In a row of arches the thrusts of neighbouring arches cancel over each intermediate pier, which may therefore be slender; at the ends of the row nothing balances them, so the outermost piers must be made wider or buttressed.
Rules · Walls · Materials · Façades
Rustic work at the foot
Rusticate the lowest storey or the basement, its stones marked by deep joints, as the plainest and strongest part of the building; keep the dressed stone, the orders and the ornament for the storeys above.
Serlio treats rustic work with the Tuscan order, the strongest and plainest, and shows it mixed with the orders on gates and the ground storeys of palaces. The joints may be cut horizontally only (banded rustication), as square channels between every stone, with the edges of the stones chamfered, or with the faces worked as if eaten by worms (vermiculation).
Over a window or door the joints radiate as voussoirs to a keystone, so that the opening is spanned by a flat arch of the rustication itself.
Related rules
Front a basilican church with two storeys of the order: the lower as wide as nave and chapels, the upper as wide as the nave alone, joined by scrolls and crowned by a pediment.
Il Gesù (reconstructed): lower ≈ 34 m wide, upper ≈ 20 m; scrolls fill the difference
Build up a façade in layers: let the wall advance in stages towards the central bay, double the pilasters or columns as it advances, and break the entablature forward over every support.
To unify a façade of two or more storeys, run a single order of pilasters or columns through all of them, from the base to the main cornice.
Let the wall of a façade curve in plan (concave, convex, concave) so that the front answers the street, the light and the space within, and the order bends with it.
Lift the dome on a cylindrical or polygonal drum pierced with windows between the ring of the pendentives and the springing of the dome, to light the centre of the church and to make the dome visible from afar.
drum height ≈ ⅓–1 × its radius (Byzantine); much taller in Russian churches
Cite this page Chris Paton, “Rustic work at the foot”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/rustic-base. Text, drawings and models licensed under CC BY-NC 4.0.