Rafter

Also called rafters, flying rafter, feizi

One of the inclined timbers running from ridge or purlin down to the eaves and carrying the roof covering. In Chinese roofs the eave rafters are extended by flatter flying rafters (feizi).

Rules that use the word

Qing jǔjià: five-tenths at the eaves, nine at the ridge. Give each rafter span a fixed slope, increasing from the eaves to the ridge: half-pitch (5 jǔ) for the eave span, then about 6½ or 7, 7½, and 9 tenths for the span below the ridge.

Let the eaves grow out at the corners. From the intermediate bracket set of the second bay the rafter ends advance progressively outward, so that at the corner the eave projects further (by 4 cun for a hall of one bay, 5 for three bays, 7 for five bays) and rises with the corner beam.

Eaves in proportion to the rafters. 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.

Kiwari: size every member from the bay. Fix the bay (the distance between column centres) and derive every other member from it by fixed ratios: the column from the bay, the brackets and beams from the column, the rafters and their spacing from the brackets, the eaves from the rafters.

Tie the feet of the rafters: the truss. To roof a wide span, join each pair of rafters to a tie beam at their feet so that the three form a triangle that cannot spread; hang the tie beam from the apex by a king post, or by two queen posts on larger spans.

Where it appears in the book

In the chapters Post and Lintel, The Roof, The Doric Order, The Ionic Order, China, Japan and Korea.

A feature of Craftsman architecture.

Nearby in the glossary

Quincunx · Quinto acuto · Quoin · Radiating chapels · Ratha · Redented · Regula · Regulating lines