Rafter attachment scheme

Mauerlat is a part of the roof of any structure, which is a beam that is laid on top of the outer wall around the entire perimeter.

Its purpose is to evenly distribute the load from the roofing system to the entire surface of the load-bearing walls. It can be made from wood or metal. In the case of using a metal Mauerlat, finished products are taken: an I-beam, a channel, a corner.

To perform its function, the Mauerlat must be securely fastened. There are two ways: attaching the Mauerlat to aerated concrete without armored belt and with armored belt.

Mauerlat mount with armored belt

Using aerated concrete as the main material for laying walls, it must be understood that it will not be able to withstand the load of the truss system and roofing, so the creation of an armored belt is mandatory.

Purpose and dimensions of the armored belt

Armopoyas - a closed structure made of reinforced concrete, passing along the perimeter of the structure. The purpose of the armored belt:

• prevention of deformation of load-bearing walls;
• giving additional rigidity to the structure of aerated concrete;
• uniform load distribution on the surface of the walls.

Armopoyas is essentially the foundation for the roofing system. The dimensions of the armored belt depend on the width of the walls; for aerated concrete, the width of the armored belt is approximately 25 cm, while the extreme row is laid out in U-shaped blocks, which will later play the role of formwork for pouring concrete mortar.

Important! Armoyas must be a continuous monolithic structure!

Prepared formwork before concreting

Armo-belt device technology:

1. Construction of formwork around the perimeter of the building.
2. Creation of an armored belt from concrete blocks.
3. Reinforcement frame assembly.
4. Installation of studs for fastening.
5. Pouring concrete blocks.
6. Removing the formwork after the concrete has set.

After the armo-belt is ready, and the formwork is removed, you can proceed directly to fixing the Mauerlat.

How to fix the Mauerlat to aerated concrete

Its resistance to external influences, service life, noise and waterproofing characteristics and strength depend on its proper fastening to the load-bearing walls and the truss system of the building.

Mauerlat must be made of the same material as the truss system. If metal structures are used, then metal beams, channels, corners are used as Mauerlat. For a wooden truss system, the Mauerlat will be made of wooden beams. The cross section of the beams depends on the calculated load, the type of roof and the diameter of the rafter beams.

Before installing a wooden Mauerlat on aerated concrete blocks, it is necessary to treat the wooden beams with an antiseptic solution that protects the wood from insects and decay. It is also advisable to wrap the bars with a layer of waterproofing material. To do this, you can use hydroisol, elastoizol, hydrostekloizol, glass mast. These materials will not weigh down the structure and will create a layer of additional moisture insulation.

Mauerlat is attached to aerated concrete walls using anchors, studs or metal wire. When laying the beams, it is necessary to connect them at the joints with metal brackets.

Mounting scheme with studs (right) and brackets (left)

Next, you need to fasten the rafters to the Mauerlat. The connection occurs by cutting, tie-in, washed down, but it should occupy no more than 25% of the timber. Fastening is carried out using self-tapping screws, bolts, corners, metal plates and mounting foam.

The main methods of fastening, starting with the more preferred:

• Stud fastening. This type of fastening can be used in the construction of both simple one-story buildings and auxiliary structures: baths, summer kitchens, garages, outbuildings, small country houses. This method of fastening with studs is preferred for most buildings.
• Fastening with chemical anchors. The beams are attached to aerated concrete with a special chemical adhesive: “liquid dowel”, glued anchor, etc. The composition is based on polymers and contains adhesives in the form of synthetic resins. A hole is made in the aerated concrete wall as for a conventional anchor, which is filled with adhesive, then a rod (reinforcement) is inserted into the prepared hole, on which a Mauerlat is then installed. The strength of this design is quite high, however, with a large Mauerlat perimeter, this method will be expensive.
• Fastening with steel wire. This method can be used if, even at the stage of laying the walls, a metal wire was pushed between the aerated concrete blocks. Holes are made in the Mauerlat where the wire is inserted and the strapping is made. It is very important that the number of wire harnesses is not less than the number of supported rafters.

Mauerlat fastening to aerated concrete wall without armored belt

In accordance with SNiP, fastening without a preliminary armored belt is allowed only in exceptional cases. Aerated concrete is not a strong enough material, and will not withstand a spacer snow load, as well as a dynamic wind load, so an armored belt is required!

In some cases, fastening a Mauerlat to walls made of aerated concrete blocks is possible without an armored belt. This greatly reduces the cost and speeds up construction. However, this is possible under the following conditions:

• as a basis, a light wooden beam with a cross section of not more than 20 cm is used;
• the timber will be reinforced with metal elements: locks, nails, metal profiles;
• snow and wind loads in your area are negligible;
• the design of the truss system eliminates spacer loads.

Mauerlat is located at a distance of 0.5–1 cm from the outer edge of the load-bearing wall, and studs, chemical anchors or steel wire are used to fix it on aerated concrete.

When arranging a pitched roof, the installation of the truss system cannot be performed directly on the walls of the building. An additional element that receives loads from the rafters and transfers them to the walls will be the Mauerlat. Usually this is a special beam that is laid along the perimeter of the walls. Since it takes a serious load from the roof, it is very important to securely fix the Mauerlat on the wall. In the case of brick or concrete walls, everything is simple and clear. But how is the Mauerlat fastened to aerated concrete without an armored belt, because the gas block itself is quite 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 truss system. Most often it is made from a wooden beam. However, if the truss system is made of metal, then this structural part can be made of a channel or an I-beam.

Usually this element is made of the following materials:

• Wooden beam with a section of 100x100 mm, 150x150 mm or 200x300 mm. The beam is made of hardwood and undergoes mandatory antiseptic treatment. The product is laid around the perimeter on the walls of the structure. Joints are fixed with nails or a direct 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 bar or steel beam is attached to the walls. In this case, different methods of fastening can be used. Further, the rafter legs rest on the Mauerlat. They exert a load on this element, which, in turn, evenly distributing it, transfers it to the walls of the building. In addition, this beam keeps the truss system from moving.

Important: since aerated concrete does not tolerate long-term point loads, gradually collapsing, it is recommended that a monolithic reinforced belt be erected on top of the walls before laying the Mauerlat.

However, there are ways to lay 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, as well as facilitate inspection and repair of roof structures.

Mounting methods

Mounting a Mauerlat to aerated concrete is much more difficult than to a brick wall.

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

• steel wire;
• anchor fasteners built into the masonry;
• special chemical anchors;
• steel pins.

Important: anchors are used to attach the support beam to the reinforced belt or brick walls.

After installing the beam, the rafter leg is attracted to the wall with the help of a twist made of twisted metal wire with a diameter of 3 mm. To fix the wire below the timber, a steel shorty is mounted 6 cm. 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 onto the walls of the house.

To connect 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 staples are used to reinforce the corner parts of the structure.

Using wire to fasten the beam

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 walls when performing the last few rows. At the same time, the following sequence of actions is followed:

1. During the laying of aerated concrete blocks, two or three rows before the end of the laying 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.
2. At the same time, the middle part of the fastener 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.
3. The number of wires used should be equal to the number of rafters installed.

Fixation with pins

Mounting the Mauerlat to the wall of aerated concrete with studs is allowed when installing light roofs on small houses. The materials used to form the roofing pie 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 not possible to equip the armored belt. In such a situation, the timber itself will act 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 beam to aerated concrete, you will need the following elements:

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

We perform the work in the following order:

1. We drill holes in the walls of the gas block in increments of 100-150 cm.
2. We insert the studs into the holes and fix them with cement milk or a non-shrinking mortar.
3. Next, you need to perform waterproofing. To do this, two layers of roofing material are laid on the walls. At the location of the studs in the material, holes must be pierced to ensure its snug fit to the walls. Waterproofing will protect the wooden beam from saturation with moisture and subsequent rot, which can come from the walls.
4. With the same step as the studs were installed, holes of a diameter suitable for the studs are drilled in the Mauerlat.
5. Then the beam is mounted on the studs on top of the waterproofing, washers are installed and tightened with nuts.
6. After mounting the beam, the ends, in which individual fragments of the beam are joined, are pulled together with forged steel brackets.
7. Now you can proceed with the installation of the truss system.

If the studs are mounted in the armored belt, then we work as follows:

1. Before the start of pouring the armored belt, studs are placed in it with a step of no more than 100 cm.
2. They are fastened with a knitting wire to the reinforcing cage of the belt. Plastic ties can be used instead of wire to fix the studs.
3. The accuracy of the installation of the studs horizontally and vertically is checked.
4. Concrete is poured into the formwork of the armored belt.
5. After it hardens, the prepared beam is put on with holes on the protruding ends of the studs and is attracted to the surface with nuts.

chemical anchor

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

Important: unlike other fasteners, the liquid dowel does not create expansion stress 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 friction forces and expansion of the dowel made of polymers, the chemical anchor is fixed due to the fact that the adhesive penetrates into the pores of aerated concrete to a considerable depth and firmly fixes the rod in the wall.

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

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

Advantages of using a liquid dowel:

• The service life of such fasteners is more than 50 years.
• This method of fixation can be used on the edge of the walls, without fear that it may crack.
• Fasteners have a fairly high chemical resistance.
• Fastening is allowed to be carried out on wet material, that is, installation can be carried out even in rainy weather.
• Work on the installation of the Mauerlat and the arrangement of the roof can be carried out without the use of a reinforced belt, since the chemical anchor is much more firmly fixed in a fragile material than a mechanical dowel.
• This method is ideal for working with aerated concrete.
• The depth of the hole may be less than when installing a mechanical anchor, which must be deepened by 2-3 rows of masonry.

The only drawback of this method of fixation is that it is impossible to perform welding work with a rod attached to a liquid dowel, since the polymer material is destroyed by heating, and the fixation strength decreases.

Mechanical anchor (anchor bolt)

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

• external spacer;
• internal threaded rod.

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

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

1. A prepared beam is laid along the perimeter of the walls.
2. Further, holes are drilled along the entire length of this product for installing anchor bolts. The pitch of the holes is 1 m. It is important to try that the installation sites of the anchors must fall on the corners of the building and the junction of the two ends of the timber.
3. 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 less than 2 or even 3 rows of masonry.
4. 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 a thread M 12 or 14.
5. After that, the 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.

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

Mauerlat - definition

Mauerlat- an element of the building structure, connecting together all the elements of the roof truss system with each other and with the walls of the building. Mauerlat main functions:

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

Mauerlat is laid and fixed along the entire perimeter of the upper part of the outer wall of the building with a slight indent from the outer edge. Each element of the Mauerlat is firmly connected to two adjacent ones.

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

Selection of material and calculation of parameters

For the manufacture of Mauerlat, a beam with a section is used:

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

There is a use of a board with a section of 50x150 mm. However, for an aerated concrete wall 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 vertical loads from the rafter legs to the wall.

To create a one-piece structure that can withstand the load transmitted by the rafters, the edges of the bars are connected in series with 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 of the roof and walls largely depends on the correct choice of design, the method of attachment to the walls and the accuracy of calculating the dimensions of the Mauerlat.

Consider the main factors influencing the choice of Mauerlat section:

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

When choosing the design and section of the Mauerlat, it should be taken into account that the aerated concrete wall 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 truss system.

Structural structures include:

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

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

• hanging rafters without puffs;
• layered rafters with rigid fastening of supports.

The horizontal forces transmitted to the wall by the spacer structures of the truss systems must be taken up 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 Mauerlat is calculated by the formulas:

• (Mauerlat volume) \u003d (Bar section) x (House perimeter);
• (Mass of timber) \u003d (Volume of Mauerlat) x (Density of wood).

Varieties of fastening Mauerlat to aerated concrete

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

• light;
• perfectly processed;
• has good thermal insulation properties;
• blocks have a clear geometric shape.

But there are also some peculiarities. Aerated concrete is a rather fragile material. It copes well with moderate compressive loads, but the application of tensile or shear forces easily leads to cracking.

Accordingly, when choosing a method of attaching the Mauerlat to the wall, this must be taken into account.

Mauerlat on aerated concrete without armored belt

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

Fastening with steel wire

The easiest mounting option.
It has gained popularity due to the low cost of materials.

Sequencing:

• several rows (at least three) before the completion of the masonry, segments of soft steel wire with a diameter of 6 mm are laid across the wall;
• the mauerlat is laid after the completion of the masonry of the wall and the curing of the adhesive;
• by twisting the ends of the wire, the mauerlat beam is firmly pressed against the wall.

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

The laying step must match the step of the rafters.

Fastening with anchor bolts

Anchor bolt (mechanical anchor) consists of:

• from an internal rod with a threaded part;
• outer spacer.

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

Sequencing:

• Mauerlat beam laid out around the perimeter of the wall.
• Holes for anchor bolts are drilled along the entire length of the Mauerlat. The distance between adjacent holes is not more than 1 meter. It is necessary to strive so that the locations of the anchors must necessarily fall on the corners of the building and the joints of the beams.
• Through the holes in the Mauerlat with the help of a drill, the masonry of the wall is drilled to 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 threaded.
• The puck is put on. The nut is tightened with force. The plastic or metal dowel included in the anchor design is unclenched, pressed into the walls of the channel and securely fixes the anchor bolt in the wall.

Mounting the Mauerlat with mechanical anchors has become widespread. Limited by the relatively high cost of fasteners.

chemical anchor

Modern technologies for the manufacture of mechanical anchors for fastening in aerated concrete have reached perfection. However, the main drawback inherent in the principle of operation remains. The anchor was attached to aerated concrete by creating bursting forces. With an increase in the load on the anchor, splitting of the aerated concrete block may occur.

The so-called chemical anchor. Instead of a dowel, a synthetic adhesive is used. It penetrates deep into the pores of aerated concrete. Hardening, firmly fixes the metal rod in the wall material.

Sequencing:

• a hole is drilled as for a mechanical anchor bolt, but of 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 stud M12 - M14 or a piece of reinforcement of a similar diameter is inserted into the hole;
• at an ambient temperature of 20 degrees Celsius, the composition gains strength in about 20 minutes.

The positive qualities of a chemical anchor include:

• The fastening strength is much 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, work in the rain.
• Long service life (more than 50 years).

Disadvantages of chemical anchor:

• The adhesive composition does not withstand high temperatures.
• It is impossible to carry out welding work directly with the metal rod of the anchor.

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. It is much easier and more reliable to fix the Mauerlat to the aerated concrete wall through the armored belt. In addition to facilitating the fastening of the Mauerlat, the armored belt has other positive qualities.

• Armo-belt, like a hoop in a tub, pulls together the upper part of the walls of the building and preserves its geometry with uneven shrinkage of the foundation, seasonal soil movements.
• Increases rigidity and strength of the entire building.
• Evenly distributes point loads from rafter legs on the walls of the building.
• Is the best(and in the case of aerated concrete walls and the only) means of counteracting the bursting loads on the walls with the expansion structure of the truss system.
• Changing the thickness of the armored belt it is convenient to align the upper cut of the walls of the building horizontally. The level errors made during laying are leveled.

The armored belt is made in the form of a concrete strip along the entire length of the bearing walls of the building.

Formwork manufacturing

• It is convenient to use U-shaped blocks. With their help, a continuous gutter is formed in the upper row of masonry, which acts as a fixed formwork. With this manufacturing method, cold bridges are not created. The wall will not freeze.
• The top row on the outer side of the wall is made of blocks with a thickness of 100 mm. From the inside - brickwork "on the edge". More labor intensity compared to the use of U-shaped blocks. Thermal insulation properties are somewhat worse. Material cost is lower.
• A removable formwork is formed over the entire width of the wall from boards or OSB boards. The method is often used due to the low cost of materials. Cold bridges are formed. It is necessary to take measures for additional insulation of the wall in the area of ​​the armored belt.

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 a wire with a diameter of 6 mm. The connection of the frame elements to each other should be carried out using twists of soft steel wire or plastic ties.

It is desirable to fill the armo-belt with M200 concrete at a time, avoiding long breaks in work. The use of a vibrator for concrete compaction significantly increases the strength and durability of a reinforced concrete structure.

Fastening with metal studs

Threaded metal studs are considered to be the simplest and most convenient element for attaching a Mauerlat to an armored belt. Stud diameter from 12 to 14 mm. The length is sufficient so that the upper edge of the hairpin protrudes 4–5 cm above the surface of the Mauerlat. The lower edge of the hairpin is bent in the form of the letter “G”.

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

Sequencing:

• studs with a step of no more than 1 meter are placed in the formwork of the armored belt before the operation of pouring concrete;
• attached to the reinforcing cage using a knitting wire or plastic ties;
• the accuracy of installation vertically and horizontally is controlled;
• after the concrete has hardened, the Mauerlat beam is put on with holes on the protruding ends of the studs, tightly attracted by nuts to the surface of the armored belt.

The importance of waterproofing during installation

Regardless of the chosen method of fastening, the Mauerlat and the wall surface must be reliably separated from each other by a layer of waterproofing. The condensate formed during the temperature difference at the junction of various materials leads to wetting and destruction of the Mauerlat wooden beam.

There is a large selection of materials for waterproofing during installation. Usually lay two layers of roofing material or one layer of waterproofing. The treatment of a wooden beam with an antiseptic composition will not be superfluous.

Building a house is a long and difficult journey. Regardless of whether you are building a house with your own hands or entrusting the work to third-party specialists, you need to clearly understand how to take EVERY step along the way correctly. 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.

Good day or evening!

I see that you carefully approach the solution of the problems of each issue, I really liked it, so I decided to apply!
So there is no such problem, but there is psychological discomfort (about it a little later), due to the fact that there is no armored belt.
More.
The house is built as follows.

1. The soil on which the foundation stands is sand and clay (because when the piles were drilled, this mixture (light in the form of sand) came out).
2. According to groundwater, the water in summer is somewhere around 4 meters (according to the person who sold the site), but when the piles were made to a depth of about 2.4 m, there was no water; a ditch was dug behind the site to collect spring water and lead out to the road, 1.5 meters deep.
3. The site is flat (a slight slope of 10-5 cm by 8 meters), but 300 meters in front of it is a mountain, and 200 meters behind it is a railway (the highway to Moscow through Perm), sometimes a slight vibration is felt.
4. Foundation 7.15 m by 8.12 m with a lintel in the form of a cross inside the house, grillage 60 cm (height) * 40 (width) cm (40 in the ground + 20 above it), piles were made every 1.1-1.3 from each other (from edge to edge of the pile) with a diameter of 40 cm by 2 m from the bottom point of the grillage, not excluding the lintels (an approximate view of the foundation is attached), reinforcement was used 10 ".
5. Poured in October last year (2012), concrete grade M200, (diagram attached).
6. This year he began to build walls (June 2013).
7. Then roofing material was laid out in 2 layers, a basement in three M150 bricks (with 2 pieces of air per room).
8. Next we went gas block (600 * 188 * 300). The first floor of 13 rows is somewhere 2.4 m, floor beams (10 pieces) are laid on them, since the first floor of 5 walls, the beams were located as follows: the back of the house (where there is no bay window) beams 150 * 150 somewhere then 4 meters each, leaning on a wall and a partition of 30 cm each (for the entire width of the block), the front of the house (with a bay window) beams 100 * 150 5 meters each, well, one from the bay window to the partition of 6 m, everyone rests on each side 30 cm (wrapped with roofing material).
9. Next, an attic was erected, side walls of 1.2 meters each, and a high pediment of 2.3 m each.
10. The blocks were glued.

Here is the most denouement.
I began to think about how to put the mansard roof, what to attach it to, well, I got into the Internet to read what and how. I read that an armored belt was needed (I hadn’t heard of this before, I thought the gas block was laid like a brick, and therefore I didn’t climb the Internet and the builders said the house would stand for 100 years) and the neighbors didn’t make it and they screwed the beam to the block, but here on you, the armored belt it was needed between the first and second floors and at a level of 1.2 from the second floor before erecting gables, luggage reinforcement between the rows of the gas block. What a miracle material, how to shake over a child. But it's too late, everything is built. "Here he is an elbow, but you won't bite" Well, I began to ask on the forums what and how, but everyone screams at me, it will fall apart, take everything apart and do it again. Decided to ask you for advice. There is no extra money to break everything and do it all over again.

Here is the psychological moment. They scared me with all sorts of horror stories. I was thinking of erecting a broken armored belt (along the sloped surfaces of the gable walls) in 3 fiberglass reinforcements of 8 with a dressing of 1 m, the width of the belt is 25 cm and a height of 20 cm, on it a beam of 100 * 150 mm with a step of studs of 1.5 meters, then erect an attic with a rafter foot step of 600-700 mm (board 50 * 150). A view of the rafters is attached and an approximate view of the roof. What can you say about this situation, maybe something needs to be strengthened, maybe not? How to build an attic from a gas block 600 * 188 (height) * 300 (width)?

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 armo-belt is for, and what the Mauerlat is and its purpose.

Aerated concrete - is it?

But first of all, we denote that the construction of houses from aerated concrete is at the peak of popularity, and the demand for this building material is growing. So, many people face 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 latter 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, distributing evenly the loads from the roof onto 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 element of the roof simplifies the fastening of the truss system to the walls.

Armopoyas: design features

Now about the armored belt. Its main task is to fasten the Mauerlat. And if it is not in the design of the house being built, then certain problems arise that are associated specifically with the fasteners of the Mauerlat beam. There are several mounting methods. They are perfectly 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 fix the Mauerlat to aerated concrete. It remains to deal with the methods and understand one important idea. And the idea is that the proposed fastener options must be accepted with a large number of reservations. Because the installation of a Mauerlat on aerated concrete blocks without pouring a reinforcing belt is a rather dubious undertaking.

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 a 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 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 tied together with reliable puffs;
• if layered rafter legs are installed, supported along the axis of laying the ridge beam.

By the way, the last option is best suited for 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 it is worth carrying out this process without pouring the armored belt.

Option number 1

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

• the wire must be laid in the laying of aerated concrete stones in the third or fourth row before the end of the laying, that is, 3–4 rows of blocks must be laid above the wire;
• the length of the twist should be such that on 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 mounting the rafter legs.

An example of fastening a Mauerlat beam with wire

Before laying a Mauerlat without an armored belt on aerated concrete walls, it is necessary to waterproof the ends of the walls. The easiest way is to spread the roofing material in two layers. After that, the beam itself is laid. It must be aligned either on the outer surface of the wall, or on the inside. Be sure to align horizontally. After that, the wire braids are tightened using a mount. The main thing is that the screed is strong and dense.

An example of correctly tightened wire braids using a pry bar

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

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

Option number 2

Installation of a Mauerlat beam without an armored belt using anchors and dowels. For fastening, it is suggested here to use anchors with a length of at least 30 cm, preferably 50. They look like this:

How this process is carried out:

1. Mauerlat is laid on the walls after waterproofing their upper ends.
2. 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 selected to match the diameter of the dowel for the anchor.
3. Dowels are clogged.
4. Anchor bolts are screwed into them.

For fastening 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 this concerned a reinforcing belt made of concrete mortar, then there was no doubt. This is a 100% secure 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 severe loads emanating from the roof structure. It is one thing to fix a shelf, cabinet or TV on aerated concrete, and another thing when the loads from the roof are not one ton of different materials.

Option number 3

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

In this case, the Mauerlat on aerated concrete is laid in exactly the same way as in previous cases. But the fastening is done by wire twisting. Loops are made at the ends of the steel “pigtail”, 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;
• twisted wire is thrown over the wall, respectively, and Mauerlat;
• the free loop at the opposite end is inserted into the free end of the hairpin;
• tightening with a nut and washer;
• a mount is required, which twists the twist over the Mauerlat beam, that is, the latter is pulled to the wall.

We must pay tribute to this method of attaching the Mauerlat to a wall built from gas blocks. In many respects, it is more reliable. Firstly, the wire does not come into contact with the aerated concrete material. So, from its twisting there is no load that could cut it. Secondly, the stud 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 fasteners.

Option number 4

Today we need to talk about innovative fastening methods, because scientific and technological progress does not stand still and offers us new materials that increase the strength of 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 composition is poured into the hole made, which, when 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:

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

The process of fastening 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 a 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 composition.

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

Now, as for the reliability of 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 it should work.

Option number 5

All the same studs are used here, only they will be installed vertically and serve as anchors. Steel strips with a thickness of 5 mm, a width of 50 mm, and a length equal to the width of the wall are welded to them. The fixture is installed at the stage of wall construction below the upper plane of the end by 2–3 blocks. Therefore, it is important to accurately determine the length of the hairpin. Installation landmark - a strip across the wall. The option is best used if the walls are raised from two blocks, so the studs will be between the blocks without violating their integrity.

A good 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 mounting structure, the better.

Generalization on the topic

Several options for fastening the Mauerlat without pouring the armored belt are proposed. It is difficult to say how the whole structure will behave, whether fasteners will be reliable. Therefore, do not take risks and avoid expenses. Fill in the armo-belt and all your problems will be solved at once.