Have a frequent “sewage type” smell in my basement and sometimes it moves up to living area. The odor began after an addition to the house. Our septic lines and tank were replaced and are not adjacent to the area of the odor. There are no floor drains in the basement and no dry traps. The odor is most noticable when there is moisture outside-rain, snow , high hunidity; otherwise generally not present. No odor from sump pump or sealed ejector pit and pump. Vent stacks have been checked and are clear. All drain and sewer ines inthe basement are new and are exposed. None are leaking and no direct odor assoicated with them. No moisture on floor or at joints with walls. Crawl space is dry and no odor. Brine tank for water softner has ben cleaned. At a loss for source of odor or how to solve. Any thoughts?