Tim - No Tenon, the peg essentially acts as a large nail - And the peg on the Common Purlins is not as atypical as the pegged Principal Rafter to Tie Beam. Unbroken often full length Purlins are through pegged as often as not.
George - As Will suggests this is a regional variation, though I wouldn't describe it as ever having been common, not even to it's small home region, (I've seen it but a handful of times) it was probably used by a finite few framers who all worked with and influenced each other
Where is this barn? It would be good to know, just to help establish how widely this variation was used. Do you have any sense of when it was built?
I'd like to see it if time can be found before I return to the current project restoration.
I'm kind of a student of these things, particularly home region variations - And speak to that, and the current project in my last two weblog entries > Link below
