This paper analyzes rectangular columns, rectangular cross section columns, in “Minka”, vernacular houses. The subject to research is rectangular columns in 227 vernacular houses designated as Important Cultural Properties. rectangular column's ratio of long side to short side in this paper is over 1.2 to 1. Three purposes in rectangular column are revealed as below.
First main purpose is aim of design which the carpenters pretended to be thick column while conserving materials. Rectangular columns are distributed in “Doma”, which is earth floored area, “Hiroma”, which is living room, beside entrance of “Doma”, or in outside appearance. The places which rectangular columns are distributed among vernacular houses designated as Important Cultural Properties are "Doma" (13%), "Hiroma"(5%), appearance(6%), "Zashiki"(2%), guest room. A large number of rectangular columns exist in east area of Japan and Mid-Edo period. In this case, average ratio of long side to short side is 1.28 to 1.
Second purpose is low accuracy of carpenter's process. In this case, directions of rectangular columns in vernacular houses are not systematic, namely long side of rectangular columns are not all front.
Third purpose is to adjust width of column to “Tatamiwari”, which is the system to adjust bays of columns to dimensions of “Tatami”, which is floor covering mat. This purpose is due to construction method mainly, however this is also due to design to pretend to be thick column.
A large number of rectangular columns exist in east area of Japan and Mid-Edo period.
