What is the starter row for architectural shingles?

What the starter row does

• Wind: its sealant bonds the bottom edge of the first course, the spot where wind gets its first grip.
• Water: it fills the space under the gaps in the first course so water does not reach the underlayment there.
• Alignment: it sets a straight line for the rest of the roof.

Why you need a dedicated starter

With old 3-tab roofs, installers cut the tabs off a shingle and used the top strip as starter. Architectural shingles do not work that way: their lower layer has irregular gaps, and their sealant sits in the wrong place if you flip or rotate them. Turned-around architectural shingles leave openings and put no sealant at the edge. Manufacturers make starter strips with factory sealant positioned near the eave, and their wind warranties often require using their own starter product.

How it is installed

1. Drip edge goes on the eave, then underlayment laps over it.
2. Starter is nailed along the eave, sealant toward the edge, overhanging the drip edge by the small amount the manufacturer specifies, typically a fraction of an inch.
3. Starter is run up the rakes as the manufacturer recommends, so the side edges are sealed too.
4. The first course goes on with its joints offset from the starter joints.

Common mistakes

Skipping starter, using upside-down field shingles, too much overhang that catches wind, too little overhang that lets water run behind the gutter, and lined-up joints. If the first course along your eaves blows off in storms while the rest of the roof holds, a missing or wrong starter is a likely cause. See drip edge explained and wind damage to roofs in Georgia.