Estimativa paramétrica para orçamentação de obras na etapa de análise de viabilidade

Abstract

Feasibility analysis is a fundamental step in the planning and design of any construction project, as it directly affects decision-making regarding its technical and financial viability. In this context, the objective of this study was to estimate the construction cost of a 70m² residential building using two different cost estimation methodologies. The first method applied was the stage-based cost estimation. This approach began with the calculation of the total cost using the Basic Unit Cost (CUB), followed by the application of proportional cost distributions for each construction stage, as defined by previous studies in the field. The second method was based on parametric equations developed by other authors, which enable the estimation of service quantities based on the built area. These quantities are then multiplied by unit costs to determine the total project cost. To evaluate and compare the accuracy of both methods, a detailed budget of the construction was prepared. The results showed that the cost estimated using the stage-based method was 8,5% lower than the amount calculated through the detailed budget. In contrast, the parametric approach was able to estimate only 65% of the total construction cost, due to the lack of available equations for certain services such as foundation and roofing. By estimating the remaining 35% using values from the detailed budget, the total cost calculated via the parametric method would be approximately 0.56% higher than the detailed estimate. Accordingly, the unit costs obtained through the two estimation methods were R$ 2,949.36/m² (parametric) and R$ 2,733.59/m² (stage-based), while the detailed budget indicated a cost of R$ 2,718.27/m². In conclusion, both methodologies proved to be useful in the early stages of project development, provided they are supported by up-to-date, region-specific, and project-appropriate data.