Praise to the peg! The tree-nails that hold our structures together. What follows is some detail about pegs in general, and how we do things at TimberHomes specifically.
There is more than meets the eye when it comes to determining the pegs needed for a structure, and then coaxing their lovely shape from a raw hunk of wood. Pegs come in different sizes – we typically use 1” pegs for important, structural joinery where the peg itself is expected to bear load or resist force (tie beam joinery, often post top tenons), and 13/16” pegs in places where the peg’s work is mostly to pull the joint together and keep it tight over time (braces, girts). Wood species is also considered. We use the fabulous, easy-to-split, bendy white ash for well-protected or interior structures, but turn to naturally rot-resistant white oak or locust for outdoor structures that have more exposure to the elements.
Something that distinguishes TimberHomes from other larger timber framing companies is that we use hand-riven pegs, rather than pegs that are sawn and then turned on a lathe. Riving is the process of splitting wood. Just like what happens when chopping firewood, during riving, the wood splits along its own path of least resistance, leaving continuous wood fibers intact. With a machine made peg the wood fibers are severed by a blade, resulting in a weaker peg. Engineering calculations are based on turned/machine made pegs, and using these weaker pegs will not result in catastrophic failure, but a machine made peg is more likely to splinter as it’s hammered into place, meaning more waste and frustration on site. There is an important aesthetic difference as well – a machine made peg will be straight along its length, and round in cross section. Riven pegs are octagonal in cross section, and may have a slight bend along their length, as their shape follows the grain of the wood, rather than the slicing of a straight blade.
Now, what goes into making a hand riven peg? Key tools include a froe for making blanks, and a shave horse and a draw knife to turn a blank into a peg. Starting with a full round section of a tree that has been rough-cut to the length of your peg (typically 13” for use on a 8” timber), a grid is drawn for splitting. The froe is placed upon a center grid line, and slammed with a beefy mallet.
The wood splits, and each resulting chunk is split again until you are eventually left with rough rectangles of wood approximately the size of the peg you wish to make, or ‘blanks’. A single blank is brought to the shave horse, where it can be clamped in place in front of the peg maker. This person will then use the draw knife to shave the blank down to the desired shape – an octagon in length, with a slight taper at the tip, and a more dramatic taper at the tip that ends in a small ¼” square, not a sharp point.
