Inspecting Asphalt Shingle Roof

If when inspecting an asphalt shingled roof, you notice that the tar lines on each shingle is visible, instead of being glued beneath the shingle above, would this constitute an improperly installed shingle?


Seems like I remember something about guidelines for amount of overhang for wood shake or some other type, but not asphalt. I’d say it is safe to call it a defect. The tar line is there to glue the layers together when they get warm.

Are you sure it wasn’t a shadow line in the granule coloring? Pics would be nice.

Based on your description the shingles are not covering the seal strip and are improperly installed. I have also seen the sealing strip transferring to the shingle below in the packing when improperly stored/handled. Attach a picture.

Yep…pics would help.

Thanks guys, I would love to attach a photo, but this question was just a question from something I saw a while back, and I did call it out at that time, but I no longer have a picture of it. It’s just something I intended to inquire about, but never got around to it until now; but I agree with you guys that it is a defect. That is what the strip is there for, according to some reading that I have done. Thanks for your responses!

If you were seeing part of the adhesive strip, then it was improper installation. If you were seeing a shadowline that consisted of dark-colored granules that was part of the shingle design, which wouldn’t be unusual, then it was probably OK. Shingle exposure is typically 5"-5.5".