Height of buildings; floor area between fire walls

No building hereafter erected or altered shall exceed four stories or fifty-five feet in height, unless it be of fireproof construction, when it shall not exceed fifteen stories or one hundred and ninety feet. Except when built as specified in SECTION 5-25-920, no building hereafter erected having walls of hollow terra-cotta or concrete blocks shall exceed three stories or forty feet in height. The floor area between fire walls of nonfireproof buildings shall not exceed the following: When fronting on one street, five thousand square feet; when fronting on two streets, six thousand square feet; and when fronting on three streets, seven thousand five hundred square feet. These area limits may be increased under the following conditions, as indicated: For nonfireproof buildings, fully equipped with approved automatic sprinklers, fifty per cent; for fireproof buildings, not exceeding one hundred and twenty-five feet in height, fifty per cent; for fireproof buildings, not exceeding one hundred and twenty-five feet in height, fully equipped with approved automatic sprinklers, one hundred per cent.