A Building permit is required to construct any new structure or improve existing buildings and other structures. The Building Services Division issues building permits for residential and commercial structures in the unincorporated areas of San Diego County.We've got 16 windows and a sliding door. When completing multi-family projects, we typically work with the building's owner or property manager to replace all the windows in the building at one time. Existing doors or windows to be replaced are not required to be fire-resistive or compliant with the Very High Fire Hazard Severity Zone (VHFHSZ) requirements. Glass windows on the building have been shattering, but no one knows why. If you're adding a new window or door or changing the size of an existing one, then you are changing structure. Are your old windows costing you money? Learn when to replace them, and about the costs of and steps for a window installation in San Diego.