Good afternoon, dear guests and subscribers of the "Build for myself" channel!
This question was asked to me by one of my subscribers and to be honest, I have already heard about this technology abroad several times, but I have not even thought about using it here.
In this article I will try to answer the question posed from the comment:
In Europe, like in our country, there are a lot of building solutions. As for the blind area, there is a very common hidden or soft blind area on which you can make a green lawn - this is very beautiful and practical.
The answer to the question
Indeed, the option of a concrete blind area, as part of the foundation, is not prohibited, it takes place and is done in two ways:
1. A common reinforcing cage is knitted and poured with concrete in one step. Concreting occurs as usual, starting from the base of the foundation and ending with pouring the blind area. As a result, we get one one-piece monolithic structure.
2. The reinforcing cage is knitted with the outlets of the reinforcement and the foundation is first poured, and then a blind area is formed and its frame is connected to the foundation frame. In this case, the blind area adjoins the foundation along the "cold seam" and a small gap appears. If the gap opens too much, it is filled with anchoring mixture through a syringe (Anchorage mixture is a self-expanding cement-based mixture).
Why is it not used with us?
There are several reasons for this:
The main reason is the climate. In Russia, the climate is harsher and the temperature range is higher. Since there is native soil under the blind area and the depth to the ground is not more than a shovel bayonet (30 cm), then this base will definitely raise with frost heaving, and this is a threat to tear off the blind area from foundation.
It is forbidden to lay sand or crushed stone under the blind area, since this soil must be equal to or with a higher density than the soil around the house, otherwise the foundation will be locked under the foundation.
To reduce the effects of frost heaving forces, you can lay the lower tensile reinforcement, as well as perform an expansion joint by means of PSB of low density, for example 15 kg / m3. Then the PSB will simply crumple from the acting forces and parasitic stresses in the structure. will not be.
Further, the figure (PSB + working fittings):
But, there is a second reason - a cold bridge. If the climate in the region is very cold, then there is a high probability of getting mold in the house. This blind area solution is not energy efficient.
If we consider this option for the southern regions, then it is worthy of attention, although it is a little laborious and inconvenient in terms of work.
In addition, such a phenomenon is widespread in Russia when plots along one street are at different heights, a neighbor may have 30 cm. the plot is higher. Therefore, when laying the foundation, you can simply not know where, after construction, the level of paths, lawns, and so on will be. It is absolutely clear that laying a blind area at this stage is at least stupid!
I will add that from above, in order to protect against the effects of atmospheric precipitation, such a blind area should be treated with water-repellent impregnations or covered with paving slabs.
I think I answered the question and really hope that the article was useful to you!
Thanks for attention!
Read also:
Sewer passage through the foundation. What is important to know and do before installation?
Quicksilver when reinforcing corners = transverse chipping of the foundation. How to properly reinforce the corners and crosshairs of the tape?
"There was not enough concrete for the foundation!" The builder explained what to do if there is no way to buy concrete