Timber Framers Guild Forums General General Forum Questions collar ties and queen posts

Does anyone know if there is a best or preferred way of joining rafters, collar ties, and queen posts. The way I see it , there are three ways to do it: collar ties into rafters and queen posts into collar ties: collar ties into queen posts and queens into rafters: and collar ties and queen posts into rafters. Aesthetics aside, I always think to put the collar ties in the topp third and the queen posts into the lower third of the rafter, thus offsetting the joinery. Anyone have anything to share on this topic?By the way I am mostly thinking in terms of a tie below the plate ,extended post design.

Excellent question.

I've been wondering about that also as I finalize my (pretty much identical) design.
I currently have the ties in the bottom of the top third, with the queens in the top of the bottom third.

First of all there was some discussion about this some time ago where a fellow mentioned the name "Collar tie." And Ed Levin did some FEA research and found that the "collar" is only acting as a "tie" (in tension) when it was low between the rafters. Somewhere around one foot above the rafter foot in elevation or lower. Above this point that "collar" is in compression, that is holding the rafter apart or from sagging in.
This fellow mentioned that the name really shouldn't be "collar tie" but should be "collar beam" as it really isn't tying, again unless located where mentioned above.
He did however have a third name which escapes me at the moment. These three names would be used for a "collar" depending on their actual location in the frame, based on elevation above the rafter's foot location.
Since reading this discussion, again some time ago, I have tried my best to use the term "collar beam" to describe the beam going between two rafters.

You are correct that there could be these three locations, and I feel that the correct location depends on several factors. Some of these would/could be length of rafter, roof load, rafter pitch, over all frame design, height clearance needed (head room).

It maybe that each individual frame design has to be carefully analyzed to determine exactly where the collar should be placed.
So much so that you can't just say, one location is the right one and the other two are wrong....

A common answer is "it depends"......

One thing to consider for option 1 (collar into rafters, queens into collar) is the shrinkage of the collar. Is has a bearing surface on both the top (to the rafters) and the bottom (to the queens). As is shrinks, it may transfer some of it's load out to the rafter feet.

Another thing to consider is ease of raising. Again, with option one, you may want to fly in the collar/rafter pair as a sub-assembly. CB.

thanks Daiku. What do you find easiest to raise for yourself and also if one were attempting a hand raising with assist of a gin pole perhaps? I look at queen post trusses and they mostly have in common that queen post is joining into rafter with the collar tie taking a bit of a back seat, so to speak, and joining offset to the queen post below its top. Of course there are many examples but this is something I have noticed. Then again what we are talking about here is not so much a truss as the tie beam is not making the truss triangle like it should because of the extended post design, but still perhaps this a good point to look at when answering this question that perhaps it is better the queen joins into the rafter than the collar tie if one must choose ? I wonder how does shrinkage affect the queen rafter connection? is it better or worse effects than the collar ties'. Then also what is to be said for the design of both the queen and the collar joining respectively into their third of the rafter? So much to learn and so many mistakes to be made but it is all so fun and exciting for me to stop...Let me know if anyone has anything to share, as this seems to be a topic worth studying. tb

TB:

First, you are right about this not really being a truss. Just a way of mitigating rafter thurst by shunting the bulk of the load down to the dropped tie beam, and then to a post in the middle of that tie beam. It's critical that your queen/collar arrangement do this. If the joinery is not executed correctly to give you solid bearing surfaces, or not designd to take shrinkage into account, then the load will shift to the rafter feet, which will push out on the post tops, which act as a lever to pry apart the tie-to-post joint. CB.