Client from 18 months ago called to see if I could help find someone who could identify and fix a bad smell in the house. House is 18 years old and seemed in good shape. He characterizes the smell as "acid metallic" and says it is year round but stronger in summer. They notice it in the basement and one second floor bedroom. He said it is not a sewer smell nor a sulfur smell. It does not seem to be linked to the water system or heating system. He has had a plumber and HVAC person there to look (smell) around. He has cleaned the heat ducts, the floor drain, the sump, the sanitary sump, and the basement surfaces. (I believe the regular sump is not sealed.) I might have thought aldehydes, like from some heating systems, but would have thought the HVAC visit would have ruled that out.
There is a well, which he will chlorinate this week, but he says the odor does not seem to originate from the water system.
My report at the time indicated that the house seemed to have excess moisture - I had a note saying it should not need a humidifier in winter in our climate. He said they use two humidifiers ( he did not tell me what prompts them to believe they need them), but the basement has no seepage and the sump pump runs no more than once a day, even with our heavy rains.

I plan to go over there and smell for myself, but wondered what ideas folks might have as to what to look for.
For lack of better idea now, I gave him a lead to one of our Wisconsin IAQ friends.

Roger
First thing I would do is call and confirm the agent who handled the deal is still alive?
Seriously, I'll bet it is moisture related. When different type soils or products get wet they give off different odors. The humidifier is probably the tip of the ice berg.
Good luck, but a friendly word of advice, do not offer any opinions on what the cause is unless you’re absolutely positive. This also has the smell of a potential law suit and whatever you say may and will be held against you. Remember, in our profession no good deed goes unpunished.

__________________
Jerry McCarthy
Construction Consultant
www.expertbuildingconsultants.com

The smell could be anything but damp humid conditions have a way of bringing dormant smells or odors back to life, pet urine stains particularly.

Oh, sure, blame it on the dog. Hey, man, humans urinate too, ya know. And half of 'em miss!

Sincerely, Rusty
Doggone Best Home Inspections

In the old days of Veterans' Stadium (aka - The Vet), that's where all the smells came from.

Don't assume anything.

" I might have thought aldehydes, like from some heating systems, but would have thought the HVAC visit would have ruled that out."

One person to confirm all things. Recheck everything.

Jerry has a good point about moisture.

You may look and see if any other reports were done on the home as part of the sale. In Calif we file Structural pest report with the state. these reports can be requested from 2 years back from the date of inspection.

Have the owner pull any information about the sale and the disclosures forms.

If the you have slab floors do a sound check by tapping on the concrete. I find Voids under slabs all the time and they can be a problem area.

Best

Ron