(a) Decks or patios that are enclosed by windows or screens and a permanent roof shall be considered as accessory structures rather than as part of the principal building. Such decks shall be subject to the requirements of Tables 33 and 34, Sections 1159.20 and 1159.21.
(b) No open porch shall cover more than twenty percent (20%) of the required front yard, or of the actual front yard if it is smaller than the required front yard.