What gauge mesh in slab - 200 x200 x ?

[Rick]

Hi … just completed shuttering & base prep for a concrete raft.
The raft is fairly simple aprox. 8.6 x 6.5m rectangle, 150mm
thick across main portion, thickened to 300mm this for a
width of 600mm all around perimeter.
Had a local guy do the drawings for Building Reds submission - he specified 2 layers of mesh 50mm apart across the slab, with a third lower dog leg section in the thickened perimeter.

Building regs didn't pick this mesh reference error up, and I don't want to ask them, in case they then push for structural calcs or over engineer on the steel.

I went back to the guy, initially he advised using A393,
when I looked this up it's 200 x 200 in 10mm steel ...
I queried if this was correct as the mesh in slab of the house
was A193 which is 200 x 200 in 7mm, he then advised
going to A252 which is 200 x 200 in 8mm.

As the house size was 7mm, would assume the car port/garage would need no more, as it has a far less loading, although in the house there is the standard runs of 10mm rebar cages around the perimeter, and the slab mesh is I guess in the main just for anti-crack.

Anybody know of any guides ? .. I don't want to under
engineer, or waste money on steel I don't want.

The loading is light, as it is a timber `barn' type carport,
with closed off timber garage section on one side.

[luke32]

hello rick, as a company we build in s/east at presant we have just over 800 units on the go with the majority having garages every single one uses a142 with the difference only being a couple of pounds in price on one unit the decision is yours to make..