A smell that seems to come from inside a wall is one of the harder dead-animal problems, because the place the smell points to is the one place nobody can see. This article sets out what can be checked without cutting anything, what this site can and cannot help with, and what the Mississippi State Department of Health says about the animals that matter most for health.
Why the smell seems to come from the wall
Odour moves. It can travel along the cavities between studs, through gaps around pipes and wiring, and through the space between floors, so the spot where a smell is strongest is not always where the animal is. A wall can be the place a smell collects rather than the place it starts.
Small animals that get into a house can die in places nobody sees. Some of those places are inside a closed wall. Others are close to it: on the top of the wall in the attic, under the floor in a crawl space, or behind something stored against it.
What can be checked without cutting
Before anyone talks about a wall, check the spaces around it that already have a way in:
- The attic above the wall, through the existing attic access. Look along the tops of the walls and in the insulation near where the smell is strongest.
- The crawl space below, if the house has one, through its existing opening.
- Under decks, porches and steps that sit against that side of the house.
- A garage, utility room or closet that shares the wall, including behind stored boxes and appliances that can be moved.
Flies gathering at one spot, such as an outlet, a baseboard or a ceiling corner, can help narrow the search. If the source turns out to be in the attic, the crawl space or under a deck and can be reached through an existing opening, that is work an independent operator can do where one covers your address. The pages on a dead animal in the attic, in a crawl space and a smell with no animal in sight cover the cases that can be reached. This site does not pass on dead mice, rats or wild birds.
What this site does and does not route
This site passes on calls and forms about dead animals that can be reached through an existing opening: an attic access, a crawl-space hatch, the open side of a deck. It does not route work that means cutting into a finished wall, ceiling or floor, and nothing here is a promise that anyone will open a wall.
Whether to open a wall is a decision for the homeowner and whoever they hire for that kind of work. It brings repairs afterwards, and the source can still be hard to find once a section is open. That is a reason to check every reachable space first.
How long the smell lasts
No single figure fits. How long an odour lasts depends on the animal's size, temperature, humidity, airflow and location. A mouse in a cool, airy space and a larger animal in a warm, closed cavity are very different cases. This site does not give a timeline, because the factors vary too much from one house to the next.
While the smell is there
- Move air out of the house where you can: open windows and run fans that push air outdoors.
- Keep children and pets away from any spot where flies are gathering.
- Do not handle any animal you find with bare hands.
- Note where the smell is strongest and whether it changes through the day. That helps anyone who looks at it later.
If it might be a bat
The Mississippi State Department of Health says not to handle live bats or bats that seem to be dead, and that any bat that may have had contact with a person or pet should be tested for rabies. For instructions on having a bat tested, call its Office of Epidemiology at 601-576-7725. The department also advises against handling live or dead raccoons, skunks, foxes and coyotes, which can carry rabies too.