The roof has rafters and a ridge purlin with plaster between.
The two transverse frames are apparently pairs of base crucks with tie beams supporting a crown post and collar purlin roof.
Low Priority Paint steel roof purlins, replace rotten timbers within the purlin angle sections.
The old porch was removed and a new one designed using an oak purlin from the wagon roof in the nave.
Purlin: Longitudinal timber between trusses, located about half way down the principal rafters, used to support the common rafters.