Hello everyone,
We are currently in the early phase of the shell construction of our single-family house with a basement garage. The garage basement has already been built, and the slab for the single-family house will follow in one or two weeks.
Our builder warned us yesterday during a conversation that we will definitely see significant cracks in the concrete ceilings, because in his opinion, too much steel reinforcement (a total of 16 tons for the entire structure; footprint of the single-family house 290m² (3,123 sq ft); footprint of the basement garage 130m² (1,399 sq ft); we have many beams and lintels, etc.) was calculated by the structural engineer, and from his experience, "too much steel causes cracks". He said that, for example, with the ground floor slab, we will be able to "see through" the surface reinforcement in the form of cracks—that is, parallel cracks will appear where the rebar is located.
What do you think about this statement? Is it normal or worrying?
This naturally makes us feel uncertain. On Monday, we have a meeting scheduled with our structural engineer about this. However, he refuses to conduct a site inspection at the appropriate time to approve the reinforcement, as he claims not to have time for it. (Maybe he wants to avoid potential liability?)
Do you have any advice on whom we could bring to the site instead to inspect the reinforcement before the concrete is poured? Would a building surveyor / structural consultant be allowed or suitable to perform this task, that is, to review reinforcement installed by a third party?
Thank you very much for your input!
We are currently in the early phase of the shell construction of our single-family house with a basement garage. The garage basement has already been built, and the slab for the single-family house will follow in one or two weeks.
Our builder warned us yesterday during a conversation that we will definitely see significant cracks in the concrete ceilings, because in his opinion, too much steel reinforcement (a total of 16 tons for the entire structure; footprint of the single-family house 290m² (3,123 sq ft); footprint of the basement garage 130m² (1,399 sq ft); we have many beams and lintels, etc.) was calculated by the structural engineer, and from his experience, "too much steel causes cracks". He said that, for example, with the ground floor slab, we will be able to "see through" the surface reinforcement in the form of cracks—that is, parallel cracks will appear where the rebar is located.
What do you think about this statement? Is it normal or worrying?
This naturally makes us feel uncertain. On Monday, we have a meeting scheduled with our structural engineer about this. However, he refuses to conduct a site inspection at the appropriate time to approve the reinforcement, as he claims not to have time for it. (Maybe he wants to avoid potential liability?)
Do you have any advice on whom we could bring to the site instead to inspect the reinforcement before the concrete is poured? Would a building surveyor / structural consultant be allowed or suitable to perform this task, that is, to review reinforcement installed by a third party?
Thank you very much for your input!
H
hanghaus202316 Mar 2026 11:1211ant schrieb:
The concrete cover on both sides is what serves that purpose. The reinforcement is to be understood as a team and is responsible overall for tension and compression; in this sense, there is no top or bottom. I am aware of that. It’s just that the contractor only referred to the top side. 😉
A
ajokr20255 Apr 2026 20:1311ant schrieb:
which reinforcement the structural engineer recommends, and adjust the overall thickness of the ceilings accordingly. Of course, this also makes the ceilings heavier, which is why involving the structural engineer in dialogue makes sense. You will now either have to adjust the building height and stairs or accept reduced clear ceiling heights due to the thicker slabs. This is rather the wrong approach. The structural engineer specifies the reinforcement and the concrete cover. From this, the designer determines the necessary compatible support cages for the top reinforcement. If they were overlooked, the support cages must be replaced, not the slab cast thicker.
ajokr2025 schrieb:
This is rather the wrong approach. The structural engineer specifies the reinforcement and the concrete cover. From that, the designer determines the necessary matching support chairs for the top reinforcement. If that was overlooked, the support chairs must be replaced, not the slab thickened. So you mean: in the case of thicker bars, the structural engineer would recommend adjusting the vertical spacing between the reinforcements rather than ensuring sufficient concrete cover by increasing the slab thickness?
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ajokr202524 Apr 2026 07:5711ant schrieb:
So you mean: in the case of thicker bars, the structural engineer would rather recommend adjusting the vertical spacing between the reinforcements than guarantee sufficient concrete cover by increasing the slab thickness (?) That should be the case.
It’s just inconvenient with precast slabs that already have spacers cast in. Then the question often comes up to the designer whether they happen to have a large front yard to dispose of the incorrectly produced slab elements.
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