So basically I started reroofing my garage when I realized I was installing a typical 3 tab shingle upside down. Instead of the 3 tabs facing down they are facing up. Now, as far as I can figure this shouldn’t actually mess anything up as far as weatherproofing goes. After looking at the shingles it seems like the 3 tabs are merely cosmetic. The only problem I might be able to see is that the grooves between the three tabs are facing up instead of down, however, I have still installed the shingles such that there is 1 to 1.5 inches overlap and the tab grooves and nails are completely covered by the bottom (i.e. top) of the next overlying row of shingles.
So, I’ve only gotten 1/3 of one side of the garage done and I really don’t want to redo it I don’t have to. Although I will be installing the shingles here on out the correct way (yes, I know the will be a color difference) should I reinstall the ones I’ve done or can I treat them as a very long bottom strip of shingles and restart (allowing for the proper overlap concerning going the correct way now) from here on out? Basically, is there any reason beyond cosmetic reasons?
The top is what I’ve done, the bottom is how it’s supposed to be.