BIM cost estimation guidelines for Brazilian public sector infrastructure

The cost estimation of public sector projects in Brazil must observe the prevailing legislative framework to reduce the likelihood of under-and-over pricing of construction works and potential corruption. Therefore, initial estimates for projects must be prepared using the National System of Costs and Civil Construction Indices (SINAPI). This is a labor-intensive process, and the result estimates produced may be inaccurate. Therefore, it becomes difficult to determine if the under-or-over pricing of works has arisen during the tendering process. The problem is approached with new guidelines for improving the accuracy of estimates that utilizes SINAPI methodology with Building Information Modelling cost estimation. The research method used was Design Science Research (DSR) developing: problem diagnosis, solution proposition, implementation, and evaluation of contributions. The proposed guidelines were tested in two projects: a multi-family residential building and a Reference Center for Social Assistance (CRAS) using a BIM authoring platform. It has been demonstrated that text parameters can be used to identify material specifications, the geometry of elements, and specify substrates, improving the process to generate an estimate following ‘SINAPI factors’ tree’ elemental costs. The guidelines comply with prevailing Brazilian legislation and can improve the process and accuracy of the pre-tender estimate.