Yes, a building permit is required for this type of building alteration. A patio slab is not typically constructed with a foundation and will require some additional support to carry the loads of the new walls and windows. Also, many enclosed patios include extensive use of windows and glass doors, therefore code issues involving tempered glass and lateral bracing requirements should be discussed with a Plans Examiner. The use of metal structural components will require engineered drawings, which are signed and sealed by an engineer licensed in the State of Mississippi.