Calculating how wide the foundation should be

CALCULATION OF FOUNDATIONS

122. Calculation of foundations for crushers includes:
a) determination of the amplitudes of horizontal vibrations of the upper edge of the foundation;

b) determination of the static pressure transmitted by the foundation to the base;

c) checking the strength of foundation structures.

123. Determination of the amplitudes of forced vibrations of foundations for gyratory and jaw crushers is carried out according to the formulas of paragraphs. - section of these technical conditions.

The calculated value of the amplitude of horizontal vibrations of the upper edge of the foundation should not exceed 0.3 mm.

124. When determining the amplitudes of forced vibrations of foundations for gyratory and jaw crushers, unbalanced inertial forces (disturbing forces), taken according to the data of the machine manufacturer, are introduced into the calculation.

In the absence of such data, the determination of disturbing forces can be made in accordance with the Appendix.

125. Determination of the amplitudes of horizontal vibrations of massive group foundations for gyratory crushers is carried out using the same formulas in paragraphs. - section of these technical conditions, and the resultant of the unbalanced inertial forces of all crushers, determined by the formula, is introduced into the calculation

where P is the magnitude of the unbalanced centrifugal force (disturbing force) of one crusher (see appendix);

— coefficient taken equal to:

a) the number of crushers - when the number of crushers is less than 4;

b) 4 - when the number of crushers is from 4 to 8;

c) half the number of crushers - if the number of crushers is more than 8.

126. It is not necessary to determine the vibration amplitudes of foundations for roller crushers.

127. Determination of static pressure on the base of foundations for crushing equipment is carried out from the action of the following loads:

a) own weight of the foundation;

b) the dead weight of the crusher and other equipment installed on the foundation;

c) drive belt tension (in cases where the crusher and electric motor are installed on different foundations).

The reduction factor for the design resistance of the base (see paragraph) is accepted.

128. The strength of foundation structures for jaw and gyratory crushers (frames, beams and weakened wall structural elements) is checked for the following:

a) own weight of structural elements and equipment;

b) unbalanced inertial forces of the corresponding crusher, increased (for jaw and gyratory crushers) by 5 times.

129. Calculation of foundations of mill installations comes down to checking the pressure on the foundation, while the load is taken to be the own weight of the foundation and all elements of the mill installation.

The reduction factor for the design soil resistance (see paragraph) is accepted.

Options for high foundations

In strip foundations, the above-ground part is 4 times greater than the width.
In the practice of constructing strip foundations, it is customary to make the above-ground part four times as high as the width. These ratios were determined by calculations for an average house with a shallow load-bearing foundation and filling the space between the strips with soil and sand.

The depth of the foundation is usually greater than its above-ground part. If there is space under the floor in the house, it is necessary to install ventilation holes in the strips, which are necessary for constant ventilation of the underground space.

When the question arises of what the tape supporting frame should be, the following design options with a high above-ground part are considered:

• strip elements with a depth below the freezing depth;
• strip elements with a depth higher than the freezing depth;
• beams with columnar supporting parts and grillages on piles.

The depth of the foundation is below the freezing depth

The base of a strip foundation with a depth below the freezing depth is located at a distance of 1.5-2 m from the surface of the earth, and a solid wall rises from it to the top of the entire element. Crushed stone and concrete preparation is usually arranged for load-bearing elements. About what the height of the foundation should be above the ground is the opinion of a specialist in this video:

The total height of the product, taking into account the buried and above-ground parts, is 2-2.5 m.

Depth above freezing depth

Strip foundations with a laying depth higher than the freezing depth are used for lightweight structures resting on them. These are houses made of timber, rounded logs, aerated concrete and structures built using frame technology.

The foundation for such elements is made by replacing heaving soil with sandy soil. In addition, polystyrene foam is placed under the sole, thanks to the thermal insulation properties of which the base does not freeze and does not exert harmful pressure on the load-bearing element. The height of such foundations is 1-1.5 meters. To learn how to determine the foundation depth, watch this video:

Application of columnar or pile structures

Foundation beams or beams rest on columnar foundations, which in turn rest on a foundation located below the frost depth. Non-heaving soils are poured under the beams and a thermal insulation layer of expanded polystyrene is installed. The average height of the beams is 0.5 meters.

Heavy walls of concrete and brick can be erected on foundation beams supported on glasses and on grillages on piles.

Preliminary studies

Foundation fm1

To determine what your foundation should be, you need to do some research on the site. You need to know the type of soil, its freezing level, groundwater level and the amount of soil water. To do this, it will be enough to drill several wells on the site to collect soil. This work can be done using a hand probe. Separately, it is worth mentioning the depth of the wells; when building a small wooden house, a depth of 5 meters is quite sufficient, and for a heavier one made of brick or stone – 8-10 meters.

Wells need to be drilled in the corners of the future building. However, in many cases it is impossible to do without special equipment, despite the fact that this entails additional costs, it is not worth saving and it is better to do everything according to the rules.

Thanks to such research, you will receive a lot of necessary information, for example, how the soil has changed over recent seasons, the composition and thickness of the layers, the depth of occurrence and their physical properties.

It is also necessary to find out what the behavior of the soil is during the period of snow melting and when it rains, since it is during these periods that the soil receives the greatest amount of water, which can adversely affect the operational characteristics of the base of the structure, and, in particular, the basement of the house, if such is provided.

A high groundwater level will require the installation of a drainage system with which you can lower it. It is worth noting that conducting geological research in an area with high humidity before laying the foundation is mandatory, otherwise no one will vouch for the reliability of your structure. Only this approach will help you decide on the choice of foundation.

Height of the pile foundation above the ground

At the design stage, individual foundation parameters are selected in accordance with the type of building: the area of ​​the base, on which the width of the foundation and the height of the foundation above the ground depend.

The optimal height of the basement part, elevated above the ground, is 30–40 cm. If the house has an underground floor, the height can reach 1.5–2 m.

To determine the height of the base, you need to pay attention to atmospheric phenomena in the area:

• Temperature indoors and outdoors in winter;
• Snow level;
• Abundance of precipitation;
• Possibility of flooding;
• Ground water level.

The above-ground part of the foundation is the most susceptible to destruction under the influence of atmospheric phenomena.

Why is this part of the foundation necessary? Let's take a closer look:

• The lower part of the foundation is a plinth, which makes this part predominantly better than the foundation + plinth design.
• This is the part that is most protected from moisture by raising the “foundation + wall” boundary as high as possible (at least 200 mm).
• Sometimes a foundation elevation above the ground is used to build a basement. The height is selected depending on the design data.
• For columnar and pile foundations, the height above the ground is also 200 mm. Thanks to this, the soil does not affect the building. This indicator is more possible if, for example, the terrain has a slope.
• When choosing a height, the shrinkage of the house is taken into account, depending on the quality of the soil and the load of the structure.
• By increasing the height, in some cases it is possible to prevent the destruction of walls (baths, for example). The value of this height is 500 mm. In some cases, a base made of other building materials is added.

Based on all these indicators, we can conclude that the optimal height above ground level is 350–400 mm. If the foundation is located high above the ground, this is good in all respects. You also need to take into account the heat and waterproofing of the lower part of the foundation. After all, these indicators will not only preserve your foundation, but also reduce heat losses.

Balancing between necessity and redundancy

The customer makes the main contribution of money in building the foundation. If you choose a special area and take into account all the nuances, the foundation will be a durable platform for the entire house.

The height of the pile foundation above the ground is used together with the area of ​​the base and their width. And it depends on the type of construction of the structure.

Finishing the above-ground part with metal siding

Basement cladding with metal siding has become the most popular.

Siding finishing principle:

• Work begins with finishing and surface preparation. It is necessary to remove defects in the rough wall. If the walls are uneven, it is better to make lathing than to level them.
• After all this, we install the starting rail and mount it in a horizontal position (approximately at a height of 40–45 mm above the bottom point).
• Next, the siding sheet is installed in the guide rail and secured with self-tapping screws or fixing elements.
• Then you need to insert the 2nd sheet of siding, moving it towards the previous one. In order for the material to expand without problems when heated, it is necessary to leave a minimum gap at the joints. The thickness of the finishing elements will be slightly reduced by the minimum temperature.
• As a result, according to this scheme, you need to finish the entire basement area.

Types of foundation. Relation to ground level

Dependence of the height of the foundation above the ground:

• Depending on the type of soil. Sandy, capricious, swampy soils are problematic. This is taken into account at the design stage.
• On the level of occurrence and freezing of aquifers. The construction of the foundation should not be higher than these points. Insulation and waterproofing will be required.
• Depending on the type of object (bathhouse, housing, outbuildings). The weight of the structure, depending on the number of storeys of the house and the loads experienced, is of deep importance.
• From the purpose of the basement and basement.

From all these points we can conclude that if all conditions are met, it is important to determine the height of the foundation.

There are 4 types of foundation:

• Tape
• Columnar
• Monolithic
• Pile

A strip foundation is a reinforced concrete strip over the entire area of ​​the building. It is used in the construction of private houses. Thanks to the simple design, you can make a warm underground. Strip foundations are used in the construction of heavy walls. The optimal height is 2 m.

Columnar foundations are used in light structures of one-story houses. Used only on stationary soils. Cannot be used on swollen soils. Easy to make, can be used on slopes. Service life 50 years. With this type of foundation it is impossible to create a basement. A columnar foundation can be built from brick, asbestos pipes, or wood. Pole height 1.5 m.

A monolithic foundation is a reinforced foundation. Easy to build, does not require special equipment. A large area distributes the load on the ground. The monolithic foundation is reliable and has a long service life. This foundation is made of reinforced concrete and has a height of 300 mm. Monolithic foundations are built on all types of soils. The indicator for this type of foundation is 1.2 m.

Pile foundations are used in all types of constructions. It has low cost and high load-bearing capacity. Used on all types of soils, except rocky ones. If the structure is uneven, it may shrink. Its service life is 100 years. The height of the pile foundation is 2–2.2 m.

DIY arched canopy

An arched canopy is an indispensable extension on the territory of a summer house, country house or cottage. The most commonly used material now is polycarbonate. It is lightweight, durable, fireproof, and much stronger than plastic.

The first step is to concrete the base for the posts, then install the arches on the posts. The structure is fixed simultaneously on opposite sides to avoid distortions. We connect the trusses and racks, and connect the arches with the guides. Holes are drilled into the polycarbonate at a distance of no more than 30 cm and rubber gaskets are secured. Connect the frame and polycarbonate. Apply sealant to the joints once the canopy has been installed.

Optimal foundation height for a wooden house

The optimal foundation height for a wooden house depends on a number of factors:

• Depending on the climatic conditions of the area. Level of permafrost and water layers.
• From geological conditions.
• From the selected type.
• From the load. Seasonal or year-round operation.

Rounded log or laminated veneer lumber. What's better?

The disadvantage of rounded logs is their shrinkage after the construction period. Over time, such houses may become askew. Glued laminated timber retains its shape for many years and the house does not lose its external and internal beauty. The strength of laminated veneer lumber depends on its manufacturing technology.

A rounded log is made from solid wood, by mechanical processing, and has a rounded shape. Glued laminated timber is made from high quality boards. Coniferous trees are used for its production. The boards are impregnated with a special solution and trimmed. After all this, the boards are glued together so that the wood fibers match. Therefore, laminated timber is better for the house.

Individual heating of a house made of rounded logs.

The most common heating method in a rounded house is a gas boiler. Fuel is much cheaper, high efficiency.

Also chosen as heating:

1. Electric wall or floor boilers.
2. Coal or wood stoves.
3. Wood-burning, electric fireplaces

Repairing a house made of rounded logs: disadvantages

• It should take 6 months from the start of construction to finishing work. High percentage of wood shrinkage 10-12%. If you do not wait until the end of the active phase, you will end up with through cracks in the walls and a skewed frame.
• After 2 years, the second caulking procedure is repeated.
• Wooden walls require preventive maintenance and repairs.

You can build your own house, but we recommend that you contact quality specialists who will perform any type of work. With us you save up to 500,000 rubles.

What is the height of the foundation above the ground?

What foundation to make for a block house

As you know, the foundation of any cottage is buried into the ground to a certain distance, depending on the design features of the building, design loads, characteristics of the soil base and the location of groundwater. Naturally, the underground part of the foundation can be of very different depths, up to 1.2 meters with no space involved. With the creation of a basement or equipped basement, this depth can reach 3 meters. The question naturally arises about that part of the base that protrudes above ground level - that is, above the zero height mark. Many believe that this part can be neglected and save significant funds on more than one cubic meter of monolith or brick.

In fact, those few tens of centimeters separating the surface of the earth from the beginning of the load-bearing walls are designed to provide increased protection of the entire structure from adverse external influences. The height of the foundation above the zero level is determined at the design stage by our architects and designers. This part of the building’s foundation is treated in the same way as all other elements - waterproofing, insulation, decorative external cladding. But in addition to aesthetic beauty, the basement distance also carries a functional load, which we do not recommend discounting if you want your country mansion to last for a very long time and not require repairs.

How high should the foundation be above ground level?

This issue is very relevant, since most protective processes are not visible during operation, and all the benefits appear only in the long term. Based on this, many developers are trying to save on this design and exclude it from construction and estimate documentation.

However, many generations of builders and architects have repeatedly tested different options for constructing a country cottage, which has led, as a result, to the widespread use of above-ground basement distances in the construction of all houses. For each type of building material from which the cottage will be built, there are certain requirements about how high the foundation should be above ground level, which is necessarily taken into account by the designers.

The most common parameter is in the range from 30 to 50 centimeters - which optimally provides protection for a house built in central Russia. If the maximum level of snowfall reaches 20 centimeters, then the distance can be increased.

It is also worth considering the fact that about 10 centimeters of this height will be occupied by a blind area with surface finishing material - so you will have to increase the distance to the ground. Naturally, there are cases when 20 centimeters of height of the above-ground part of the foundation is enough - this is in those areas where the soils are not heaving and the maximum snowfall does not exceed 5 centimeters - in the south of our country.

We cannot ignore the fact that when constructing a country house, the height between the ground and the base of the walls is used to give the building originality and a unique style - for example, terraces are built below floor level with wide steps, or the platform can be built on stilts, which will give the house has charm and slight sophistication. The entrance block also has several steps with railings and a veranda, which also affects the image of your country residence. Perhaps the height of the above-ground part of the foundation is that rare case in architecture when purely functional details of a house could be turned into its highlight and an unusual decorative element. There are even cases when the basement part is made protruding, in the form of an ancient “heap” - there are no restrictions on design and engineering ideas, as long as this part of the foundation regularly performs its main functions of protecting the house.

What is the optimal height of the foundation above the ground for the types of structures?

Based on the base material from which the supporting structure of the building will be created, the parameters of the distance from the zero mark are also selected. For example, the height of a shallow strip foundation is almost always equal to its underground part - that is, about 50-60 centimeters. At the same time, there is no particular difference where the strip foundation in the Moscow region will be laid, since the approximate profile of the soil layer is the same for the entire central region and most surrounding regions of the country. By type of construction, you can provide approximate indicators for the distance from the edge of the wall to the zero ground level:

• 30-40 centimeters – for brick and monolithic structures;
• 40-50 centimeters – when using gas-foam blocks, large-sized ceramic materials;
• Over 50 centimeters - when constructing a frame, prefabricated or wooden house, since the material is most susceptible to external influences.

How high should a monolithic foundation be made?

This question arises most often, since the strip foundation has a fairly small surface area of ​​the foundation, which can be increased using various building materials. In the pile and screw version of the foundation, the technology itself provides for a minimum of 20 centimeters from the extreme point of the ground to the bottom of the grillage frame. Since a monolithic foundation slab, the price of which is already quite high, requires uniform pouring to a certain height, it is best to consult with the specialists of our company on how to simplify the design of the base and reduce the financial costs of creating a slab foundation. It is quite possible that the building design will allow you to create contour building of the base part using bricks, and filling the interior space with a more accessible floor screed. In any case, professional help will never hurt when creating a reliable and durable foundation.

Only a trained InnovaStroy specialist can determine exactly what foundation height will be sufficient for your specific cottage. More than 7 years of practice and our own experience in the field of suburban construction make it possible to provide each customer with objective and substantiated data on all the nuances of building a foundation for a cottage not only in Moscow, but throughout Russia. Use the services of professionals to prevent premature and unexpected costs for repairs and restoration of load-bearing parts of the cottage.

What influences the final width of the foundation

In the article, where we gave an example of calculating the foundation, considerable attention was paid to the selection of the main parameters of the foundation for the house - including thickness. If we consider only the strip foundation, then the width of the strip depends on:

• the total estimated area of ​​the foundation base, which is calculated based on the loads from the building (you can read how to calculate them here) and the soil itself, or rather its load-bearing capacity indicators. First, we calculate the total value of the area, based on which we take the minimum value of the width of the foundation;
• the thickness of the load-bearing walls that are planned to be erected on the foundation strip. Given this indicator, the thickness of the foundation should be at least 100 mm greater than the thickness of the walls. This value should be enough for subsequent finishing of the facade of the house;
• reinforcement of a concrete monolith. It is necessary to take into account that the reinforcement for the foundation must work in conjunction with concrete, and for this, a distance (at least 200 mm) must be maintained between the longitudinal rods. We wrote about how to calculate reinforcement for a foundation in a feature article - we recommend that you take the information presented into account

Calculation of the width of the foundation based on the area of ​​the base of the foundation

Let's say we carried out all the calculations on soil and loads and found that the minimum area of ​​the base of the foundation for a 6x9 m house turned out to be 5 sq. m. m. We take the width of the tape equal to X, then the total area of ​​the tape is calculated as follows:

Hence X1=0.17 m and X2=7.3 m. Obviously, in our case the actual value is X1=0.17 m. This will be the minimum allowable width of the foundation strip.

What should be the width of the base of the house if the thickness of the walls is known?

However, the value obtained above is only indicative. Let’s say that the house design includes load-bearing walls with a thickness of 300 mm, which is almost twice the calculated width of the strip foundation. Taking into account that the width of the tape should be 100 mm larger, we obtain the calculated value: 300+100=400 mm. In total, the margin of foundation width will be: 0.4:0.17×100-100=135% more than the minimum.

Reinforcement dependence

Typically, reinforcement with a diameter of 12, 14 or 16 mm is used for strip foundations. To assess whether the selected material fits into the selected parameters of the base (in this case, its width), it is necessary to calculate the cross-sectional area of ​​the tape and the percentage that is allocated in the monolith specifically to the reinforcement cage for the foundation. To do this, we take the height of the tape, for example, 0.8 m (depending on the project) and, using the table below, we calculate whether in this case it is possible to use 4 longitudinal reinforcement bars with a diameter of 12, 14 or 16 mm.

The cross-sectional area of ​​the tape will be equal to: 40×80=3200 sq. cm. Provided that the reinforcement should occupy 0.001 part of the cross-sectional area of ​​the tape, we have: 3200 × 0.001 = 3.2 sq. see. The table above shows that this value is relevant when using 4 reinforcement bars with a diameter of 12 mm.

The width of the foundation is chosen correctly.

The size of the foundation, its height, width

The height will be determined by the following factors:

• Weight of the building
• View of the base
• The material from which the house is planned to be made
• The architecture of the building
• Snow level
• The relief of the soil on which the house is being built

There is no specific standard for the height of the foundation, since from the listed points it is clear that these measures are individual and depend on many small factors. However, for practical reasons, engineers lay a monolithic strip so that the height of the foundation protruding above the ground is on average about 30-45 centimeters.

It is logical that the width of the foundation varies depending on the type of building. For one-story country houses and bathhouses, the minimum foundation height is 25-30 centimeters. For large houses, it is better to choose a width from 30 to 40 centimeters.

If the walls of the building are located below normal, the entire structure and building materials of the house will get wet, which will lead to disastrous consequences - cracks, subsidence and partial or complete release of the material from the inside

If you plan to build an ordinary country house, then standard height dimensions will do. But, if the building is made of wood, then it is better to almost double the height – 60-80 centimeters. And in the case when the layout includes a basement, these indicators for the height of the foundation for the house can be safely increased to 1.5 -2 meters.

Balancing between necessity and redundancy

Considering that the construction of a foundation is associated with a significant cost item for the construction of a suburban building, the desire of an individual developer to minimize its parameters is quite understandable. And if the calculated depth and width of the foundation are parameters that you have to come to terms with, then what about the height of the foundation above the ground? After all, in essence, what is above the zero mark is the above-ground part of the house, which can be built from more affordable building materials.

What determines the height of the foundation above the ground?

It is necessary to understand that the above-ground part of the base of the building serves as a connecting link, a kind of jumper in the adjacent “soil-external environment” section. And this area, like no other, during the operation of the building is exposed to external factors: high humidity and temperature fluctuations. Therefore, in order to answer the question “To what height should we raise the foundation of a house?”, we will indicate why it is generally necessary to raise the foundation above the ground:

for constructing the basement of a house, when part of the foundation takes on the role of a basement. Obviously, the solid structure has better characteristics than the “foundation + base” design; to protect the walls of the house from high humidity. Even despite the blind area, the lower side part of the house will be constantly moistened, so it is better to raise the “foundation-wall” transition as high as possible. How specific? The minimum height of the foundation above the ground is 200 mm, but higher is possible. An observant developer in one of the winters can estimate the thickness of the snow cover on the site, to which you can add 100 mm and get the optimal height of the foundation; Often the foundation rises above the ground due to the construction of the basement. In this case, the height of the foundation is determined based on the design data; for columnar and pile foundations, the minimum height above the ground is also 200 mm. Such a “retreat” from the surface of the earth is necessary so that the heaving soil does not affect the building

It may be larger, for example, if the terrain of the construction site has a slope; when calculating the height of the foundation, it is also necessary to take into account the possible shrinkage of the house, the magnitude of which depends on the characteristics of the soil and the load on it from the structure; In some cases, increasing the height helps prevent the destruction of the building wall material. This is especially true for wooden buildings, for example, baths

In this case, either a high foundation (about 500 mm) is immediately installed, or a base is erected from other building materials

To summarize the above

It is necessary to determine the height of the above-ground part of the foundation. We take into account a minimum of 200 mm. We evaluate the thickness of the snow cover and, if necessary, change the parameters of the base of the building. The higher the foundation is located above the ground, the better, and the less effort required to preserve the lower part of the house. The optimal values ​​are considered to be 350-400 mm above ground level. Do not forget about hydro- and thermal insulation of the above-ground part of the foundation! These measures will not only preserve the foundation of the building (prevent moisture seepage and destruction of the foundation reinforcement), but also reduce heat losses.

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Foundation for a house and its height: goals and purpose

The foundation for a house performs a very important function. It is the basis of a wooden, brick and any other house or utility structure. It is this that bears the entire main load during operation. The foundation for a house connects what should be underground during construction and the upper, above-ground part of the building. That is why you should correctly calculate the height of the foundation, and higher does not mean better. Usually it's the other way around.

The foundation for a house protects walls from the negative effects of moisture. It can simultaneously perform the functions of a plinth. Such a monolithic design is much better than 2 separate ones.

The height of the foundation for a wooden or any other house is also important because during operation a house or other economic structure can undergo significant shrinkage. The foundation, in turn, can prevent the destruction of a house, especially a wooden one.

A columnar foundation is very suitable for a wooden house. It is designed specifically to ensure that the lower part of the structure does not come into contact with the soil and the soil does not have a negative impact on the building.

It turns out that to calculate the minimum height of the foundation of a house above ground level, the following factors must be taken into account:

Formwork for strip foundations.

1. The material from which the house is built.
2. Features and type of soil.
3. Does the project include the absence or presence of a basement?
4. What is the level of snow cover in the winter season.
5. Precipitation at other times of the year.
6. Availability of groundwater.
7. Soil freezing depth level.
8. And much more.

According to GOSTs and SNiPs, the height of the foundation for a house above ground level must be at least 20 cm. However, this is the minimum. In practice, this value is much higher. That is, the minimum is 35-40 cm. If the foundation for the house and the building itself are built on clay soil, then the height can reach 80-90 cm. For sandy soils, 50 cm is usually enough. When calculating the height of the foundation for a house, it is necessary to take into account the type of supporting structure .

Foundation construction technology

Design features of the foundation with a high groundwater level
After preparing the foundation pit, taking into account the depth of the foundation, the construction site allocated for its construction is drained and leveled. For this purpose, a ditch is prepared with a depth of 0.3 meters and a width of 0.2 meters with a retreat from the perimeter of 0.5 meters. This ditch will serve for storage and drainage. Construction of the foundation in groundwater is unacceptable due to erosion of the solution, and, consequently, weakening of the slab. Next, perform the following work:

1. The soil on the site is compacted and concrete preparation is carried out. A layer of concrete up to 25 mm is laid. This will level the surface and allow you to begin waterproofing work.
2. After the solution has hardened, it is overlapped with a double layer of rolled waterproofing materials (roofing felt), which are then secured with bitumen.
3. The mesh reinforcement for pouring is being installed. The thickness of the slab can range from 15 to 30 cm, but the thicker it is, the better the foundation will perform its immediate function.
4. Once the concrete has been poured and completely cured, the process of laying the blocks begins. After this process is completed, a kind of monolithic well is obtained.
5. Protection is provided from the effects of nearby groundwater.

The type of foundation structure discussed above is one of the most expensive, but undoubtedly one of the most reliable.

Required foundation height

In accordance with GOST requirements, the height of the foundation part above the ground is determined to be twenty centimeters, but in practice this figure increases by one and a half to two times. If construction is carried out on clayey areas, it is recommended to lay the height up to eighty centimeters; on sandy soil, it is enough to raise the foundation by half a meter.

When calculating the foundation height for an object, you should take into account the type of designed foundation.

Tape

Such a base is a wall evenly loaded with structures being built on it. This type of foundation has proven itself to be the most profitable option for the construction of large structures.

Strip foundations can be monolithic or prefabricated; metal and concrete mortar are used for their construction. The foundations are strong because they are based on reinforcement cages.

If a multi-storey facility is being built, then prefabricated reinforcement elements are used, which, as a rule, are reinforced concrete slab material. But if the construction is supposed to be based on a heaving soil composition, then it is dangerous to build a prefabricated foundation, because displacements will occur at the joints of the beams due to frost heaving. In such situations, preference should be given to monolithic foundations, inside of which there are steel frames.

There are two ways to build this type of foundation. In the first case, a trench is prepared, the walls of which are covered with roofing material. After this, a sand and gravel cushion is placed at the bottom and concrete mortar is poured.

The second option is used if a basement is planned. A pit of appropriate dimensions is prepared, a formwork system is installed, and concreting is carried out. The height of the strip foundation above the ground should be at least thirty centimeters. The part that rises above the soil surface can be made of brick material and insulated from the outside.

The reliability of the building and its operational period depend on the quality of construction work.

Plitnogo

How high should a slab foundation be if a heavy object is to be built on weak soil composition or in a place where groundwater comes close to the surface? After all, such a foundation is quite expensive, and calculations for it must be done correctly in order to know how much reinforcement and concrete mortar will be required for construction.

When talking about a slab base, we mean by its height the thickness of the slab itself. You can calculate this value yourself or using a special program. In most cases, the height of the slab foundation above the ground will be thirty centimeters. You can make it thinner, but you will have to strengthen the reinforcing frame.

Before laying the foundation on a site with close groundwater, you will have to first install waterproofing. For this purpose, a cushion of sand and crushed stone was previously poured, and everything was filled with bitumen. Now a layer of roofing felt material is placed over the pillow, reliably gluing its connecting points.

Pile

In the construction industry, screw pile supports are often used. They can be installed in any weather conditions. The design is durable, can withstand significant loads, and does not at all react to the quality characteristics of the soil composition. Installing support piles does not require much effort and a lot of time.

Now let’s figure out what the height of the foundation should be above the ground. As a rule, for the construction of a wooden house, supports are installed, the height of which is two and a half meters.

When using pile posts, there are numerous factors to consider that affect the cost and quality of the installation. This means that preliminary calculations must be entrusted to experienced specialists.

The biggest mistake is unscrewing the supports to adjust the height of the pile foundation above the ground. The peculiarity is that the ability of the pile support to carry loads is achieved by screwing it into the ground. An unscrewed pile leaves a layer of loose soil underneath and can sag due to the load.

Another wrong decision is to screw piles into holes previously prepared for other purposes.

To ensure sufficient load-bearing capacity, the pile should be buried sixty to eighty centimeters into the main soil composition. This value is conditional and depends on certain conditions. If you need to install a pile two and a half meters high, then you will have to screw it into the ground at least one and a half meters. When the upper soil layers are unstable, they should be completely penetrated, resting the pile on dense soil.

Effect of altitude

The planting depth of the base plays a significant role. It protects the cosmetic finishing of rooms from mechanical damage during snow removal and other work carried out to clean up the territory.

It serves as an important indicator that influences the mechanism of operation of the drainage system, which is necessarily implemented in cases where construction takes place near reservoirs or areas located in lowlands.

For a dwelling made of wooden beams, the elevation of the base is of great importance. Since rotting of the lower part of the crown is the main problem

The gap between the floor and the ground affects the thermal insulation characteristics and the lifespan of the ceiling.

How high should the base be?

In order for the basement part of the building to perform all the functions assigned to it, it must have sufficient height. Otherwise, moisture will penetrate into residential premises, and the façade of the building will remain unprotected from pollution and mechanical stress.

According to building codes and regulations (SNiP), this parameter should not be less than 20 cm. This is the minimum indicator. It is better not to save money and build a base with a height of 30 to 40 cm. Structures built from wood are more susceptible to moisture, so the distance above ground level for the lower part should be at least half a meter and reach up to 90 cm.

The parameter from 20 to 90 cm is the recommended plinth height for buildings in the design of which there is no basement. If a house is being built with a basement, it can reach 2 meters. Taking into account climatic conditions and average precipitation allows you to calculate a more accurate indicator of the required height.

Doing this on your own is quite difficult, but possible. For this purpose, the average depth of snow cover over several years is calculated, and 10 cm is added to the resulting value. This data can be obtained by analyzing weather forecasts.

Calculation of foundation width

The calculation process consists of several stages:

• At the first stage, you should decide on the type of soil, as discussed above;
• Next, using a special table, you need to determine how much load can be given on one centimeter of a square pillar that stands on different soils.

Next, you should determine the porosity of the soil. To do this, you need to carefully cut out a ten-centimeter cube of earth and weigh it.

You need to grind it and determine the volume using a measuring cup. Then the following formulas are used: A=1-P1/P; Р1=П/В0;Р=П/В1.

In these formulas, P and P1 are the volumetric weight of the earth in a natural and compacted state, P is the weight of one unit volume of soil, B0 and B1 are the volumes of soil in a natural and compacted state.

And now again, using a special table, we select the soil resistance. For example, sandy loam has a resistance of 3 kilograms per square centimeter with a coefficient of 0.5.

The third step is to calculate the weight of the building that will be located on this foundation.

Next, taking into account the bearing capacity of the soil where the building stands, you can calculate the number of pillars, or rather the step at which they should be installed. This will also help to calculate the cross-section of each pillar.

For example, you can take the following data from the table

Wooden or frame-panel walls, the thickness of which is 15 centimeters, exert a pressure of approximately 40 kilograms of force per square meter.

It is important to build the foundation according to the rules, otherwise, before you can move into the house, you will have to repair the foundation

Thus, we calculate the total weight of the walls and use another table to look at the load from the floor. For example, a reinforced concrete basement floor exerts a load of 300-500 kilograms of force per square meter of foundation. One square meter of a wall made of cellular blocks with a density of 600 kilograms per cubic meter exerts a pressure of approximately 120 kilograms of force per square meter.

Again we calculate the total load from the entire floor. Then we calculate the load from the roof in the same way. After this calculation, it is necessary to add up all the resulting masses and obtain the total mass of the entire house or building.

When the weight is found, you can add to it the weight of the decoration and furniture. Then we simply divide the entire weight by the number of pillars and get the mass that falls on one pillar. After this, we divide the mass by the area of ​​support of one pillar.

For example, let the resulting mass per column be about 10,000 kilograms. Let the pillar have a square cross-section with a side of approximately 1 meter. Then its support area will be 1 times 1 - 1 square meter, that is, 10,000 square centimeters.

From these calculations it is not difficult to calculate the weight per square centimeter of soil under the pillar, that is, divide 10,000 by 10,000, and we get exactly 1 kilogram per square centimeter.

Then we look from the table in the first paragraph to see what bearing capacity the soil on which the building stands has. If it is less than this figure, then the area of ​​the pillar or the number of pillars should be increased, but if it is larger, then all the foundation data have been selected correctly.

Cement consumption

When calculating the weight of a house, it is allowed not to take into account the weight of the interior decoration and furniture, just like the people in the house. This is not due to the fact that this weight is small, but to the fact that when calculating the mass of the walls, openings were not taken into account, that is, doors, windows, arches, and so on.

How does the type of base affect the height?

A protruding base is the most expensive option, but is necessary in cases where the project provides for a usable basement. The height in this case should be maximum. Otherwise, it is impossible to achieve good thermal insulation characteristics. There can be no savings in this case.

For buildings that do not have a basement or ground floor, it is most advisable to choose a sinking option. The facade overhanging wall becomes an ideal protection for the foundation of the house from mechanical damage and adverse atmospheric precipitation. The height of such a base is kept to a minimum. The higher it is, the lower the degree of protection.

What should be the height of the foundation of the house?

What does the height of the foundation affect?

For a wooden house, the height of the foundation is especially important; rotting of the lower crown is an eternal problem with structures made of logs or timber. The distance between the soil and the floor affects the thermal insulation characteristics of the subfloor and the durability of the floor, which is true for columnar, strip and pile foundations.

A high base or foundation, rising above the ground and performing its functions, protects the finishing of the house from mechanical damage during snow removal and other yard work. The higher the concrete subfloor is above ground level, the less heat will leak into the lower part of the house. However, it should be remembered that the above-ground part should not be higher than the underground, otherwise the structure will not be stable. If you decide to build a separate plinth, then from the point of view of strength, a solid foundation strip is superior to the “foundation-plinth-wall” design.

Minimum foundation height

In accordance with the requirements of SNiP, the minimum height of the foundation above the ground must be at least 20 cm, but in practice this rule is used only in the case of a monolithic slab lying at the base of the house. A minimum of 35-40 cm is considered reasonable; in most cases, strip foundations rise to this height.

A slab foundation is most often built on weak or heaving soils; its height for a two-story house made of timber, aerated concrete or sip panels can be about 20 cm. For a light one-story building, the strength of a reinforced slab 10 cm high is sufficient. If a three-story mansion is built from solid brick, the height of the foundation should be at least 35-40 cm.

When constructing a pile foundation, the piles are placed below the freezing depth, while they rest on a solid foundation. The level at which this foundation is located is determined using geological studies.

If a strip foundation is being erected, it is recommended to choose a laying depth of 0.5 m when the freezing level of non-heaving soil is less than 2 m or slightly heaving soil - less than 1 m. When the freezing depth of non-heaving soil is 2-3 m, and slightly heaving soil is less than 1.5 m, strip the foundation is laid to a depth of 0.75 m. If slightly heaving soil freezes at 1.5-2.5 m, and heaving soil freezes at more than 3 m, the foundation of the building is built at a depth of 100 cm.

Height of strip foundation

The full height of the foundation is made up of its above-ground and underground parts. The optimal height of a monolithic strip foundation above the ground is about 35-40 cm. In some cases, this value may change. But its underground depth depends on the properties of the soil.

According to the provisions of SNiP, the foundation depth is determined as follows:

• Freezing of non-heaving soil by 2 m or slightly heaving soil by 1 m - the foundation is buried 50 cm.
• Freezing of non-heaving soil by 3 m or slightly heaving soil by 1.5 m - the foundation is deepened to 75 cm.
• Freezing of non-heaving soil more than 3 m or slightly heaving soil by 2.5 m - the foundation is buried 100 cm.
• Freezing of slightly heaving soil by 3-3.5 m - the foundation is deepened to 150 cm.

The depth of the strip foundation very much depends on the groundwater level. When groundwater is located close to the surface, it is strictly not recommended to lay weakly buried foundations.

Regardless of the level of soil freezing and soil characteristics. Groundwater contributes not only to dampening of the foundation, but also to its sedimentation, distortion and gradual destruction.

Parameters that determine height

In the design calculation, the minimum height above the ground of the building's foundation is determined by a complex of factors present. You can display the required value for the selected type of base if you know the following parameters:

• materials for construction;
• soil characteristics;
• presence of a basement;
• snow depth;
• groundwater levels, storm water levels;
• freezing depth.

In practice, the minimum of 0.2 m is rarely observed; more often, a lifting height of 0.35 m - 0.4 m is prudently chosen. In cases where the building is erected on an area with clay soil, the height can reach 0.8 m -0.9 m On sandy soils, 0.5 m is usually sufficient.

The height of the slab foundation, depending on the total weight of the building, will be from 0.2 m to 0.4 m.

In a monolithic MZLF, vents are installed for ventilation, which have established standard dimensions, and this also affects the height of the above-ground part. Water should not flow into them and small rodents should not crawl into them, so they are located at a level of 20 cm and above.

Products on the tape

The level location of such openings can be seen in this photo:

The easiest way to maintain the optimal height is to build the base on screw metal piles. It will not require a large amount of excavation work, costs for formwork and special construction equipment. The pile is screwed in manually. To strengthen the structure, concrete is poured inside.

Each pillar can have a different immersion depth when achieving reliable support on solid layers of rock. The height of the pipe remaining above ground level makes it possible to take into account the terrain and cut all elements into a single horizon after the entire pile field has been assembled.

Add-ons

For a rough estimate, it is assumed that the cost of the foundation is about 30% of the total estimate for building a house. You can save on the consumption of materials for any type of foundation at the height of the structure above the ground.

The design calculation of a screw foundation for buildings consisting of light frames, log houses, prefabricated panels is not very difficult. Work is carried out at any time of the year, on sites of any terrain (except for rocky and rocky soils). When the site is densely built, without causing damage to nature in the forest or on the river bank, small holiday houses, bathhouses, gazebos, and fences are often placed on screw supports. Building a dacha on high pillars allows you to make good use of the space underneath (summer kitchen, car parking).

For monolithic solutions and brickwork, a standard of 10 cm in excess of the snow cover characteristic of a given climatic region is used.

How to determine in practice, using a water level, what the actual height difference of a monolithic strip foundation is, can be found in this video:

When marking and installing the support, it should be remembered that the height of the foundation at each point must be such that the upper plane has deviations from the horizontal surface no more than permissible values.

Minimum size

To ensure protection of the walls of the house from the effects of precipitation and soil moisture, heaving movement of the soil, it is necessary to create a gap between the crown of the house and the ground. It is precisely this goal that meets the height of the foundation above the ground, which is taken to be no less than 0.2 m for MZLF and columnar supports.

If the site has a slope, then this distance in different places can be greater.

The project, based on engineering and geological surveys, includes the possibility of how much the building can undergo subsequent shrinkage.

This approach is especially relevant for wooden buildings - log houses, bathhouses. In this situation, a sufficiently high base is usually provided on screw piles or bored-type columnar supports.

Height of supports for change house

It is enough to install light temporary buildings on block pads to create an air gap between the ground and the bottom of the wooden structure, as in this photo:

For special-purpose buildings, the minimum height is determined by the installed communications and manholes for inspection and cleaning of the subfloor.

For example, raising a bathhouse above ground level makes it possible not only to break the connection with freezing soil and storm flows, but also to achieve natural drainage of used water through cracks in the floor.

The necessary ventilation and access to the underground for cleaning are provided with a pile foundation having a height of at least 0.5 m from the ground level.

We make calculations

To determine how wide the foundation should be, it is necessary to make calculations. Any soil absorbs the load exerted by the building.

To make correct calculations, it is important to know about two main parameters:

• The weight of the building is calculated together with furniture and snow load. It's not difficult to do. You just need to spend a little time and the calculation will be done.
• Type of load-bearing soil. Since there are several types of soil, it is worth knowing that they all have different load-bearing capacities.

Now you can go directly to the calculations. Let's take a two-story building as an example. We will calculate the house without taking into account the basement. It is best to make all calculations in kilograms and centimeters.

Let's determine the approximate weight of the roof:

House weight calculations

1. The roof is made of wood, so its weight will be approximately 3000 kg;
2. The roof will be made of metal tiles, so it will be 800 kg;
3. The wind and snow load has a relatively small mass, so we will assume that it is equal to 2000 kg.

From all this it follows that the total mass of the roof will be equal to 5800 kg.

Now it’s worth calculating the weight of the box at home, which will be made by hand:

• To build the box you will need approximately 15 thousand bricks. The weight of one brick is 4 kg. We multiply the mass by the number of bricks: 15000 * 4, in the end we get 60 thousand kg;
• During construction, approximately 2.5 thousand shell rock will be used, one block of which weighs about 15 kg. We multiply the mass by the quantity: 15*2500, as a result we get 80700 kg;
• 12 thousand red bricks will be used to make partitions and main walls. The weight of one brick is 3.8 kg. We multiply the mass by the quantity: 3.8 * 12000 we get 45600 kg;
• The floor of the house is made of reinforced concrete slabs in the amount of 34 pieces. The weight of one plate is 2200 kg. We multiply the mass by the quantity: 2200 * 34 we get 74800 kg;
• The weight of shell rock and mortar for laying bricks is 63 thousand kg;
• The weight of furniture and equipment is approximately 5 thousand kg.

Construction design

Adding up all the results obtained, it turns out that the mass of the building box will be 329,100 kg.

Now you need to calculate the mass of the foundation and plinth:

• To build the basement, approximately 6.5 thousand bricks will be required. The weight of one red brick is 3.8 kg. We multiply the mass by the quantity: 3.8 * 6500 we get 24700 kg;
• For the base, 20 foundation blocks will be used. The foundation is laid out in two rows. The weight of one block is 1600 kg. This means that 20 * 2 * 1600 we get 64 thousand kg;
• The weight of the grillage made of concrete is 15840 kg;
• The brick mortar will weigh 1040 kg;
• The fittings used for the grillage weigh 500 kg.

As a result, it turns out that the mass of the foundation and plinth will be 106080 kg. The total weight of the building, rounded up, will be 441,000 kg.

Now you need to find out what the minimum width of the sole will be. Most often, the width of the sole will match the width of the block used. The block size is 50.0 centimeters. The length of the entire perimeter is 4800 centimeters.

Multiplying the perimeter by the width of the block, we get the area of ​​the house support, which will be 240 thousand square centimeters.

If a building is built on soil containing clay, then it can be assumed that its plasticity is equal to 2 kilograms per square meter. centimeter. We teach that the area of ​​the structure is 480 thousand kilograms per 1 sq. centimeter.

Knowing all these characteristics, we can find out the safety margin. We subtract the mass of the entire house from the maximum permissible load: 480000-440989, we get 39011.

From all this it follows that the size of the foundation is 50 centimeters wide, and the permissible mass is 39 tons. If desired, you can add a load that will not exceed 39 tons.

Optimal foundation height

Taking into account the main building materials from which it is planned to construct the walls and roofing, the optimal value of the height of the foundation above the ground surface is selected. For example, a shallow foundation strip is almost always equal to its underground part, which is 0.5 - 0.6 m. And there is no difference where the strip foundation is planned to be laid, because the approximate soil profiles are almost the same for many regions.

Taking into account the type of structure being built, it is possible to establish an approximate indicator of the distance of the edge of the wall to the zero soil level.

For home

When constructing a brick or monolithic building, it is raised above the ground to thirty to forty centimeters. If the walls are built from gas or foam blocks, this parameter increases by ten centimeters.

For a wooden house

Note that the height must be sufficient, because this protects the building from rotting processes. The base can be made of metal and concrete materials, laid with brickwork or laid from wooden beams. In each case, waterproofing is performed using rolled and coating building materials.

When choosing the optimal height of the basement, it is necessary to take into account the climate of the region where construction is to be done.

In a normal situation, the above-ground part should exceed the snow layer by at least ten centimeters.

For the bath

For frame or prefabricated houses, a height gap of fifty centimeters is provided, since the wall materials are highly exposed to external influences.

The above-ground part of the foundation is not only an architectural detail of the house, called the plinth, but also a constructive solution that allows you to protect the load-bearing elements of the building from the harmful effects of moisture and other adverse influences.

The height of the supporting structure, its depth, the materials used and other parameters are determined at the design stage.

Criterias of choice

In the construction estimate, the height of the foundation will directly affect the cost of the work. Therefore, it is necessary to choose a reasonable balance between the minimum required rise above ground level and the desired size of the plinth, porch and associated structures.

The supporting area of ​​the base largely depends on the weight of the building, while at the same time the level of the foundation above the ground determines the need for protection from environmental conditions (heat loss, preventing moisture from penetrating through the floors).

For each case, it will be necessary to perform a calculation in which the height of the strip-type foundation will significantly affect the total mass of the structure. But the height of the pile foundation above the ground (for example, for a bathhouse) can be chosen based more on the terrain, the height of the snow cover and ease of use.

The different needs for the MZLF insulation scheme, determined by how much their top elevation is above the ground, are shown in the diagram:

High altitude

The total height of the supports consists of 2 components: above-ground and underground parts. Typically, most of the part is located below the surface of the earth for stability. If the project includes a high base, its above-ground size cannot be more than ½ of the total value.

A limitation on the lower mark may be a high groundwater level. If the groundwater level on the site is lower than 2.5 m, then the foundation will allow you to immediately place a room with a height of 1.7 m to 1.9 m in its underground part, without a high base going above the ground. It is necessary to maintain a distance of 0.5 m to the level of the maximum seasonal rise of water in the soil. The beneficial use of the internal volume of the foundation structure significantly increases the scale of excavation work, since it is necessary to remove all the soil in the pit and go deep to the solid load-bearing rocks.

The house will have a basement

Do-it-yourself work when installing a buried foundation can be seen in this photo:

Minimum size

To ensure protection of the walls of the house from the effects of precipitation and soil moisture, heaving movement of the soil, it is necessary to create a gap between the crown of the house and the ground. It is precisely this goal that meets the height of the foundation above the ground, which is taken to be no less than 0.2 m for MZLF and columnar supports.

If the site has a slope, then this distance in different places can be greater.

The project, based on engineering and geological surveys, includes the possibility of how much the building can undergo subsequent shrinkage.

This approach is especially relevant for wooden buildings - log houses, bathhouses. In this situation, a sufficiently high base is usually provided on screw piles or bored-type columnar supports.

Height of supports for change house

It is enough to install light temporary buildings on block pads to create an air gap between the ground and the bottom of the wooden structure, as in this photo:

For special-purpose buildings, the minimum height is determined by the installed communications and manholes for inspection and cleaning of the subfloor.

For example, raising a bathhouse above ground level makes it possible not only to break the connection with freezing soil and storm flows, but also to achieve natural drainage of used water through cracks in the floor.

What determines the apparent (above ground) height of the foundation?

It is necessary to understand that this part of the base serves as a connecting link, a kind of jumper in the adjacent area “soil - external environment”. And this area, like no other, during the operation of the building is exposed to external factors - high humidity and temperature fluctuations. The foundation must be raised above the zero level for the following purposes:

for constructing the basement of a house, when part of the foundation takes on the role of a basement.

Obviously, the solid structure has better characteristics than the “foundation + plinth” design for protecting the walls of the house from high humidity. Even despite the blind area, the lower side part of the house will be constantly moistened, so it is better to raise the “foundation-walls” transition as high as possible. How specific?

At least 200 mm from the ground, higher is possible. An observant developer in one of the winters can estimate the thickness of the snow cover on the site, to which you can add 100 mm and get the optimal height of the foundation; often the foundation rises above the ground due to the construction of the basement. In this case, the height of the base is determined based on the design data; for columnar and pile foundations, the minimum rise above the ground is also 200 mm, this is required so that the heaving soil does not affect the building.

The height may be greater, for example, if the topography of the construction site has a slope; when calculating the height of the foundation, it is also necessary to take into account the possible shrinkage of the house, the magnitude of which depends on the characteristics of the soil and the load on it from the structure; increasing the height in some cases helps prevent the destruction of the material walls of the building. This is especially true for wooden buildings, for example baths. In this case, either a high foundation (about 500 mm) is immediately installed, or a base is erected from other building materials.