https://penzu.com/p/667134efe927f639">https://penzu.com/p/667134efe927f639. A quality roofing system will have them mounted all over the side of the roofline, where upright walls fulfill the roof covering incline, https://lilyoepw924417.blogdeazar.com/39878074/the-best-strategy-to-use-for-stay-dry-roofing