Joinery detail

FalconFan · July 22, 2016, 10:30:39 AM

I have tried (and failed) to find a good diagram of the joinery where a tie beam and two wall plates join a post, all at the same height on the post. Specifically, I am wanting to know how you determine the lengths of the 3 tenons and how you would peg each of the beams. I have gathered that it is best to use a housed tenon for the tie beam and not house the wall plates, is that correct?

Dave Shepard · July 22, 2016, 11:03:54 AM

One of the reasons it would be hard to find that would be that it is a poor joint. If you take an inch for each housing from an 8" x8" post, you only have 3" for each girt tenon.(It would not be a plate at the level.) Now, if you take an inch for the tie beam housing, you only have 3" for the tie beam tenon, which is vastly inadequate for a tie beam. I would get Jack Sobon's Historic American Timber Joinery and move those girts up or down.

FalconFan · July 22, 2016, 11:52:09 AM

Thanks for the reply Dave and I agree it is taking out a lot of material but as I look through Steve Chappell's book, A Timber Framer's Workshop, it does not appear to be an uncommon joint and it seems like it would have to be done when framing for a second level floor, correct?

timberwrestler · July 22, 2016, 12:16:33 PM

That's really because Chappell's book isn't very traditional at all. It's the forms of the buildings that are important, not the fact they're put together with fancy joints.

But...yes, that comes up some times. I would house the tie beam with a long tenon, and I would house (nom. 1/2") and screw the girts. The girts can likely be smaller because there's half the load on them as the joists. Sometimes you can skip the girt entirely, and plan for a nailer to be buried in whatever the enclosure wall is.

VictorH · July 22, 2016, 04:13:32 PM

If there is no way to raise or lower the tie or wall plates then you should consider flaring the post to give more wood to work with.

This is an example of what I mean.

Roger Nair · July 22, 2016, 05:52:24 PM

I try to avoid but have on occasion made threeway plus post connections.

1. Increase post to at least 8 x 10.

2. Make tie tenon half height and extend to the opposite side.

3. Join housed girts with a free tenon or spline that crosses over the tie tenon.