How should furring strips be installed to accommodate joists that extend below others?

Choosing tapered wedges to fill the gaps between joists and furring strips is the correct method because it allows for a level surface, which is crucial in ensuring that finishes like drywall or paneling can be installed evenly. This technique allows for precise adjustments to compensate for the variations in the heights of joists, maintaining structural integrity and providing a solid backing for attached materials.

Using notches in the lower edge of the low joists can compromise their strength and stability, potentially leading to structural issues. Directly attaching furring strips to the lower joists might not solve the underlying problem of uneven heights, risking a misaligned surface for finish materials. While installing additional joists could theoretically provide alignment, it would be labor-intensive and unnecessary when wedges can effectively level the installation without requiring extensive modification to the existing structure.