In areas of high snowfall, the beam framing of minka is generally both stouter and more complex than in other areas. In the snowy Tо̄hoku region, even in sasu-gumi framing, roof posts (tsuka 束) are erected under the ridgepole (mune 棟) and internally in order to support the weight of the snow, effectively turning the sasu-gumi into a wa-goya construction where the beams also bear the roof load, transferred to them from the rafters via the tsuka.
Because the amount of snow on a roof is influenced by prevailing wind direction and incident sunlight, and therefore differs between different faces of the same roof, framing methods known as hon-goya (本小屋, lit. ‘true koya’) and masu-zukuri (桝造り, a masu is a square wooden sake cup) were developed, where beams are built up in multiple layers to prevent the twisting of the structure under this uneven load distribution. Examples of these types of construction can be seen above the main ‘gathering’ or ‘social’ rooms and doma in minka across the northern part of the Kantо̄ region and the Tо̄hoku region.
An example of hon-goya framing, with many tiers of beams and ties.
In the Kaga, Nо̄tо̄, and Etchū areas of the Hokuriku region, there is a characteristic form of construction called waku no uchi zukuri (枠の内造り, lit. ‘inside the frame construction’) in which the beam framing above the gathering room (known as the hiroma or oe) forms a strong cross-framed (igeta-gumi 井桁組) structure, and the framing of the other rooms is constructed as an accompaniment around this core. Two daikoku-bashira are erected on the central axis of the room, on opposing sides of the space; these are complemented by four corner posts, giving a total of six posts supporting the jо̄-ya part of the roof structure. Naturally there are many variations on this basic form.
An example of waku no uchi zukuri framing.
A waku no uchi zukuri (枠の内造り) structure showing a massive longitudinal beam (ushimon うしもん or 丑物) bearing on a daikoku-bashira post that looks slender in comparison, and cross beams (harimamon 梁間物).
The waku no uchi zukuri (枠の内造り) structure with various members labelled: the deep lintel beams (hiramon ひらもん, here ヒラモン), roof posts (tsuka 束, here ツカ), and two tiers of penetrating ties (nuki 貫, here ヌキ). Crossing the space are two longitudinal beams (ushimon うしもん) and two transverse beams, with a ‘hollow’ centre, indicating this as an igeta-gumi (井桁組) construction.
This atypical example shows four equal ushimon longitudinal beams, two bearing on main posts and two on roof posts that are in turn supported on the hiramon lintel beam, and a single harimamon cross-beam.
An eight-mat ‘living’ or ‘gathering’ room (hiroma or oe)
The frame of the structure above the level of the openings is formed of three or four tiers of timbers around the perimeter of the space, with infill plastering. The lowest tier, above the openings, consists of massive lintel beams (sashi-gamoi 差鴨居) known as hiramon (ひらもん), grooved to take the sliding partitions. Above this are tiers of ties that penetrate the posts, a longitudinal beam (here known as an ushimon, うしもん or 丑物) that spans across the centre of the space and ties the two daikoku-bashira, and perpendicular to this the cross-beams harimamon (梁間物). This arrangement results in a cruciform structure, but there are also igeta examples with twin ushimon Magnificent large section Japanese zelkova (keyaki 欅) beams finished into an octagonal section. To this strong central framework is added kake-gi (懸木, literal ‘hanging timbers’ for eaves (hisashi 庇) or lean-to structures front and back, and the roof framing of the rooms to the left and right.