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 timber frame 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
timber frame 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 timber framing'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.
