I'm putting 3 tab shingles on a shed roof. The roof is exactly 12' wide, but I want to leave a 1" overhang on the gables. Since the 3 tab shingles are 36" long, this means exactly 4 shingles will cover the span left to right. How do I move/stagger them to leave the desired 1" overhang? The more I look at this, the more confused I get. Thank you very much!

I will add pictures. First let me say i have contacted the township and the superviser was here. He stated there is nothing they can do. The ditch starts as road drain at intersection goes beside the road at my meighbirs property and ends at mine. The water looks like a river through my yard when it rains. Our house as well as neighbors is below grade of the road. We have a in ground pool with a vinyl liner in the back yard when we drained it last year it rained and the water from this was so bad it floated the liner in the pool untill it had water in it. I had to install interior french drains in the basement to keep it dry from all this water. I have a video of the rain and the river in my yard. What can I do. The guy from township said he would check and get back to me on what they could or would and its been 2 months with no return calls. I try calling and nothing. I know its time for reelection because his sign is in my neighbors yard. Shouldnt they have to fix this. It is causing me problems. Especially the pool there is no waterproofing option for it. The house is a 2% grade below the road then the property levels out. So this water just then collects in the back yard so much so that my riding mower sinks. What can I do? Any suggestions or advice would be great. If I new all the problems this house had before I would have ran from it.