Building Information Modelling and the documentation of architectural heritage: Between the ‘typical’ and the ‘specific’

One of the greatest challenges to using Building Information Modelling (BIM) for the documentation of architectural heritage is in overcoming the propensity of the software toward standardization. Most BIM applications are optimized for industrialized building systems where even a minor deviation in geometry or dimension between like elements is considered problematic. Heritage buildings, on the other hand, are more typically constructed of unique elements that, while sometimes similar, can never be assumed to be identical. For example, two Corinthian capitals from the Temple of Mars Ultor may be similar, but they are not the same. In this paper, we discuss a novel method for developing a BIM for a unique vernacular building in eastern Ontario, Canada. Constructed anonymously in two discrete stages during the last half of the 19C, the builders employed both stacked log and an idiosyncratic balloon frame construction. Both types of construction are far from the standard assemblies found in commercial BIM software. In discussing the construction of the model, we will outline the integration of detailed survey data, including pointcloud, with a library of `typical', but parametric, construction details under development by our research group. While the survey provides an accurate geometrical record of the building under discussion - including structural deformations - the library is used to develop the specific assemblies and is based on, and fully indexed to, `typical' details culled from construction manuals available in Canada during the late 19C.