Why do asphalt shingles have several tabs? Is it just for the sake of ornament?
At a house I'm helping with, there is a storage shed with a shingled roof. Along the edge of the roof there are places where the material under the shingles has split open exactly at the gap between the tabs of the shingles. The material under the shingle looks like a heavy tar paper or flat strip of asphalt material. The splits allow water to leak into the eaves. So it naturally makes me wonder "Why did they have to put those gaps in shingles?". I also wonder why the material under the shingles decided to split exactly at the gaps between the tabs.