The advent of digital architecture, including parametric design, enabled the customization in housing design. The parametric typological design allowed diversity, difference, and individuality with the same ease of mass- standardized production. Accordingly, the paper investigated the customization of housing components to satisfy the customer's options and in response to different local conditions. The research problem was the application of customization in parametric typological design to generate prototypes for single-family houses of Ain Al Iraq project in Mosul city. The research aims were to identify the customization methodology and to apply it in a case study. The previous studies put forward different approaches combining generative systems controlled by a set of parameters, constraints and rules developed by the designer, and the interactive customized systems that allow customers to participate in the design process. In the light of these studies, the paper presented a theoretical framework to define the methodology of applying the customization in the parametric typological design process using four vocabularies to identify the types of customization, the methods of standardization, and the roles of a designer and a customer. In the practical study, the approach was applied to create a parametric model using (Grasshopper) software, in order to generate initial plans for single-family houses that were customized according to the customer's need. The user interface was also designed by the researchers to provide direct interaction and ease of use by regular customers. The results showed the generation of initial plans having varied parameters according to the customer's options.