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.
Rules · Cities · Façades · Materials
One street, one front
Build every house on a new street to the same alignment, in dressed stone, with its floors, balconies and cornice at the levels of its neighbours, and keep the fronts clean, so that the street reads as a single wall.
The 1852 decree gave the city control of alignment and required plans before building and the periodic cleaning of façades; on the most important new streets and places the conditions of sale went further and prescribed the elevation itself. The rest was done by the market and by habit: builders used the same stone, the same storey heights and the same continuous balconies, so that a boulevard of hundreds of separately built houses reads as one long palace front.
Against this neutral wall the monuments (the Opéra, the churches, the stations) could be as rich as the Beaux-Arts cared to make them.
Related rules
Understand every building as a combination of four elements (the hearth, the roof on its supports, the enclosure and the mound), each descended from a craft: ceramics, carpentry, weaving and masonry.
Do not leave the fronts of houses to the whim of each builder: let the authorities fix their line, height and design so that a street or square is composed as a whole, and vary the designs from one street to the next so that uniformity does not become tedium.
Cut new straight streets through the old city to join its railway stations to one another and to its centre, and end each one on a monument (a station, a church, an opera house) so that it has an object as well as a use.
Tie the height of every house front to the width of its street: on streets 20 m wide or more the cornice may stand at 20 m, on narrower streets lower; above the cornice the roof must stay inside a line rising at 45°.
street ≥ 20 m → cornice ≤ 20 m; street < 20 m → cornice ≤ c. 17.5 m (older rule); roof inside 45°
Where many avenues meet, make a round place with a monument at its centre, bring the avenues to it at equal angles, and wall the place with uniform buildings between them.
Cite this page Chris Paton, “One street, one front”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/paris-uniform-street-wall. Text, drawings and models licensed under CC BY-NC 4.0.