Metal shed flooring

[craigap]

I have an 8x10' metal shed in the garden on a concrete base, with the shed bolted down to a wooden floor. Been in for about 3years now.
The constant issue I have the edges inside the shed getting very wet and the moisture sub sequentially travelling along the wooden floor further in to the shed and causing issues to stored items. So I'm looking to add another floor to hopefully prevent this happening as I assume the issue is where the shed base sits on the wooden floor. What recommendations does anyone have on either material or how to tackle this?
The shed itself is in good condition and seems fairly weather proof so no real leaking issues/condensation (vents front front and back) other than the floor.

TIA

 

[craigap]

Been chatting this over with a friend and we think the solution may be to use shallow strut on the floor to raise it above the finished level of the current floor, then lay a new timber floor down. I will lose about 30-40mm height but liveable. Anyone done anything similar, what timber floor do you recommend, marine ply?

 

[scbk]

Have you any photos? Is the moisture condensation running down the walls onto the floor, damp coming up, or rainwater coming in under the walls?

 

[craigap]

Have you any photos? Is the moisture condensation running down the walls onto the floor, damp coming up, or rainwater coming in under the walls?

Seems to be rain water seeping under the base of the shed as the metal frame is sat on the wooden floor, which sits out pas the frame by about 25mm all around.

 

[scbk]

Can you try and stop the rainwater getting in? Line of sealant along the outside? Or some sort of flashing like flashband? A Gutter?