Sour or ammonia like odor in house
We cannot figure out an intermittent smell we have in our house. It seems to absorb into certain fabric very quickly and only really gets strong on high humidity or rainy days. Our house is very old (100 yrs) but a lot of the house is updated with newer drywall where the previous owners built on additions or renovated. The rest is plaster. The smell seems concentrated near the left side where plumbing stack is but the plumber found no visible issues when looking at the cast iron pipe in the casement. Pest company also do not believe it’s caused by rodents as there are no signs. We have no visible issue with most of our sinks, tubs etc. Everything seems to drain decently except one sink that’s opposite side of the house. I’m really starting to lose it. The smell becomes so abundant when I’ve been away and i have a bag or something that the odor has absorbed into. We do in addition have a “old house” smell which I’m sure is the material aging but something else I’ll need to solve for after this! Anyone have similar issues and found the source?