No permit shall be required in the case of any repair work as follows:
(a) The stopping of leaks in drains, soil waste, or vent pipes which are defective; but if it becomes necessary to remove or replace the same with new material in any part or parts, the same shall be considered as new work, and a permit shall be procured and inspection made as hereinbefore provided.
(b) The clearing of stoppages or the repairing of leaks in pipes, valves, or fixtures, when these repairs do not involve or require the replacement or rearrangement of valves, pipes, or fixtures.
(1980 Code 174.09)