Shape the space between buildings as carefully as the rooms: make outdoor spaces partly enclosed and convex, like outdoor rooms, rather than leftover gaps around freestanding objects.
Rules · Roofs · Façades · Site
Emphasise the horizontal
On flat land, keep the house low and let its lines run parallel to the ground: low-pitched hipped roofs with deep overhangs, continuous sills and copings, bands of windows, and terraces extending into the garden.
roof pitch ≈ 15°–25° · eaves projecting 1.5–3 m
Wright described the prairie of the Midwest as having a quiet level beauty of its own, and designed his houses to belong to it: the gently sloping roofs sheltering broad eaves, the long bands of leaded glass, the low walls and planters stretching the house into the land. The Robie House in Chicago (1909–10) cantilevers its roof some 6 m beyond its last support. The deep overhang also shades the windows from the summer sun.
Related rules
Make the roof visible, and bring its eaves down low enough, and far enough out, that the building reads as a shelter from the street and the garden.
A thin curved shell carries load by the membrane forces in its surface, not by bending; so shape it to its loads and supports, and it can span great distances with a thickness of a few centimetres.
span ÷ thickness of a good shell ≈ 400–1000 (an egg: ≈ 100)
A fabric or cable-net roof is stable only if it is prestressed into an anticlastic (saddle) shape, curved upward in one direction and downward in the other, so that wind from either side meets a surface already in tension.
On an equator-facing window, make the overhang deep enough to shade the whole window from the high noon sun of summer, and no deeper, so that the low winter sun passes beneath it into the room.
noon sun altitude = 90° − latitude ± 23.44° · overhang D = window height ⁄ tan(summer altitude)
Give each room the aspect that suits the hours it is used: the drawing room to the south-east, the morning room to the east, the library a little east of south-east, the dining room to the north or north-east, cool and out of the evening sun, and the kitchen and offices to the north; the best aspect of all is south-east, the worst south-west.
Cite this page Chris Paton, “Emphasise the horizontal”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/prairie-horizontal. Text, drawings and models licensed under CC BY-NC 4.0.