Will and Tim:

I know very little about the whole "2 foot mark." If you have some pictures of any on a post please "post" them so I will know what to look for. But good to know that the 2 foot mark typically stood on its own and did not include a mortise location.

Will, finding more of these CG frames (and many of them scribed) is opening up new questions. Because there are no top plates,the question you ask about referencing for the 2 foot mark location is pretty intriguing. And to clarify, I said I've found these barns within a 20 mile radius of Portland..., I should have said they are found north of Portland. I have not explored much south of here.

If anybody else has seen this frame type, please speak up.

Tim, I think you're onto something: the mark doesn't always have to be 2 feet. Sobon's little book "the scribe rule or the square rule" says they are occasionally found at 18 inches. And, yes, why not include the girt at two feet as well?

Sobon includes an excerpt about the 2 foot mark from Edward Shaw's Civil Architecture, 1832:

First, the mortises should be made and the faces got out of wind. Second, after finding the length of the timber, in which the tenons are to be made, for convenience apply the 2 foot square.

Third, take out the size of the mortised timber on the end of the square; suppose 10 inches to be the one mortised, then 14 inches remain on the square; make a distinct mark at the end of the square, which is called the 2 feet mark. Fourth, measure from this mark for the shoulder, 15 inches, which leaves 1 inch to be scribed; after the tenon is made and entered, the mortises in the shoulders are brought together or to a bearing, then cut the shoulders to the scribe, and when put together they will remain out of wind, as when scribed. This process is generally applied to sills, posts, and principal rafters.

Because of the the way this is punctuated and written, I find myself having to read this over and over again in order to grasp it.

What's interesting is Shaw is talking about applying the 2 foot square, meaning a framing square. Wasn't the steel square a new device in 1830 and one that typically did not get employed in scribe rule?

Another point I find interesting is after the fourth step: "which leaves one inch to be scribed." The girts on the white barn are 23 inches from the post's tenon shoulder.


I'll leave it here for now; I have more to discuss/post regarding bracing in these structures later...