Framework for (semi) automatised construction specification and quantity takeoff in the context of small and medium architectural design offices

Abstract

BIM-based construction specification and quantity takeoff (QTO) processes have proven faster and more reliable than traditional methods. However, their execution and integration still rely on time-consuming and error-prone manual or semi-automatic interventions to deal with the lack of completeness, suitability and granularity of produced BIM models in design practice, mostly related to elements and activities not digitally represented in these models. In addition, besides the BIM authoring tool, they demand other proprietary platforms to obtain the expected outcomes, leading to interoperability issues and representing an obstacle to small and medium architectural design offices in terms of needed investment and customisations inherent to their business model. This work addresses the problem by proposing a BIM-based framework for automatised coordinated construction specification and quantity takeoff. It encompasses information modelling requirements, establishing a construction specification database and an add-in on the authoring tool that automatically produces joint construction specifications and quantity QTO documentation. The proposed system improves current BIM-based practices by mitigating the number of non-automatised intermediary steps, not requiring any other proprietary BIM platform rather than the authoring tool. Besides, it structures alternative ways of digitally representing elements and activities not graphically expressed in the model, allowing automated, more efficient, faster and cheaper production of coordinated reports of quantities and construction specifications. Two real projects validated the implementation of the framework, as well as the capabilities of the add-in, demonstrating its applicability in practical cases.