Strip foundation planning. Drafting
Today, as a base for residential and industrial buildings, it is often used strip foundation. It is quite simple to perform and does not require the creation of complex drawings. In addition, it is important to note that the most important advantage of this type of foundation is the affordable cost.
Everything you need to know about strip foundation
Specialists in the construction industry attribute the tape type of foundation to monolithic foundations, but only with the exception of one, but very significant difference - efficiency and availability. Despite the fact that the amount of concrete mortar required for the work is reduced, the foundation does not lose its strength characteristics and is distinguished by a special degree of reliability. Today it is used for the construction of high-rise buildings, industrial and public facilities, as well as, of course, in the construction of country cottages of any number of storeys.
Supports for strip base
The supporting structures that are used for this type of foundation are of 2 varieties, namely:
- Tape monolithic foundation. The concrete mixture is gradually and evenly poured into the pit;
- Prefabricated strip foundation. In addition to the solution, ready-made reinforced concrete structures are also used.
In order to determine how deep the trench should be in this case, it is necessary to be guided by a map of soil freezing. It is different for each locality, and if an inaccurate indicator is used during the work, then such an oversight may be fraught with shrinkage of the structure or even destruction of the entire foundation. The width of the pit depends on what load will be placed on the foundation during the direct operation of the house.
What should be taken into account during calculations?
In order to make calculations correctly, it is important to consider the following characteristics:
- weight of the future structure. To calculate this indicator, you should be guided by the total weight of the materials that will be used for construction. An important factor is the number of storeys of the building.
- soil type. It has a direct effect on the degree of shrinkage.
- the degree of load on the foundation during the period of operation.
Making a plan right
When creating supports for a strip foundation, the drawing must meet the following requirements.
- When determining the most appropriate scale, it is highly recommended to choose either 1 in 100 or 1 in 400.
- Before starting construction work, the site should be marked.
- If you plan to create a house or a public structure with columns, be sure to indicate this designation and section in the drawing.
- All lines on paper must be clear and precise, the thickness of each of them is 0.5-0.8 millimeters.
In the general scheme, there must certainly be a designation of the sole, as well as places in which there will be various bulges or recesses. This is important in order to calculate the location of communications from the central highways.
Such holes and protrusions must be displayed on the diagram in contour and broken lines. If necessary, you can make explanatory notes and footnotes.
Complex sections of the circuit
If you plan to build a capital and large-scale structure, then it will certainly require the creation of a complex prefabricated or monolithic base. As a rule, such schemes cannot fit on one drawing. Therefore, experts in the construction industry strongly recommend developing separate schemes for complex sites. Alternatively, you can apply additional centerlines and a section designation (if necessary) to the main plan, as well as create large cuts on the sheet, after making a note about this. In addition, depending on the degree of the section, it is recommended to choose a scale of 1 to 20, 1 to 25, or 1 to 50 in order to bring the section and complex structural elements as close as possible.
Additions to the scheme
In the event that you are going to create a monolithic or prefabricated type of strip base, then, to clarify the drawings, they should be accompanied by the following technical documents:
- Scheme of reinforcing the site based on the future load of the structure on the foundation;
- An application that displays the design features of the building;
- Recommendations regarding preparatory work Location on;
- Tables and diagrams that are necessary for waterproofing and thermal insulation of foundations.
- Data on the norms of load on the base supports.
Determination of the degree of deepening
As already mentioned, the depth of the trench to create a tape type base is calculated depending on the scope of the supports. Today, 2 main types of structures are popular - deep and shallow. After you decide which of the options should be preferred, an appropriate designation should be made on the plan.
- The first type of base is characterized by reinforced reinforcement and is an excellent choice for large structures, the design of which involves the creation of basements, attics or heavy partitions. It is believed that the most optimal indicator of the degree of deepening of the trench for the tape is an indicator that is 20-25 meters higher than the level of a particular region.
- The drawings certainly contain information about how deep the tape will be buried. It is important to remember that the number of consumables for the formation of recessed supports is an order of magnitude larger.
Fundamental differences between support schemes
Above, we tried to describe in as much detail as possible the process of creating a structure plan, for which a strip foundation drawing is used. But at the same time, one should not forget that the drawings containing information about the prefabricated type of supports differ radically from monolithic ones in that it has a section, as well as the designation of straight and corner reinforced concrete structures.
We do our own calculations
We assure you that today a sufficient amount of information is provided on the network in order to carry out all the necessary calculations as much as possible. To do this, it is absolutely not necessary to be an engineer and have a technical education. With a responsible approach to the issue, as well as being an observant and attentive person, you can easily calculate all the criteria necessary to create, for example, a strip base for a non-residential structure or a building envelope. It is important to consider the following:
- Vertical impact on the ground;
- The weight load of the main structure on the base;
- The weight of the roof and truss system (but only if you are going to build a barn or non-residential outbuilding);
- When creating a foundation drawing, in order to eliminate errors, the results must be multiplied by "2%". This will help to insure against possible shortcomings in the process of independent design.
Will the services of professional specialists be required to create a drawing?
Of course, a strip foundation plan for a residential building needs much more accurate and detailed calculations, which are best entrusted to a specialist. Turning to the master of your craft, you can be sure that the drawing will be:
- easy to read;
- as accurate as possible;
- meeting all the requirements of SNiP;
- containing comprehensive information about the preparatory work;
- having, in addition to the main drawing, technical applications in the form of various tables, diagrams, etc.
In this article, we tried to provide comprehensive information about the process and principle of creating a drawing of a strip foundation for a residential as well as non-residential structure. And remember that if you are not confident in your abilities, then do not try on your own or with the help of unlicensed programs to carry out the calculations necessary for such a basis. Savings in this case can be fraught with huge losses or even the destruction of the entire building or fence.
The foundation is the lower part of the building. It takes on all the loads, transferring them further into the layers of dense soil. There are several types of foundations, among which the tape is considered the most durable. This is a reinforced concrete strip laid along the perimeter and under the inner walls of the entire structure. But in order for the structure to fulfill its purpose, it must be built correctly. That is why the main element of preparation for work is the strip foundation scheme.
Do you need a plan?
Among all construction documentation, the foundation scheme occupies the main place. This document specifies characteristics that depend on factors such as:
- The weight of the building under design, under which the foundation will be erected. This indicator depends on the number of storeys of the future structure, its purpose, internal layout, materials used for the construction, and others.
- Design features. We are talking about the presence of a basement, a basement or the absence of these, if the building is without a basement and other features.
If the design of the strip foundation is done incorrectly with errors or errors, the consequences can be serious - ranging from the inability to build a structure to the destruction of the foundation, which will entail the destruction of the entire structure.
Schema creation: what should be considered?
The most important aspects, without which it is impossible to draw a plan correctly, are the following indicators:
- The weight of the finished building.
- Variety (type) of soil. How strongly the foundation can shrink depends on its density.
- The degree of loading of the finished structure.
This information is the basis for determining the geometric parameters of the structure and materials that can be used in the construction of the foundation for the house. Be sure to tie the future structure to the planned area.
Features of drawing up a plan
When drawing up a plan for any structure, scaling is used - this is a decrease in indicators by a certain number, which happens from 1 to 100, up to 1 to 400.
First of all, markup is carried out along the axes. If it is planned to build columns in the building, it is necessary to note the general direction of the axes, since their intersection is preserved. The outline of the base should be drawn in lines from 5 to 8 mm.
The strip foundation plan should include such nodes as:
- Sole.
- Places where different areas foundations have different depth indicators if you have to build a strip foundation on a slope.
- Footing - device and type.
- Section configuration.
- Holes for communications (with reference to the axes and designation of the lower points). Sometimes information about the designation of the parameters of the holes for communications (lower point, diameter) is taken out separately, and on the plan they are marked with dots.
- Burying depth. This information is represented by the mark of the surveyor. If it does not exist, the foundation plan is considered unready for execution, since in the future it is fraught with various manifestations - unnecessary costs or destructive processes. If the depth of the foundation is the same, geodetic marks should be placed on each ledge. Only those places where the depth will be different should be marked on the plan.
An important detail: if the outer walls are shown on the plan of the tape monolithic foundation, the blind area should also be displayed in section. In addition, the width, length and thickness of the walls, the dimensions of the ledges should be indicated.
Reinforcement planning
Unfortunately, the strip foundation is a vulnerable structure: its strength depends on:
- Compliance with the conditions of the area in which the construction is carried out, and the parameters of the foundation.
- Correct load calculation.
- Pledged margin of safety.
Reinforcement is used to strengthen the strip foundation. For this purpose reinforcing bars are used. When drawing up the plan, a concrete strip reinforcement scheme is also created: the diameter of the reinforcing material is selected, its placement in space and the required amount are determined.
To create a reinforced frame, hot-rolled products are usually used, with the help of which prestressed and conventional structures are strengthened. Rebar is selected for specific types of buildings according to its strength class, which ranges from A1 to A4 and depends on the grade of steel used in the production. So, for the manufacture of products of classes 1 and 2, low-carbon steel is used, for 3-4 - alloyed. This allows you to create the most suitable reinforcement frame in terms of strength indicators for a particular structure, taking into account its operational features. If the height of the base is higher than 1.3 m, it will also be necessary to carry out transverse reinforcement, which is also drawn in the plan.
basis classical scheme reinforcement is a rectangle reinforced from above and below and longitudinal reinforcement connected by vertical and transverse reinforcement. All this together creates a box, which gives strength to the foundation frame. The number of tiers depends on the height to which the monolithic strip foundation should rise. The layout of the reinforcement must be depicted in the project. In addition, the strip foundation plan contains a drawing of the placement of the reinforcing box, taking into account the necessary clearances between the formwork and reinforcement.
Foundation section in planning documentation
The section of the strip foundation depicts:
- The contours of the supports according to the reference to the terrain.
- Waterproofing. Each node must be specified.
- Blind area.
- Sizes of ledges with indication of levels.
- Foundation sole.
- Shotgun.
- Land surface.
- Zero mark of the floor.
To make the plan easy to read, additional numbers are taken out of the figure and the direction is indicated by arrows. The section of the strip foundation is carried out on a scale from 1 to 20 to 1 to 50. All data can be indicated not on one sheet, but on several.
In addition to the basic documentation for the strip foundation, clarifying (additional) documents may also be attached:
- Table with load standards.
- Mounting plan and development. Required for prefabricated poles.
- Information about elements located below the zero level.
- Notes on the preparatory stage of foundation construction, thermal and waterproofing scheme, design features, and more. They can be on separate sheets or included in the overall plan.
Additional strip footing plan options
The calculation of the column-strip foundation is not complete without a table that indicates the load standards for this type of structure. This number also includes metal or concrete elements that will be located below the floor level.
Attention: the most significant parameter is the margin of safety, which must be taken into account at this stage. If it is not enough, concrete reinforcement is designed with additional reinforcement.
The finished plan is verified in AutoCAD. This is the name of a program that allows you to see an image in 2D or 3D. Moreover, the entire amount of work is performed by the computer after the dynamic input of the parameters of the future design.
Tape in construction is called this type of foundation, which is monolithic and is a structure filled along the contour concrete base, i.e. "ribbon". Due to its strength and large area of \u200b\u200bbearing surfaces, the strip foundation is used for the construction of the most different types buildings, but in order for it to be filled correctly, it will be necessary not only to carry out rather heavy and long earthworks. One of the main elements at the preparatory stage is the strip foundation scheme for the house.
The foundation plan is the main one in the list of construction documents, and it should indicate those linear characteristics on which the following factors depend:
- the weight for which this foundation is designed (depends on the materials used for construction, the number of floors, the internal layout, the purpose of the building, etc.);
- design features (with or without a basement, underground, cellar, with or without the possibility of creating a basement floor).
If the strip foundation scheme is created with errors or major errors, then this can lead to the most different consequences: from the inability to carry out the required implementation of the house project as it was conceived, to the destructive processes in the foundation and, as a result, in the entire structure of the building.
What should be considered when creating a foundation scheme?
The following aspects need to be taken into account:
- type of soil: the degree of shrinkage of the foundation depends on this;
- estimated weight of the building;
- degree of load during operation.
Scheme of the strip foundation device - construction features
Usually, to create a plan, scaling is used from 1 to 100 to 1 to 400. First, marking along the axes is performed. If columns are provided in the structure, then common axial directions should be marked along their contours: their intersection is preserved. The outlines of the base are applied in lines from 0.5 to 0.8 cm. The layout of the strip foundation should include the sole, footing, transition points along the depth of various sections of the foundation (with an uneven ground surface) and beams. Also on the diagram, holes for communications should be marked, which should be tied to the axial markings and marked lower points. Sometimes only the points of placement of such holes are marked on the plan, and their parameters (diameter, lower point) are taken out in separate information or on an explication.
In addition, it is necessary to indicate the depth of occurrence on the diagram: a strip foundation, the plan of which does not include this information in the form of surveyor's marks, is not considered ready for pouring, since an incorrect calculation of the depth is fraught with further destructive processes if it is insufficient, and unnecessary costs if it is will be too big. Geodetic marks are placed on each ledge, and if the depth is the same throughout the foundation, then the base of the foundation is indicated in the explication, and only those parts that have a different depth should be noted on the diagram itself.
To indicate openings for communications or ledges, a broken line or shading of such areas is used. Some parts of the plan can be depicted with a large scale on a separate sheet if their design is a complex type of layout. Also, on the plans of strip foundations, indicators are applied for the width of cutoffs and soles with a ratio of axial indicators. Sections can be drawn on a scale of 1 to 20, 1 to 25 or 1 to 50, and if they are small, you can place them on the same sheet as the main plan. When creating a section, they show the outlines of the foundation, the level of the floors, the presence of basements, the level of the ground, and the presence of thermal and waterproofing.
Important! If external walls are displayed, then the blind area is also displayed in the section. It should also show the parameters of the ledges, the length, width and thickness of the walls. It is best if the axle mark is indicated here.
What else can a strip foundation plan include?
The scheme may also include a table that provides the norms for loads on this type of foundation and the features of parts of the structure made of metal and concrete, which are installed below the floor level. The plan also needs to indicate the amount of reinforcement that is needed to strengthen the concrete: it must be above and below the foundation, and inside it the reinforcement is placed horizontally. With a height of 1.5 meters and above, the foundation must also be reinforced across.
Also, the layout of the strip foundation contains notes and notes placed on a separate sheet or free space, which indicate information about the structural details, the preparatory stage for creating the foundation, the method of thermal and waterproofing, etc.
Important advice! One of the essential parameters when creating a circuit is the margin of safety, and it should be taken into account immediately. This may require strengthening the concrete with additional reinforcement.
In general, the layout of the strip foundation on the plan must be accurate, contain accurate information on the base of the building, so that after it is drawn up, pouring can already begin.
In private and public housing construction, a tape-type bearing base is often used. It is considered the most practical and does not require large financial costs, as well as the use of heavy special equipment. But first it is necessary to properly plan the strip foundation, drawing, project and miscalculation - this is what any foundation requires in order to be really strong and ensure the stability of the entire structure.
Calculation of the depth and width of the strip foundation
Design works with basic parameters, so before creating a house plan, you need to know the characteristics of the soil, the dimensions of the future building. For a large residential facility, the foundation should be buried below the freezing point of the soil up to 0.6 m, while the total depth of occurrence can reach 2-3 m, especially on soft and moving soils. A light secondary structure or wooden structure can be deepened up to half a meter. Homogeneous and strong soils allow deepening of the foundation by 0.45 m.
The project takes into account the layout, dimensions and width of the external, internal load-bearing walls, under which a monolithic or block foundation is arranged. The minimum width of the supporting base must be no less than the width of the walls. It is permissible to hang a wall element over the foundation, but not more than 13 cm, and when arranging only one type of bearing base - this is a reinforced concrete foundation. It has greater strength in comparison with the materials of the wall structure, therefore it has the ability to withstand massive loads. A narrowed foundation will save on the cost of materials and fittings.
Depending on how wide the foundation will be, its sole, the total width is calculated load-bearing structure. To do this, the project reflects all the loads (sum) that put pressure on the foundation. Therefore, the preliminary plan of the house will come in handy, as well as the conclusion of the geologists, which indicates the main points: soil properties, freezing level and height of aquifers.
Advice! If there are reference books on geological exploration data, then the freezing point of the soil and the heaving, the severity of the soil can be found from there. In this case, it is not necessary to order geological exploration. But in heaving soils there is a possibility of a change in the level of groundwater, so it is better to play it safe so as not to redo later not only the project, but also the foundation of the house itself.
Do not forget that a sandy or gravel fine-grained cushion up to 10-20 cm wide is necessarily arranged under the supporting base, so the trench is dug out taking into account this depth. You can take a sand-gravel mixture in a ratio of 40:6.
The width of the carrier base is calculated from total load wall panels, floors, roofs and net weight of materials. To this mass is added the weight of the furniture and everything that will be in the premises, so the plan of the house should also provide for such nuances.
Important! The dimensions of the base of the foundation are calculated so that the magnitude of the loads does not exceed the allowable weight on the soil layers of the construction site! The design resistance of the soil should not be less than the specific gravity of the pressure of the building mass.
If the house plan involves a construction in the form of a rectangle or square, then calculating the required volume and size is quite simple, another thing is pouring complex bases. Here you will have to divide each node into basic elements and calculate the volumes and sizes from them, then adding the resulting values. After calculations, it is easy to think over the amount of materials needed for the construction of the foundation, concrete mix, reinforcement, formwork and other things.
Calculation of the bearing capacity of the foundation
Bearing capacity is the maximum possible load on the foundation, which it can withstand without loss of quality and strength characteristics. As a rule, the indicator includes certain times for the formation of deflections, the level of stiffness and the width of the crack opening.
Ground masses consist of particles filled with water and air. Under the influence of the load, the particles are compressed, changing their shape, so the soil in the total mass also changes and can sometimes even protrude from under the bearing base. This is called shifts, as a result of which even a monolithic foundation can warp, the house settles, loses its stability. Therefore, when starting to think over a project or building plan, it is important to take into account such factors.
Important! Knowledge maximum load on the ground is necessary to calculate the mass of the building. If the indicators are exceeded, the soils are displaced by an unacceptable amount. The settlement of a monolithic, block or piled strip foundation is determined by the ratio of deformation and stress calculations - this is the average value of the pressure that has its effect on the soil masses.
Features of a shallow foundation
This type of carrier base does not need to be made high so as not to exceed the allowable stiffness standards. A sufficient height is considered to be 40-50 cm. In addition to imparting unnecessary qualities, a high foundation entails an overrun of reinforcement and concrete mix. A low load-bearing base is a more economical and fairly durable structure.
Thermal, waterproofing materials will help improve the performance and reliability of the building. Therefore, when designing a house plan, it is worthwhile to thoroughly consider each node based on actual values, indications and characteristics.
An example of planning, calculating materials and the size of the foundation of a house
Building materials required for work:
- Pure sand of fine-grained fraction;
- Crushed stone, fine gravel;
- Cement;
- Reinforcing rod, wire, steel rods;
- The basis of the underground part of the foundation: rubble stone, wire, metal pieces.
Any bearing base consists of ground and underground parts. Measurements of length, width, height are necessary for calculating the dimensions of a monolithic reinforced concrete foundation. In order to determine the volume of the flooded area of the above-ground part, the length of the trench around the perimeter is summed up, multiplied by the width and planned height, it is better to reflect this in the plan of the house. Example: if the total length of the supporting base is 30 m, the width is not more than 30 cm, and the total depth is 1 m, then the volume of the foundation is 9 m3.
The same data will help you buy the right amount of sand and cement, but you need so much reinforcement to lay 2 times around the entire perimeter of the foundation, that is, the length of the supporting base is multiplied by 2 and it turns out 60 m. That's 60 meters of reinforcement and you need. But at the same time, the reinforcing bars pass in a vertical position in a cut of 1 meter (height). The pitch of the rod is 50 cm, which means that you will have to buy 60 reinforcement rods of 1 meter in length. Bottom line: 60 m + 60 m = 120 meters of reinforcing bar is necessary for the foundation of our building. And all this should be taken into account in the project.
In addition, it is necessary to calculate the number of formwork boards. This is not difficult: multiply the height of the above-ground part of the supporting base by the length of the formwork and another 2. Thus, an estimate is calculated according to the plan of the future structure, where each node, connection is indicated and trifles and nuances are taken into account.