Don’t Miss the Shingle Stagger! The Science Behind Your Inspection By Tom Feiza, Mr. Fix-It, Inc. HowTo OperateYourHome.com
Do asphalt roof shingles really stagger? In my part of the country, they do. Stagger is a term some roofing contractors use for the shingle offset—that is, the spacing between butt joints of adjacent shingles. Some contractors call it “shingle offset” or “edge-to-edge spacing.” I like to call it stagger like the local boys do. No matter what you call it, maintaining shingle stagger is really important to prevent roof leaks and to conform with manufacturers’ instructions. See Figure 1: Shingle Spacing Typical and Figure 2: Shingle Spacing, Starter, Deck as these are graphic representations of this technique. If the shingle stagger is too small—less than 4 inches—water can travel into the shingle butt edge to the butt edge joint of the shingle below (less than 4 inches away) and leak in. You know what leaks cause: rot, mold and lawsuits. Do you check the shingle stagger when you inspect roofs? How do you check it on modern laminated shingles? Checking the old three-tab shingles was easy, but things have changed. Shingles Have Changed I do miss the good old three-tab shingles! Until a few years ago we were always inspecting three-tab asphalt shingle roofs. Now it seems most of the asphalt shingle roofs consist of laminated or architectural shingles or some type of hybrid made to look like shakes or tile or wood shingles. In my market, about 85 percent of the asphalt shingle sales are some type of laminated shingles.
Figure 1: Shingle Spacing - Typical
Why do I miss the three-tabs? Because they were easy to inspect. The tabs were about 12 inches wide and separated by a slot. When installing a roof, the contractor just cut about 6 inches off the edge of the starter of each row of shingles, creating a simple stagger. When there are three-tab shingles on a roof, you can easily see the alignment of the tabs/slots and the edges of the shingles. This makes it easy to check the stagger. (Photo 1: Three–Tab Shingles, Page 28). In fact, unless there was a really unusual pattern of tabs or slots, I never checked the stagger with three-tab shingles, because it was always right. Maybe the contractors or DIYs got it right because the three-tab shingles were easy to install, or maybe because mistakes with stagger were easy to see. The slots just didn’t look right if the spacing was off…and the DIY’s wife could see it from the ground. The new laminated shingles (Figure 3: Laminated Shingle Nailing, Page 25 and Photo 2: Laminated Shingles, Page 28) have no tabs and no slots. When the shingles are properly installed, it is 26 Working RE Inspector Winter/Spring 2021
Figure 2: Shingle Spacing, Starter, Deck
