Long Sill to Short Sill Connection

Fred Pilkington · October 02, 2024, 12:06:13 PM

Hello!

In the Sobon and Beemer garden shed timber frame plans, all tenons are oriented vertically, except the ones on the short sills which run horizontally.

My first question is, why is this?

Secondly, for our timber frame design, the sills won't be sitting on continuous foundations but on posts (for reasons due to non-level ground and for termite protection). Given these short sill joints will be therefore under more stress due to less contact points, would it make sense to orientate these tenons vertically? Intuitively it seems likely - more strength/volume in the orientation with largest load.

I can't seem to find a discussion around this in either the three common Sobon, Chappell or Beemer books.

Thanks for reading.

Dave Shepard · October 02, 2024, 06:59:00 PM

Leave the design alone. Put a pier under the sill at each post location.

Jim_Rogers · October 03, 2024, 10:04:06 AM

Quote from: Dave Shepard on October 02, 2024, 06:59:00 PMLeave the design alone. Put a pier under the sill at each post location.

Put the pier under both the long sill and the short "cross" sill connection. So that the cross sill is setting on the pier as well. Problem solved.
You never put a mortise cross grain. All mortises go with the grain.

Jim Rogers

Dave Shepard · October 03, 2024, 02:26:09 PM

Putting a pier under each post does support the corner joint.

Fred Pilkington · October 04, 2024, 07:45:09 AM

Thanks for the responses.

Whether the tenon is vertical or horizontal, it's always going to be with the grain. Does anyone know why the sill tenons are horizontal rather than vertical like for every other joint?

Yeah the plan is to put piers under each of the four posts - going to make a square 16'x16' cabin. Thinking the best way joint for the pier to the sills would be stub tenons.

Jim_Rogers · October 04, 2024, 09:33:21 AM

Quote from: fabpilkington on October 04, 2024, 07:45:09 AMThanks for the responses.

Whether the tenon is vertical or horizontal, it's always going to be with the grain. Does anyone know why the sill tenons are horizontal rather than vertical like for every other joint?

You answered your own question. Tenon have to go with the grain. NOT CROSS GRAIN. If you put the tenon vertical from cross sill to long sill it would be cross grain.