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The typical lap for shingles when installed on a roof is generally in the range of 5 to 6 inches. This distance is essential for ensuring that each row of shingles properly overlaps the row below it, providing effective protection against water infiltration.

When shingles are overlapped correctly, the underlayment and shingle design work together to channel water off the roof, preventing it from seeping underneath the shingles, which could lead to leaks and structural damage. In climates with significant rainfall or snowfall, adhering to this lap measurement helps maintain the roof's integrity over time.

Using a lap of 5 to 6 inches aligns with industry standards, making installations more consistent and reliable, which is critical for building inspectors to understand in assessing the quality and durability of roofing work.