The aim of this research was to examine the design considerations needed to control the access of sunlight in exterior and interior architecture that ensure healthy buildings to avoid deficiency of Vitamin D. The study was conducted in the city of Jeddah, Saudi Arabia through field visits to one hundred and fifty residential buildings for the purpose of measuring the extent of their application considerations in external and internal design. The external considerations usually were imposed on the users and this made them difficult to modify, whilst interior design was shared between the thoughts and experience of designer and the needs and desires of the users. The research question was: What is the extent of design considerations in residential buildings to ensure sufficient sunlight access inside the house? It was found from the results that there are shortcomings in the application of considerations concerning external design, which is the architect and designer's responsibility, such as the direction of the building, setback, landscaping, window size, direction and height of the building. In terms of internal design, considerations included distribution of spatial activities, functional methods and design of systems and technology. A lot of users failed to utilize this design to their advantage to ensure deficiency of Vitamin D inside the house in order to maintain their health as well as to maintain their culture and privacy.