Each element enables the roof to span across the building and support the tiles/covering on top as well as being able to transfer the loads (weight) created by any wind and snow down to the walls.
Mae pob elfen yn galluogi'r to i rychwantu'r adeilad cyfan, a chynnal y teils/gorchudd sydd arno'n ogystal â throsglwyddo'r llwythi (pwysau) a grëir gan unrhyw wynt ac eira i lawr i'r waliau.