The Distinction between Mushroom and Umbrella Structures in Slovene Architecture

Abstract

A brief historical overview of the development of tree-inspired structures is given first. It starts with the world's first three mushroom slab constructions built from 1906 to 1908 and continues with several tree-inspired roof structures of the first half of the twentieth century. The main part of the paper describes eight selected buildings in Ljubljana, Slovenia, all of them examples of mushroom or umbrella structures made of reinforced concrete. The oldest described building is an experimental structure from 1933, then come two pavilions built at Ljubljana's Exhibition Centre, three different examples of gas stations, canopies for cars, and canopies at the Ljubljana's main railway station. Except the oldest one, all were built in the 1960's and early 1970's. The buildings are compared quantitatively regarding their overall size, shape of the roof, and the number of the repetitive structures these buildings are made of. The type of each described structure is examined and compared to others. Laymen and even some experts often use the terms mushroom and umbrella structure imprecisely, the indifference and the lack of knowledge being the most probable reasons. Based on the presented analysis it is asserted that the distinction between mushroom and umbrella structures must be made regarding how the load force is transferred from the roof to the pillar. This distinction should also be made first when classifying recently built tree-inspired structures.