Traditional Mortise and Tenon Joinery
The top
of a post or end of a beam is sawed by hand into a tenon. A
corresponding mortise is cut with drill and chisel in the side of
another timber. Peg holes, slightly offset, are drilled in each
timber. The tenon is inserted into the mortise and a hardwood peg
is driven through the holes, drawing the timbers tightly together.
This is the joiner's craft, the essence of timber framing. Repeated
hundreds of times in a hundred or more timbers, the result is a
structural frame whose joints can hold tight for centuries. A
timber frame is literally defined by these pegged connections.
(Post and beam, on the other hand, relies on metal fasteners to
make the connections between timbers.)
The use
of mortise and tenon joinery in building is so ancient that its
origins are obscure. We know it was used for temples and houses in
classical Greece and Rome, and probably reached its highest
expression and refinement in the halls, manors and churches of
medieval Europe. Similar traditions and levels of refinement
evolved in Japan, China, and southeast Asia. Wherever forests, iron
and civilization met, it seems, timber framing became a standard
for building.
Over the centuries, individual joints were perfected through a long
process of trial, error and improvement, each joint designed and
executed to resist the forces particular to individual places in a
frame. So we have the English tying joint designed to efficiently
lock together post, plate, and tie beam; the wedged half-dovetail
to resist the outward thrust of the roof load where a tie beam
meets a post below the plate; the diminished haunch soffit tenon to
join joist to summer beam or other carrying timber while preserving
as much carrying capacity as possible. And so on.
In most
historic American timberframe houses, a majority of the timbers and
their elegant wooden connections were unceremoniously buried behind
plaster in the walls and ceiling. More often than not, the frame
simply wasn't seen as an aesthetic element of the building, but
simply as the structure to which the finishes were
applied.
That situation has changed, and today most people who commission
timberframe buildings do so out of an appreciation for the beauty
and integrity of the timbers and joinery. These are left exposed
and become the aesthetic focus of the building. In cutting our
frames, we remain keenly aware not only of the long tradition of
craftsmanship that traces timberframing's history, but also the
expectation that the finished frame will be both the sound
structure of a house and an enduring thing of beauty.
