Rather than buying posts from a big box store or even purchasing 6×6 timbers from a local sawmill, I wanted to use some of the alders and maples that cover most of my property. Without a broadaxe or adze, I have limited means to hew the timbers square, so I’ll be using them as roundwood. Fortunately, Ben Law’s book on Roundwood Timber Framing provides a great resource to plan it out.
I am planning to rest the eight upright posts on prepared padstones rather than sink them into the ground in concrete like a conventional pole barn. The height of the posts is only going to be 7’6” above ground, since the barn is meant for goats and me (at 5’6”, I’m the tallest in my immediate family!). To give myself some wiggle room, I would cut the poles at 9’ long. The sides of the octagon are square, meaning the posts stand 7’6” apart from their neighbors. The horizontal beams, then, need to span that distance and extend at least a little beyond the tops of the poles, so I’ll cut those at about 9’ as well. The rafters will need to span a little over halfway across the diameter of the walls, but will also need about 24” of eave overhand to protect the cordwood walls from rain. I decided on a 14’ length for these.
The first step was harvesting the timber and getting it drying. I started in November 2013 (though I’m only blogging about it now). I scouted my woods looking for suitable posts, beams, and rafters. I wanted logs of a suitable mass to be able to support the weight of the rafter and the living roof, but still possible for me to handle moving alone without power equipment or draft animals. I ended up selecting post sections of about 8” diameter (tapering to 6” or s0), and beam dimensions in the 4”-6” range. My rafters started at about 6” at the base, tapering to about 4”-5” after their 14-foot length.
Here are some of the trees on the ground…
...and my fancy lumber truck (otherwise known as a Hyundai Santa Fe)