Now that the rear of the extension is up to the wallplate height, I have started to frame the vaulted roof using 47×175 graded timber that I bought from A10 Timber

My reasoning behind this early start on the roof is to get a dry area to store some materials. In hindsight I would build the wall up at the gable end first in future.

There are two large rooflights to go into this roof to allow light into the interior of the ground floor, these are framed with double joists either side and double trimmers between, all bolted together with coach bolts and timber connectors.