King Post to Ridge Beam Joints and Truss – green oak barn

Monday 22/3/21

A lot of thought has gone into the joints between the ridge beam and the king posts and this is the design we have settled on.

King Post to Ridge Beam Joint

The constraints on us were:

  1. We didn’t want to take too much out of the king post otherwise we would have interfered with the principal rafter joints that are in the same area.
  2. But we also didn’t want to weaken the ridge beam as I plan to attach a hook so that a hoist can be used in the future. So it needs to be able to take heavy weights.

The above design deals with both of these constraints. The size of the ridge passing through the majority of the king post is greatly reduced but the joint features bearing surfaces for the non-reduced ridge. This should enable it to take significant weight if required.

I found this joint complicated to mark-up and cut.

Mark up of the king post to ridge joint - 2

I tried to use the saw to remove the waste but this wasn’t very effective as the cuts were with the grain so the wood didn’t crack out in the way it does when you cut across the grain..

Cutting the king post to ridge beam joint - 2

So most of the work was done with a hammer and chisel.

Cutting the king post to ridge beam joint - 3

Once the waste was removed it took an hour or so of fettling to get the joint to fit.

King post to ridge beam joint - 1

But eventually it went together beautifully. This is probably the most pleasing joint I’ve done so far in the whole project.

King post to ridge beam joint - 2

Meanwhile, Ben cracked on with the truss. Today he focussed on the first principal rafter.

Ben cutting the principal rafter tenons

By the end of the day both tenons were cut and a start had been made on both of the mortices.

Principal rafters with tenons

Tomorrow I will focus on fitting the first ridge brace and Ben will carry on with the truss.




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3 Responses to King Post to Ridge Beam Joints and Truss – green oak barn

  1. DavP says:

    Hi Simon. Sorry to bother you again but I think your kingpost design is something I hope to emulate soon. It’s a fascinating resource that you’ve created. I wonder do you have a record of the dimensions of the space removed at the top of the king post for the ridge beam. I’m placing a 150 x 230 mm ridge beam over 3 king trusses. In your diagram above: what is the narrowist dimension of the thinned portion of the ridge beam and how much bearing surface have you allowed on the king for the ridge to rest on? Thanks

  2. Simon Berry says:

    Hello David
    Don’t apologise. It’s great to get comments on the blog.
    My ridge is 175 x 125mm. I came up with the joint concept and then ‘did it by eye’ on-site. With the overall dimension of the ridge in mind, looking at the pictures above and knowing how I think(!), I would say that the narrowest dimension is 75mm and the bearing surface is around 25mm. The latter may seem a little small given the future shrinkage but there’s likely to be little shrinkage over the length of the ridge.
    I hope this is helpful.

  3. DavP says:

    It looks really great. Very satisfying when the pieces come together as planned.

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