No building or any porch thereof shall be erected and no building or any porch thereof shall be reconstructed or altered so as to project in anywise beyond the average setback line observed by the buildings on the same side of the street, within the block, at the time of the passage of this chapter. Where there are existing buildings at the time of passage of this chapter on only one side of the street within the block, then the setback line on the vacant side shall be the same as the average setback line on the improved side of the street within the block. The foregoing rule shall, however, in no case be applied so as to keep the street wall, walls or porches of buildings further back from the street line than the maximum depth of front yard indicated in the Schedule Limiting Height and Bulk of Buildings for the zone in which such building is located.[1] Where there is no existing building on either side of the street within the block, no new building shall be erected with its street wall, walls or porches nearer to the street line than the maximum or minimum depth of front yard shown for each respective zone in the schedule.

Encroachments into front yards are hereby permitted in residential districts as provided in this section, only for one-story porticos and open terraces not to exceed a maximum of eight feet in width, provided that the encroachment is no more than five feet.