Hello everyone,
I have already gathered some information on this topic through this forum. Our foundation slab was poured last week. The formwork has now been removed, and I noticed the following:
1. At one spot (on the side), the reinforcement is visible (see picture). I am concerned that the concrete cover at the edge of the slab may generally be insufficient to protect the reinforcement from corrosion. Are there spacers used at the edge of a foundation slab to ensure the concrete cover? Before the concrete was poured, I didn’t see any spacers here (only the support strips on the construction foil). Should a concrete cover of 3–4 cm (1.2–1.6 inches) also be guaranteed at the edge? Could this be fixed by slightly increasing the size of the slab?
2. The foundation slab measures about 10 x 10 meters (33 x 33 feet). The structural calculations assume a slab thickness of 30 cm (12 inches). However, at one corner (approximately 3 meters (10 feet) long), the slab is only 23 cm (9 inches) thick. Before I take this issue to the structural engineer, I wanted to hear your opinions on whether this could possibly be remedied by adding concrete to fill the 7 cm (2.8 inches) difference?
Thank you in advance for your feedback.
Best regards
I have already gathered some information on this topic through this forum. Our foundation slab was poured last week. The formwork has now been removed, and I noticed the following:
1. At one spot (on the side), the reinforcement is visible (see picture). I am concerned that the concrete cover at the edge of the slab may generally be insufficient to protect the reinforcement from corrosion. Are there spacers used at the edge of a foundation slab to ensure the concrete cover? Before the concrete was poured, I didn’t see any spacers here (only the support strips on the construction foil). Should a concrete cover of 3–4 cm (1.2–1.6 inches) also be guaranteed at the edge? Could this be fixed by slightly increasing the size of the slab?
2. The foundation slab measures about 10 x 10 meters (33 x 33 feet). The structural calculations assume a slab thickness of 30 cm (12 inches). However, at one corner (approximately 3 meters (10 feet) long), the slab is only 23 cm (9 inches) thick. Before I take this issue to the structural engineer, I wanted to hear your opinions on whether this could possibly be remedied by adding concrete to fill the 7 cm (2.8 inches) difference?
Thank you in advance for your feedback.
Best regards
Knöpfchen schrieb:
Photos showing how it was executed might allow for some conclusions.
Elli must have taken clear pictures as proof of how the grounding was done. It is mandatory according to DIN 18014.
Read through it, it’s worth it. Theory and practice...
ecCurity schrieb:
Could this be fixed by slightly enlarging the foundation slab?
Are there spacers available for the edge of the foundation slab to ensure the correct concrete cover? Of course, there are options. However, I’m not an expert, and it’s difficult to assess based on a photo. Considering that your foundation slab is not even 30cm (12 inches) thick, but in some places up to 25% thinner, it would be advisable to have a discussion with your construction company.
Having an expert inspect it wouldn’t hurt either. It will cost you around 2,000–3,000 EUR during your building process, but it’s a well-invested amount.
In cases of such deviations from the specifications, I would refuse to accept the work. I’m not more papal than the pope, but this is too much. The reinforcement must be properly protected without exception; it cannot be done by splicing pieces together. Otherwise, the gaps will be too large.
Thank you for the feedback so far.
We have reviewed everything again with the structural engineer and recalculated. Fortunately, the thickness of the foundation slab is sufficient.
I only have one question regarding the lateral reinforcement of the foundation slab. As can be seen in the picture, the reinforcement is visible at the edge of the slab (only at one spot). Are there usually no spacers for the reinforcement at the edge area of the foundation slab?
Our architect's suggestion for that one spot:
1. Zinc flake coating,
2. PCC concrete replacement, and
3. Bitumen coating or bituminous membrane.
What are your thoughts on this?
I would appreciate any feedback regarding the spacers and the architect’s proposal.
Thanks and best regards
We have reviewed everything again with the structural engineer and recalculated. Fortunately, the thickness of the foundation slab is sufficient.
I only have one question regarding the lateral reinforcement of the foundation slab. As can be seen in the picture, the reinforcement is visible at the edge of the slab (only at one spot). Are there usually no spacers for the reinforcement at the edge area of the foundation slab?
Our architect's suggestion for that one spot:
1. Zinc flake coating,
2. PCC concrete replacement, and
3. Bitumen coating or bituminous membrane.
What are your thoughts on this?
I would appreciate any feedback regarding the spacers and the architect’s proposal.
Thanks and best regards
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