Roofing/Backwards ridge cap shingles
I received a quote from a well-regarded area roofer to re-seal vent pipes, furnace collar, some errant exposed nail-heads, etc. Basically, just get on my 11 year-old roof and see if it needs anything. He showed me pictures and recommended replacing the first 4 or so ridge cap shingles on each of my three dormers, as they run "backwards" before transitioning to the correct direction. The attached picture is a birds-eye view of one, where the main roof transitions to a dormer. It seems to make sense to me...but I was just looking for a second opinion.
In theory a really heavy rain could continue the flow of water under the ridge caps but the water would have to go under 6 inches before it hit the other end of the cap underneath. I guess it could also hit the nail heads on the way. But as soon and the water transfers from running down the main roof and then goes horizontally into the ridge caps the force of water flow stops because it is no longer being pulled downhill by gravity. If they were first being installed it would have been better to turn them around but now it might not be worth the trouble. If it hasn't leaked yet will it ever. There is also another theory to face the openings of the ridge caps away from the prevailing winds. That could keep the ridge caps facing the way they are.