A comparative analysis of durability by design of two similar architectural projects from the point of view of the architect is presented to understand factors that affect their service life by means of a methodological approach consisted in analyzing several variables that affect and determine the response variable which refers to the Estimated Service Life (ESL) of the building. The results show that one of the projects complies with the premise that ESL is greater than Reference Service Life (RSL), therefore, it does not require re-design and can move directly to the construction phase; on the contrary, in the other project, ESL does not exceed RSL, and in this way, it is recommended to return to the design phase to be improved once durability key points are identified. It is concluded that it is an approximate method that can be very useful in the early stages of design and also to plan the maintenance phase.