The person who designs a roof system has to consider two main areas. They are the field of a roof and flashings. A field is the open part of a roof.
Flashings are the edges around anything that interrupt the field.
Flashings are installed around walls and penetrations. The field and flashing materials may be different. They may be applied in different ways. The field and flashings are two areas of a roof. A low-slope roof also has four parts.