If you're remodeling your basement, you'll probably want to raise the level of the floor. This will help keep moisture from the new flooring material and it will also be warmer, because insulation is added to the cavity between the concrete and the level of the new floor. Once you lay down the new subfloor, you're ready to lay carpeting or even hardwood flooring in your newly remodeled basement.
Thoroughly clean the basement floor by sweeping and vacuuming with a shop vac.
Lay the 6 mil thick plastic on the basement floor. The plastic should also go up the walls by about 4 to 6 inches. Use construction adhesive to adhere the plastic to the foundation walls. If it is necessary to piece together enough plastic to fit the room, secure the seams with construction adhesive.
Install pressure-treated 2-by-4 lumber on their wide, flat side around the perimeter of the room. Secure them to the concrete floor using a powder actuated nail gun.
Lay out the pressure-treated 2-by-4 lumber with the larger side face down on the concrete. Space the 2 by 4's 16 inches apart on center. This means that it should measure exactly 16 inches from the center of one 2 by 4 to the center of the next 2 by 4. Use shims under any boards where the concrete floor is lower than the surrounding area. Periodically use a carpenter's level to ensure that the grid of 2-by-4 lumber is level.
Install rigid foam insulation between the 2 by 4's.
Install oriented strand board as your new, higher basement floor. Attach the OSB to the 2 by 4's using the nail gun.