Shearing layers

Shearing layers is a concept coined by architect Frank Duffy, which was later elaborated by Stewart Brand in his book, How Buildings Learn: What Happens After They’re Built (Brand, 1994), and refers to buildings as composed of several layers of change. The concept has been adopted by a number of technology vendors to also describe the different layers of systems within an organisation.

Description

The Shearing layers concept views buildings as a set of components that evolve in different timescales; Frank Duffy summarized this view in his phrase: “Our basic argument is that there isn't any such thing as a building. A building properly conceived is several layers of longevity of built components” (quoted in (Brand, 1994)).

The layers are (quoted from Brand, 1994):

Theory

The concept is based on the work of ecologists (O’Neill et al., 1985) and systems theorists (Salthe, 1993). The idea is that there are processes in nature, which operate in different timescales and as a result there is little or no exchange of energy/mass/information between them. Brand transferred this intuition to buildings and noticed that traditional buildings were able to adapt because they allowed “slippage” of layers: i.e. faster layers (services) were not obstructed by slower ones (structure).