The present research work displays a proposal of cost estimation guidelines for private architectural projects in Colombia. Based on the theory that a classification model allows for more specific developments depending on the particularities of each project, three classes were defined in a scope function, and the guidelines were adjusted to each of them. As a result of the research, in addition to the aforementioned guidelines, a cost breakdown structure (CBS) is provided for each project class with the typical packages that make up its budget in terms of product scope, project scope, management associated costs, environmental costs, legal costs, financial costs, contingency and reserves costs. The objective is to provide Colombian companies with elements of easy understanding and use, which will allow them to develop more accurate estimates, reducing the risk of deviations in costs due to this factor.