Self-supporting walls: the difference between the construction of load-bearing and non-bearing walls. Scheme of a strip foundation for a house, preparation and marking Self-supporting walls
one of the most widespread types of walls. Task bearing walls- withstand the load from floors and roofs, as well as provide the necessary thermal insulation. For the construction of load-bearing walls, materials with sufficient strength are used: natural stone, brick, cinder block, concrete blocks, monolithic concrete etc. However, the greater the strength of the material, the greater its density and, accordingly, the lower its resistance to heat transfer. Therefore, the thickness of the bearing walls made of brick, natural stone or heavy concrete, sufficient for the strength and stability of the wall, is often insufficient to provide thermal insulation according to the latest thermal standards. If before the thickness brickwork curtain wall 51cm for some climatic regions was considered enough, now even 77 cm of brickwork thickness of the outer wall for the same areas is not always enough. Therefore, external load-bearing walls are increasingly being made not from one material, but at least from two. In this case, the first material provides the necessary strength and stability, and the second - thermal insulation. V low-rise construction external load-bearing walls can be made of less durable materials, such as cinder block, lightweight, porous and cellular concrete.
Self-supporting walls
are made in frame buildings, often self-supporting walls are called enclosing structures. In frame buildings, the frame is calculated for the load from floors, overlying walls and roofs, so self-supporting walls are only loaded from the own weight of the material from which self-supporting walls are made. This allows you to use for the construction of self-supporting walls almost any material that can withstand wind load and the impact of precipitation. Self-supporting walls can be both brick and stone and heavy concrete, but for the reasons given above, materials with the necessary resistance to heat transfer are usually used for the construction of self-supporting walls. In addition, wall materials must have good frost resistance and low water absorption. The more water is absorbed by the wall material, the worse the thermal insulation will be in the end and the faster the destruction of the material can occur when it freezes in winter time absorbed water. But as a rule, less dense materials due to their structure have a sufficiently high water absorption and therefore often need additional protection.
Well, now let's take a closer look at the most commonly used
Wall materials:
Building materials used for the construction of walls can be classified according to various criteria: by origin, by production method, by strength, by weight, by thermal conductivity, by size, by ease and speed of installation, by availability, by aesthetics, by environmental friendliness, by price etc. Each of the above signs is certainly important, so choose the most suitable option when building your own house is not so simple. One of the most revealing to me seems to be the classification of wall materials by size and weight, since most construction sites of private houses combine low level mechanization, meaning that most loads are lifted manually. Further, the materials for the walls are considered from this position, while at the same time they are given brief characteristics materials on other specified grounds.
By size, wall materials are divided into:
Small wall materials.
Small pieces are materials that can be laid relatively easily by hand. As a rule, the weight of one element does not exceed 20-30 kg. Accordingly, wall elements made of denser materials are smaller than elements made of less dense materials. To small pieces wall materials relate:
A natural stone
obtained from rocks.
Mud and earth walls are also built using formwork, but such walls are Lately- a rarity.
As you can see, despite the fact that people have long descended from the trees, left the caves and got out of the dugouts, wood, stones, and sometimes clay also serve as the material for the walls. So don’t believe after that in genetic memory ...
During the construction of houses, both multi-storey and private country houses, load-bearing or self-supporting walls can be erected. The first type of enclosing structures experiences serious loads from floors and roofs. Self-supporting walls are vertical elements of a building on which nothing rests. During the operation of the house, loads in such structures arise only from their own weight.
What are they?
Basic distinctive feature self-supporting walls, in comparison with loaded ones, is that they have a small thickness. Material during their construction, respectively, takes less. The thickness of the walls of this variety, depending on what they were built from, can vary between 50-380 mm.
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During the construction of the rear, among other things, non-bearing enclosing structures can also be assembled. Such walls also do not perceive the load from the elements of the house located above. In another way, structures of this type are called hinged. They are always built within the same floor. However, if their height exceeds 6 m, they can already be considered self-supporting. Their design and calculation are carried out accordingly.
Self-supporting walls are basically only external enclosing structures. Such elements of the building simply protect it interior spaces from wind and precipitation, adjacent to the main frame. Ceilings to such walls are attached to the side on all floors in height. During the construction of houses, both single-layer and multi-layer self-supporting enclosing structures can be erected. If walls of this type are inside the building, they only serve as partitions.
Operation features
According to the SNiP standards, in such structures, when redevelopment is carried out in multi-storey and country houses it is allowed to make openings or expand them to the required parameters. Also, the walls of this variety, in some cases, can even be dismantled and rebuilt without the risk of collapse of other building structures.
Payment
Before the start of the construction of any house, of course, a detailed project is also drawn up. At the same time, such an operation as the calculation of walls of self-supporting, non-bearing and loaded for stability is also performed. For brick structures, for example, such calculations are made taking into account the data of several tables from paragraphs 6.16-6.20 of SNiP II-22-81. In any case, when calculating the stability of a self-supporting wall, the ratio of its thickness to height is determined at given geometry normative values.
Construction features
It is allowed to build such enclosing structures from almost any material. Self-supporting walls are building elements that can be built from wood, brick, blocks. In any case, such structures are assembled exclusively on strong supports. Their foundations are poured simultaneously with the foundation of the building itself.
Brick, block, etc. self-supporting walls are mated with other types of enclosing structures exclusively using flexible connections. When using rigid ones, due to the unequal degree of loading, the elements of the building may subsequently crack and deform. Accordingly, it will become unsafe to live in the house.
Self-supporting walls are structures that are supposed to be reinforced when laying bricks or blocks according to the standards. However, such enclosing parts of buildings are usually not as carefully strengthened as loaded ones. Rods in the construction of walls of this type are inserted through large quantity masonry rows. Reinforcement for such structures, according to the standards, is allowed to use a diameter of 1-2 mm.
Materials for multi-storey buildings
During the construction of high-rise buildings, self-supporting external walls can be built from:
- ceramic bricks of hollow, porous, full-bodied;
- silicate brick.
When erecting buildings of not too high number of storeys, blocks are sometimes also used:
- arbolite;
- ceramic;
- from foam or aerated concrete;
- expanded clay concrete and any other large format.
A feature of such materials in comparison, for example, with the same brick, is a relatively low degree of strength. Therefore, their standards are allowed to be used, depending on the variety, when building houses with a height of no more than 3-5 floors.
9. Walls of civil buildings. Primary requirements. outdoor and internal walls, load-bearing, self-supporting and non-bearing walls, partitions.
Walls- These are vertical fences that separate the premises from the external environment and from each other. The walls must withstand the loads that fall on them, ensure a constant temperature regime in the room and its soundproofing. In construction, depending on the purpose, the walls are classified into external and internal. Depending on the accepted material, walls are made of artificial materials (concrete, brick, asbestos-cement) and natural (limestone, shell rock, tuff, wood). Depending on the perception of loads from the building, the walls can be load-bearing, self-supporting and non-bearing. Carriers walls perceive loads from other parts of the building (ceilings, roofs) and, together with their own weight, transfer them to foundations. Self-supporting the walls rest on the foundations, but the load is carried only from their own weight. Non-bearing(curtain) walls are fences, based on each floor on other elements of the building (frame) and perceive their own weight within one floor.
The walls of civil buildings must meet the following requirements: be strong and stable; have a durability corresponding to the class of the building; correspond to the degree of fire resistance of the building; be an energy-saving element of the building; have resistance to heat transfer in accordance with thermal engineering standards, while providing the necessary temperature and humidity comfort in the premises; have sufficient soundproofing properties; have a structure that meets modern methods of erecting wall structures; types of walls should be economically justified based on the given architectural and artistic solution, meet the customer's capabilities; material consumption (consumption of materials) should be as minimal as possible, as this greatly contributes to reducing labor costs for the construction of walls and overall construction costs.
Partitions are called relatively thin walls that serve to divide the internal space within one floor into separate rooms. The partitions are supported in each floor on the floors and do not carry any load other than their own weight.
PARTITIONS. Partitions must be soundproof, nailed, durable, stable. Partitions are installed on the floor structure before flooring. At the junction of partitions made of combustible materials to stoves and chimneys, brick cuttings should be arranged along the entire height so that the distance from the partition to the inner surface of the stove or chimney is at least 40 cm. FRAME. GYPSUM PARTITIONS. BRICK PARTITIONS. Brick partitions are laid with a thickness of 1/2 brick (12 cm). The basis for partitions can serve concrete preparation under the floors of the first floor or reinforced concrete floors. On wooden floors, brick partitions should not be made due to their significant weight. A non-bearing wall, or partition, can only be internal.
Bearing wall (Fig. 1)- the main carrier-enclosing vertical design building, which rests and transfers to the foundation the load from the ceilings and the self-weight of the wall, separating adjacent rooms in the building and protecting them from the effects of the external environment.
Self-supporting wall (Fig. 2)- an external enclosing vertical structure that protects the interior of the building from the effects of the external environment, resting and transferring the load from its own weight to the foundation.
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| Fig.2. Self-supporting wall (outer wall rests on the foundation, and the ceiling adjoins the wall) |
Curtain wall (Fig. 3)- an external wall resting on a ceiling within one floor with a floor height of not more than 6 m. (with a higher floor height, these walls are self-supporting) and protecting the building from the outside from the effects of the external environment.
Partition- an internal vertical enclosing non-bearing wall, based on the floor, and separating adjacent rooms in the building.
In buildings with self-supporting and non-load-bearing external walls, loads from coatings, ceilings, etc. are transferred to the frame or transverse structures of buildings.
In the house, the walls that stand on the foundation and on which the ceilings rest will be carriers.
And the walls standing on the foundation without resting the ceiling on them will be self-supporting.
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| Fig.3. Non-bearing wall (outer wall rests on the floor slab) |
Walls of different design purposes carry different loads. To provide the necessary bearing capacity for different walls choose a certain wall thickness and the strength of the materials used.
For example, internal and external load-bearing walls of buildings made of aerated concrete blocks up to 3 floors inclusive are recommended to be made from blocks of classes in compressive strength not lower than B2.5, with glue or mortar of grade not lower than M75; at a height of up to 2 floors inclusive - not lower than B2 on glue or on a solution of grade not lower than M50.
For self-supporting walls of buildings up to 3 floors high, the block class must be at least B2.
I wrote this article in April. And I put it aside in the hope that I will pick up illustrations, and perhaps break them into small blocks - more suitable for the format of this LJ.
But it's already January next year - and when I'll do it - I don't know.
Therefore, I post it in its entirety, without illustrations, and if someone masters it to the end - tell me about it - I will write you down as a hero :)
Walls:
The walls of buildings are load-bearing, self-supporting and carried.
What is the difference, how it works and how it manifests itself externally and in architectural aesthetics.
A load-bearing wall is a wall that holds the roof structure (or balconies, or any other load) - this wall, which is a structural element. Part of a working structure. Like a post or beam in a post-and-beam system.
A self-supporting wall is a wall that does not carry anything additional - but has its own weight. That is, it carries its own weight, at least. The higher it gets, the more more weight, the more it is similar in properties to the carrier.
A wall that is carried is a wall that rests not on what is below, but on what is on the side or above. That is, if it is quite simple, then either a thing suspended on something, or nailed to a certain structure as a lining. Such a wall mainly has a protecting function - almost unrelated to the structure.
And now imagine a self-supporting wall of brick or stone.
Ideally, stones and bricks lie flat in it, the load presses from top to bottom. The lower - the greater the load - it is normal if the wall begins to expand and strengthen towards the bottom. Perhaps the wall will have a slope - like the walls of fortresses - from above - narrower.
If the wall is loaded and it is a load-bearing (or very large self-supporting) - this whole ideal picture will not work. Because a lot of additional loads will appear in the wall - although by design they should act strictly vertically - in fact - due to non-ideal density, due to loads that have some lateral shifts, etc. - there will be a lot of stresses inside the wall. Of the obvious and understandable - to the edge of the wall, to the corner of the building, all sorts of lateral moments will accumulate and the corner will have the greatest load. Therefore, the corners seem to be strengthened and thickened in even simple buildings. It is often necessary to remove excess load from window and doorways- to make the jumper easier. Sometimes during the construction process, some tension accumulates that needs to be removed.
Load-distributing arches, etc., appear in the wall. things.
This is the picture for all load-bearing and self-supporting walls. The corners are reinforced, the masonry is difficult so that there are dressings, the load accumulates towards the bottom and the wall thickens.
This is suitable for traditional materials- stone and brick. All modern blocks have the same picture (in fact, these are the same stones - just artificial ones). The same picture is near reinforced concrete (monolithic) walls. Only there, internal stresses immediately go to the reinforcement and the strength is much higher than that of natural stone. But the principle is the same.
A tree is a little different - because you can’t put a distributing arch in it. But they don’t build from wood and very high or heavily loaded walls. But more effort goes to the corner, structures that facilitate jumpers arise - that is general principles are saved.
There is an architectural - aesthetic - expression for load-bearing and self-supporting walls. Just as an order is the ideal expression of a post-and-beam structure in stone and wood, so for a wall there is architectural element- rust. Rust is an image of large masonry blocks in the wall. Sometimes laid out of stone, sometimes purely decorative - from plaster. When rusting, the architect tells us that the wall is load-bearing. Or at least self-supporting. The more powerful the rust, the more likely it is that it is a load-bearing wall. Making a pronounced rust against a wall that is clearly self-supporting is rather strange. Can. But less justified. And the rust (even exaggeratedly decorative) on the carried panels is simply not an understanding of its essence and design in general.
Remember, we talked about whether the order on the Colosseum is decorative or not. (link)
So - in the Renaissance, almost the same combination of two structural systems on the facade. On the one hand, the wall is rusticated, that is, it tells the viewer that it is load-bearing. On the other hand, pilasters rise up, which, as it were, show that there is a kind of rack-and-beam frame inside.
And researchers talk about the contradiction of these systems. Or - about the fact that the order on such facades is purely decorative.
Firstly - for some reason, no one says that it can be a real carnass - and the filling with the wall between is self-supporting (well, they don’t say - because it’s really not so - at least in the Renaissance, although I think if you dig - in the 19th century such mixed structures already existed - when the frame was connected to the wall)
Secondly, as with the Colosseum, these systems complement and intertwine each other.
How it happens in a real design: in the most primitive form - A leveling beam is placed on the load-bearing wall, which distributes all further loads evenly. On it - with a certain step are placed cross beams that hold the cover. If there were no beams, the beams would press pointwise and the internal loads in the wall would be more diverse.
But nevertheless - the beams do not press evenly on every cm of the wall.
The second - what we said - there is a big load on the corners.
And the third - if the building has transverse walls - and there are more than 2-3 windows on the facade - then at the points of their connection with the main wall - there is also a large horizontal load (and, by the way, a smaller vertical one - if the transverse wall is also load-bearing, but it is usually self-supporting)
So the appearance on the facade of some vertical elements - semi-columns, pilasters - seemingly from the post-beam system may well be justified. Of course - if they express interior layout buildings and repeat the internal walls - this is doubly justified. But often you have to cheat somewhere and add extra ones - for an even step or the beauty of the facade.
Still call it pure decorative elements- it is forbidden. They are tectonic.
Working in monolithic reinforced concrete, we can extinguish all these loads with reinforcement. And make a perfectly smooth, even wall. Nevertheless - this flat wall will be just a decoration - not reflecting the inner work.
Perhaps, in order for a reinforced concrete wall to be a truly pronounced structure, its reinforcement should, as it were, “shine through” - like veins on a person’s arms or read like a skeleton. Seeing a living being, we will not be able to draw its skeleton. But present the main load-bearing structure inside - we can do it. Nevertheless - the principle of operation of a reinforced concrete wall is not much different from stone (yes, it is stronger, yes - you can do more complex things, large ledges and lintels - but the principles are the same - the load acts from top to bottom)
So - at the beginning of the 20th century, structures appeared that made it possible to simply hang a wall on them. And make any wall. Glass. Lightweight foam, etc. Bearable walls appear.
It must be said that in architecture a load-bearing, self-supporting or carried structure is a very important criterion. They often differ sharply, are painted radically different colors- like black and white fachwerk or white - color classicism.
Therefore, if the wall is carried, it is very important to show and emphasize (well, because we remember that tectonics is the main principle of architecture - and exceptions only confirm the rules)
That is, there are two options - to identify, aestheticize the modern hinged structure. Or deliberately abandon the principle of tectonics - and create something completely different. What do deconstructivists do? But it must be done a) skillfully b) explicitly. Like a bright focus, theatrical performance. Or pure decorativeness - with bright color. Ideally, an elegant joke. So far, in the mass architecture, I do not see this application and the way. This is a separate discussion, of course ...
So - if the wall is borne - then it would be good to identify and emphasize it. How can I do that?
1. identify and show the supporting frame making the wall almost invisible. For example glass. So at Foster - in a cucumber. Frame - revealed. Glass is unbearable. By the way, and Koolhaas (despite the fact that he is a deconstructivist and in general in a Chinese skyscraper does not come from the design). Any building "just glass" - this criterion does not meet, because the frame is not detected.
2. to develop a decorative expression of the fact that the wall is not supported by what is below, but by what is on the side (or suspended). It could be rivets. (or any other fasteners according to the principle - nails, screws, etc.) These may be some kind of latches around the perimeter - according to the principle of glass in frames. Such options were made by Otto Wagner for cladding (by the way, this can all apply to just decorative wall cladding) - this is not rust - these are panels "nailed" to the wall or frame. In modern architecture, this option is not developed at all.
3. Look for the aesthetics of old load-bearing walls for load-bearing walls. For example, in skins that were stretched over the frame of yurts, etc. dwellings ... To go by demonstrating that the wall is flexible and cannot hold without an internal supporting frame - it means that it is there. Perhaps the time has not yet come for this - and not yet modern technology flexible fabric for walls. Especially as it provides windows. Although I think it's quite possible. But this is a question for technologists ... this is partly expressed by Zaha Hadid - in her flexible walls.
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