https://peterjackson.mee.nu/where_i_work#c2746">https://peterjackson.mee.nu/where_i_work#c2746. A quality roof covering will have them mounted around the edge of the roofline, where vertical walls meet the roofing https://haseeboxew500654.bloggazza.com/38312598/the-ultimate-guide-to-stay-dry-roofing