Can you put decking on top of patio?

[happyguineapig]

We have a couple of patio areas which I would like to replace with decking. Can we put it on top? I understand you need some kind of joists underneath but can these go on the patio or do we need to dig it all up first?

You can buy decking squares that can go directly onto patio without a frame

Why would you do this?

Decking attracts rats
It needs a lot of upkeep
You get splinters in your feet if barefoot

We have decking that was laid on joists on top of the paving slabs. Perfectly ok to do it that way, and probably easier and cheaper than pulling up the slabs.

We put decking over slabs and broken concrete in our last house. The joist framework had to be packed out so it was level. It also paid to use the best quality timber for the deck. Bought from a timber merchants not DIY store. It was still in excellent condition 10 years later.
Having said all that I’d now relay a patio instead. Eventually it did attract rats that had to be eradicated by pest control. Ugh!