Decking using concrete slab supports

Hello

I'm putting together a small 3m x 3.5m low level deck replacing an existing concrete patio. i've lifted the most the slabs and left 9 in place to act as support the joists/frame. My concern is there is quite a bit of contact with the joists and slabs and hence over time the frame could start to rot.

i'm looking at options to slightly elevate the frame above the slabs, including 4'x4' USP structural connecting composite post bases, EasyFix rubber feet joist support system & using a standard bolt post down support and a short 4'x4' decking post.

i'm wondering if these might just be fairly expensive & over complicated options. Would say a 2cm high bit of treated 4x4 decking put underneath the joists at regular intervals, with a bit of damp proofing between that and the joist be sufficient?

I've also noted that some on the forum suggest not bothering with joist hangers and just to use screws for the frame and inner joists. Is there are a reason for this ie. cheaper, easier?

would welcome any comments or ideas.

Carters

Just put the frame on the concrete. Using a membrane wont help, as water will still sit, plastic or not.

Slabs won't retain water for a long period of time, they will absorb it and soak it away eventually.

No problem at all putting it on concrete slabs as long as you secrue the frame to them.