This document has been developed for the purpose of providing guidance for installing pre-assembled unit skylights onto a roof. The guidelines have been organized into two major groupings. Sections 6.1 to 6.13 cover pitched/steep slope applications and Sections 6.14 to 6.19 cover low slope/flat applications. A steep slope roof has a pitch/slope equal to or greater than 3 in 12 (about 15 degrees from horizontal) up to 75 degrees (15 degrees from vertical). A low slope/flat roof will have a pitch/slope less than 3 in 12. Unit skylights are typically designed to be installed at specific ranges of slope,and some can even be installed at near vertical slopes. Within these sections the installation of several types of available unit skylights are addressed.