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A Weird Smell Is Coming From the Ceiling

Renee Miller
Odors coming from your ceiling may indicate a problem in one of several areas of your home.

A strange odor coming from your ceiling is not only frustrating, but the source of the odor may pose a health risk for your family. There are several reasons why an odor might occur in or around the ceiling, including animal infestations, plumbing problems, HVAC issues or poor ventilation. It’s important to determine the source of the odor so it can be quickly addressed by a professional.


Several species of small animals such as birds, mice, squirrels and raccoons, like to make homes in your attic. If these animals die, a putrid odor can result. It doesn’t take a big animal to make a lot of stink. Even a dead mouse in your ceiling can cause a very powerful smell. If they’ve made nests, urine and fecal matter will also give off a foul odor. Inspect your attic for signs of animal activity, such as chewed wires, joists and insulation, or visible droppings. The presence of flies concentrated in a specific area of your home is also an indicator of a dead animal. Contact a wildlife removal professional to inspect your ceiling and walls and to remove the animal if possible. The odor from a dead animal is usually faint at first, but gets progressively stronger. It can linger for weeks, but as the animal decays and its carcass dries out, the smell eventually goes away.


A leaky pipe in the ceiling can lead to smelly mold or mildew growth, but more serious problems, such as a clogged drain-waste-vent, are common sources of rotten or sewage-like odors. Mold and mildew growth caused by a leaky pipe seriously affects your home’s indoor air quality, as well as producing bad smells. Mold growth anywhere in your home can lead to illness and a clogged vent pipe, which is typically connected to pipes that remove waste from your home’s plumbing, can also cause health problems if sewer gases are entering your home through the plumbing drains. Contact a plumber to inspect your pipes and vents. A plumber can easily determine if plumbing issues are the source of the odor and correct the problem.

HVAC System Issues

Odors in your HVAC system and ductwork can be carried through your home from a variety of sources. Insulation that has been subjected to moisture or animal droppings can give off odors that carry through your ductwork. According to Inspectapedia, some cellulose insulation can give off a strange smell if the manufacturer used an ammonium and sulfate-borate mixture. If the smell is stronger when you turn on your HVAC system, the odor may not be in your ceiling at all. If you notice the odor only when your heating system is turned on, contact an HVAC professional immediately. Some types of heating systems, such as propane and gas, pose carbon monoxide or flue gas hazards and a strange smell may be an indicator of a leak or malfunction that needs professional repair.

Poor Ventilation

Poor ventilation causes moisture problems in your home, and moisture can lead to smelly mold and mildew growth. According to the University of Missouri, you should have 1 square foot of roof or gable vent for every 300 square feet of floor space in your attic. A poorly vented attic isn’t the only area that can cause smells to linger around your ceiling. Improper ventilation in your kitchen and bathroom can also cause odors to occur. Bath and kitchen fans remove moisture, which reduces the risk of mold and mildew growth, and they remove odors.