SHAPE AND STRUCTURE OF THE GASSHO-STYLE HOUSE
One of the most characteristic features of Gassho-style houses,
one which is never seen in the farmhouses of other regions, is
the structural separation of the roof and body frame -- where
the roof structure above the usu-bari (the horizontal bottom member of the truss) is clearly divided
structurally from the body structure composed of posts, girders
and beams.
In typical Japanese farmhouses, short posts supporting the roof
rafters stand directly on top of the girders or beams which compose
the main body structure, or in other cases where a truss-like
structure is used the beams or girders of the main structure serve
also as the bottom member of the truss frame, joined directly
to the columns. In both of these cases, the main body structure
and the roof structure are joined together structurally -- not
separate, independent frames as is the case with the Gassho-style
structure (Fig.6-2, 3, 4).
Also, in typical farmhouses, most of the interior living space
has no ceiling and the roof structure is visible from below. In
Gassho-style houses the upper portion of the one-story main body
structure is assembled from flat beams and girders, and the usu-bari
are simply lined up on top of the beams, separating the roof structure
from the main body structure (Fig.2-1, 2, 3).
The clear structural separation between the body frame and the
roof structure of Gassho-style houses is related to the construction
method used to build these houses. In this region the construction
of the body frame structure is done by skilled professional carpenters,
but such work as the setting of foundation stones, the fabrication
of the roof frame structure, and the roof thatching work, including
the material preparation, is done by non-professionals working
together under the traditional system of mutual labor exchange,
or yui.
Therefore the members of the body-frame structure typically have
highly crafted finishes, achieved with the use of planes and other
special finishing tools, and the frames are assembled by various
wooden joinery techniques. On the other hand, for the roof frame
structure and the roofing, the materials are used mostly in their
natural state with a natural finish or rough-hewn by use of adzes.
Instead of using carved wooden joints, the members are lashed
together with straw ropes or natural vines.
This construction method, in which construction costs are incurred
only in the fabrication and erection of the main body frame, was
a necessity in this poor mountain area where it was difficult
to obtain sufficient cash income to pay professionals. The clear
separation between the professional work scope and the mutual
labor exchange work scope is another special characteristic of
this area which is not found in other areas.
In the deep mountain villages in this area, there was not enough
steady work for professional carpenters to make a living, so when
necessary carpenters had to be called in from other regions.
