Thoughts on Tile Valleys
Today I visited a homeowner who had a roof leak. I noticed their tile roof had a closed valley. A closed valley may look nicer, but they often are the culprit you've been looking for.
Why does a closed valley cause roof leaks?Water always needs an exit and a clear path off your roof. Over time there is a build up of dirt and leaves on closed valleys, causing barriers on the side and underneath the tile. This accumulation doesn't allow for the underlayment to dry quickly eventually deteriorating the paper and causing leaks.
The Open Valley
The open valley may not look as nice, but it functions as intended, directing water off your roof. It stays cleaner and preserves the underlayment over the years. I always recommend it, and you should request it when installing your roof.