King post truss

What a king post truss is

A king post truss stands a single post at the centre with diagonal braces to either side, forming triangles. Because a triangle resists distortion, the frame balances its own forces and needs no column beneath it, unlike a Wagoya.

Wide buildings use it. The Showa storehouse at the Sakai brewery in Nagano Prefecture, from the early Showa period, is described as a single-storey brewing store about 22 by 11 metres, Kirizuma-zukuri and pantiled, boarded inside and roofed on trusses of this kind, its base finished in artificial stone with small hoods on iron Mochiokuri over its high windows.

The Kinryo soy sauce store in Kagawa Prefecture, from the Taisho period, is described as a single-storey building about 22 metres long, gabled and pantiled, distinguished by a monitor running almost the whole length of its ridge, roofed on the same trusses, and formerly used for mixing malting materials and housing machinery.

Schools used it as well. The south wing of the former Ayukawa school in Akita Prefecture, built in 1954, is roofed on these trusses, and the entry values it for conveying the classroom planning and construction of its day in a building of warm timber.

Set against the native roof frame

A Wagoya stands short posts on the beams to carry the purlins, passing the load straight down. A truss makes triangles of diagonal members and carries the force along their length. The principles differ, so the same span calls for different timber sizes.

Records keep the two apart. The Sanjido Sasaki storehouse in Miyagi Prefecture, from the middle Taisho period, is described as roofed on a Western truss, and the front store at the Yokoya brewery in Iwate Prefecture, built in 1902, as a long two-storey building in Dozo-zukuri about 41 by 12 metres roofed on trussed framing. The type is named where it can be identified precisely.

It concentrates in breweries, schools and factories, buildings that need wide unobstructed interiors. A storehouse exterior over a Western roof frame is a common combination in modern industrial architecture.

The roof frame also suggests a date. Western trusses spread in the modern period, so an otherwise traditional storehouse can be placed by what is above its ceiling.

On site, look up inside a building with no ceiling. A single upright post at the centre with diagonals running down to the ends of the beam identifies the type.