You may have unfinished masonry walls in your basement. To insulate them, you’ve first got to create wall studs to hold the insulation material. Using masonry nails, fasten 2×2 furring strips in place vertically, placing them 16 or 24 inches apart (measure from the center of each strip to the center of the next strip). Then insulate as with any other unfinished wall.
Be sure you get insulation in the spaces around unfinished walls, doors, and windows. Because the framing area is narrow, loose insulation must be hand-packed into it.
