Rules · Façades · Walls · Structure
Set the columns back from the edge of the slab, so that the outer wall carries nothing and can be opened, closed or glazed at will.
cantilever of slab beyond column line ≈ ⅕–⅓ of the bay
Once the slab cantilevers beyond the last row of columns, the façade becomes a light membrane (a thin wall, a band of glass, or both) designed for light, view and composition rather than for load. The same principle, carried to its limit in steel, produces the glass curtain wall.
A saddle surface in which two opposite corners are raised and two lowered is a hyperbolic paraboloid; it contains two families of straight lines, so it can be formed with straight boards and yet has double curvature.
y = k·x·z (or any bilinear patch through four points not in one plane)
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)
Span the whole depth of the building with the structure so that each floor is a single open plate, adaptable to uses that cannot be foreseen.
Pompidou: 48 m clear span between column lines, 13 bays of 12.8 m
In a framed building the columns and beams carry every load; the outer wall can be reduced to a light cladding hung on the frame, floor by floor, and need grow no thicker as the building rises.
load-bearing wall: thickness grows with height · frame: cladding thickness constant
Build the house as a standard skeleton of flat concrete slabs, a few columns set back from the slab edges, and a stair; everything else (walls, windows, partitions) is infill that can be placed freely.
3 slabs + 6 columns + 1 stair
With a concrete frame, a house should stand on pilotis, have a free plan and a free façade, be lit by horizontal ribbon windows, and carry a garden on its flat roof.
pilotis · free plan · free façade · ribbon window · roof garden
Cite this page Chris Paton, “The free façade”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/free-facade. Text, drawings and models licensed under CC BY-NC 4.0.