Shaun
Jon had expressed concerns over perceived shortcomings in what I took to be an early revival type, post to rafter connection – common purlin / connecting girt frame, A frame completely without members which bridge from bay to bay, and a typology largely without the existent historical record you suggest.
A 19th century connecting girt frame in western Mass would, I believe be quite a rarity. Which is not to say such a thing could not exist, A framer from my area could have been transplanted. Here common purlins were a dominant system from a very early period , though English tying type frames with continuous plates and ties were by far the most common frame type built up through at least the 1830’s. For a brief period in the latter half of the century and as the evolution of historical timberframing was drawing to a close and largly as a response to the almost total deforestation of the time connecting girts became the dominant system in New Hampshire, parts of Maine and the Connecticut Valley region of Vermont. ( Jon I would be greatly interested in hearing if historical examples of either CG’s or CP’s are common to your part of Vermont )
The difference between these historical frames and the typology described above are multiple, common purlins typically bridge two bays and are often staggered to allow for through tenons or relish beyond daps, connecting girt frames tend to be quite large with girts at the upper and lower arcade lines and in the roof system struts, sometimes at the end of overriding ties, a kind of flying plate to form the eaves. Ten to twelve girts or more per bay, not the four and sometimes only two often common to early revival frames.
In the early 90’s the structural inadequacies of timberframes held together by a minimal number of girts with 3-4” tenons and drop in dovetails on common purlins began to be discussed openly in this community. Most framers chose to evolve their thinking and their product in any of several ways, by moving to free-tenons in their girts, some moved towards a myriad of metal based connections, others looked to historical record and introduced continuous wall and purlin plates, ties, joists and purlins into their designs.
I fall squarely into the latter group, often describing myself as a hyper-traditonalist, but am not, however, too proud to apply a strap to a frame if it means it will be better for it.
Moreover, Jon suggested his engineer was involved only in the sizing of the timber and had no input whatever into how they would be connected. More importantly, it is still common for newbies and owner-builders to base frame design on books and articles from the early years of the revival. I was reading between the lines and guessing that Jon fell into this category and that he subsequently found later writings which suggested there was room for structural improvement in his design
In the end, I was simply stepping up and answering his direct question.
