Clip upper corner???

[Marc]

I'm in the process of replacing my roof cover.  The Atlas Pristine instructions for closed cut valleys say to 'cut the upper corner' of the overlaying shingles.  The diagram isn't clear.

I've heard that before but I'm not clear on it.  Anyone know what they mean by 'cut upper corner'? Why is it needed?

Thanks, Marc

[Mike Lamb]

I assume it's to push water towards the valley.

[Erby]

Watch this.  Your question is answered at about 3:34.
 

 

[John Kogel]

It stops water streaming down the valley from running along the top of a shingle strip.

Good luck with that. If I was closer I'd stop by to lend a hand.😷

[Marc]

Thanks fellas. I guess a good way to describe it is to not allow the top edge of the shingle to reach the valley. Cut it two inches back with a vertical cut.

Edited May 2, 2020 by Marc

[Chad Fabry]

I didn't know to cut the top corner when I did my first roof ever. It leaked during wind driven rains. The factory rep schooled me. I find and report it on about 80% of the roofs I inspect with closed cut valleys.