We have the same problem, and we've had it for over a year.
We live in a condo complex and have tried to get the management company to find the problem, and of course, no one can really smell it when they come by to check it out.
We've had plumbers, pest control people (because when this first started, we could hear something scurrying in the walls and ceiling, but no more, but the smell remains.)
Our smell arrives in late afternoon and throughout the evening. We've kept a log, and it doesn't seem to occur when the heat comes on or after we use the plumbing.
The one pest control guy we had come over when it did smell (in the AM) he only noticed a faint ammonia smell. He then left without any idea what was causing it.
We are at wits end! Do we just start tearing into the walls and floors?
It's weird, because we can smell it so strongly, but we can't pin-point its origin.
We haven't had our heating vents cleaned out, but I did get an estimate from a guy who said that if anything were in the vents, you'd see insulation parts at the vent opening. We don't see any of that. But, sometimes it does seem like we can smell it faintly at other vents.
So, here's what we know:
--The smell: ammonia/urine-like
--The location: strongest at entry into bedroom, which is near a bathroom
--The experts: a plumber checked for leaks (in a cursory way, if you ask me) and found none; pest control found no point of entry for possible pests, nor any pellets; contractors found no screens on vent openings open or broken
--The last plumber was also a contractor and his only advice was that we start tearing up walls, which he was sure we didn't want to do. However, he couldn't smell the smell and has no idea how annoying and unpleasant it is.
Does anyone know if this ammonia-like smell is toxic? Our daughter sleeps in that room!
Perhaps it's worth having the vents cleaned out just in case (this isn't cheap!)
sign me, stinkycondoinCA
[This message has been edited by arichardson (edited November 15, 2003).]