Over time, hardwood floors begin to creak. To eliminate this unpleasant defect by applying supporting rods. I have done that. In a few places drilled the boards with joists through the drill bit, Ø 4.5 mm. by Measuring the distance from the floor surface to the concrete base, cut out nails or steel rod Ø 5 mm support rods of appropriate length and hammered them into the holes firmly into the concrete. The M6 bolts were sawed off heads, cut slots under the screwdriver and screwed a threaded tube received in the holes in the boards flush — fixed floor on the rods at the desired height. Then putty the holes and paint.
M. SUVOROV, Ryazan