How wide are starter row shingles compared to full shingles?

Starter row shingles are specifically designed to be half the width of full shingles. This design is intentional to ensure a proper overlap and seal when being applied alongside full shingles. The reduced width of starter shingles helps prevent wind uplift and enhances water shedding by creating a more effective barrier at the edge of the roof. In particular, they act as a critical first layer that assists in protecting the roof from water infiltration.

The choice indicating that they are the same width does not align with standard practices in roofing, as variations in width serve important functional purposes. The alternatives suggesting they are a quarter or double the width of full shingles also do not fit the established roofing guidelines or industry standards. Therefore, understanding that starter row shingles being half the width of full shingles is essential for correct application and effective roof performance.