Good afternoon, dear guests and subscribers of the "Build for Myself" channel!
Many do not believe that by ordering engineering and geological surveys, you can save a considerable amount when building a house.
The cost of an examination is not cheap and ranges from 25 to 40,000 rubles, and sometimes higher - it all depends on the region. But is it worth it?
3 years ago I started building a house, and as usual, construction was economical. Before organizing construction work - walked through the neighbors, looked at their basements, appreciated the mirror in wells, asked about the foundations and made a decision for myself about the device of a monolithic tape foundation. After that, the project of the house and the designer were ordered, confirming my intentions about the strip foundation - he calculated it for me, collecting the loads from the future house acting on the ground.
And the project of the second house, which is currently being built by a neighbor, was made according to all the rules. Preliminary engineering-geological studies were made and a geological section was drawn up with an analysis of each layer.
Comparison
So, my project of a strip foundation for a house from a ceramic large-format block, which was developed without geotechnical surveys, is presented in the illustration below:
Please note that due to the lack of information about the soil, the project was carried out according to the lowest bearing capacity of the soil: 75 kPa or 0.75 kg / sq. Cm. This value is close to when objects are erected on bulk, insufficiently compacted soil or in former landfills.
Why is the bearing capacity of the soil important?
This is exactly the indicator that all developers are guided by. If you exceed the pressure on the ground (support more mass than the ground is capable of carrying), the house will simply give shrinkage, which will affect both the foundation and the entire structure in the form of cracks with subsequent destruction building!
Now, back to my project. So, all the collected loads from the elements of the house fall on the ground and therefore, in order to ensure the design pressure is not more than 75 KPa, the width the soles of the foundation of the outer walls of my house should be, according to the calculations of the designer, from 0.6 to 0.8 m, according to the central one, the heaviest wall 1 m.
Thus, the construction of the foundation is as follows:
With such a foundation design, work is carried out in two stages:
- the formation of the base of the foundation to ensure the necessary support of the structure on the ground;
- erection of the strip foundation wall.
Further, since the soil is deliberately assumed to be weak, engineers lay the appropriate reinforcement and, of course, with a margin. Thus, according to the project, I have reinforcement with a diameter of 14 mm everywhere. with a step of 300 mm. In places of compression - 10 and 12 fittings, as well as anti-shrink mesh - from a rod of 12 diameter.
Neighbor's house
Alexey (a neighbor) has a house of about the same size 8 * 10, but only heavier - made of brick, and the foundation according to the project is made strictly according to the thickness of the wall - no more, no less. There is no sole that increases the area of contact with the ground - no.
By ordering geological studies, he received a soil bearing capacity of 2.26 kg / cm 2, which is three times more than my value accepted by a design engineer, equal to 0.75.
Alexey's project was made with the expectation of 200 kPa, and even so, the weight of the brick house in terms of the load on the base - fit into the width of the sole of only 50 see, in this way the neighbor poured the foundation simply into the trench, having previously made a foundation, a reinforcing cage and stretching along the walls of the trench film.
As a result, my expenses exceeded those of my neighbor on the following points:
- the volume of the trench and excavated soil is twice as large, since the base of the foundation was organized;
- filling in two stages - first the sole, then the wall;
- cost of formwork for the entire depth of the foundation;
- backfilling;
- double overrun of reinforcement by weight.
I enclose a comparison chart:
Outcome
Despite the fact that at the very beginning of construction, a geological examination was carried out for 32,500 rubles, in the end, Aleksey's savings amounted to about 84,000. And besides, you can sleep peacefully without worrying that the foundation will shrink. This example gives an understanding that, indeed, soil analysis gives savings, and what is important is the peace of mind of the residents.
The article does not contain any advertising regarding the organizations conducting the examination, but only the facts of my construction are stated!
That's all, I really hope that the article was useful to you!
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