Installing a roof on aerated concrete blocks. How to attach a roof to foam block walls: work order. Preparing a wooden structure

The roof is one of the important and responsible parts of the house. And from the strength of the connection roofing system and walls largely depends on the ability of the house to withstand the effects of natural elements: snow and wind loads.

Mauerlat - definition

Mauerlat- a structural element of a building that links all elements together rafter system roofs between each other and with the walls of the building. Main functions of the Mauerlat:

keeps the roof from moving in relation to the wall;
evenly distributes and transfers to the walls the load concentrated at the support points of the rafters.

The Mauerlat is laid and secured along the entire perimeter of the upper part outer wall buildings with a slight indentation from the outer edge. Each element of the Mauerlat is firmly connected to two neighboring ones.

Together with the rafter system, it creates a reliable, stable spatial structure of the roofing system. Provides a strong connection between the roofing system and the walls of the building, evenly distributing the load from the roof along the entire perimeter of the wall.

Selection of material and calculation of parameters

To manufacture the Mauerlat, timber with the following cross-section is used:

100x100 mm;
100x150 mm;
150x150 mm.

It is common to use boards with a cross section of 50x150 mm. However, for a wall made of aerated concrete without a reinforcing belt, it is advisable to avoid this option. A board laid flat does not have sufficient rigidity to absorb and distribute point impacts. vertical loads from the rafters to the wall.

To create a solid structure capable of withstanding the load transmitted by the rafters, the edges of the beams are connected in series using a direct lock. The Mauerlat bars are strengthened closer to the inside of the wall so that the distance to the outer edge remains at least 50 mm.

The top of the Mauerlat should be located at a distance of 300 to 500 mm from the top of the ceiling. Such a gap provides sufficient conditions for ventilation of the under-roof space and does not impede access for periodic inspection and repair of the Mauerlat and the lower part of the rafter legs.

The strength and reliability of the connection between the roof and the walls largely depends on the correct choice of design, the method of fastening to the walls and the accuracy of calculating the dimensions of the Mauerlat.

Let's consider the main factors influencing the choice of Mauerlat cross-section:

shape and area of the building covered by the roof;
type of roof structure (hanging or layered rafters, pitch size and angle of inclination of rafter legs);
material and weight of the rafter system and roofing;
presence or absence attic floor in the house;
calculated snow and wind load of the roof, determined climatic conditions region.

When choosing the design and cross-section of the Mauerlat, it should be taken into account that a wall made of aerated concrete weakly resists horizontal loads (thrust). The presence or absence of spacer forces at the lower ends of the rafter legs is determined by the design of the rafter system.

Non-thrust structures include:

hanging rafters using tie rods;
layered rafters with an upper freely rotating fastening, and a lower freely rotating and movable fastening in the direction of the beam axis.

Rafter systems that create horizontal loads (thrust) in the walls:

hanging rafters without tightening;
layered rafters with rigidly fastened supports.

The horizontal forces transmitted to the wall by the spacer structures of the rafter systems must be absorbed by the reinforcing belt. Attempts to compensate for these efforts only by increasing the cross-section of the mauerlat beam are a construction mistake and lead to negative results.

The volume and mass of timber for the manufacture of the Mauerlat is calculated using the formulas:

(Volume of the Mauerlat) = (Section of the timber) x (Perimeter of the house);
(Mass of timber) = (Volume of Mauerlat) x (Density of wood).

Types of fastening the Mauerlat to aerated concrete

Aerated concrete, how wall material, has a whole range of positive properties:

easy;
perfectly processed;
has good thermal insulation properties;
the blocks have a clear geometric shape.

But it also has its own characteristics. Aerated concrete is a fairly fragile material. It copes well with moderate compressive loads, but the application of tensile or shear forces easily leads to the formation of cracks.

Accordingly, when choosing a method for attaching the Mauerlat to the wall, you need to take this into account.

Mauerlat for aerated concrete without armored belt

In construction practice, sometimes it becomes necessary to attach a Mauerlat to a wall made of aerated concrete without installing a reinforcing belt. The fragility of aerated concrete imposes a number of restrictions on the choice of fastening method, but does not exclude this possibility.

Fastening with steel wire

The simplest mounting option.
It has become widespread due to the low cost of materials.

Sequence of actions:

several rows (at least three) before the completion of the masonry, pieces of soft steel wire with a diameter of 6 mm are laid across the wall;
the mauerlat is laid after the wall is laid and the glue has set its strength;
by twisting the ends of the wire, the mauerlat beam is firmly pressed against the wall.

The length of the ends of the wire must be sufficient to cover the upper rows of the wall, the mauerlat beam and twist.

The laying pitch must coincide with the pitch of the rafters.

Fastening with anchor bolts

An anchor bolt (mechanical anchor) consists of:

from an internal rod with a threaded part;
external spacer part.

When the nut is screwed onto the inner rod, the spacer part is deformed and fixes the anchor bolt in the channel of the wall hole.

Sequence of actions:

Mauerlat beam laid out along the entire perimeter of the wall.
Holes for anchor bolts are drilled along the entire length of the Mauerlat.. The distance between adjacent holes is no more than 1 meter. It is necessary to strive to ensure that the locations of the anchors necessarily fall on the corners of the building and the joints of the beams.
Through the holes in the Mauerlat using a drill, drilling into the masonry wall is the length of the anchor, but not less than 2 - 3 rows.
An anchor bolt is inserted into the hole at least 500 mm long and M12 or M14 thread.
The washer is put on. The nut is tightened with force. The plastic or metal dowel included in the anchor design is expanded, pressed into the channel walls and securely fixes the anchor bolt in the wall.

Fastening the Mauerlat using mechanical anchors has become widespread. Limited by the relatively high cost of fasteners.

Chemical anchor

Modern technologies The manufacture of mechanical anchors for fastening in aerated concrete has reached perfection. However, the main drawback inherent in the principle of operation remains. An anchor is attached to aerated concrete by creating bursting forces. As the load on the anchor increases, the aerated concrete block may split.

The so-called chemical anchor. Instead of dowels, a synthetic adhesive composition is used. It penetrates deeply into the pores of aerated concrete. When hardened, it firmly fixes the metal rod in the wall material.

Sequence of actions:

a hole is drilled as for a mechanical anchor bolt, but with a slightly larger diameter;
using compressed air or a special brush, dust and crumbs of material are removed from the hole channel;
the hole channel is filled with adhesive;
a threaded rod M12 - M14 or a piece of reinforcement of a similar diameter is inserted into the hole;
at temperature environment 20 degrees Celsius the composition gains strength in about 20 minutes.

TO positive qualities chemical anchors include:

The fastening strength is significantly higher than that of an anchor with mechanical fixation.
Absence of bursting stresses in aerated concrete. Mounting on the edge of the wall is allowed.
Chemical resistance.
Can be attached to wet material and work in the rain.
Long service life (more than 50 years).

Disadvantages of chemical anchor:

The adhesive composition does not withstand high temperatures.
Cannot be produced welding work directly with the metal anchor rod.

Arrangement of a reinforcing belt

And yet, if the design of the house allows you to make a reinforcing belt, it is recommended to take advantage of this opportunity. Attaching the Mauerlat to an aerated concrete wall using an armored belt is much easier and more reliable. In addition to making it easier to attach the Mauerlat, the armored belt also has other positive qualities.

Armored belt, like a hoop in a tub, tightens the upper part of the walls of the building and preserves its geometry during uneven shrinkage of the foundation and seasonal soil movements.
Increases rigidity and the strength of the entire building.
Distributes evenly point loads from rafter legs on the walls of the building.
Is the best(and in the case of aerated concrete walls, the only) means of counteracting the thrusting loads on the walls during the spacer structure of the rafter system.
Changing the thickness of the armored belt It is convenient to align the top cut of the building walls horizontally. Level errors made during laying are leveled out.

The armored belt is made in the form of a concrete strip along its entire length load-bearing walls buildings.

Manufacturing of formwork

Convenient to use U-shaped blocks. With their help, a continuous gutter is formed in the top row of the masonry, which performs the functions permanent formwork. With this manufacturing method, cold bridges are not created. The wall will not freeze.
The top row on the outside of the wall is made of blocks 100 mm thick. WITH inside– brickwork “on edge”. More labor intensive compared to using U-shaped blocks. Thermal insulation properties are somewhat worse. The cost of the material is lower.
The entire width of the wall is made of boards or OSB boards removable formwork is formed. The method is often used due to the low cost of materials. Cold bridges form. Measures must be taken to additional insulation walls in the armored belt area.

Belt reinforcement

Four - six threads of reinforcement with a diameter of 10 - 12 mm are used to make a frame in the form of a spatial box. Cross connections are made with wire with a diameter of 6 mm. The connection of frame elements to each other should be done using soft steel wire twists or plastic ties.

It is advisable to fill the armored belt with M200 grade concrete at one time, avoiding long interruptions in work. Using a vibrator to compact concrete significantly increases strength and durability reinforced concrete structure.

Fastening with metal studs

Threaded metal studs are rightfully considered the simplest and most convenient element for attaching the Mauerlat to the armored belt. The diameter of the pin is from 12 to 14 mm. The length is sufficient for the upper edge of the pin to protrude 4–5 cm above the surface of the Mauerlat. The lower edge of the pin is bent in the shape of the letter “G”.

Bolts may be used. In this case, metal plates in the shape of a rectangle are welded to the caps.

Sequence of actions:

studs with a pitch of no more than 1 meter are placed in the armored belt formwork before the concrete pouring operation is completed;
attached to the reinforcement frame using binding wire or plastic ties;
the accuracy of installation vertically and horizontally is controlled;
After the concrete hardens, the Mauerlat beam is put on the protruding ends of the studs with holes and tightly pulled with nuts to the surface of the reinforced belt.

The importance of waterproofing during installation

Regardless of the chosen method of fastening, the Mauerlat and the wall surface must be securely separated from each other by a layer of waterproofing. Condensation formed when there is a temperature difference at the junction various materials, leads to wetting and destruction of the wooden beam of the Mauerlat.

Exists large selection materials for waterproofing during installation. Usually two layers of roofing material or one layer of waterproofing are laid. It will not be unnecessary to treat the wooden beams with an antiseptic composition.

Building a house is a long and difficult path. Regardless of whether you are building a house with your own hands or have entrusted the work to third-party specialists, you need to clearly understand how to correctly take EVERY step along this path. Only personal control of the correctness of the chosen decisions and the quality of work will allow the house to serve for a long time and bring joy to you and your children.

Installing a Mauerlat is not difficult, but it requires some skills and precise calculations. A competent owner can easily handle this on his own. Let's try to figure out what and how best to attach the Mauerlat to aerated concrete, and also talk about the importance of waterproofing.

What is the Mauerlat fastening like?

In the process of building a house, the Mauerlat is given special attention– he is entrusted with an important mission in the roof structure. The rafter system puts a very large load on the walls, to avoid this, beams are installed around the perimeter, and then fastened to them rafter legs– thus, the load is evenly distributed on the walls of the house.

Fixing the Mauerlat can be done in three ways, using studs, anchors or steel wire. Typically the method depends on general sizes buildings or houses. Experts have long come to the unanimous opinion that fastening the Mauerlat to aerated concrete should be accompanied by the creation of an armored belt. Then the structure will be ideally strong and rigid, less susceptible to shrinkage.

Since the wooden logs of the Mauerlat are responsible for reliable fixation rafter beams - they must be secured as efficiently and powerfully as possible. Otherwise, they will not be able to take on part of the load properly.

Parameters of suitable timber for the role of Mauerlat

Bars are well suited for this deciduous trees(most often oak). The recommended size is 10x10, but larger is possible - 15x15. Be sure to treat the wood with an antiseptic to protect it from rotting. Using a direct lock and additional nails for reliability, the mauerlat is fastened together, evenly covering the top of the walls.

Important: it happens that you have to take “raw” wood, in this case, do not forget that for 5 years you will need to tighten the anchor nut annually due to frequent shrinkage of the wood - take care of the possibility of adjusting it. Over time, this will not be necessary.

Before installing the Mauerlat, the top of the walls must be covered with a layer of waterproofing, otherwise the wood will begin to deteriorate upon contact with the wall surface. For this, you can use ordinary roofing felt, but modern builders still do not recommend it - it is better to choose a high-quality bitumen-polymer material. It will provide more reliable waterproofing.

Fastening with anchors

It is this fastening that is used with the armored belt - together they create
very durable and reliable design. The armored belt is a kind of frame made of 12 mm reinforcement, which fits into a special gutter.

What you will need:

Reinforcement 10-12 mm thick to create a frame.

Rods 6 mm thick, for transverse intersections of armored belts

Concrete grade M-200
U-shaped blocks - they will be a container for reinforcement and concrete

U-blocks will help you lay out a groove on the surface of the walls without resorting to cutting aerated concrete - just install the blocks along the upper edge of the walls.

You should end up with a continuous “ditch” - for this you need to place blocks with sawn-off sides in the corners.

Then, install a reinforced belt into the resulting gutter.

Attach a threaded anchor to the belt, use wire to do this, and stretch fishing line or thick thread as guides.

Now you can fill it all with concrete.

After the concrete has dried, apply a waterproofing layer.

Important: the anchors must protrude beyond the concrete - you will put the Mauerlat on them. Fill concrete mixture should occur without interruption, so to speak, in one go at once the required amount.

Despite the existence of other methods of fastening to aerated concrete, the use of a reinforced belt cannot be compared with any other in terms of quality and power.

Metal studs - where this type of fastening is appropriate

This option is good for very small houses or other buildings where there is no heavy load on the aerated concrete walls. Well, or for some reason it is not possible to build an armored belt. In other cases, metal studs are quite weak and cannot withstand excessive pressure, so experts do not recommend using them to attach the Mauerlat to the walls of large buildings.

Stages of work:

To insert studs into aerated concrete, you must drill holes in it at a distance of one to one and a half meters.

Insert SPT 12 studs into the aerated concrete.

Then the hairpin needs to be filled with solution.

Before putting the Mauerlat on the studs, install a layer of waterproofing - you can use roofing felt, but as mentioned above, it is better to use a more modern material.

Place the Mauerlat timber on the insulation, placing it on the washers.

Tighten the nuts.

At the junction points, the Mauerlat is tightened with staples.

Important: it happens that during the work there are already gables - it is better to remove them. Lay the bars along the edges of the walls, then file the rafter legs - this way, you will be able to redirect the thrust from the rafters to the beam.

Fastening the Mauerlat with wire without an armored belt

This method is much easier than the first ones two, but less resistant and strong - well suited where you need to fasten the Mauerlat to aerated concrete as quickly as possible. Used in the construction of small, simple buildings. If in the method with construction studs an armored belt is installed if necessary, then everything happens without it in any case. Its advantage is that for the work you only need steel wire.

Work process:

At the stage of building walls when laying aerated concrete blocks, you need to insert a wire between the joints of the bricks and embed it. This should be done so that its middle is tightly secured with blocks. It is advisable to start installing the wire somewhere three or four rows before the wall is completed.

The steel wire must be long. Keep in mind that part of it will be under the bricks, and the ends must penetrate the hole in the beam, braid it, and then they must be tightly tightened and secured. Thus, the Mauerlat will be able to quite confidently hold the entire structure of the rafter system, taking part of the load from the walls onto itself.

Do not forget that the Mauerlat must be fastened in such a way that there is a free space between the beams and the outer edge of the wall of at least 5 cm.

Wooden boards must be sanded well to avoid cracks or knots.

Waterproofing is one of the important points– if it is not laid, then moisture will form between the wood and aerated concrete, and it will very quickly ruin the timber.

"Raw" wood is permitted, but must comply with building codes.

As you can see, attaching the Mauerlat to aerated concrete without an armored belt or with it is not as difficult as it might seem at first glance. But in any case, it would be useful to consult with experienced builder.

Video

One of the most important nuances technology for building a house from aerated concrete is the fastening of the Mauerlat. The characteristics of the blocks do not allow them to withstand high point loads; without taking structural measures, the walls will simply collapse. Correctly performed fastening involves laying an armored belt; it is not recommended to skip this stage. If it is impossible to organize it, the Mauerlat comes into direct contact 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 work It's better to leave 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 the masonry or blocks. The first method, in addition to ensuring maximum reliability, helps to redistribute loads, levels the walls and protects them from deformations, including shrinkage. The presence of an armored belt is mandatory when carrying out construction in areas with seismic activity, erecting houses made of aerated concrete over one floor, using heavy roofing materials, complex shape roofs.

Standard instructions for laying it include the following steps:

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

You can begin the next stage of tying the Mauerlat to the aerated concrete walls in a week. All formwork structures are removed (they are used when pouring a monolithic reinforced concrete pad along the entire perimeter and width, this design is typical for brickwork, but is sometimes used for houses made of gas silicate). Next, 2 layers of waterproofing are laid or coated on top of the upper side in contact with the future Mauerlat; this stage cannot be skipped. Attachment points are marked on a wooden beam treated with antiseptics and fire retardants and well dried. The easiest way to do this is by placing it on the armored belt over the studs and hitting it with a sledgehammer; holes are drilled according to the diameter of the rods (at least 14 mm). After this, all that remains is 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; at least 2 people will be required. In addition to main walls, the armored belt is mounted on any areas on which roof elements rest (for example, ridge posts or beds). If you have no experience, you should watch video instructions on the topic “how to properly attach the Mauerlat.” If you need to eliminate errors that occurred during the laying process, it is better to contact specialists, at least for advice. Installation of rafters is possible only after completion of all work on fixing the Mauerlat and checking the quality of connections.

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

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

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

Fastening the mauerlat beam wooden dowels possible both when laying an armored belt and without it. They are long corks treated with antiseptics and well dried. They are mounted into a wall made of aerated concrete closer to the top edge and connected to the Mauerlat using brackets. Alternative option is their laying between the blocks, the number of pieces is not less than the number of rafters.

High reliability of fastening is ensured using anchors: mechanical or chemical. In the first case, the method consists of screwing expanding dowels with a cross-section within 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 secure the Mauerlat without complex organizational measures in the process of laying gas blocks; it is quite easy to do it yourself. Nevertheless, best results observed with maximally stationary hardware, that is, either laid simultaneously with an armored belt, or fixed with the help chemical compositions(in the latter case, welding work near the connections is prohibited). The disadvantages of this method include its high cost: of all the technologies for 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 Mauerlat fastening technology when doing DIY work include:

Lack of waterproofing layer between the beam and top part walls. Preference is given to modern bitumen-polymer mastics, budget option is roofing material, polyethylene film not suitable for these purposes due to low strength. The minimum number of waterproofing layers is 2.
Planting a mauerlat that has not been treated with antiseptics (the contacting side remains unprotected) or the use of wet wood.
Installing anchors or studs at an angle makes the connection unreliable.
Incorrectly selected reinforcement for the frame, lack of overlaps (the recommended minimum if it is necessary to extend the rods is 20 cm), close contact of the metal to the walls of aerated concrete (plastic stands are well suited to provide the required 5 cm).

When using raw wood, the Mauerlat is fixed with a nut, the reliability of the fastenings is periodically checked, and 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 established beam practically does not need tightening; its inspection is carried out for preventive purposes.

In design small house from aerated concrete blocks with a simple sloping roof, there is no particular need to cast reinforcing tape; it is much cheaper and faster to attach the Mauerlat to aerated concrete without an armor belt. The technology reduces time costs, construction goes faster, but does not make the work easier, since this method of attaching Mauerlat beams directly to the walls requires care and precision.

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

Simply put, without knowing technological techniques correct installation, it’s better not to take risks and use the classic method, with laying reinforcement and concreting the tape. On the other hand, the problem is only in following the technology, there are no secrets in this, and with due patience and accuracy, secure wooden beam without an armored belt it will not be difficult.

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

Advice! The method of securing the Mauerlat without an armored belt must be chosen before the walls are laid out. You need to make a decision before the last three rows of blocks are laid out. It is at the level of the third rows from the top that the penultimate layer of wall reinforcement is laid, which is convenient to use to secure the beam directly to the wall made of aerated concrete.

The situation with the rafters will become clearer if you look at the diagram below.

Hanging rafter beams after installation and alignment on the ridge and the mauerlat, they must be connected and tightened with horizontal timber ties.

If the layered beam is placed on a ridge girder using a hinge, then the heel of the rafter, with which it rests on the surface of the mauerlat, must be secured to a sliding connection. Otherwise, the weight of the roof will tear the wooden beam from the surface.

Strong arguments against the armored belt

Most craftsmen involved in the construction of buildings made of aerated concrete are confident that installing an armored belt can solve all problems with installing the mauerlat and 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 armored belt, which successfully work on brick, block and concrete buildings, to aerated concrete walls.

There are only two fundamental objections to the armored belt:

First of all, with any manufacturing scheme, the reinforced belt can be secured only to the top row of aerated concrete, so the roof has to be made with the same restrictions, as in the case when this belt is not present. The concrete frame redistributes the thrust load well, but all the forces from the reinforced belt fall only on the top row of aerated concrete, hence the appearance of cracks along the upper edge of the walls;
Attaching the Mauerlat to an armored belt means creating huge problems with a cold bridge in that part of the roof where aerated concrete is least ventilated. Even laying a layer of EPS insulation helps little; you have to look for ways to install vents to remove condensation from the reinforced belt.

The third argument against concreting is related to costs. The installation of reinforcing tape will cost an amount approximately equal to a third of the estimate for the construction of the foundation. For a house 4x8 m this is approximately 60-100 thousand rubles. It is clear that it is much easier to fasten the Mauerlat and roof frame to a Mauerlat rigidly connected to a concrete reinforced belt. Sometimes master roofers even refuse to install a roof on aerated concrete without an armored belt, but technologically this is quite possible.

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

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

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

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

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

This is the only method, the use of which must be immediately and without a doubt; it is better not to take risks without an armored belt.

The anchor fastening works great on an armored belt made of concrete, brick, or cinder block, but due to the small contact surface area of the support sleeve, the fastener can be torn out of the aerated concrete body by the first strong wind.

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

Fastening with studs

The easiest way to build a building made of aerated concrete without a reinforcing belt is to secure a wooden beam using an embedded element and a stud with a thread of at least M16. The method is very similar to the option 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 caveat to this method of fastening. Before laying the last three rows of box blocks, it is necessary to mark the planned installation lines for the future threaded fasteners of the Mauerlat. Usually they simply draw vertical lines on the walls. Next, 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 secure the studs in the wall, you will need:

Drill vertical hole with a diameter of 20-25 mm to the level of the plate embedded in aerated concrete, usually it is necessary to drill with a drill to a depth of a meter;
Screw the threaded rod into the nut with the plate;
To properly fasten the pin, it will need to be leveled and wedged in the hole;
After all the rods have been aligned and secured, the free space is filled with concrete or adhesive mixture.

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

Mounting the Mauerlat on dowels

It is clear that it is not always possible to prudently lay plates in walls made of aerated concrete, and it is simply not possible to punch horizontal holes for laying fasteners. If the aerated concrete box has small sizes, then you can fasten the Mauerlat without an armored belt using carpentry, using dowels.

The technology is practically no different from the previous method. Initially, centering holes are drilled in the mauerlat laid on aerated concrete, and the timber is secured to the surface of the walls with ordinary self-tapping screws. This allows you to correctly align and splice the Mauerlat until the moment of final fastening.

Waterproofing is successively applied under the timber, roofing felt is laid, after which 25-30 mm holes can be drilled for oak dowels to a depth of 70-80 cm. All that remains is to pour in the glue and secure the rods. The tops of the rods are cut off, a carpentry screw is turned inside, allowing the dowel to be wedged out and thereby firmly securing the Mauerlat. At first glance, this method gives the impression of being the most unreliable, but the practice of installing a 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 board almost anywhere on an 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.

First, markings are carried out on the walls of the points where it is planned to fix the timber. Next, the Mauerlat boards are dismantled, and holes are drilled in the aerated concrete for installing chemical plugs. In order for the anchor bolt to hold firmly in the thickness of the aerated concrete, it is necessary that the diameter of the plug cavity be at least 35 mm.

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

Before fixing the anchor, the hole is purged with air. Can be used hand pump for inflating tires or any similar device. Next, you need to attach a plastic nozzle to the hole, through which the resin mixed with the hardener is pressed with a syringe.

After 10 minutes, it is necessary to tighten the anchor bolt, align it vertically and temporarily secure it 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 to aerated concrete. The advantage of chemical anchors is simple technology and high reliability of fastening, without the use of an armored belt. The downside is the high cost of the self-hardening resin and the inability to fix the Mauerlat at temperatures below 15 o C.

Fastening the Mauerlat to aerated concrete with wire

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

Advice! If aerated concrete walls 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.

Advantage this method is the exceptional simplicity of the process. In order to secure the Mauerlat timber to the wall, it is enough to tie a wire loop and pull the wood to the supporting surface, as in the video

Before you begin installation, you will need to solve two problems. Firstly, you will need to immediately install a thick and very heavy beam on the walls and splice the individual parts of the Mauerlat into 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 laying the last reinforcing layer. Sections of walls above 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 securing the beam, put a spiral spring wound from pieces of wire rod 2 mm thick onto the wire. An improvised tube is inserted into 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 if the rafters are not balanced correctly, but it does not allow the wire pigtail to cut the wall like a hacksaw during gusts of wind.

Since there is no durable concrete reinforced belt under the Mauerlat, special attention must be paid to the correct and uniform tightening of the nuts on the studs or anchors. Usually the fasteners are tightened with a wrench, following the diagonal rule. That is, each subsequent point for the nut should be located on the opposite side of the wall from the previous nut.

Conclusion

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

Aerated concrete, like foam concrete, has a porous structure, which causes some difficulties when installing the Mauerlat. Since the installation of a Mauerlat is mandatory on buildings constructed from foam concrete, aerated concrete, and so on, below is a number of ways to attach the Mauerlat to such materials.

Since the Mauerlat helps to hold the roof on the walls of the building, it must be securely fastened to them.

You can attach the Mauerlat to aerated concrete in the following ways:

Steel wire. When laying walls in two to three rows, steel wire with a diameter of 0.6 millimeters is laid between the blocks. After which one end of the wire is inserted into the hole in the Mauerlat and twisted with the other. It should be noted that the length of the laid wire must be sufficient to secure the Mauerlat well. It is recommended to lay the amount of wire equal to the number of rafters.
Metal studs. This method of attaching the Mauerlat is usually used on small buildings. The essence of the fastener is as follows: one row before the end of the wall, studs with metal coins welded to them of at least 5x5 centimeters are laid between the blocks.
After that, the Mauerlat is installed on the studs through the holes and pressed against the wall with nuts and washers. The length of the studs above the wall surface should be the thickness of the mauerlat beam plus at least 5 cm in order to tighten the nuts and washers. It is also recommended to lay studs in increments of 1-1.5 meters.
Anchor bolts. Fastening the Mauerlat with anchor bolts to aerated concrete is one of the most reliable of all the proposed methods. Since aerated concrete is a fragile material, to fasten the Mauerlat with anchor bolts it is necessary to construct an armored belt.
The armored belt will not only allow you to fasten the Mauerlat, but also strengthen and securely connect the walls of the building while removing the thrust load from them from the roof. The construction of an armored belt can be done in two ways:
- Using U-shaped blocks.
- Using wooden formwork.

In the first and second methods, reinforcement with a diameter of at least 6 mm is used, which is placed in a constructed trench and filled with concrete. Pouring concrete for the armored belt must be done at one time without interruption along the entire perimeter of the load-bearing walls of the building.

Before pouring the reinforced belt with concrete, it is necessary to attach anchor bolts to its frame. Bolts can be secured using tie wire or welding machine. The number of anchor bolts must be no less than the number of rafters. After installing the bolts and pouring the reinforced belt, in a couple of days, when the concrete has strengthened, you can install the Mauerlat.

Under no circumstances should the armored belt be interrupted, since its fastening effect is completely lost and it will not remove the bursting load from the walls from the weight of the roof.

The anchor bolts must be installed exactly along the thread so that they are in the middle of the mauerlat beam. Regardless of the method of fastening the Mauerlat, it is necessary to lay waterproofing material.

Arrangement of a reinforcing belt

To construct an armored belt, you will need the following materials:

Sand, crushed stone and cement grade M-400 for the production of concrete.
Reinforcement with a diameter of 6 to 12 mm for the construction of an armored belt frame.
U shaped blocks or boards for making formwork.
Hammer and nails (for wooden formwork).
A concrete mixer, since it is impossible to mix the concrete solution properly by hand.

The arrangement of the armored belt consists of the following stages:

If wooden formwork is used to make an armored belt, then the lower beams with which it is held together, its walls remain in concrete. This fact does not affect the quality of the belt in any way, so you don’t have to worry about it. You can make concrete for the armored belt yourself or purchase ready-made ones - this will make its installation easier.

Preparing a wooden structure

To make wooden formwork for an armored belt, you will need the following materials:

A board with a thickness of at least 30 mm and a height of at least 20 centimeters.
Hammer and nails.
Wooden blocks.
Hacksaw.
Roulette.

Also, for convenience, instead of a hammer and nails, you can use a screwdriver with wood screws.

The construction of wooden formwork for an armored belt is carried out as follows:

The width of the walls is laid wooden blocks at a distance of 1 meter from each other.
After laying the bars boards are attached to them on both sides of the wall.
Top of the boards fastened together wooden blocks also at a distance of 1 meter from each other.
Installed boards at the joints need to be securely tied together using wooden blocks or a small piece of board.

How to attach the Mauerlat to aerated concrete?

In cases where the construction of an armored belt is impossible, the Mauerlat is fastened in the following ways:

To fasten the Mauerlat with mechanical anchors, you will need the following tools:

Impact drill.
Wedge anchors.
Special pump for removing chips from the hole.

Fastening the Mauerlat with mechanical anchors consists of the following steps:

Holes are drilled in pre-marked locations on the wall.
The finished holes are cleaned of concrete chips with a special pump.
Wedge anchors are inserted into the holes and tightened.
After installing the anchors on the walls, it is necessary to lay the waterproofing material and the Mauerlat can be installed.

Using wedge anchors, you can reliably and quickly install the Mauerlat. The only disadvantage of this method of fastening the Mauerlat is the price of the anchors, approximately from 2500 rubles per piece.

Chemical method of fastening the Mauerlat. For fastening the Mauerlat chemically use liquid anchors (chemical anchor). Chemical anchor is a liquid mixture of polymer synthetic resin supplied in bottles for a gun as a sealant.
The adhesive mass of the anchor penetrates deeply into the structure of the material and reliably fastens metal element with a wall.
The advantage of chemical anchors is that they do not create a bursting effect like mechanical ones; this feature allows them to be used fragile materials like aerated concrete, shell rock, etc.

To install the Mauerlat using chemical anchors, the following tools are required:

Impact drill.
Drills for concrete.
Gun for capsule of liquid anchors.
Liquid anchor capsule.
Metal anchor bolts.
Compressor for supplying compressed air.
Nuts with washers.
Thick gloves to protect your hands from getting the adhesive mixture.

Instead of a compressor, you can use a special pump to clean the hole from debris.

The method of attaching the Mauerlat chemically consists of the following steps:

On the last row of the wall where the Mauerlat will be installed impact drill It is necessary to drill a hole with a diameter slightly larger than the anchor bolt.
From a finished hole in the wall dust and concrete shavings must be removed. This can be done using a compressor, blowing out all the dust and dirt with compressed air.
Into the cleaned hole using a gun it is necessary to pour in the adhesive mixture of the anchor, and then insert its metal part. It is necessary to fill the hole 60% with the adhesive mixture to avoid leakage when inserting the anchor bolt.
45 minutes after installation chemical anchors can be used to install the Mauerlat.

The number of chemical anchors must at least correspond to the number of rafters. Holes for the Mauerlat must be drilled in the middle of the block with a depth of 70% of its height.

It is also not recommended to carry out welding work with the metal part of the chemical anchor, since high temperature destroys the composition of the polymer resin. The chemical anchor has a long service life of more than fifty years and high resistance to atmospheric influences.

Let's sum it up

For reliable and high-quality fastening Mauerlat to aerated concrete must use an armored belt.
Formwork for armored belt can be made from planks or U-shaped blocks.
Armobelt in addition to fixing the Mauerlat ensures the removal of the bursting load from the walls from the weight of the roof.
In cases where the application With an armored belt, it is impossible to attach the Mauerlat to aerated concrete using mechanical or chemical anchors.
Regardless of the type of Mauerlat fastener After installing it, it is necessary to lay waterproofing material.