Starter Strip
A specially designed shingle or modified material strip installed at the eave before the first course of shingles.
What It Does
A starter strip (or starter course) is a strip of shingle material installed along the eaves and rakes before the first visible course of shingles goes down. It has an adhesive strip positioned to bond directly beneath the first course's tabs and seal the shingle edges and cutouts — gaps that would otherwise be an open entry point for wind-driven rain.
Why Skipping It Voids Warranties
Every major shingle manufacturer (GAF, Owens Corning, CertainTeed) requires factory starter strip — not cut-down field shingles turned upside down — as a condition of their wind warranty. Without proper starter strip, the first course has nothing to seal against below it, and it's the single most common reason we see wind uplift start at the eaves on roofs that are otherwise only a few years old.