What type of rafter sits on a double top plate?

A common rafter is designed to sit on a double top plate, which is part of the wall structure of a building. The double top plate serves as a structural support that helps to distribute the weight of the roof and provides a stable base for the rafters. Common rafters are typically the main structural members used in a roof framing system that extend from the top plate up to the ridge or peak of the roof, creating the overall slope and shape of the roof.

This function distinguishes common rafters from other types, such as ceiling joists that primarily support the ceiling and create a separation between roof structure and living spaces below. Facia rafters, which are less common and typically related to the fascia board on the roof's edge, also serve a different purpose and are not structurally engaged in the same way with the double top plate. Jack rafters, on the other hand, are shorter rafters that span from the common rafters to a hip or valley, and do not directly rest on the double top plate. Therefore, the functionality and placement of common rafters make them the correct choice in this context.