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So you think there’s a dead animal in the wall

Q. We occupy the top two floors of a three-story, two-family house. The past few weeks we have smelled what we think is a dead mouse. The smell is very strong for a day or so, then goes away and comes back again a week later.

How can we pinpoint the source of the smell without tearing the whole house apart? If it is indeed a dead mouse, will the smell eventually go away once it has completely rotted? Is it worth calling an exterminator?

If there is some way I can handle this myself without involving the woman who occupies the first floor, that would be optimal. She tends to overreact. I can see her demanding that the entire house be gutted or fumigated or whatever. Any advice would be much appreciated.



A. The dead animal can take weeks to months to decompose, depending on its size. Common culprits include mice, rats, squirrels, opossums, and raccoons.

Probably the biggest problem is that many animals will crawl into small spaces to die, making the carcass very difficult to find. A foul smell and flies are usually the only clues you get, so knowing the kind of places animals will try to hide is a skill generally developed with experience. If you’re handy and have the stomach, you can try this yourself, but a pro will locate and remove it, or, if need be, cut a small, precise hole in the wall for retrieval.

The first thing you need to do is locate the animal. Sometimes looking for a point of entry helps. Common areas to check are crawl spaces, chimneys, basements, and attics — the walls in some older homes are balloon framed, which means the studs basically run from the basement to the attic, giving an animal a lot of places to move around.


If you do locate a small dead animal like a mouse, put on gloves, place it in a sealed plastic bag, and dispose of it in the trash. If you don’t know what the animal is or if it’s big, call in a professional. Be sure to remove any soiled insulation and wash the area with a special enzyme-based cleaner that destroys biohazard waste (BioShield, for example).

If you’re unable to locate the animal and don’t call in a professional, you can just wait it out. Ionic air cleaners have been used with some positive results, as have enzymatic candles designed to remove pet odors. Area sprays will probably just add another odor rather than lessen the bad one.

If your home is in a humid location, you should consider the use of a dehumidifier. Odors tend to be stronger in high humidity and heat.

If it were me, I’d hire a professional.

Q. I have a concrete and flagstone walkway in need of repair or replacement. I like the look of flagstones, with their various colors. I have had two landscapers come, telling me that pavers are the way to go. I have more than enough flagstones to do the job. Are they trying to get me to spend more money? Can the flagstones be placed without using concrete, which can crumble? Thanks in advance.


A. I’m not a fan of flagstones in dirt. Set this way, they tend to move around in the wet seasons. If you have a lot of flagstones already, like the look, and are on a budget, it makes sense to use them. You can install the stones you have in mortar or in a bed of sand, stone dust, or gravel.


The mortared look, if properly installed, will last a long time. Sand and gravel settings will require periodic maintenance; as the stones settle or shift, the sand and gravel will need to be replaced at the joints. Flagstone is durable and will work just fine.

Rob Robillard is a general contractor, carpenter, editor of, and principal of a carpentry and renovation business. Send your questions to or tweet them to @robertrobillard.