The technology of pouring such a base is simple;
The device of the base plate carries a number of advantages for the developer, who decided to choose this version of the supporting base for their construction.
Among the main advantages that the tile foundation has are the following:
- High strength. The presence of bulk reinforcement and monolithic concrete fill allow you to create a solid base plate that can successfully withstand external influences and physical stress.
- The simplicity of the technology allows you to pour the monolithic slab of the foundation with your own hands without the involvement of professionals and special construction equipment. Filling a slab foundation with your own hands can significantly reduce the overall estimated cost of building a house.
- Low ground pressure. This indicator for the base plate is about 0.1 kg per square meter. see what is the record for all types of bearing bases. This is achieved by a uniform distribution of the weight of the building over the entire area of the support and allows you to build quite massive structures on weak soils.
- The rigid design of the concrete platform allows it to evenly fall and rise in the winter and summer periods, which is especially important for areas with heaving ground. The forces acting in this case on the foundation slab do not lead to its deformation, which helps prevent cracking of the walls of the building. Analogous forces acting from below on the strip foundation, are capable of simply splitting it with all the negative consequences for the building.
- Increase the pace of construction. The possibility of combining the functions of the base and the floor makes it possible to reduce the total construction time and simplify the whole process. Arrangement of the base plate with their own hands in itself does not take much time due to the simplicity of the design and technology of casting. Before you make the foundation, you do not need to carry out long preparatory work on digging trenches and installing formwork of complex shape.
Filling of the basis plate
Plate Base Device
Despite the simplicity of the slab foundation, the technology of its device should be observed as clearly as possible. Before you pour the slab under the foundation, you should be familiar with a number of nuances that will allow you to get a really high-quality and durable base.
Below are instructions on how to properly pour a monolithic base plate. If a private developer wants to do all the work with his own hands, step-by-step guide will provide him with invaluable assistance.
Before you make the foundation, you need to make technological calculations and create a project for the future construction on paper.
A construction project is being made with the fullest possible consideration of all aspects that may affect the construction and further operation of the foundation. Allowed in the calculation of errors can most negatively affect the entire future process of building a house.
Among the main factors that need to be taken into account when drafting a project, it is worth mentioning:
- characteristics of the soil: its strength, the height of the subsoil waters, relief;
- possible external effects on the base: erosion by rainwater, pressure of heaving forces, shrinkage of the structure;
- the size of the building. The more massive the building will be built on a monolithic slab, the greater must be the thickness of the slab and the more rationally distributed load across its entire area.
When building small buildings, such as baths, garages, lightweight country house, the calculation can be made by eye. Even a small layer of reinforced monolithic concrete will be enough to sustain their weight. But if on the basis of the slab will be constructed capital residential structure, it is best to seek help from specialists with engineering education.
Due to the complexity of the calculations, there is a high probability to make mistakes in the design, which will later be very difficult to correct.
The markup is done on the leveled cleaned area.
This stage of work includes the layout of the site, excavation and dumping of the soil. First of all, it is necessary to clear the construction site of vegetation: cut down trees and shrubs, uproot stumps. After that, remove the top fertile soil layer, rich in organic matter.
Organic inclusions in the soil tend to rot over time, as a result of which the volume of soil decreases, so the plate poured over organic material sooner or later becomes suspended, which does not have the best effect on its carrying capacity.
After removing the black soil, it will be necessary to plan the site – leveling it in a horizontal plane. For this, a level is usually used, by which the horizontal is determined. But since not every owner of the land has this tool, and not everyone knows how to use it, you can use a laser level.
The lowest point of the base of the future building is taken as a “zero” and the entire site is aligned along it. You can also use the combined method of excavation and dumping, when the soil selected in the high part of the site is used to raise its low part.
When pouring the foundation, the dumping should be used very carefully, as the bulk soil has low bearing capacity. The dumped part of the site should be carefully tamped to avoid subsidence of the foundation in this place after construction.
Formation of a protective cushion
Sand-gravel pad will soften the impact of the soil on the slab
The next step is to create a multi-layer protective cushion, which plays the role of a buffer between the concrete fill and the soil. A layer of coarse sand, gravel or crushed stone with a thickness of 10-15 cm is poured over the ground. It is necessary to alleviate the pressure on the concrete base from the side of the seasonal heaving forces.
The sand-gravel pad after dumping is rammed for greater density by a vibrating plate or by hand tamping in the form of a chock with handles attached to it. When building the foundation on clay or marshy soils before dumping gravel, the soil is covered with geotextile, which will prevent the protective layer from deepening into the soil.
A protective leveling screed made of “lean” concrete, grades M-100… M-200, is poured over the gravel. This solution got its name due to the small percentage of cement in relation to fillers.
Lay a layer of insulation on the gravel layer.
A heat-insulating layer is laid above the leveling screed to prevent freezing of rough floors in winter. It is made of high density foam or extruded polystyrene foam.
Between the layer of insulation and sand and gravel cushion, a layer of waterproofing is made of rolled materials – roofing material or its modern counterparts. With the help of waterproofing stop the penetration of moisture from the soil into the layer of insulation. Above the heat-insulating materials, a second layer of waterproofing is placed, after which the concrete plate is directly concreted.
Formwork installation and reinforcement
Install the metal frame inside the formwork
The formwork for the monolithic slab compared to the formwork for strip foundations is characterized by simplicity of design. On the entire perimeter of the future base, boards are installed, which are fixed in a vertical position with stops. Inside the formwork, a volume reinforcing framework is arranged above the waterproofing layer. Structurally, it consists of two rebar meshes, one above the other.
Grids are made of steel or fiberglass reinforcement. For these purposes, reinforcement with a diameter of 10 – 16 mm is taken, while it is desirable that the lower mesh be made of thicker reinforcement than the upper one.
On the one hand, between the grids and the waterproofing, and the slab surface, on the other, there should be a protective layer of concrete at least 3-5 cm. Therefore, mortgages made of metal or stone are installed under the lower grid, and the upper grid is fixed so that the surface to be filled is above it.
The mesh size of the grid should be 2 x 2 or 3 x 3 cm. Metal fittings can be interconnected by means of electric welding, or they can be tied with wire. Fiberglass fittings are fastened to each other with special clips. The upper grid is connected to the lower grid by means of vertical racks, resulting in a spatial structure. For full details of the editing process, see this video:
Flooded solution compacted with a vibrator
For pouring the monolithic slab foundation, concrete of a grade not lower than M-200 is used. When building massive buildings – for example, houses made of brick or stone, the best option would be concrete grade M-300 – M-400. The technology of pouring itself is not difficult – the concrete is poured to the desired level and leveled.
When pouring, the mortar must be compacted using a vibrator. Flooded concrete contains in its composition a large number of air bubbles, which makes it less dense, porous, and this reduces the overall strength of the entire supporting structure.
During vibration, the concrete mortar condenses, fills all the space inside the formwork, air bubbles escape from it, rising up.
Another nuance that must be observed when concreting slab base – so that everything is done without stopping, in one day. If one part of the casting is allowed to dry up, in this place, during further work, a joint joint is inevitably formed. And he is the very “weak link” capable of weakening the monolithic slab. For information on how to apply a deep vibrator, see this video:
Also, when pouring the slab, one should carefully level its surface. In the future, this will greatly simplify the finishing work, will save time and effort when installing finishing floors.
As can be seen from the instructions, to make a slab base for the house is quite accessible to everyone, even those who do not have much experience in construction. The most important thing here is to make the correct calculation and carefully observe the technology of building the foundation slab.
Construction of slab foundation
Calculation of the base plate
Laying reinforcement in slab foundation
Do-it-yourself basement foundation: step by step instructions, tips, photo
DIY slab foundation: step by step instructions © 2014-2016 Postroj-sam.ru
The slab foundation, or as it is also called – the monolithic slab, is considered the most reliable support for the construction of the future home. This foundation is suitable for almost any type of building, ranging from wooden, and ending with concrete, block or brick low-rise private houses.
Another undeniable quality of the slab foundation is that the laying technology is so simple that it can be easily done with your own hands.
Now let’s consider the step-by-step instructions on how to lay the slab foundation with our own hands, which we will divide into several stages.
The markup is not a difficult, but very important stage of construction. Without accurate marking, the further construction of the house can turn into continuous agony and trouble with the alignment of not only the foundation itself, but also the walls with a roof.
How to accurately lay out the foundation under the house with your own hands – I described in one of the previous articles, we will not dwell on this. Consider only some minor differences:
- For slab foundations, the markings are much easier, because it is enough to mark only the perimeter of the house. And where the internal walls and partitions will be located, you can decide on the finished foundation.
- The slab foundation is laid out, in each direction, a meter wider than the perimeter of the house. This is necessary in order to implement the drainage system and the blind area.
- As a rule, if the house has terraces, balconies, a porch or extensions, they are also laid out and poured together with the main foundation, because the slab foundation must be monolithic. Otherwise, no one can guarantee the integrity of the walls of the future home.
The depth of the slab foundation, first of all, depends on the type of soil on the construction site.
- In the case of dense soil rocks, a excavation pit is dug, usually about 50 cm deep.
- If at the site there are very weak soil rocks, such as peat, for example, then it is necessary to completely remove these layers. The depth of such a pit can reach 1 meter or more.
- The bottom of the excavated trench needs to be leveled with the horizon, high accuracy is not required, but still it should be approximately even.
- For digging the pit, you need to hire special equipment. Digging your own hands is much more expensive and longer. Manually, you can only level the bottom and edges, as well as remove all the flaws that will make the excavator.
- If the excavator digs in some places deeper than you need, then in no case do not fall asleep these pits with the same soil that you dig. They can be filled only with sand, which will not shrink.
- In the case when the drainage system is arranged with the drainage of water, it is necessary to immediately take into account and dig out all the bends in advance, taking into account the height difference.
It is worth noting that in the case of a good drainage system, it is necessary to make a small height difference, at the bottom of the pit, in the direction of the water drainage.
After the foundation pit is ready and leveled, the next step of our instructions for laying the slab foundation begins: do-it-yourself sand and gravel pad installation:
- Sand is poured into the excavated pit. The sand should be washed, without clay, chalk, lime and other impurities that may shrink in the future. It is filled up so that less than 20 cm is left for the surface of the ground for the next layer. Such a sandy pillow is necessary, firstly, in order to evenly transfer the load of the building to the ground, and secondly, to ensure that there was no heaving soil under the foundation, which would have a detrimental effect on the slab foundation.
- Sand must be tamped. If the pit is deep, then the sand is rammed in layers. In other words – each layer of 30-40 cm must be compacted, and only then the next layer is poured. This procedure is necessary so that during the operation of a house on a slab foundation – it does not sink.
- Already at this stage, or even earlier, it is necessary to take care of all communications that will be entered into the house. If electricity with gas can be and then enter, then the water and sewage will need to think in advance.
- A geotextile or similar material is spread over the compacted sand. It will prevent the sand from mixing with the next layer – rubble, but will pass water through itself. Since there will be a lot of voids in the layer of rubble, and if, over time, they are filled with sand, then the whole structure together with the slab foundation and the house will drain.
- A gravel pad is piled on the geotextile (a layer of crushed granite with a thickness of about 20 cm). This layer is necessary so that the water formed by precipitation, or any other phenomena, does not linger around the plate and goes into the sand, then distributed evenly into the ground. Also, crushed stone is necessary for even more even distribution of the load from the foundation and the house to the ground.
- The gravel should be distributed over the sand evenly, and so that this layer is either flush with the main ground level on the site, or slightly higher, but strictly horizontal. Horizontalness can be checked by level, or the usual hydro level. The layer of rubble, as well as sand, is carefully compacted. If this is not done, it will be compacted by itself, but later, when the house is already built, and this may entail uneven shrinkage and damage to both the foundation and the house as a whole.
It should be noted that there are various technologies for the device slab foundation with their own hands. Sometimes a sand and gravel cushion is already arranged in the formwork, and between it and the edges of the pit, a separate drainage system is arranged, but in general, the result is almost the same.
In the device formwork and waterproofing for the slab foundation with their own hands there is nothing difficult. Here is a small step by step guide:
- The next step in the device slab foundation with your own hands will be the installation of formwork. It is arranged around the perimeter of the house of the boards, 50 mm thick. Do not confuse, the pit was dug 1 meter more in each direction, and the formwork is set around the perimeter of the house, the rest will be used as drainage.
- Formwork must be set to a height equal to the thickness of the slab, and also, using cords and level, level it horizontally. This is necessary so that when pouring concrete, the issue with the horizontal plate does not arise. If this does not work out, then before pouring you will have to put labels on the formwork itself. The thickness of the slab must be calculated, for light houses it may be less, for heavy ones, respectively. The average thickness of the plate – 20-30 cm.
- After the formwork is exposed and rigidly fixed, it is necessary to lay a waterproofing layer. As a rule, waterproofing is made of rolled materials on a bitumen basis.
- The strips of waterproofing material are stacked with an overlap on the formwork along its entire height and are welded together. This will not allow water and moisture from the soil to penetrate to the base plate. Filling on the formwork is necessary for better waterproofing, the elimination of holes between the boards, and it also allows you to easily disassemble the formwork after the concrete has hardened.
It is worth noting that sometimes under a layer of waterproofing stack plate insulation. As a rule, it is extruded polystyrene foam (EPS) with a high density.
The reinforcement of the slab foundation is carried out only after the complete installation of waterproofing, after reinforcement, the installation of the waterproofing layer will be almost impossible.
- Reinforce slab foundation necessary metal reinforcement. The diameter is calculated depending on the load on the foundation, but, as a rule, reinforcement with a diameter of 10-14 mm is used.
- The reinforcement cage is knitted in two rows. The bottom row is placed on special clamps, so that between reinforcement and waterproofing was 5-7cm. A reinforcing mesh with a pitch of 20-25 cm is knitted with a hook for knitting reinforcement. The material used for tying the reinforcement is ordinary knitting wire.
- The second row fits in so that after pouring the concrete, the reinforcement disappears at least 5 cm inside. Both rows must be connected with vertical posts made of the same reinforcement. They are needed, firstly, to hold the top row of the grid, and secondly, they will not allow the slab to delaminate, under certain loads.
- When the reinforcement cage is ready, you can start pouring concrete into the formwork. Concrete must be brand M200 and above. Very often used brand M300. Concrete must be poured at a time. In other words, if you want a solid and reliable slab foundation – fill it in one day. Moreover, the smaller the intervals between delivery, the better. In the process of pouring, it is desirable to vibrate the concrete with an industrial vibrator.
- Flooded slab must be leveled horizontally, the smoother it will be, the easier it will be later in the process of building walls and flooring. The slab foundation is leveled with the rule, either with an even batten or board.
- After the concrete is poured and leveled, it needs to stand for 28 days. until complete curing. Ideal conditions for the process of hardening of concrete – +20 o C. and humidity around 80%. Therefore, if it is hot outside, then the next day it is necessary to shed it with water and cover it with a film that will not allow moisture to evaporate quickly. In winter – you need to take care of the heating of the concrete.
It is worth noting that if the slab foundation is poured, you leave it for a long time, and especially for the whole winter without a roof, it is necessary to take care of its “preservation”, i.e. cover so as to prevent precipitation from falling on it.
- If you have marshy ground on the site, then any foundation, including slab, must be provided with a reliable drainage system. It will contribute to the diversion of water from under it, thereby improving the behavior of the foundation on the ground.
- Do not listen to those who say that one row of reinforcing mesh is enough for the slab. In order for the foundation to be reliable, it is necessary to tie two rows, one above the base by 5-7 cm. And the second, respectively, below the top plane of the slab by the same 5-7cm.
- The armature must be tied so securely that when the concrete is poured and pressure on it, it remains in place, displacements are not allowed.
- When calculating, always buy everything with a stock. The shortage of any material can stop the construction process for a day or even longer.
- Do not load the foundation until it is completely cured (28 days). This may lead to irreparable consequences.
- With a concrete volume of more than 2-3 cubic meters. Cooking it yourself in one day is a difficult task. Therefore, it is better to use purchased concrete, there and the quality will be higher.
Good day. After reading this article, I had only one question. “It is necessary to reinforce the slab foundation with metal reinforcement” why you write so categorically about metal reinforcement. After all, time does not stand still and for several years already there exists a wonderful alternative in the form of composite reinforcement. He used it himself both in slab and strip foundations, in terms of reliability he is not inferior to metal, and in terms of ease of installation only wins.
1. Please do not engage in self-promotion.
2. Composite fittings, and this has already been proven, works well in tension. But at the break – metal is much more attractive.
3. Today, whoever does not release these valves, and, accordingly, the percentage of marriage increases. I do not want anyone to get burned after my approval for using composite reinforcement foundations.
I completely agree!
What kind of composite armature is this? It is clear that the economy should be economical, but also cut on everything – a meaningless undertaking, which can go sideways in time. How can you save on the foundation, foundation and support of housing?
And under the article, I also had a small question. Undoubtedly, a beautiful foundation came out, it is worth noting separately But what kind of bearing abilities can he take on? After all, there is no grillage in it. Under the “skeleton” fit perfectly, but if he can cope with a more “powerful” design? For example, the foam block + face eternal brick.
Such reinforcement is also called fiberglass.
And so, everything is necessary, at least an approximate calculation, here we must take into account not only the foundation itself, but also the ground beneath it, ground water, etc. etc.
Sources: http://osnovam.ru/fundament/plita-svoimi-rukami, http://kakfundament.ru/plitnyj/svoimi-rukami-poshagovaya-instrukciya-2, http://postroj-sam.ru/fundament- doma / plitnyj-fundament-svoimi-rukami-poshagovaya-instruktsiya-sovety-foto.html