Step 7 · Insulate Between Floor Joists

Access the space between the floor joists (from above) or ceiling joists (from below). Cut and fit pieces of acoustic insulation batts or blown-in insulation snugly into the cavities. Ensure there are no gaps or compression of the insulation, as this can reduce its effectiveness. If accessing from below, ensure the insulation is held in place by a backing material, such as a vapor barrier or a wire mesh, to prevent it from falling out. For stairwells, this may involve working within the wall cavities adjacent to the stairs.