I want to make a timber frame shed in the shape of a hexagon. Have others done this? I would like to hear how you did the joints at the intersections.

I have a chain mortiser, but of course the angles for the hexagon are not square. How do you approach this?

Robert

You can do a lap joint over the post, but you then have 3 timbers coming into a fairly small location. Another approach is to use pairs of posts at each intersection, so no post directly at the corner. Not sure of the size of your shed, but you may also have tie beams, or principal rafters at the corners as well.

Hi Robert,

This should be a really fun project and ambitious if new to woodworking...but more than doable. Any enjoyable and well done project will start with good planning, creating a
good schematic/blueprint and/or working scale model to reference a cutlist to and how to approach your given hexagonal design for the shed…

I have built/helped with a few over the years. There are many others today, and in history, that have done this type of challenging timber framing as well. If you just “Google” timber frame hexagons and hit images you will see a lot of examples. I don’t recommend some of them because without PE oversight folks are taking a serious risk actually understanding the load paths and what they require for proper joinery in a given design. As such, I always recommend folks to have their design PE approved from an engineer that actually understands timber framing, otherwise one must assume the risk themselves knowingly!

The “joints at the intersections,” will depend on the overall approach to the project and how you wish the timber frame to look in the final design. The joinery for such a project can be done in many different styles from a “hammer truss” approach which can be found in some spires and cathedrals of Europe to many different styles of bracketed/corbeled and spline joinery found in Bell Towers, Pagodas and related spiritual structures of India, China, Korea and Japan which probably represent the oldest version of octagonal timber frames in existence. As another related architectural example, during the heyday of the Adirondack lodge and boathouse craze (circa 1840 to 1890) there had been many such gazebos built, some having a lot of wood joinery...

As for your tooling, much of this will have to be done by hand...or...you will have to create a reference jig system to better facilitate the use of chain mortisers and related “reference plane” tools. That is a rather common practice for those of us that work “in the round” and/or with live edge timbers…

Your next challenge, and coming from style again, is what layout system you will use to facilitate your design. The oldest examples of such complex timber frames would have been done in a “line rule” system often with templates. I would say the next oldest and effective method would be stereotomy and/or lofting layout methods. These later systems are labor intensive requiring a lot of movement of material, testing of joinery and enough room for a lofting floor. With “line rule” there is little test fitting (if any) or much handling of materials other than cutting the joint, then raising the frame. Line layout systems relying instead on set geometric understanding from the design being transcribed by template to targets on the snapped lines of a given timber. Both methods are highly effective…

Hope that was of some help...