The only way you will know, is to have someone come and test the sheetrock. Since its worst in the bathroom, have them check for sewer gas, and improper venting, etc. I would not start tearing stuff up, until you definitely know just where the smell is coming from.

Thank you. I am thinking about who to contact, and am thinking a home inspector might be the way to go. Can you think of another option besides a mold specialist?

I would try an air circulating fan. Based on the sq footage, 1,100, I would try 300 cfm.

eta: i would try an air circulating fan to change the air in the building. open some doors , windows and turn on the fan.

If your hvac is forced air, change the filters.

my thougts are: if your air is ”funky” change it.

A good home inspector can recommend good testing companies. A lot of testing companies are really scammy. So much of it comes down to getting a super experienced tester with a heart of gold who will help you brainstorm anything it could be and what they have seen over the years.

Do others smell the odor as strongly as you do? If you run a dehumidifier in the basement, does much water come out? If you run it around the clock does the odor go away? Have you used a window fan facing outwards to suck the air out of the house and see if that helps? Do you only smell it in the basement? What is the source that is causing the mildew on the joists? You had this area remediated, but did you figure out what the root cause of it was?

So sorry you are dealing with this. I'm terribly sensitive to odors, have lots of allergies, and dealt with this once myself as well.

I would think about the ramifications of testing and when you eventually sell, do you have to disclose the result of tests you have done and if so within what time period.

My husband says he sometimes smells an odor but thinks its the cat’s litter box. (Its definitely not that.) We have a dehumidifier running 24/7 in the basement and it’s helped but it didn’t make a huge difference as far as any odors go.

I haven’t tried a window fan, but just started journaling daily to see if any patterns arise. I haven’t been able to pinpoint a pattern in the years we’ve been here but I figured if I write the info down, maybe one will start to appear.

I haven‘t asked many other visitors if they notice the smell, but i did ask my inlaws, and my mother in law said there used to be an odor but she doesnt smell it now. My brother in law said he smells something, but that its not a ”bad” odor, more like new construction.

I’m at complete loss at this point.

Thank you for the recommendation of contacting the health dept, as I hadn’t thought of that.

As far as selling the house goes, I’m not sure about what has to be disclosed by law, but i would have all documentation of testing and remediation available, if needed.

Thank you to all who responded to this post. I think I may have found at least one of the major sources: our air purifier. I do change the filters regularly, and clean it out too, but after our cat, who likes to "dance" on it lol turned it off and we didn't catch that right away, it stayed turned off for a few days. I noticed that the smell was dissipating, and realized that it's probably the purifier. I'm not sure about how long these appliances are made to last, but ours is about seven years old and has been through a lot, I suppose. We are getting rid of it and I am thrilled beyond words. I always wished we could have an easy fix to this situation like the ones I've read about and here we are!

Have you tried using odor-absorbing products or maybe even a dehumidifier in the basement to see if it helps? Sometimes those work wonders. As for an "odor expert," that's a fascinating idea! I didn't know they existed either. Maybe there's someone out there who can sniff out the root cause. Have you considered reaching out to a local contractor or even your home insurance to see if they have any recommendations? They might have come across similar situations. I stumbled upon this End of Tenancy Cleaning service – not sure if they could help, but they might have insights. Here's the link https://www.eotcleanic.co.uk. Maybe they have some tips or could connect you with someone in the know.