So this account overtook me 🤦‍♂️. The foundation slab in my house cracked. Reasons and conclusions.

Probably every self-builder, before starting construction, thinks that he will do everything perfectly... So I dreamed about it, but the further the case moves, the more severe the reality becomes.

For me personally, the foundation has always been the main part in all construction. And I was ready for jambs in any other part of the house, as long as everything was in order with the base.

But, not without unpleasant surprises.

Let me remind you briefly: my foundation is a 100 mm slab with 400 x 400 mm stiffeners. and for a one-story house made of aerated concrete, this is quite enough. But there are some nuances.

The main one is the basement.

It is rarely made under slab foundations, but I have it. And its main disadvantage is that in this place the stove hangs in the air. And given that its thickness is minimal (100, maybe 120 mm with one row of reinforcement), then there may be problems with strength.

Of course, I thought about it before starting construction, but then it seemed to me enough.

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The area of ​​the "hanging" section is 3 by 3 meters, and it will be a passage, without any additional loads.

But one day, I saw this.

Just above the basement, a crack, albeit very thin, was formed.

Moreover, two years have passed since the foundation was poured, and a year since the walls were erected, and only now I noticed her. Although it may have appeared a long time ago, I don't know.

And its size, in length, is not small.

She goes from one side, along the perimeter of the basement. It starts from the corner of the entrance to the basement, goes along the wall, passes through the ventilation holes and mortgages, and then after passing a little more disappears.

It turns out that the beginning comes from the manhole. Or rather from the corner.

Moreover, in the opposite corner there is also a crack, but it does not go far, but ends almost immediately.

• It turns out that the entrance to the basement has become a weak point in the slab. And since the crack is visible, it turns out that it was not formed from the deflection of the slab (otherwise it would only be visible from below).
• Another option is if the slab sagged along the edges and cracked just in the middle, with the crack opening at the top. But then the crack would go along the entire slab, from edge to edge of the house, and would not be limited only by the perimeter of the basement.
• The third option is shrinkage, which is more similar. The concrete shrank and cracked at its weakest point, through the holes in the slab.

In this case, the crack will open both above and below. But from below I still have boards that served as formwork when pouring the foundation, and it is a big problem to remove them.

But there is one option - this is to look at the opening exactly in the corner of the entrance to the basement. But dismantling is also required there.

At least the reason will be clear, and the options for the development of this problem in the future.

✅ I am waiting for your opinion, and most importantly, possible solutions to the problem.

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