larger than that of a conventional anchor bolt.
With the help of a special brush or compressed air, dust, debris and metal crumbs are removed from the channel.
A special chemical adhesive is poured into the hole prepared in the wall.
After that, a steel rod is inserted there - a threaded rod M 12-14. Also, for these purposes, you can take a piece of reinforcement of a suitable diameter.
The adhesive composition gains the required strength in 20 minutes, provided that the ambient temperature is approximately 20 ° C.
After the chemical composition has solidified, the rod is securely fixed in the wall. Moreover, the fastening strength is much higher than that of the mechanical method.

Benefits of using a liquid dowel:

The service life of such fasteners is more than 50 years.
This fixing method can be used on the edge of walls without the fear of splitting.
The fasteners have a fairly high chemical resistance.
Mounting is allowed to be carried out on damp material, that is, installation can be carried out even in rainy weather.
The installation of the Mauerlat and the arrangement of the roof can be performed without using reinforced belt, since a chemical anchor is much stronger anchored in a fragile material than a mechanical anchor.
This method is ideal for working with aerated concrete.
The hole depth can be less than when installing a mechanical anchor, which must be buried 2-3 rows of masonry.

The only drawback of this method of fixation is that welding cannot be performed with a rod attached to a liquid dowel, since the polymer material is destroyed by heating, and the fixing strength decreases.

Mechanical anchor (anchor bolt)

This is a fairly common way of fixing timber to walls. An anchor bolt consists of the following parts:

outer spacer part;
internal threaded rod.

Fixation occurs due to the fact that at the moment the nut is screwed onto the rod, the spacer structure is deformed in such a way that it reliably fixes the product in the hole drilled in the wall.

The installation of a mechanical anchor is performed in the following order:

A prepared timber is laid along the perimeter of the walls.
Further, along the entire length of this product, holes are drilled for installing anchor bolts. The step of the holes is 1 m. It is important to try to ensure that the anchors are installed in the corners of the building and at the junction of the two ends of the timber.
After that, with the help of a drill, holes are drilled in the walls through the holes prepared in the Mauerlat to a depth equal to the length of the anchor. In this case, it is not allowed to make the depth of the anchor insertion less than 2 or even 3 rows of masonry.
An anchor bolt is installed in the hole. For these purposes, it is better to take products with a length of at least 50 cm with M 12 or 14 threads.
After that, a washer is put on and the nut is screwed tightly. As a result, the steel or plastic dowel is unclenched so that it is firmly pressed into the material and fixes the bolt in the wall.

Attaching the Mauerlat to aerated concrete is quite simple. Careful preparation of all components is of paramount importance: wooden beams, fasteners, reinforcement cage, reliable waterproofing. Let's take a look at the order of work.

Fastening the Mauerlat to aerated concrete

Before directly attaching the Mauerlat, you should prepare the base. Reinforcing belt – required condition when arranging a roof, if the walls are made of aerated concrete or any similar material.

The reinforced concrete strapping belt prevents the punching of aerated concrete blocks and allows you to evenly distribute the dynamic and static forces coming from the roof completely over the wall area.

Arrangement of a reinforcing belt

The minimum size of the concrete tape is 200x150 m. It is attached from the inner surface of the wall.

Installation steps:

formwork is being built around the perimeter of the house. The pediments must be processed;
u-shaped blocks create a reinforced concrete belt;
a frame is assembled from reinforcement with a thickness of 10 mm. The armature should protrude 4 cm;
for rigid attachment of the Mauerltat to aerated concrete, threaded studs are installed with an interval of 1 m. Their diameter is 14mm;
the blocks are filled with M-200 concrete;
after a week, you can remove parts of the formwork and fasten the Mauerlat.

Important: at the stage of preparation for the start of work, builders are required to calculate the number of studs and the future distance between them. The points of attachment of the wooden structure to the rafters and the points of connection with the reinforcing belt should be located in different places. Check that the number of rafter legs and studs is the same.

Preparation of a wooden structure

The bars are processed before installation antiseptics preventing wood decay. A log or bar with a section of 100x100 mm or 150x150 mm is wrapped with a waterproofing material. For this purpose, a bitumen-polymer waterproofing material is suitable. Roofing material is not used.

Quality materials will create a solid structure. The tree must be free of knots and cracks. Humidity must comply with building codes.

If the developer uses "raw" wood, it should be possible to adjust the anchor nut.

This operation is performed once a year for 5 years. During this period, intense shrinkage of wet wood occurs. As the bars dry, tighten the nut less and less.

In this photo you can clearly see one of the ways of attaching the Mauerlat on the walls of aerated concrete.

How to properly attach the Mauerlat to aerated concrete?

An anchor with washer and nut is used. The shape of the anchors: T- and L-shaped. Thread: M12 or M14. According to international building codes, in earthquake-prone areas between adjacent anchors, the pitch should not exceed 1 - 1.2 m.

Mechanical type of fastener

Procedure:

dowels are inserted into the prepared holes;
screw in the fastener;
the harpoon teeth are firmly pressed into the aerated concrete;
the surface expands;
the structure is securely fixed.

Great option installing a Mauerlat on aerated concrete has only one drawback - a high cost. 1 anchor and a special dowel with a harpoon cost more than 3 thousand rubles.

Another video on how to fix the Mauerlat to aerated concrete.

Installing Mauerlat

Another method is used to firmly fix the Mauerlat in aerated concrete walls. It will take chemical capsule... Its cost is much lower - 150 rubles. for a unit.

Reliable fixation of the structure is achieved due to the penetration of chemicals into the pores of the material. Additionally concrete surface gets heat and waterproofing.

The final stage

After installing the Mauerlat on aerated concrete, they proceed to installation of the truss structure... There are two ways.

First option

in the boards, they perform a wash down to 1/3 of the depth of the board;
nails and metal corners will allow you to securely fasten the rafters;
nails (2 pcs.) are hammered crosswise from the sides;
an additional nail is driven in from above;
the mounting angles finally secure the joint.

Second option

in the rafter, the saw is not performed;
a special support bar is hemmed from below, abutting against the Mauerlat;
nails are driven in, as in the first option.

The support bar is 1 m long. The second option is suitable for rafters with a low height.

Fastening the tie bar can only be performed after accurate calculations and the procurement of high-quality materials. Buying timber of inadequate quality with high humidity can compromise the strength of the structure.

To fasten the Mauerlat to an aerated concrete wall, use an anchor with special dowels or chemical method installation. Be sure to follow thermal insulation of the reinforcing belt made of extruded polystyrene foam.

Compliance with the requirements will allow you to securely fix the Mauerlat and create a solid rafter structure.

One of the most important nuances the technology of building a house from aerated concrete is the Mauerlat mount. The characteristics of the blocks do not allow them to withstand high point loads; without taking constructive measures, the walls will simply collapse. Correctly performed fastening implies the laying of an armored belt, this stage is not recommended to be skipped. If it is impossible to organize it, the Mauerlat comes into contact directly with the wall and is fixed with wire, anchors, pins or dowels. The method is determined in advance, in the absence of experience this type construction works it is better to entrust it to specialists.

Possible fastening methods

Depending on the type of strapping scheme, one of two options for attaching the Mauerlat to aerated concrete is selected: pouring a monolithic reinforced concrete belt around the entire perimeter of the building or placing fixing elements directly into masonry or blocks. The first method, in addition to ensuring maximum reliability, contributes to the redistribution of loads, levels the walls and protects them from deformations, including shrinkage. The presence of an armored belt is mandatory when conducting construction in areas with seismic activity, building houses from aerated concrete over one floor, using heavy roofing materials, complex shape of the roof.

The standard instructions for setting it up include the following steps:

Preparatory: calculation of fasteners and selection of the interval between them. The main guideline is the layout of the rafters: with an equal number, the attachment points to the Mauerlat should not coincide with the twist points of the studs.
Laying U-shaped blocks on top of the last row along the entire perimeter of the aerated concrete wall. They act as formwork, the recommended width is from 25 cm.
Assembling a reinforcing frame from rods with a thickness of 10 mm. At this stage, it is planned to lay the pins for fixing the Mauerlat with an interval of no more than 1 m, strictly vertically, with a wire tied to the main rows. Particular attention is paid to the corners, in these areas the metal rods are bent to a length not less than the width of the belt. Similar actions are repeated around the entire perimeter. load-bearing walls including gables and partitions.
Organization of an insulating layer made of compacted polystyrene foam. It is placed closer to the outer edge of the aerated concrete wall.
Filling the inner cavity with concrete with a strength grade of at least M200, compaction, removal of excess and careful leveling of the top layer. Covering with polyethylene and standard moisture care during the first days.

You can start the next stage of tying the Mauerlat to the walls of aerated concrete in a week. All formwork structures are removed (they are used when pouring a monolithic reinforced concrete cushion along the entire perimeter and width, this design is typical for brickwork, but sometimes it is also used for gas silicate houses). Further, on top of the upper side in contact with the future Mauerlat, 2 layers of waterproofing are laid or coated, this stage cannot be skipped. Attachment points are marked on a well-dried wooden beam treated with antiseptics and fire retardants. The easiest way to do this is by attaching it to the armored belt over the studs and hitting with a sledgehammer, the holes are drilled according to the diameter of the rods (at least 14 mm). After that, it remains only to attach the Mauerlat to the aerated concrete wall and tighten it with nuts or washers.

The final stages of the work are difficult to complete on your own; the forces of at least 2 people will be required. In addition to the main walls, the armopoyas is mounted on any areas on which the roofing elements rest (for example, ridge posts or beds). In the absence of experience, it is worth watching video instructions on the topic "how to properly mount the Mauerlat". If it is necessary to eliminate errors that have arisen during the masonry process, it is better to contact specialists, at least for advice. Installation of rafters is possible only after all work on fixing the Mauerlat and checking the quality of the connections.

How is the Mauerlat attached to the wall in the absence of an armored belt?

It is not always possible to lay a monolithic tape with your own hands; in some cases, they resort to other methods of binding the timber. The easiest way is to lay 3-4 rows before the top of the steel wire between the blocks. Its length is selected taking into account the section of the Mauerlat: when folded in half, it should be enough for girth and twisting. The step depends on the distance between the rafter structures. This option is often referred to when attaching the timber to the wall. one-storey house from aerated concrete.

For light and small-sized buildings, the Mauerlat attachment for threaded rods made of galvanized or stainless steel is also suitable. They are mounted in the masonry 1-2 rows up to the upper edge, the minimum permissible depth of penetration of such products into the aerated concrete wall is 2 times the height of the block. The standard length of the studs is within 1 m, the diameter is from 8 to 24 mm. If necessary, the protruding sections are then cut off.

Fastening the Mauerlat bar with wooden dowels is possible both when laying an armored belt, and without it. They are treated with antiseptics and well-dried long plugs. They are mounted in a wall of aerated concrete closer to the upper edge and connected to the Mauerlat by means of staples. Alternative option is their laying between blocks, the number of pieces is not less than the number of rafters.

High reliability of fastening is provided by means of anchors: mechanical or chemical. In the first case, the method consists in screwing expanding dowels with a cross section of 12-14 mm into aerated concrete. The second is in the use of chemical anchors (capsule or in the form of a tube with compositions based on polymer resins). The minimum depth of the hole to be laid is 2 rows of masonry.

The main advantage of anchoring is the ability to fix the Mauerlat without complicated organizational measures in the process of laying gas blocks, it is quite easy to carry out it yourself. However, top scores are observed in the most motionless hardware, that is, either laid simultaneously with the armored belt, or fixed with the help chemical compositions(in the latter case, it is forbidden to carry out welding work near the joints). The disadvantages of the method include the high cost: of all the technologies, fastening without an armored belt, anchoring will cost the most, and the more reliable it is, the higher the final costs will be.

Violations of the technology for attaching the Mauerlat during do-it-yourself work include:

Lack of a waterproofing layer between the timber and the upper part of the wall. Preference is given to modern bitumen-polymer mastics, budget option is a roofing material, a plastic film is not suitable for these purposes due to its low strength. The minimum number of waterproofing layers is 2.
Planting Mauerlat, untreated with antiseptics (the contacting side remains unprotected) or using wet wood.
Installation of anchors or studs at an angle, the connection is unreliable.
Incorrectly selected reinforcement for the frame, no overlaps (the recommended minimum if it is necessary to extend the rods is 20 cm), close adhesion of the metal to the walls of aerated concrete (plastic supports are well suited to ensure the required 5 cm).

When using raw wood, the Mauerlat is fixed with a nut, the reliability of the fasteners is periodically checked, if necessary, they are tightened. This operation is carried out at least once a year for 4-5 years, until the end of the shrinkage processes. A completely dry and well-established timber practically does not need pulling up, it is inspected for preventive purposes.

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