Sorry, my other post keeps saying it is invalid and also when I try to contact the administrator of the forum. :-(
We have had 5" gutters installed and are having problems with water entry into the back of the house. You can see photos here: https://www.flickr.com/photos/125591537@N04/ and our roof measurements.
It looks like to me we may need an 8" gutter in places, but the primary problem now is that in even a moderate rain the water overshoots the gutter completely.
Any ideas? We have talked to many gutter people and none have a system to determine what size we need, what shape or how to install them.
Any help or suggestions would be greatly appreciated.