This paper aims to quantify the labor productivity improvement reached by the implementation of a masonry wall project design to guide field construction. A masonry wall project design is an instrument of rationalization, developed to specify the layout and steps of a masonry walls execution. The methodology is of quantitative nature and involves a practical case. The work of an enterprise in Goiânia (Brazil) was tracked by the collection of productivity data, firstly of a crew that didn’t have access to a masonry wall project design, and then of a crew that had access to the project. The evaluation of the productivity improvement was processed by means of statistical analysis, such as location and dispersion measures, average and variance, T-test, and F-value. Hypothesis tests were also performed to prove that the changes in productivity were caused by the implementation of the masonry project. The results showed that the project deployment optimized the production process in the field. There was a 26% increase in the team average productivity with access to the project design according to the hypothesis tests. The main contribution of this work is to present the beneficial impact of a masonry wall project design tailored for field construction, which allows a formal and rational approach to a heavily artisanal technique.