You can smell it, you cannot see it
Tracing a dead animal smell in Toledo
Decomposition smells like nothing else, so people are rarely wrong about what it is. Locating it is the difficult part, and narrowing it down tells you which kind of problem you have.
Narrow it down first
- Walk the house and note where it is strongest, and at what height.
- See whether it rises and falls with the furnace or the air conditioning running. That points at a duct run or a return.
- Look for flies gathering at one spot, or a stain on a ceiling. Both are close markers.
- Open the crawl space or attic hatch if you can do it safely, and note whether it is much stronger in there.
- Check outside too. Under a deck, in a vent, in a window well or behind a soffit reads as an indoor smell from the wrong room.
If it narrows to somewhere reachable
A crawl space, an attic, a duct that opens, a vent with a removable cover, a void with a hatch, the gap behind an appliance. That is a removal job, and the smell usually leaves with the source. What reachable means in practice.
If it narrows to a sealed wall or ceiling
An animal of any size in a closed wall, ceiling or plaster cavity cannot be reached without opening finished surface, and the operator does not cut into drywall, plaster or ceilings, so this is not a removal job. The smell generally lessens as decomposition runs its course, but nobody can tell you a sealed-cavity smell reliably clears by a fixed date, because it depends on the animal, the season and how much air moves through that wall. Treat a precise promise as a warning sign.
When it is genuinely worth a visit
Two situations. Either you have narrowed it to a reachable space and want it out, or you honestly cannot tell which of the two you have and want that established. The second is a fair reason to call. It is the difference between a removal job and a smell that generally eases with time, and looking settles it better than guessing does.
What will not fix it. Air fresheners, ozone machines and bowls of vinegar cover the smell while the source sits there. It eases when the source is gone, or as decomposition runs its course, and not before.