ᐅ Thickness of concrete slab for a two-story building

Created on: 18 Sep 2021 20:45
B
BauherrKA79
B
BauherrKA79
18 Sep 2021 20:45
How thick should a proper concrete slab be for a two-story building? The building is not yet planned, but the concrete slab is going to be poured on about 50% of the planned area and therefore needs to be adequately sized. Would 30cm (12 inches) be sufficient?
tomtom7918 Sep 2021 20:53
This is basically the job of a structural engineer. Roughly speaking, if there is enough steel reinforcement, 20cm (8 inches) is sufficient.
B
BauherrKA79
18 Sep 2021 21:02
tomtom79 schrieb:

This is basically the job of a structural engineer. Roughly speaking, if there is enough steel reinforcement, 20cm (8 inches) is sufficient.

A structural engineer won’t give any definitive advice before I specify exactly what loads will be applied, so the rule of thumb is to use a bit more steel and a slightly thicker slab rather than having to redo it later.
tomtom7918 Sep 2021 21:26
You do realize that structural calculations are required for a building permit / planning permission application, right? Once the process moves forward, it is unlikely that anyone will do calculations for you or take any responsibility.
B
BauherrKA79
18 Sep 2021 21:32
tomtom79 schrieb:

You do realize that a structural calculation is necessary for a building permit / planning permission? Once it moves forward, nobody will likely run calculations for you or take any liability.

At first, nothing will be built except the foundation slab for the next 2 years... the documents will then be submitted to the structural engineer later when the building is planned to check if it’s suitable. Alternatively, we could just put something thin down as a parking area for cars or office containers and remove it later. I think it’s simply easier to dimension it properly from the start and have it approved later.

Or can structural engineers create a structural plan based on rough specifications that will hold up later?
K1300S18 Sep 2021 22:22
BauherrKA79 schrieb:

For now, nothing will be built except the foundation slab for the next 2 years.

Without a building permit / planning permission, you are not allowed to build even just the foundation slab. Aside from the contradiction in your statement, you might as well have the structural engineer answer this question.

They will also tell you whether you need a slab foundation, pile foundation, strip footings, or something else.