Bar Chairs at what height for a 100mm slab

[Specialized29er]

Hi Folks, I'm in the process of boxing up a slab area for a 10 x 4m carport and I have Googled the question and it recommends 65mm for the height of the reinforcing mesh.
The slab is to be 100mm thick and I'm getting 25mpa concrete and having the mesh at 65mm is that okay to prevent cracking.
The carport is to house a Ford RTV trayback.

[wood spirit]

Sorry can't help with that. When I read the brief title thought you were making a bar out of a 100mm slab and wondering about seating heights.

[riverbuilder]

40 mm is normal for 100 mm

[Picko]

It must depend on variables like soil type because around here engineers always specify "top" for a single layer of mesh.

[Specialized29er]

How far down from the top?

[Beardy]

40mm cover from the surface for an exposed slab

[Warrangarree]

The reinforcement in a slab on ground is not really structural and is usually placed in the centre of the slab for water protection.
It does play a role in that it ties the slab together but a structural slab would have 2 layers as it resists forces in the 'sag' and 'heave' directions.
Cover on reinforcement in contact with the ground having no plastic membrane would ideally be 65mm or so, membrane reduces this considerably.

[riverbuilder]

Water protection?

[Warrangarree]

Water protection?

Steel in slabs will rust if not covered by an appropriate amount of concrete. Concrete Cancer

[rwbuild]

Water protection?

I know what your thinking and I agree