Hi all,

First post here so be gentle....:)
I've been playing with sketchup for a little bit and as I'm experimenting around with a frame I find myself wondering what is a good tying joint design i can use where a post, tie-beam, plate and common rafter all meet?

Below is what I've been playing with - any constructive criticism , comments or refs on pics of joints solving this on are welcome.

...Some thoughts I've wrestled with in playing with this combination of intersections:
a) should the common-rafter sit on the plate or the tie beam? - i'm thinking tie-beam(which is not what i have in my pic)
b) ..if on the plate then should the rafter enter on the front-side of the plate or the middle?
c) can i peg this thing?
d) can i assemble this thing?

Dan

I think you should look at Jack Sobon's Historic American Joinery book (published by the Guild).

There is a lot of joinery in one location, and a jowled (flared) post is perhaps a better way to try to accommodate that. The tie beam in an English tying joint sits over the plate, and the rafter then, on top of the tie beam. Other common rafters then sits on the plate (or not with purlins). The book shows other sorts of tying joints as well. As a general rule it's a good idea in the frame design to try to avoid intersecting joinery.

Hi Dan, and Welcome.

First of all, nice sketchup drawing. I assume that's why you posted here in the software forum. But actually, your post belongs in the design forum. This forum is supposed to be about issues with the software itself. One other friendly tip: When creating jpgs for popsting on the forum, drop down the resolution when you export from Sketchup, so the picture is a little smaller.

To answer your question, though, Brad's already given you the best advice: before you try to make up your own joinery, go back and look at historical examples. They're "classics" for a reason: they work, and have stood the test of time. In this particular case, you want to do some research on the English Tying Joint.

Again, nice drawing, and welcome to the forums. CB.

Hi Timberwrestler,

Thanks for the comments.
Yep - I've check'd out that book and its a wonderful collection of examples - the best I've come across! I also noticed how flared posts were used to give a bit more realestate to play with - up to this point i wasn't considering flared posts, and the English tying joint example looks to terminate principal rafters only which don't have overhang(I'm looking for some overhang past the plate on this frame). I am looking at modifying my design at this point to prevent this crowded meeting.


Hi Clark,
Thanks for the comments as well....and the TF Rubies! Too Cool.

Yep - i posted here because I was doing it in sketchup - I'll put future design questions in the proper forum and post smaller pictures. =)

-Dan

You can do ETJ with common rafters having overhang.
Do you have a ridge?
Why do you need the plate and tiebeam on the same level?

Sweet drawing Mark!

Nope - no ridge. This joint is in the middle of a shed dormer and adjusting the height a little is possible, but I'm trying to preserve as much headroom as possible. If i were to split the two it would likely have to be the tiebeam that drops or else my plate would likely have to become two timbers.

Dan:

It doesn't seem to me that this work well structurally without a ridge. You need to tie that dormer plate back to the frame at the ends, not just in the middle. The rafter thrust will bend out the corners of the dormer. It may still work if you tie the outer shed rafter pairs to the adjacent main rafter pairs at the peak, as the mains are supported by principla purlins, but the engineering to prove that is over my head. CB.

The purlin could be bumped up with a couple of very short posts and a parallel purlin under the dormer rafters...

u mean somefin like this

I see you've added a ridge as well, which you probably don't need now that you have the purlins.

Why so many "studs" under the dormer window? Or are you doing a stick-frame infill?

it's an existing stick frame home and we're dropping the TF "into" it. Mark and I designed the "inner" frame to support the roof system on it's own, taking most of the loads off of the existing 2x4 walls. The engineer loves the idea and it looks like the existing walls will not need any extra/major work (he's still reviewing the plans).

Nice Frwinks,

Thanks for the pic - I was playing around with Mark's suggestion last night an figured that's what he talking about - but you know what a picture is worth....

I also played with your idea as well Clark, on tying the ends in - I'll try to post a few pics tonight as well.

thanks for all the feedback.
-Dan

...Took a bit longer than expected to post this - a house next to the duplex i own went up in flames on Sunday - it torched the side and roof of my duplex and I've been dealing with the fallout from that.

....Anyway....I've added ties on the end of the dormer plate and posted up the purlin for the dormer rafters - I've also dropped the plate slightly to reduce the joint intersection.

Thanks for the input.

-Dan