Reinforced belts: types and purpose

Recommendation points

• When the armopoyas is not needed
• Types of reinforced belts
• Grillage
• Base armopoyas
• Interfloor reinforced belt
• Under-roof or Mauerlat armo-belt
• Formwork and concrete work

Armopoyas is an indispensable element in the construction of a house, which performs many important functions. We will talk about the types, purpose and technology of making a reinforced belt with our own hands in our article.

In general, a reinforcing belt is a monolithic reinforced concrete structure encircling the load-bearing or at least the outer walls of a building. There are several names for this element: seismic belt, unloading belt, reinforced belt, armored belt, etc. In any case, this is a frame or mesh made of reinforcement, filled with concrete. A prerequisite for any armored belt is that it should not be interrupted, and therefore the filling is performed in a circular manner without interruptions, at a time.

Armopoyas performs several main functions:

1. Strengthens the walls and prevents them from “parting”.
2. Evenly distributes the load on the walls of the lower floor from the walls of the upper.
3. Avoids uneven building shrinkage and cracking.
4. Performs leveling of masonry by distributing liquid concrete strictly in the horizontal plane.
5. Sometimes point loads occur due to distortions or mistakes of builders, and the use of an armored belt allows you to avoid these harmful phenomena.

Depending on the construction method, the number of storeys of the building, the type of foundation and the geological features of the area, from one to 4 reinforced belts are used.

When the armopoyas is not needed

Let’s say right away that interfloor and under-roof armored belts are always needed. In the case of a monolithic foundation on a slab-cushion, the grillage and the basement armored belt are not needed.

Also, they are not used in the construction of wooden and frame-panel houses, although sometimes pile grillages are used when the house is on swampy soil, and also when they want to additionally strengthen an already not so strong structure.

The pile grillage serves as a basement armored belt, so its construction is quite rational. If the grillage is not made under the prefabricated strip foundation, then the second belt can also not be done, there will be no benefit from it, and such a house will not stand for long.

Types of reinforced belts

There are 4 main types of armored belts in total:

1. Grillage, or basement armopoyas, as well as pile grillage.
2. Armopoyas between the foundation and the walls of the building, basement armopoyas.
3. Reinforced belt along the upper row of walls, on which floor slabs will be laid (interfloor belt).
4. Unloading belt under the roof, to which the Mauerlat will be attached.

If the number of storeys in a building increases, the number of interfloor belts increases accordingly. Now it is worth considering each of the listed reinforced belts separately..

Grillage

The grillage is the lower, most often underground armopoyas, on which the walls of the strip foundation rest. Also, an armored belt is called a grillage, which connects individual pillars or piles of columnar or pile foundations. In this case, it most often plays the role of a basement belt..

If the reinforced belt performs the function of supporting the walls of the strip foundation, then it is necessary to dig a trench under it to a depth that the engineer must determine, based on climatic, geodetic, seismic and other initial data of the area selected for construction. The bottom of the trench is covered with sand mixed with rubble, sometimes with clean sand, if the soil is solid and not watery.

The height of the grillage is usually 30-50 cm, and the width is from 70 to 120 cm. Unlike other types of belts, the grillage fits under all the load-bearing walls of the structure. The lower belt should be the strongest, because the whole house will stand on it. This element will experience the most serious loads associated with soil shrinkage and creeping, exposure to soil moisture, etc..

It is better to use a 12–14 mm reinforcement with a 10 mm transverse strapping. Strapping step – no more than 200 mm. First, we lay on the ground two reinforcing rods 6 meters long and weld with a transverse piece of reinforcement at the edges and in the middle. We knit the rest of the transverse pieces with wire, since welding changes the strength of the reinforcement through temperature exposure, or, more simply, “lets go” of the metal.

Next, we make the same “ladder”, after which we weld these ladders with crossbars at the ends and in the middle, as before. We knit the rest of the crossbars, just knit! So we got a reinforcement cage that will be laid in the grillage. The dimensions (thickness and height) should be made so that the concrete covers the reinforcement by 5 cm on all sides. If the reinforcement touches the ground or “looks” out, it will quickly rot and the solidity of the structure will be broken.

This is the foundation of the house and must be strong. It is better to make a grillage with a margin of safety of 20-30%, not sparing reinforcement and not saving on the grade of concrete. It will pay off later.

The columnar grillage also distributes the load and ties the individual posts together, preventing them from moving apart. Also, it does not allow point shrinkage of the house to occur, but forces the building to “grow” into the ground evenly and equally at all points

However, the pile and columnar grillage is often made of wood, calling it a strapping. This is not considered an armored belt.

Base armopoyas

After the walls of the prefabricated strip foundation, for example, of concrete blocks or bricks, have been built on a solid grillage, a reinforced belt should be built again. The walls of the foundation can protrude above the ground, they can be flush with it, we build an armored belt regardless of this.

It is believed that if the grillage is made correctly and its strength is not in doubt, then the basement belt can not be particularly strengthened. But we are building “for centuries”, so we will not save on the durability of the house and its strength, but we do not need to overspend either..

For example, it is generally accepted that the basement belt is arranged only along the perimeter of the outer walls, but if the floors are slabs, it is better to do it along all load-bearing walls. If external wall insulation is not planned, then the width of the armopoyas is equal to the width of the wall. If there is insulation, then the width of the armored belt must be done taking into account the insulation, or insert prepared strips of expanded polystyrene under the formwork before pouring.

Reinforcement, in principle, is sufficient and mesh, that is, without a frame. For the mesh, we use three longitudinal rods of 12 mm and the pitch of the transverse rods is 10 cm. The height of the belt is usually 20–40 cm. It is better to make 40 or at least 30, this will be stronger and more reliable. Do not forget about waterproofing gaskets made of a double layer of roofing material or other material, so that moisture does not rise up into your house through the capillaries of concrete. This, of course, does not negate the waterproofing of the foundation, but it is still necessarily used.

Interfloor reinforced belt

The interfloor belt is constructed to strengthen the walls and evenly distribute the load from the slabs to the entire box of the house. That is why this belt is called unloading.

It also prevents walls from parting, which tend to do this under the action of axial loads. And, in the end, he evens out the plane of the box crown, which can “walk” even with a master mason.

Interfloor belts are best done with a frame of 4 longitudinal reinforcing rods 12 mm, 40 cm high and as wide as the walls, taking into account the thermal insulation. It must be laid on all load-bearing walls. Many argue that only the grillage needs to be laid under all walls, but the floor slabs will press on all supporting structures, so it is better to do the interfloor armored belt along all the walls.

Under-roof or Mauerlat armo-belt

This is also a rather important belt. Firstly, it distributes the load from the rafter system, gables and the roof as a whole. Secondly, it allows you to securely fix the Mauerlat. Thirdly, he, again, levels the horizontal of the box, which is important for the successful construction of the rafter system, where geometric accuracy is important.

The last armopoyas is performed by analogy with the previous one. If the laying of the slabs is not planned, then the belt is mounted along the perimeter of the outer walls, and if the rafters are inclined, then laying on the middle load-bearing wall, on which the ridge racks and the bed will rest, will not interfere.

Formwork and concrete work

Formwork is usually made of boards that are assembled into shields on the ground and fastened to the wall for quick assembly. Sometimes the boards are stitched with reinforcement and welded together by welding the knob. Also, this role can be performed by steel wire, which is threaded into pre-drilled holes and pulled together with a lever from reinforcement or a metal bar..

From above, the formwork boards are connected by scraps of timber or boards. In general, the methods of reinforcing the formwork depend on the methods of casting: if the casting is carried out from a sufficient height, then the formwork should be strengthened as much as possible. If concrete will be poured from buckets, then such reinsurance will not be needed. Particular attention should be paid to board joints, corners and turns.

The lower part of the formwork takes the greatest load, so sometimes it is nailed down with reinforcement with a welded lintel, which does not allow the board to move away from the wall.

The reinforcement frame is laid in such a way that the rods are covered on all sides with a layer of concrete of at least 5 cm.

Since the pouring is carried out at a height, it is advisable to use a concrete pump or a special funnel with a locking mechanism, which will be filled with concrete and open as needed to fill the formwork. Such a funnel should be transported by a crane.

The basics of monolithic casting, vibration and other similar issues are described in detail in our other articles, for example, “How to properly fill the foundation for a house.” You can read about the choice of cement in the article “How to choose a cement”. The only caveat regarding high-altitude formwork casting is the safety issue. You should also carefully vibrate so as not to damage the formwork and frame..

The formwork is removed with a crowbar or crowbar. In hot weather, this can be done in a day, in cold weather, it is better to wait two or three days. Concrete grade must be used at least M400.

So you figured out:

1. Armopoyas – a necessary element of the supporting structure.
2. Armopoyas are of several types, and all of them are necessary under certain circumstances..
3. Armopoyas is not a structurally complex element.
4. The cost of the reinforced belt justifies the benefits.

Of course, it is better that all the work on determining the parameters, applicability, necessity and other features of this structural element, as well as its manufacture, should be carried out by experienced specialists. This is the part that is almost impossible to remake, but it performs important functions. Therefore, it is better to save on something else: wallpaper or railings on the porch, but not on the armopoyas.