Hi Community,
My front of house has 2 x stairs/landings which currently are tiles on a concrete slab, pic below.

I'd like to replace the tiles with timber decking. I'd also like to widen the stairs and platform - e.g. the stairs on the right would be widened on both side to where the plants currently are, and ame for other stairs/landing on left. The widened sections would be supported by posts concreted into the ground, but I am hoping not to have to remove the concrete slab. I have seen from other threads that it is possible to lay timber decking on top of concrete but there needs to be space underneath for the battens plus a non-wood packing spacer. The current tiles are 20mm thick versus standard timeber decking 19mm thick (I think?). So after I put battens and a spacer underneath it will be higher than the current levels. I think it will be OK if the final height is a bit higher than current, but not too much. So my questions are:
What would be the min batton height I could use?
Would the longevity be better with synthetic vs timber given the limited space underneath?
If I need to, is there a way to reduce the height of the concrete slab just enough without full removal i.e. like planing down wood?
Anything else I need to be aware of?
I am undecided if I'll do this myself or get a tradesman. I did get one quote already who insisted he needed to demolish all the concrete slab at high cost.
Thanks,
Tim.