Along my concrete block walls, I have 1/2" furring strips every 16", then sheetrocks are attached to the furring strips. The furring strips make it possible for 1/2" electrical conduits and copper pipes to run across or up and down the walls.
In some cases I have 3/4" pipes or electrical conduits, so I go with 3/4" furring strips.
In some cases in a shower area, I have shower valves that sticks out further and it needs 1.5" of space. Now, I can attach 2x2 or 2x4 turned on it's face to the concrete wall and furr it out this way. Or may be at 1.5" I might as well build a real wall butt up against the concrete wall, with it's own top and bottom plates.
At what depth do you think it crosses the threshold form using furring strips to a real wall?
Thanks in advance,
MC