Why do shingles have tabs?

[Stephen Tashiro]

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.

[Andrew Hughes]

Not all shingles have tabs. Three tab shingles are probably the most common and very affordable.Theres also several ways roofers lay them I like to off set them. Some like to lay them in a brick style patten.
I don't know why your as splitting. Maybe they are old

[Jim Becker]

The tabs are merely reminiscent of materials like cedar shakes and slate visually, IMHO. Though not required, it's pretty much the most common thing in asphalt roofing shingles for a long time now. Splitting is generally caused by stress and age...

[Bill Jobe]

I'm glad someone else asked the question.

[David Helm]

Many of the shingle manufacturers have discontinued the three tab style. The largest percentage of shingles being sold now are the laminated architectural style; no tabs to tear.

[roger wiegand]

I think they were there to simulate the look of single asphalt shingles, back when someone had the bright idea of stringing three together to make for faster installation and easier spacing. Kind of like sheets of vinyl siding made to look like thee clapboards or those rows of cedar shingles that come pre-attached to a board and go up in 4 ft sections. I never put on a roof with "single tab" shingles, but I did tear them off long ago.

[Stew Hagerty]

Pure esthetics

[Bruce Wrenn]

Sounds like the starter course wasn't offset from the course that covers it, so ends line up. Being on a shed, most likely "Harry Homeowner" did the work.

[Stephen Tashiro]

Sounds like the starter course wasn't offset from the course that covers it, so ends line up. Being on a shed, most likely "Harry Homeowner" did the work.

On this particular shed, Harry didn't install a "starter strip" along the edges of the roof. I'm wondering what the simplest fix is for the problem. It's a small roof. I could put a wide strip of aluminum flashing under the shingles at the edges of the roof - seeing as I have aluminum flashing already at hand rather than shingles.