hi anonymous and all on this thread:
I am familiar with one structure at UCV (Upper Canada Village) here in Ontarion Canada, that has this type of roof framing used, and it was in a general store type building. It dates to about 1784--1820--it also has the wind bracing framed in nicely with good workmanship.
I got to say right here that I am not certain that this is wind framing, but might rather be bracing that would hold the unit square during its subsequent raising. If wind framing was necessary why is it not used in other\more structures of this period?
As you think about it it appears to me that this type of roof framing required some baces to stabilize it before the roof boarding was applied --what comments are out there?
I have pondered over such questions as how the roof framing was raised also, as well as other types of structures such as the plank and frame buildings of which there are a few around here, and which needed a special type of technique for the raising
In both of your examples I believe that one side of the roof was assembled and raised with the help of a group of men using pike poles and arm power. when the one side was up to its proper height it was braced off and secured.
At this point the individual rafters on the opposite side were put in their respective mortises and secured working from the one end of the roof to the other, inserting the (wind bracing?) as they went.
I really see this as not being a real complicated raising but just in its proper order, and under good leadership.
The diamond shape of the ridge in the first example I believe from what I can see is as follows, on the one side the ridge is square to the ends of the rafters, this would leave the upper surface of the ridge in the right plane with the top of the rafters.
The other side of the ridge appears to me to be shaped similar but the ends of the rafters are set into the ridge on an angle, and the top of the ridge has been adzed off to the the same plane as the top of those rafters, this all to accomodate the pitch of the roof.
Normally the early roofs were a 1\2 pitch and the rafters would have intersected the ridge at a 90deg. angle. In the first example the pitch of the roof seems to be less than a 1\2 pitch and created a problem with the rafter seatings at the upper ends
It is this type of detail that is very interesting and to recreate even more interesting, and I must say, using my dear friends the Lovely Rough Hewn timbers.