You cannot choose a brick for a basement without understanding what kind of architectural element it is, when it is needed and what requirements are put forward for it. Only taking these data into account can you choose the optimal brick for the basement, take into account all the parameters and performance characteristics.
The basement is a part of the building protruding above the ground level. This can be an extension of the foundation tape (called the basement part of the foundation), reinforced concrete blocks or brickwork.
The parameters of the base depend on the maximum loads.
If the house has reinforced concrete floor slabs on the first floor, then the basement should be much stronger than the walls, its width increases, building materials with suitable bearing capacity are used. In all other cases, the size of the basement may not differ from ordinary facade walls.
Often it is not economically feasible to make a base from concrete; brickwork will cost much less. A separate basement is also installed when the basements are planned to be equipped for living quarters. Brick is much warmer than concrete, which improves the comfort of stay and reduces the cost of maintaining a favorable microclimate.
We are already mentioned one feature of the basement - it must hold the largest loads of all the architectural structures of the building. But that's not all - the base is operated in the most unfavorable conditions.
Brick plinth with vents
The use of different grades of bricks makes it possible to build structures with the required parameters in thickness and height in the shortest possible time and with little financial losses.
Indicators of physical strength vary depending on the thickness of the base, thermal conductivity is regulated by the special characteristics of the brick or through the use of modern insulation. To protect the surfaces of the basement from the negative influence of climatic conditions, finishing of the walls is used. By the way, it also improves the design of the building's facade.This factor must be borne in mind, not all types of bricks are allowed to use finishing, and if it can be done, then this will require the use of expensive materials and complex construction technologies.
The requirements for basement structures are prescribed in SNiP II-22-81.
They indicate that the use of stones and blocks made of aerated concrete, ceramic or other bricks of dry manufacturing technology is not allowed. This means that the statement of some "experts" in construction that hollow bricks cannot be used for plinths is unreasonable. The types of building materials listed in building codes are unsuitable for plinths for one general reason - they react extremely negatively to high humidity. Under such operating conditions, there is a significant loss of bearing characteristics and accelerated failure.
Types of bricks
"Stone and reinforced stone structures". File for download
The main requirement for all other types of bricks is compressive and flexural strength. Modern manufacturers have mastered the most advanced technologies that make it possible to obtain very durable hollow bricks, grade M 150 and more, from which they are used to build load-bearing walls of two-story and more buildings.
Brick M 150
Why can't such material be used for the basement of one-story brick or wooden buildings? If the load allows, feel free to use them for the base.
Single brick M 150
When choosing bricks, it must be borne in mind that the larger the area of the base, the more effort it holds. Based on the total load, the material of manufacture and linear dimensions are selected. As for the heat-saving characteristics, there are no regulatory requirements for the base.
What is the result?
You cannot put a basement without knowing the total weight of the house, the height of the snow cover, the seismic characteristics of the terrain and other factors that affect the foundation and the basement.
The project of the house is prepared only after geological exploration
The parameters of brick strength and the dimensions of the base are calculated from the maximum load.
In practice, brick grades below M 100 are rarely used for a basement, but this is an optional condition. Two bricks M 50 withstand almost the same load as one M 100, only it must be distributed over the entire surface of the masonry. In the project, a safety factor is laid down, due to which minor deviations from regulatory requirements are compensated. And deviations always occur during the laying of any architectural structure.
Types of bricks
Remember that putting the base "by eye" is a very risky business.
By the way, all living quarters must have a project, otherwise they cannot be put into operation.And without an act, engineering networks are not connected, registration is not given, such buildings cannot be sold, donated or bequeathed by inheritance. Legally, they simply do not exist.
As mentioned above, our recommendations do not apply to residential buildings, they should be built only according to the project, and all the requirements and parameters of bricks are indicated in it. Consider the cases of choosing a brick for a basement only for non-residential buildings and outbuildings.
What characteristics should be used to select a material?
Frost resistance of bricks
Bricks depending on the brand and manufacturing technology, they have this figure from F15 to F100 and more. This means that the material can withstand 25-100 freeze / thaw cycles at maximum humidity. And moisture permeability ranges from 2% to 12%. State standards regulate the minimum period of natural wear and tear of buildings, it is 50 years. If a brick of the F50 brand is immersed in water fifty times and then exposed to frost, then it will lose about 30% of its original strength, which is considered a critical value.
But the basement brick will never completely get wet, it is always plastered or protected with other coatings. In practice, F50 bricks hold much more than fifty freeze / thaw cycles.
Frost resistance - the number of freeze and thaw cycles during which the stone will retain its original strength
Why do bricks lose during freezing / thawing strength and what does it depend on? During freezing, the water increases in volume by about 10%, while the forces of the ice are so great that no known building material can withstand them. The more water there is in the brick, the more ice microcrystals in the brick, the faster the destruction occurs.
Thick ceramic bricks 250 * 120 * 88 mm, M-150, F 50
Determined in accordance with GOST 530-2007, the grade of brick for laying load-bearing walls must be at least M125, with a margin of safety, the designers recommend using brick of the M150 grade for the basements.
GOST 530-2007. Ceramic bricks and stones. File for download
Bricks made of many materials and using various technologies are suitable for these indicators, but some of them cannot be used in conditions of increased humidity.
How bricks are made
Let's look at one example. The M100 brand means that the brick can withstand a load of at least 100 kg and no more than 125 kg per square centimeter.
The surface area of a standard brick is 25 cm * 12 cm = 300 cm2. One brick of M100 grade is designed for a load of at least 30 tons.
Solid brick M100
We have given the calculation so that you can more clearly imagine what efforts bricks of different brands can withstand. Of course, these values provide that the load is evenly distributed over the entire surface (bed), in practice this rarely happens due to the presence of air pockets in the masonry.
What types of bricks can be used for the basement?
|Name||Brief performance indicators|
| Water absorption ≤ 12%, strength ≥ M100, frost resistance not less than F50.
It is used most often, for universal use. The front surface must be protected from the negative effects of atmospheric precipitation.
| Water absorption ≤ 16%, strength ≥ M150, frost resistance not less than F50. It is used for plinths of light buildings without reinforced concrete floor slabs. The outer surface must be plastering with a cement-sand mortar or revetted with durable materials.
Afraid of mechanical damage.
| Water absorption ≤ 5%, strength ≥ M250, frost resistance not less than F100. In all technical parameters, it surpasses ceramic samples. It is recommended to use when laying a basement with a width of two or more bricks as an outer front row. The surface of the basement of this option does not need to be additionally finished with various building materials.
The disadvantage of clinker bricks is their high cost.
Now, having an idea of the requirements for the plinth and the technical parameters of bricks, you can consciously choose specific materials and start laying the element.
Step 1. Calculate the required number depending on the width and height of the masonry. Take data on the approximate amount from the table.
How many bricks are needed per 1 m3 of basement.
|Dimensions of bricks||Number, parameters of the joints are not taken into account||Number, including joints|
One and a half brick size
If you work with bricks of non-standard sizes, you will have to independently calculate the volume of the basement and divide it by the volume of one brick. The calculations do not represent anything complicated, there is no need to describe them.
Step 2. Check the horizontalness of the foundation strip.
If the foundation was made by responsible builders, then the deviation from the horizontal at the corners of the structure will not exceed two centimeters, such a spread can be easily eliminated without additional operations during the preparation of the base of the first row of the basement. You need to check the horizontalness of the foundation using a water or laser level. Are there significant deviations? We'll have to level the tape.
One condition - during the manufacture of the material, increase the amount of cement, it should be at least three parts per one part of sand.
Do not rush to immediately start laying the basement, strictly adhere to the recommended technology.
Step 3. Place two layers of roofing material on a flat tape to waterproof the bricks. This is very important, without waterproofing, the base will quickly collapse.
Insulation with roofing felt
You need to start laying with laying two corners. The technology depends on how many bricks are in the row in width. You can lay the corners from one, one and a half, two, two and a half and three bricks. If you don’t have experience of doing such work, then practice. First fold the bricks without mortar, then work with the mortar.
Movements should become automatic, during training, constantly use control instruments. Be sure to do the dressing, alternate spoon and butt rows. An experience has appeared - put the corners directly on the foundation tape. The height of the corners is 5-7 bricks. For a start, the height is enough, so it is easier to control the correctness of the masonry and timely correct possible deviations in the position of the base.
Chain dressing system when laying the base
Step 5. At the height of the first row of each corner, hammer in a pair of studs and pull the rope. Make sure that the rope lies exactly on the edges of the bricks. This completes the preparatory work on laying the corners of the basement, start working on the straight sections.
Base / plinth masonry
Base / plinth masonry
Base / plinth masonry
Basement row brick laid on the level
Further, the work on the plinth is no different from the work with the wall, the rows are constantly bandaged.
If you use clinker bricks for external surfaces, then use them only from the visible side.
Building level and masonry
The basement is a very important element of the building and the only one that cannot be repaired. Even problems with the foundation can be solved; there are special technologies to strengthen it. True, this will take a long time and is expensive. If the base began to collapse due to incorrect calculations, then nothing can be fixed.
We focus on this not with the aim of scaring the developers, but with the aim of making them very carefully follow all the recommendations of professionals and technologies that have been worked out over the years. We will try to answer a few questions that beginner bricklayers often ask.
Is it possible to lay mortar more than one centimeter thick to level the basement? This need arises most often on foundations made of reinforced concrete blocks. Only competent specialists under the guidance of an experienced foreman can correctly lay foundations from such materials. He must constantly monitor the position of each block with a professional level.
If the spread in height does not exceed 2-3 centimeters, then it can be eliminated with a solution. But be sure to use a metal reinforcing mesh with a wire diameter of at least 5 mm. No plastic materials can withstand the load on the base, they are only suitable for plastering walls.
Masonry with reinforcement
Laying out mortar
Is it possible to use bricks made without firing for the basement? It is possible, but undesirable, we have already dwelt on this issue above. But if you really need to put these bricks somewhere, then they can only be put inside the base, all sides should be closed ceramic bricks.
Accordingly, they can only be used on plinths with a width of at least two bricks, otherwise it is impossible to make the correct strapping and fulfill the described condition.
Use high-quality bricks
In what cases can you do without leveling the foundation strip with concrete? This is enough difficult technology, let's dwell on it in detail.
Cement and bases of mixtures
Such marks are made on all sections of the foundation on which the floor slabs should lie, in these places the basement should go to the zero mark - the level of the floor slabs. Of course, the wide variation in the height of the foundation tape indicates that it was made by frank hack-workers.
If, for example, you need to raise the height of the base by 15 cm in two rows, then this can be done only due to the solution. Lay about 2.5 cm on the foundation with the obligatory use of a metal reinforcing mesh, the upper beds of bricks are equal to the net mass. There are cases when it is necessary to use bricks of different thickness, you will have to buy them additionally. It is forbidden to use bricks split with a hammer throughout the entire thickness for the basement; they can only be cut on a special machine with a diamond disc and water cooling.
What types of base / plinths are there?
Types of base
B Depending on the position of the front surface in relation to the front wall, the plinth can be:
Disadvantage - you need to apply special measures to drain rainwater coming from the walls;
The finishing of the facade and the basement is done with the same materials and using the same technology or not at all.
What should be the height of the basement? There are no special requirements, it all depends on the presence and purpose of the basements and the horizontalness of the foundation tape. If the building does not have basements, and the tape is flat, then there is no need to make a special basement. As for the advice "at least 50-60-70" and so on centimeters, then you should not pay attention to them. The final decision is made only taking into account the architectural features of the building.
What is the height to make the base
And the last. Remember to leave air vents in the plinths for natural ventilation of the underground space. If, of course, the project of the house provides for their presence.
The basement brick performs both aesthetic and protective function
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