Alternating tread stairs are a great space saver and are a very efficient mode of travel between levels. The down side is that they are not accepted by many jurisdictions inside and outside US. Many building inspectors and fire marshals will not allow alternating tread stairs in residential installations as the only means of egress between levels.
However, there are certain cases where you are permitted to utilize alternating tread stairs. The US allows their use in industrial applications and many codes in the US will allow the use of an alternating tread device as a second means of egress from or access to a space. I have also read that alternating tread stairs can be used in residential applications if the stair is accessing a level or space that does not contain the only restroom.
I have had the fortunate pleasure of traversing several examples of alternating tread stairs. The one that I fondly remember, since it was my first introduction to the sort… was that of a concrete staircase at Castelvecchio, by Carlo Scarpa in Verona, Italy. It is not a major stair of note by any means and is actually tucked back out of the way in the museum, but never having used such a stair, the first couple of steps were tentative. It definitely takes some getting use to.
For those who don’t know, Carlo Scarpa , was an Italian architect, influenced by the materials, landscape, and the history of Venetian culture, and Japan. Scarpa was also a glass and furniture designer of note.
Scarpa was born in Venice. Much of his early childhood was spent in Vicenza, where his family relocated when he was 2 years old. After his mother’s death when he was 13, he, his father and brother moved back to Venice. Carlo attended the Academy of Fine Arts where he focused on architectural studies. Graduated from the Accademia in Venice, with the title of Professor of Architecture, he apprenticed with the architect Francesco Rinaldo. Scarpa married the Rinaldo’s niece, Onorina Lazzari.
However, Scarpa refused to sit the pro forma professional exam administrated by the Italian Government after World War II. As a consequence, he was not permitted to practice architecture without associating with an architect. Hence, those who worked with him, his clients, associates, craftspersons, called him “Professor”, rather than “architect”.
His architecture is deeply sensitive to the changes of time, from seasons to history, rooted in a sensuous material imagination. He was Mario Botta’s thesis adviser along with Giuseppe Mazzariol; the latter was the Director of the Fondazione Querini Stampalia when Scarpa completed his renovation and garden for that institution. Scarpa taught drawing and Interior Decoration at the Istituto universitario di architettura di Venezia from the late 1940s until his death. While most of his built work is located in the Veneto, he made designs of landscapes, gardens, and buildings, for other regions of Italy as well as Canada, the United States, Saudi Arabia, France and Switzerland.
Now, with that little history lesson out of the way, here are some more alternating tread stairs…. enjoy!