Do i need membrane on old conservatory concrete ?

[BuildingBlocksNoob]

Hi all,

Moved into a new house a few months ago and we're going to replace the conservatory. Currently there's a 3m x 3m footing of concrete and then on top of that is the UPCV floor to ceiling height windows and doors and then in the room itself is simply underlay and then laminate flooring. I'm looking to put a SIP panel wall on one side and then re-use the windows and door down the other and i was planning on running a roll of damp proof membrane along the outer edge of the concrete base all the way around so i can sit the windows/doors and then OSB SIP panels on it but i've watched a load of videos on this and half of them just do this and then lay the underfloor underlay and then laminate back on and some cover the ENTIRE base of the concrete with membrane so in effect when they lay the floor they lay the underlay on top of the membrane....is this needed or advised or not as i'm aware you put membrane UNDER concrete bases to stop the damp rising but not on TOP ?

Hope this makes sense and any advice would be great.

Thanks