Place Shingle Nails So the Seams Above Never Drain Onto Them

The Problem

Every nail in a shingle roof is a hole held closed by the shingle above it — unless water finds a reason to dwell there. The butt joints between shingles are exactly that reason: rain concentrates in the seam and runs down it in a channel. Put a nail in that channel's path and you've built a slow leak into a brand-new roof.

The Technique

Think about where each seam above will send its water before you drive the nails below.

1. Nail at the standard positions across the shingle, with a nail about an inch in from each end.
2. Before nailing the course, look up at the seams in the course above: every butt joint is a water channel pointed downhill.
3. Place your nails so none of them sits in line below a seam. Where the joint above "drops" its runoff, there should be solid shingle — the water running out of the seam crosses mat, not a nail head.

Do that consistently and the runoff concentrating at every joint travels over unbroken shingle the whole way down — the nails stay dry in the dead zones between seams.