Not sure how you would fall through a 300 thick slab. The only type of horizontal safety mesh I am familiar with is roof safety mesh which is used over the purlins and under metal roofing.

CRQUT

My understanding is that it is a Workplace Health and Safety requirement.

It has nothing to do with design codes.

It is a WHS requirement. On my drawings I state that Safety mesh is the builders responsibility and exclude it from any reinforcement quantities that I provide.

So where is this mesh placed? Over the scaffolding, under the formwork?

+1 to Hokie's question. I can't picture which mesh you're talking about, and why the slab depth rather than fall distance triggers it. Photo?

Safety mesh is mesh reinforcement that is in the same plane as the top reinforcement in the slab. It is used in deeper slabs (particularly PT slabs) where there is not a full mat of top reinforcement. It gives the concrete workers something to walk on while they are pouring/vibrating the concrete. It prevents the workers from sinking into the fresh concrete, which is why it is not required in thinner slabs.

Thanks, Retrograde. I have never seen that done. Back to CRQUT's question, do you know of any reference or requirement for it, or is it just a contractor's discretion thing?

I have not seen any references to safety mesh in any WHS codes of practice. I think it is more a union driven requirement.

The only thing I can think of in terms of code requirements is needing temperature and shrinkage steel on each face of thicker members and it indirectly providing the same function. But often its such small diameter bars that it needs a lot of support for being trafficked.

I mostly see it on banded slabs. Say a 200thk slab with a 450d band beam with reinforcement detailed at 300mm centres. After reinforcement is fixed, the steel fixers will place SL82 over the band. It prevents concreter's from stepping through the reinforcement when placing concrete.

I've done a lot of banded slabs, and witnessed a lot of them being cast. Never seen it. Who makes this call? The addition of the mesh could decrease the required cover or displace the main bars enough to decrease the slab strength.

Yeah, you should increase the cover by 15mm (For SL72). Generally the head contractor will make the call particularly if the concreters are with the union. I have seen concreters say they will not place the concrete until the safety mesh goes on.

Also it should be put in the Safety In Design register and Safety in Design workshop.

In that case, I would insist on increasing the slab thickness by 15mm. Some of these unions have entirely too much control.