ᐅ Concrete slab poured too large – it has now been cut down – is this acceptable?
Created on: 1 Oct 2020 09:22
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Sporttasche
Hello dear experts,
We are just at the beginning of our build, and already the first issue has occurred. The concrete slab was poured too large! It’s actually surprising how something like this can happen, but it did (by the way, the slab was done by a very well-known company).
The slab is 16 cm (6.3 inches) too long on one side, and this also affects a recess for the bay window.
This was noticed during the slab inspection. We were told that it can happen (which was visibly embarrassing for the site manager) and that they would fix it. Yesterday, the slab was "cut back" by the mentioned 16 cm (6.3 inches). They used a type of cutting disc similar to those used in road construction to grind the slab. Since the slab is much thicker than the cutting depth of the disc, the rest was painstakingly removed with a pneumatic hammer. The area was then re-plastered.
Well, apparently everything is fine now, which I really hope is true. I am not an expert, so I would like to hear the opinions of professionals here.
In my view, it can’t be as good as if it had been poured correctly. Here, a component was opened up and patched. The frost protection edge (frost skirt) that was originally 50 cm (20 inches) is now only 34 cm (13 inches) high (they say a maximum of 20 cm (8 inches) is needed and that it’s always 50 cm (20 inches) because the excavator’s bucket makes 50 cm (20 inches) wide trenches).
I’m already upset that the build started like this and I really hope we won’t have problems because of it down the line.
Which expert can give me some advice on this topic? Thank you!
P.S. By the way, it’s a KFW40+ house with a matching slab.
We are just at the beginning of our build, and already the first issue has occurred. The concrete slab was poured too large! It’s actually surprising how something like this can happen, but it did (by the way, the slab was done by a very well-known company).
The slab is 16 cm (6.3 inches) too long on one side, and this also affects a recess for the bay window.
This was noticed during the slab inspection. We were told that it can happen (which was visibly embarrassing for the site manager) and that they would fix it. Yesterday, the slab was "cut back" by the mentioned 16 cm (6.3 inches). They used a type of cutting disc similar to those used in road construction to grind the slab. Since the slab is much thicker than the cutting depth of the disc, the rest was painstakingly removed with a pneumatic hammer. The area was then re-plastered.
Well, apparently everything is fine now, which I really hope is true. I am not an expert, so I would like to hear the opinions of professionals here.
In my view, it can’t be as good as if it had been poured correctly. Here, a component was opened up and patched. The frost protection edge (frost skirt) that was originally 50 cm (20 inches) is now only 34 cm (13 inches) high (they say a maximum of 20 cm (8 inches) is needed and that it’s always 50 cm (20 inches) because the excavator’s bucket makes 50 cm (20 inches) wide trenches).
I’m already upset that the build started like this and I really hope we won’t have problems because of it down the line.
Which expert can give me some advice on this topic? Thank you!
P.S. By the way, it’s a KFW40+ house with a matching slab.
The structural engineer should definitely be involved at this point. I hope for the person responsible who cut off that part that it was done without consulting the structural engineer. Or that they know what they are doing and it has no impact on the structural integrity. But probably no one here can say that for sure (!). Therefore, contact the responsible structural engineer/architect. Or an external building inspector or similar.
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borderpuschl5 Oct 2020 08:23Also check all processes, including the foundation grounding system, to see if the measurements still match. Often, measurements are taken from the nearest edge, and if that edge was off by 16cm (6 inches), this deviation can affect other connections as well.
borderpuschl schrieb:
Also check all the drains, foundation earth conductor (grounding conductor), etc., to see if the dimensions still match.Foundation earth conductor (grounding conductor): good point – when something is casually cut off from a slab on grade without much consideration, it’s understandable to be suspicious whether it was ever complete or if the contractor just saw it as a simple base layer.https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
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Sporttasche5 Oct 2020 14:22The foundation earth electrodes should be in the correct position despite the 16 cm (6 inches) longer base slab... that’s what we were told...
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knalltüte5 Oct 2020 15:12I wouldn’t rely on verbal commitments in your situation. Someone has to approve this and take responsibility in case any damage occurs as a result of the aforementioned defects.
#Today I inspected my foundation slab before concreting. If 16cm (6 inches) were cut off at the edge, half of the edge reinforcement would be lost, which usually wouldn’t make a structural engineer very happy!
#Today I inspected my foundation slab before concreting. If 16cm (6 inches) were cut off at the edge, half of the edge reinforcement would be lost, which usually wouldn’t make a structural engineer very happy!
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Sporttasche7 Oct 2020 10:05We have now contacted the engineer who designed the structural calculations for our slab foundation. He, in turn, reached out to the site supervisor responsible for the slab foundation.
The following correspondence took place:
Hello Mr. ***Slab Foundation Supervisor***,
We have structurally examined the critical areas. Due to the load-distributing effect of the frost skirt, the omission of the reinforcing bars is acceptable from a structural standpoint. The load-bearing capacity of the structure is ensured. There are no structural concerns regarding the construction.
Note: I have directly copied Mr. ***Client*** into the distribution list, as he contacted our office by phone.
Best regards,
*** Slab Foundation Structural Engineer***
Now we hope that everything is indeed in order!
The following correspondence took place:
Hello Mr. ***Slab Foundation Supervisor***,*** Slab Foundation Structural Engineer***
Today, we received the email below from the client.
Please provide feedback on what measures were carried out on site so that we can assess them structurally.
Best regards,
Hello Mr. ***Slab Foundation Structural Engineer***,***Slab Foundation Supervisor***
We have cut back the slab foundation by 16cm (6 inches) in the areas specified in the attachment, then applied two coats of waterproof slurry and coated the edges with bitumen paint to prevent corrosion of the reinforcement.
Due to the soil excavation causing some overbreaks, we poured the frost skirt considerably wide. Attached are some pictures as well.
If you have any questions, feel free to call me.
Best regards,
Hello Mr. ***Slab Foundation Supervisor***,
We have structurally examined the critical areas. Due to the load-distributing effect of the frost skirt, the omission of the reinforcing bars is acceptable from a structural standpoint. The load-bearing capacity of the structure is ensured. There are no structural concerns regarding the construction.
Note: I have directly copied Mr. ***Client*** into the distribution list, as he contacted our office by phone.
Best regards,
*** Slab Foundation Structural Engineer***
Now we hope that everything is indeed in order!
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