Moisture can accumulate in concrete and then absorb into the wood and if this.
Pouring concrete against siding.
It is not a good idea.
You can but you should put expansion board there.
One of the most common builder errors that home inspectors have to deal with is the installation of concrete surfaces over the top of wood siding or any kind of siding for that matter.
In addition when the concrete expand you want to.
It is not a good idea.
You will sometime have to remove the vinyl siding and tearing up the concrete will be expensive.
It s never going to be a good idea to pour a concrete porch or set of stairs next to wood siding or structural framing.
Concrete should never be poured up against steel siding and or trim.