Slab reinforcement - mesh vs bars

[Adam2]

So my engineer co has designed the slab reinforcement using bars (lots - generally H16 at 150 centres) and the builder contacted them to see if they could re-do as mesh - the engineers are talking 3K to do this and say they have specified bars as in compliance with eurocode.....

 

Now, every image I can remember seeing of slabs has mesh so I'm a bit curious as to how standard specifying bars is. Engineer says using staggered laps reduces material...

 

Appreciate any thoughts - may be pretty hard to see the detail on the design if I post that up but may see if I can tomorrow if that is of interest/help in advising me - ultimately choice is pay more to have a mesh design that may be cheaper  on materials and quicker/cheaper to install vs stick with current plan. I'm estimating basement (7.5m x 5m) will has about 5 tons of reinforcement. Note that the basement only has a terrace on top but is lowest part of the build going down a hill (info in blog) .