Treated plywood to the concrete with concrete screws spaced every 16 in.
Timber floor over concrete slab.
Some manufacturers allow direct glue installation of 3 4 solid parquet flooring.
Measure the overall length of the new floor and cut a length of 2 by 4 pressure treated lumber to this dimension for both sides of the room.
It is imperative that you make use of underlayment which can increase the height of the floor by around 40mm.
Lay 6 mil polyethylene sheeting over the concrete to minimize moisture migration from the concrete up into the wood flooring.
When a concrete slab absorbs moisture it can retain it for a surprisingly long time.
A vapor retarder is always required over the concrete slab and below the subflooring material.
Installing the wrong kind of flooring over consistently damp concrete may encourage warping and wear over time.
Alternatively screw rows of treated 1x4s to the concrete 16 in.
A minimum 6 mil construction grade polyethylene film with perm of 13 or other impermeable material with a perm of 15 or less is recommended.
Fortunately a variety of flooring materials are water resistant enough to function well over a concrete slab.
If you are going to compare installing solid timber flooring on concrete slab relative to a wood subfloor the former is more complicated.