TOPIC: Anyone ever seen this on a roof?

I was inspecting a ranch house, set in the woods, facing south, the roof was 9 years old.  On the rear(north) of the house there was this little detail running the length of the roof about 3 feet up from the bottom edge.

It is 1/3 of a tab off a shingle placed under the joint between two other shingles.  It is only on the north side of the home which faces the woods, so it isn't a cosmetic “artsy” detail.  I originally thought it might be something to do with ice or snow, but I don't see what it accomplishes.  The eaves on this house are about 2 feet deep, so this detail does sit right over the line of the exterior wall.

Anyone ever seen this before and know what it is?

Interesting, I have no idea. Some sort of marker?

One critical part of 3-tab roof shingle installation is the “staggering”.  The slots between the tabs are aligned approximately centered on the tab below and the tab above, this creates about a 6” stagger and a good looking pattern, as well as proper sealing.

Looks to me that the installer either: started wrong or two installers started at different parts of the roof or whatever. But this one course has no staggering. i.e. the slots of adjacent courses line up—which is wrong and may lead to leaks. Looks like the roofer tried to “fix” the problem by adding an additional piece of shingle under each joint/slot (thus the bulge/hump under each slot of that one horizontal course along the roof). I think this looks bad, it’s unprofessional, it still may lead to leaks, or loose shingles, and may void the warranty. Maybe this was a DIY installation.

Serge,

I was so focused on the forest, I couldn't see the trees!   I swear I didn't even notice the courses were not lined up on that row.  The simplest solution makes the most sense, but WOW, that's a pretty sad mistake for a roofer.  How would a roofer not notice his courses aren't overlapping correctly, that's "Roofing 101".

Then again...  I didn't see either...   :-[

I wonder if there is any reason the roofer would purposefully choose to run that one row lined up with the row below?

Cameron--He just messed up or (stronger language). Maybe he wasn't a roofer but only THOUGHT he was.   And nobody called him on it! The client should have demanded it be redone or NO PAYMENT!

Yikes, I see what you're talking about Serge. That's no good!