Jan is right. I just looked at the picture of the CG barn I saw on the way down and it has common rafters! But keep in mind the roof was changed to a gambrel, my guess is around 1900+. It has the flying plate as part of the add-on. Crazy, maybe but a lot of years have passed and that leaves room for many variations, some of which we have lost.

Steve, I may have posting abilities soon. Its wicked frustrating not being able to. So to be a responsible poster I am going to do it.

Don the the English barn has principal rafters and common purlins, with lots of cobwebs. Tim

Don, I think Will was on the side of scrib rule for the first barn. Tim

Tim

yes, my mistake. Scribe on that first one!
my mistake...

OK, I'm confused.
You have visited two barns recently, right? The CG barn you looked at "on the way down"... is the one in Bucksport? And that one has common rafters?
And thats a true CG, right: the ties rest directly on the posts...the rafters atop the ties, right?

The English barn (w/ the cobwebs) you think could have been a CG if the plate was lower, right?
But plate height really isn't the determinant. As you know, the plates have to be interrupted. So it's really whether the tie sits on the post directly... this makes a "bent-unit": post, tie and rafter at the same plumb line.

So for the sake of everyone reading, that's what makes a CG. It really is that simple: the post, tie and rafter are all vertically aligned.

Is that what you see in the "English barn?"
Neat that you've foud a purlin roof, anyway... I know they haven't been very common up that way.

Don you have the Bucksport barn right on, and its roof was changed to a gambrel.

The local barn has a full top plate setting on the post, atop that and let into the plate by about half is the ties, and the rafters set on the ties. So If you visualize the top plate dropped about 8"-12" you could have a CG barn, they must me direct cousins, maybe incest was involved, that close.

The top connecting girt can be at different levels, we saw that in the 3 examples. There is the variation where the CG is connected to the tie in a segmented unit as well, that's CG also? Plate height doesn't determine CG, they don't have plates?

Just across the road a tad is a large barn with common rafters. I don't think one prevails over the other, a nice mix present in the area.

How does that sound? Tim

Ken --

I've seen a few and helped restore one,(got pix somewhere) I guess they would more properly called a connecting plate barn. the "plate" is tenoned into the side of the tie. Jim put up a link to pictures of one.

They are relatively uncommon in that they (connecting buildings) share the same region in which common purlins are the dominate system.

Here is the Bucksport barn with common fraters. This is my first try. Tim
http://www.flickr.com/photos/14709813@N02/2667693006/

[img]http://www.flickr.com/photos/14709813@N02/2667693010/[/img]
If this works it the same barn as the link. Tim

Hey Tim:

This whole thing is great to pick away at, and probably needs to be done so folks can get on the same page about what a CG is and isn't. I'm not the expert on CG, but I've spent considerable time since joining the forum examining them (like picking barns for the recent tour, etc)... so here's my take:

CGs don't have or weren't:

continuous plates

built or raised as longitudinal bent sections

if [b][b][b]major [/b][/b][/b]rafters they do not bear atop wall plates

They do or can have:

interrupted plates
--these must span the width between bents. Scarfed plates are not "interrupted plates"

no plates

A top girt as principal bent connector

if major rafter, they are directly atop crossties

crosstie is directly atop post

principal wall bents obviously raised transversley



In short plate location is not the determinant. Rather plates must be inturrupted in a manner other than scarfing. The plates usually serve as nailer for roof decking/ wall sheathing rather than frame stiffening.

Like I think you said earlier, a CG is basically an English tying joint w/out the plates... I think this is pretty accurate. The only specific, is that if it is a English tying joint with plates, they must be clearly inturrupted (wholly between the crossties).

how's that...?

For me a true CG has no plates at all... the CG (connecting girt) is clearly dropped, and the building has a major rafter/ purlin roof.... just like the first two we saw on the tour.

That looks like a CG to me... Nice photo.
To see the flying plate would clinch it. What's "connecting" the building. Is it the flying plate or the topmost girts? If it's the girts, I'd say it qualifies.

How odd. A CG gambrell w/ common rafters!

This second post did not show a picture, by the way.

They were filling the barn up with hay when I was there, so not available for further viewing for 9 months or so. From memory I would say the plate the rafters sit on is part of the re-roof. You can browse through a few odd pix I have on flicker. There is two more shots of the CG barn, the gable interior and a 3/4 exterior view. Tim