Timber Framers Guild

king post joinery question

Posted By: piller

king post joinery question - 09/13/02 03:23 AM

Hi, I have a question about how the principal rafters and the king post are joined at the peak of a king post truss. I have seen this joint done in three ways, is there a best method?

The sides of the rafter housings at the top of the king post can be angled up and out like a V, the sides can be angled up and in like an A, or the sides can be vertical.

I would think that the A design would be strongest but it would depend upon there being adequate material remaining in the post top. However, most of the king posts I have seen have been in the V configuration. Comments?
Chip Piller
Posted By: Roger Nair

Re: king post joinery question - 09/13/02 12:14 PM

I have used the V form, first it has purchase and bearing, it resists sliding up the post. Second, draw the V form connection as cut, now draw an overlay with the rafter with cross grain shrinkage. If you use dry stock for the king, the green rafter cord will still bear.
Posted By: Roger Nair

Re: king post joinery question - 09/13/02 12:15 PM

I have used the V form, first it has purchase and bearing, it resists sliding up the post. Second, draw the V form connection as cut, now draw an overlay with the rafter with cross grain shrinkage. If you use dry stock for the king, the green rafter cord will still bear.
Posted By: daiku

Re: king post joinery question - 09/13/02 03:41 PM

The king post should be in tension. So the V shape is the stronger joint, IMO. The rafters are pressing in on the post, and the V shape forms a wedge to keep the post from sliding down. CB.
Posted By: Roger Nair

Re: king post joinery question - 09/13/02 09:28 PM

When eating crow, where should I take the first bite?

I have over stated, the closer the rafter cord sloping cut is to square the more secure the bearing is with shrinkage would be the more accurate claim. Sorry about the double post earlier.
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