The quality of asphalt shingles is primarily determined by their ___________.

The quality of asphalt shingles is primarily determined by their weight per square. Heavier asphalt shingles typically contain a more substantial amount of asphalt, fiberglass, and other materials, which contributes to their overall durability and longevity. Higher weight often correlates with better weather resistance and longer lifespans, making them more effective at withstanding the elements, such as wind, rain, and hail.

While thickness rating can also indicate quality, it is the weight that more directly reflects the materials used and their resilience. The durability index measures other performance factors but is not a direct indicator of quality in the same way that weight is. Color per square does not impact the structural integrity of the shingles and is more of an aesthetic choice.