We’re about to build a timber workshop in the garden which will be assembled on a concrete slab base. There is an option for a tongue and groove floor but I’m wondering if I could buy the wood cheaper myself?
Which wood would be best to buy, and how would I best go about laying it? Would I need an insulating membrane on the concrete, or would the floor be slightly raised on treated joists?
Apologies for all the wood/would in this post.

If it’s a workshop, why not just use the concrete slab as the floor?

Would like it to be a bit warmer by lifting the floor off the slab.
Also thinking about the rubber tiles you can lay but I’m not sure how you’d go about fixing them to the concrete?

Treated 4 x 4 bearers, then buiold floor, and turn over and treat with numerous coats of preservative, as once the shed is built you will no longer have access, then build walls and finnaly roof

you will need a moisture barrier, 50mm insulation board then you could lay 22mm spruce plywood or chipboard flooring on top no need for nails just glue all the joints ,boards are 2.4 x 600 or you can lay 50 x 38 timber battens @ 400mm centres without any insulation then glue and nail flooring to timber battens.

Run a continuous strip of Damp Proof Course of about 150mm wide beneath each treated joist, don’t forget noggins and then cut and fit some 50mm Cellotex or Kingspan or similar between and about an inch below the top of the joists. You could also look to put in a breathable membrane over that and batten over with some 4″x1″ and then lay the TGV boards.

EDIT – as Murr says 🙂

if you haven’t build the concrete pad yet just build an insulated slab with the foam underneath