Trench for the foundation: how to dig

To dig a trench under the foundation only at first glance seems that there is nothing easier, but this is a deceptive impression of an outside observer. Before digging a pit or digging of a trench under the foundation, any architect pays more attention to the preliminary calculations of the load and the characteristics of soils than the development of the project and its maintenance. The base of the house does not begin by marking, although it is not possible to do without it, but with more important soil indicators. Also, accounting for parameters such as the shape, depth and width of the trenches for the foundation of the house or cottage is important.

Table of contents:

1. How to calculate the depth of the trench for the foundation
2. How much does it cost to dig a trench under the foundation?
3. Calculation of depth parameters and trench width
4. The scheme of the markup of the trench
5. What can be the walls of the foundation

How to calculate the depth of the trench for the foundation

The house is somewhat reminiscent of the iceberg, where the most insidious part is invisible, or the tree, the higher it is, the deeper the roots in the ground. And the roots of the same breeds themselves are very different in ordinary, creep, sandy or marshy ground. Accordingly, this principle is adjusted to the depth of the trench under the foundation. However, in order to make the right calculations, you can not do without a construction project and the right place on the site. For example, the cottage on the slope of the river in the upper and lower part should have a different foundation.

1. The factor of seasonal soil vibrations is wet clay and peat soil in a cold climate requires a deep trench for construction. This is a pit of about 1.5 2 meters, to the level of freezing of the soil meter. On such a basis, there is a high probability of seasonal flooding of the building, which is not advisable to do high and massive. A third of the finished trench, in order to save, is poured with gravel or a mixture of crushed stone with soil, then this pillow is compacted and concrete solution is laid.

2. The subsidence factor soft soils often give a significant shrinkage, worse, when the structure plunges unevenly, forming cracks. The finished building in such conditions should be correctly designed, preferably symmetrically, for equal load. Sandy soil, loam and floodplains are no less insidious, especially on the lowland, where the upper layer of groundwater is no more than 2 meters. The country house is better to build one -story, wide and quite lightweight, and the depth of the foundation deepens to 0.8 meters or to the level of freezing of the soil. Digging the trench under the foundation of the video makes it possible to evaluate all the stages of such work.

3. The probability factor of flooding with him also cannot be considered, especially in those places where the drainage system is not thought out. Sometimes there is a need for the foundation around the trench to make drainage channels along the contour. They lay a ring drainage with pipes and then closed with crushed stone. The threat of flooding requires a more thorough preparation of the trench with a drainage slope. The drainage layer under the foundation is intelligent deep into the ground. But in these measures there is no need for ordinary ground of summer cottages, places for which are chosen without such problems.

Tip: the general rule looks something like this: on gravel and sandy soil, a trench is enough up to 1 m deep, on sandy loams up to 1.3 m, on loam and clay soil about 1.5 m and on very dense soils 2 m. It is important to take care of Safety measures untouched the walls of the moat, especially on bulk soils, should immediately be filled with formwork so that the wall of the trench is crumbling.

How much does it cost to dig a trench under the foundation?

In order to independently dig a trench under the foundation, the price of such work is not so important, the main thing is to calculate your strength and the number of time spent on this. But frozen or rocky soil with your own hands, with the help of an ordinary shovel, is difficult to master, especially if you need a deep and wide trench. In such conditions, you can’t do without renting equipment or hired hands. It is much more difficult if there is no way to fit the technique to your site will have to look for an alternative option.

Before reading the marking of the trench, it is important to decide how the digging of the trench under the foundation will be organized:

• hire workers;
• rent an excavator or other heavy special equipment;
• rent a tractor cockerel;
• find time for independent digging;
• organize partners, friends, family members, etc.

Each region has its own prices for land, including how to dig a trench under the foundation.

For a cubic meter of the selected land, you will have to lay out from 800 rubles. And above, and much depends on the complexity of work, season and soil composition. It is better to find out the prices for rent and the volume of work in advance from construction organizations that are associated with this. But even if you manage to agree with your friends and relatives, you can not do without a good feast and additional premium, which is also over. And not everyone will want to take on it, especially in the cold season. Therefore, all these moments need to be decided in advance for 1 day a technician or working hands for several days. In an inaccessible place, the best option would be to call a construction brigade having all the tools and experience, they will set out all the prices, but excavation work in the cold period will cost about a third more expensive.

Calculation of depth parameters and trench width

The width of the trench under the foundation is made, at least, in the width of its concrete sole, and the foundation itself forms a little more than the width of the walls. For example, if the house is made from the cut shells, then the masonry is made in stone, that is, to the length of the rectangle, plus is added to the width of 3-5 cm for finishing work.

The depth of the trench is calculated not only taking into account the future foundation, but also with drainage and sand pillow. With the manual method of excavation of the Earth, the lower layer of soil (bottom) is removed extremely horizontally, without violating the natural density of the lower layer. The soil crumbling to the bottom is removed, since the torn soil has a small density, approximately twice as loose, and even with thorough compaction it is impossible to achieve its natural structure. After digging an excavator or tractor, loosened layers of the soil are necessarily rammed, after which drainage and sand cushion are made.

DIY trenches for the foundation with your own hands are made taking into account all the above soil features. Much depends on the number of storeys of the project of the future structure and the features of the site. The house can be built even on marshy soils or in the conditions of permafrost, but for this you will need piles or special technologies. In most cases, they independently make a trench for a strip foundation for a small country house, that is, a compact and quite easily structure. If a cellar is planned under the house, then for it you need a pit, not a strip foundation.

On ordinary soil, the optimal depth of the trench under the strip foundation is made about 1-1.5 m, taking into account the sole with a tamp. On dense inappropriate soils for a shallow foundation for a light summer cottage house, the soil itself can serve as a natural formwork, but the trench should be slightly wider. This is permissible if the trench is dug extremely neatly, with a flat vertical wall of strictly P-shaped recess (in an inverted form).

Before digging a trench to the foundation, you need to decide where the soil extracted from the pit will take shape. It is discarded up to half a meter from the edge of the recess. In no case should you remove the soil under the adjacent part of the finished building, making the foundation for the extension.

If the laying of the drainage system is required at the sole of the foundation, then the trench is expanded taking into account the diameter of the drainage pipe and plus a double indent from it 10-15 cm. On the crumbling soils of the sides of the trench, the walls are sometimes strengthened with plywood shields or plank. Digging the trench under the foundation also provides for the zabutka to fill the slopes by Bout so that the water does not nourish the foundation of the blind area.

Tip: optimally the width of the trench under the strip foundation is calculated taking into account the total width of the formwork design, waterproofing, additional fastening plus 20 cm on each side to the total width of the foundation. In most cases, the foundation trench is made for about 70 cm under a country house, it is convenient when excavating soil. When they make digging a trench with a bucket of an excavator, it is impossible to make a width less cutting edge, only wider. If people should move along the bottom of a deep trench, it is important to observe precautions so that the crumbling soil does not fall asleep. The width of such a trench is made at least 60-70 cm, and the fastening and density of the soil is necessarily checked.

The scheme of the markup of the trench

The marking of the foundation is made according to the drawings of the project, that is, in accordance with the size of the walls of the future foundation, plus additional centimeters for digging trenches, for example, in size of the bucket of special equipment.

They start with markings along the external perimeter, then cross transverse trenches under the supporting walls. Kols of wood or reinforcement are driven in the corners and a tourniquet (fishing line, strong twine) is pulled from them, checking the corners strictly at 90. After that, all sides of the rectangle and diagonals are thoroughly freezing. When they all correspond, then the corners are exactly 90, and if there are inaccuracies, then everything will have to be moved, it is better to kill the pegs more precisely. The transverse trench under the partitions dig after the perimeter. In the photo digging the trench under the foundation, an example of the correct marking is shown.

During the layout of the trench under the foundation using a water level, the lowest perimeter point is found for the arrangement of the drainage well. Excess moisture from the pit will drain there. It is better to remove the entire turf along the inner perimeter, and move the upper fertile soil layer to the garden.

The dug trench is cleaned of the crumbling soft soil, the bottom is sealed, watered with water, then filled with sand, again tamped tightly. The sand sole can be made in several layers, each of them moisturizes and compacted. After that, a waterproofing film is laid or the formwork is installed to protect against the collapse of filled concrete.

Tip: When choosing a place for the foundation, take into account the dimensions of the future building and its location on the site. The house should not be too close to the Mezhs of neighboring sections so as not to create inconvenience and undesirable shading. It is optimal when the trench under the foundation from neighboring areas is made no closer than 3 m from the fence grid, conditional border or solid fences. No one is pleased when the house is built by windows literally opposite the neighboring ones, especially without a high fence. It is not good if the high structure is being built on the boundary or along the south side of the garden, shading trees. Whatever good -neighborly relations, do not trample the generally accepted norms.

What can be the walls of the foundation

In houses with the basement of the walls of the foundation, monolithic or prefabricated. If only a concrete mixture is poured into the formwork, and the foundation of hollow or full -bodied concrete blocks fastened with each other.

1. Country houses are sometimes made on a foundation folded from sawn stone, like a wall masonry, using high -quality concrete on the lower pillow.

2. Houses with a deep basement should have a thorough foundation, and it is performed by reinforced concrete or from monolithic concrete with reinforcement. Such walls are very solid for private household, and their cost is relatively small, if you do it with your own hands.

3. The foundation of concrete blocks is the most convenient option. This guarantees the stability of the design of both the foundation itself and the entire structure. Blocks are connected with a metal rod and a cement solution is used. The upper row is doused to be connected by reinforcement, and the corners are laid so that the seams do not match, in a checkerboard pattern so that there are no cracks. Only full -bodied blocks are placed on the bottom layer, it is imperative to fill large voids with concrete, especially at the ends.

4. A brick foundation is done less and less, although such a base is no worse than concrete. The only drawback of such a foundation masonry is long -term construction. However, if there are many catchy bricks, for example, secondary use, then in order to save money you can make such a foundation. A full -colored brick is placed on the bottom layer, and it can be placed above, silicate is not used.

Sometimes such a wall is used with a decorative purpose, for example, as a wine cellar in the Provence style, a small pool or homemade cheese man. In such cases, the internal wall of the foundation is decorated with a finishing stone and treated with anti -inflacal agents. Good waterproofing is needed here, and for a brick foundation it is necessary to hire specialists.

Tip: Fanding soil does not hold shape well, and there the foundation is appropriate to make a trapezoidal shape, which is made only of brick or concrete. It is impossible not to take into account the depth of freezing of the soil in each climatic zone, and the bottom of the pit is usually made below the level of freezing, and the foundation is preferably monolithic. This basis of the construction will remain from possible cracks. A pillow from a mixture of gravel and sand supports the balance of the foundation on any soil. Drainage will provide crushed stone, and sand prevents uneven shrinkage.