Interior flat jambs are a popular choice due to their simplicity and versatility. Flat jambs are a type of door frame that do not have a recessed groove, unlike single or double rabbeted jambs. This type of jamb is typically used when the door is to be installed with a gap between the door and the jamb, rather than being flush with the wall.
Flat jambs offer a clean, simple solution for interior door installations. They are easy to install, can be used in a variety of applications, and offer a flexible solution for custom-sized doors. If you are looking for a cost-effective and versatile solution for your interior door installation, consider using flat jambs.