Ergonomic risks are a global problem in construction, with health effects that have an impact on the economy. Risk assessment allows companies to identify the risks and the exposure levels to which the workers are subjected and allows to define management plans to address them. However, studies to assess risk levels through new techniques are very scarce in construction. This study aims to evaluate ergonomic risks in construction workers using Ergo/IBV (software for the assessment of ergonomic risks and design recommendations) by the observational REBA (Rapid Entire Body Assessment) method. Data were collected from 14 public sector building projects from May to November 2023. Thirty-two construction finishing activities were identified. Through the stratified method, the five most frequently executed activities were selected: interior and exterior painting, floor ceramics, wall plastering, ceiling and wall plastering. This made it possible to evaluate the ergonomic risk in 94 workers. The evaluation shows that 40 % of the workers were exposed to a high-risk level in the trunk, 2 % in the legs, 20 % in the right arm, and 22 % in the left arm. In short, the five activities adopt forced postures, with REBA scores: medium, high and very high, with high risk level being the most relevant.