This crack may well have started as a check but but was encouraged by the thrust from the common rafters at the sides.
If it is a dovetail conection at the Tie/plate then you would get some give in the first weeks after assembly as a result of some slack in the fit as well as compression. This could be as much as 1/3rd of it's total movement. In the years following as the dovetail dries and shrinks, the plate would then be allowed to further separate.
On the bottom of the Tie at the back side of the post there seems to be a rather large gap in the mortise suggesting perhaps the inside portion of the post has been pulled out. I am puzzled why I don't see any pegs at that post to Tie M/T.

Jim, about joinery. I have showed these before, but I don't recall seeing them in HATJ. Forward if you like and I'm pretty sure I can go back and get specs on them if needed.

Thane, it could be that there is not a peg, compression is all that is needed at that point. Or a blind hole, we are looking at the non reference face It is hard to tell but is there a mortice showing on the bottom of the tie just to the inside of the post?

It looks like the top plate may be rolled a bit, but it is still reasonably close at the bottom to the plate next to the post. What does the post look like from the reference face, the door side?

Tim

Tim, the Teasels most definitely should be pinned - A high wind on a broadside could see the braces on the leeward side go into enough compression that they could potentially overcome the weight of the roof and jack the ties up higher than the depth of the dovetails or cogs, and spit the wall right off the building.

Not much likelihood of just the right array of nastiness lining up just so and seeing that happen, but while I do sometimes skip pegging joints that never go into tension, this isn't one to skimp on.

So it is most likely a blind hole. Yes, just the simple force of the braces with a wind on one side would pry the joint. A one hundred year storm.

Tim

Does anyone have any suggestions as to how this joint may have been improved so that it would not have failed like it did?
Without changing the rafter concept.

Thane, I should have mentioned that I study historic carpentry and the catagories of assemblies I listed in the beginning are for historic frames. I find your contemporary designs interesting and add complexity to trying to catagorize this connection. Your designs also show how "traditional timber framing" is not entirely traditional and we are no longer constrained to designs from the past or to working in any one style of framing all of our careers.

Ken, there is more to the story of this barn. Several years ago the owners decided they could not afford to maintain the seven remaining farm buildings on the property so they sold salvage rights to one of the two barns to a antique lumber dealer. The dealer improperly took the wall boards of the second barn and would not return them. He was taken to court and lost and is supposed to be making payments on the damages which is an ongoing struggle to collect. The owners had the barn reboarded with new boards and I think the studs were added then. There were other rotten areas of the barn and foundation work was needed. They chose not to put more money into this building, but they are maintaining four or five of the other outbuildings.

This farm complex dates from the 1790s.

I do not know if the post is checked or split. I have seen a gunstock post split from rafter thrust when after the roof system of a barn had been changed to a ccommon rafter system and put significant outward thrust onto the plate. This check/split could be either, though I doubt there was excessive rafter thrust on the plate in this design since the ridge beam acts as a supporting ridge transferring some load to the principle rafters.

There are pegs in the rafter feet and tie/post connections. The layout face is the drive floor and the pegs are, as usual, driven from the layout face. They certainly are not clear in the photo.

Mo, I do not see the exact joint in your photo in HATJ, but Jack does not have a computer so I cannot "forward" it. I would send it to him if you email me more specifics about the building at jim.derby@hotmail.com.

I also should mention that the tie/plate joint on my second image is a simple half lap which is not shown in the drawing Jim Rogers posted for us.

Jim

Will, I recall seeing such a joint with no pegging and have been through my photos but with no result. It clearly should be pegged but there have been frames assembled with out the the peg, inferior for sure, my question would be, does this frame have a peg or not. I peg all mine and rarely do I not peg most joints.

My statement of compression holding the joint was weak, I had a moment of absence.

I do feel that the joint, pictured, on the whole, is still strong.

Tim

Onward to reverse assembly which is simply when the plate is on top of the tie. This is described as being "more ancient" than normal assembly by Mr. Brunskill.

The plate on top means the frame needs to be raised in bents rather than raising the sidewalls as in normal assembly; an advantage in long barns.

One use of this type in the U.S.A. is in Swisser or Sweitzer barns in parts of Pennsylvania. As the name implies, these barns are of Swiss origin, but are often built by Pensylvania-Germans called Pensylvania-Dutch, a corruption of Deutsch the name Germans call themselves.

Robert Ensminger is one of the only people who have provided written material on this type in his book The Pennsylvania Barn, pages 250-253. Here he describes turning the outside posts one-quarter turn and replacing the plate tenon with a slot for the necked down tie to slip into. The local name for this is esel fuus or mule's foot joint. This is the joint I refered to in the beginning of this thread as "slotted post", so maybe it should fall under the reverse assembly label.

I cannot find the photo I have of a turned gunstock post so I will have to keep looking.

Jim

Jim - I'm away from my library, What regions of PA are Sweitzers' found in ? Wondering if I'm near any.

Tim - Do know my intent was not so much to edify you as it was just that I thought it important to make it clear to all that ever happen by this thread, that teasles need be pegged.

Mo - Where is that roof system in your photographs ?