Roof Systems: Timber Frame Roof Structures are offered in two styles: The Purlin System & The Rafter System.   

The Purlins/Rafters have been left out of the first bay in the illustrations below for clarity.

Roof System featuring Purlins

The Purlin roof is more common with the Bent system, but can be designed for the Post & Beam system. 

The Rafter System is more common with Post & Beam, but can be designed for use with the Bent system.