Take the section of the standard timber, the cai, as the module of the building: it is 15 fen high and 10 fen wide, and every member is dimensioned in fen.
1 cai = 15 fen (height) × 10 fen (width)
Rules · Proportion · Façades
Diminish the pagoda upward
Make each storey of a pagoda narrower than the one below and derive all from the bay of the first storey; in the oldest Japanese pagodas the top storey is about half as wide as the first.
top storey ≈ ½ first storey (Hōryū-ji)
The pagoda descends from the Indian stupa by way of the Chinese watch-tower: a reliquary raised on storeys of roofs. Its beauty depends on the rate at which the roofs diminish. At Hōryū-ji the reduction is strong, so the pagoda looks stable and grave; later pagodas diminish less and look slenderer. The Shōmei fixes the reduction storey by storey as fractions of the lowest bay. The storeys are not usable floors: the interior is a dense cage of timber around the central pillar.
Related rules
There are eight grades of cai, from 9 × 6 cun down to 4½ × 3 cun; use the first for great halls of nine or eleven bays and the smallest for pavilions and ceiling coffers.
grades 1–8: 9×6, 8¼×5½, 7½×5, 7.2×4.8, 6.6×4.4, 6×4, 5¼×3½, 4½×3 cun
For a great hall, measure the distance between the front and back eave purlins and raise the ridge purlin above them by one third of it; for lesser halls, by about a quarter.
rise = ⅓ × depth between eave purlins (halls); ≈ ¼ (+ a small addition) for ting-tang halls
Make the central bay (mingjian) the widest and let the bays diminish toward the ends; keep the eave columns no taller than the width of their bay.
Make each column a little taller than the one nearer the centre, so that the corner columns stand highest: by 2 cun per column outward from the central bay, giving 6 cun at the corners of a seven-bay hall and 1 chi 2 cun for thirteen bays.
corner rise = (bays − 1) cun · each step outward = 2 cun
Project the eaves from the centre of the eave purlin by 3½ chi for rafters of 3 cun diameter and 4 to 4½ chi for rafters of 5 cun; beyond them add flying rafters projecting six-tenths as far again.
eave projection ≈ 3½–4½ chi · flying rafters = 0.6 × eave projection
Cite this page Chris Paton, “Diminish the pagoda upward”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/pagoda-diminish. Text, drawings and models licensed under CC BY-NC 4.0.