That was my first thought upon experiencing the smell but 1. we stacked the flooring in the room for 10 days before installation and there was only a mild toasted smell from it, 2. it took me a month or so to install it and there was no smell then, 3. the room was finished for about 2 months before the odor appeared 4. the floor was pre-finished so is sealed when installed (unless the sealer is the source) and 5. when I put my nose to the floor I don't detect the smell, it seems to float in the upper air of the room, generally nearer to one wall. By the way, the tales of stinking sheetrock from China had me worried but that smell is reputed to be sulfurous and detectable right away. We used Benjamin Moore low VOC paint which was recommended to me by a paint chemist friend who does not work for Benjamin Moore. It has gotta be an animal but 1. the walls are now more sealed then they ever were- how did it get in? 2. the smelliest wall is the shared bathroom wall and there is no hint of odor in the bathroom 3. it is not a consistent smell, sometimes it is gone for days, sometimes it stinks all day and all night, sometimes I smell it, tell my wife to come smell and she detects nothing only a minute later. I am beginning to doubt my sanity. Again, a very sour pungent odor, like BO from a New York City cabbie wafting off the plastic seats.

What are the chances that somewhere in that room (above, below or sideways) some small animal could have died and left your his 'scent'?

You may want to google chinese drywall problem. Seems the problem isn't necessarily showing up right away.

Same experience here, and the culprit turned out to be the paint. I would contact your paint manufacturer's representative and ask about that.

Try googling [low voc paint fishy] and you'll see a lot of similar stories.

The guys at the paint store told me the best bet for covering it up is a primer called "Zinsser BIN". It smells like solvents at first, but is odorless when dry. They said it will seal in any smell, even cat spray and smoke damage.

Also, if you google [wall odour phenomenon] you'll find stories from England -- BBC was brave enough to do a story on it, to the chagrin of the paint companies.

Good luck!

If it's possibly paint there are several pros that are regulars in Paint forum here. Maybe they've encountered something similar, or know of it?

BIN is good stuff. We had candle soot all over rental house walls, it sealed the soot in so we could paint. (Regular primer wouldn't have worked, the stuff was slick as wax paper no matter how many times it was washed/sanded.)

Zinser BIN is a shellac based primer/sealer.

It will smell like alcohol until it dries.

You could also just use shellac.

You say the smelliest wall is the shared wall with a bathroom? Where there's a bathroom, there's a lot of potential for smells and not necessarily in the bathroom. If there is any pipe or drain on that wall, try pulling the stoppers out of the drains, snake the drains, then use a drain cleaner on the pipes. If the wall is shared with the toilet, look at the wall behind the toilet and see if you've got a moisture problem. If this room in uninhabitable, I'd be planning to rehab that bathroom next.

Spray foam insulation is good for a lot of things but it's a bad sponge if there's any moisture. If a pipe isn't vented correctly, that could also be the source. Since this smell only started after the remodel, maybe the foam damaged or uncovered a problem.

My money is on a drainpipe joint dislodged by the spray foam (the non-door/window stuff is very powerful and can crush pipes) or a nail or screw through a pipe.

If a drainpipe or vent runs through the smelliest wall (or any of them in that room) perhaps a plumber with an inspection camera could run it through those pipes and look for breaches.

Thanks for your ideas everyone. I have finally solved the problem but am still as mystified as before. Basicallly, I repainted just the ceiling with shellac-based primer (Zinzer BIN) and bingo! no smell. Been smell free for several weeks now, including during warm weather. The only theory that makes sense of this is that the ceiling paint, which was Benjamin Moore contractor grade semi gloss was causing it OR it was the original primer which was Bullseye, recommended by the BM people. Why it didn't smell from end of Feb to June I can't explain. I went back to the paint store and told them the story and they are dumfounded too. By the way, I repainted the ceiling with Ben Moore "regal", their older high end paint.