8 dangerous house smells to watch out for

Decoding which odors mean trouble

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Susan Meyer

Senior Editorial Manager

  • Licensed Insurance Agent — Property and Casualty

Susan is a licensed insurance agent and has worked as a writer and editor for over 10 years across a number of industries. She has worked at The Zebr…

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Ross Martin

Insurance Writer

  • 4+ years in the Insurance Industry

Ross joined The Zebra as a writer and researcher in 2019. He specializes in writing insurance content to help shoppers make informed decisions.

Ross h…

Your home is your sanctuary, and one of your goals is probably to keep it smelling good. Or failing that, having a neutral smell. 

But while some smells like the garbage that someone forgot to take out or the dog that needs a bath are just unpleasant, other home smells can be a sign of a bigger problem.

Here’s our list of the 8 smells that should send your nose into detective mode and what to do about them.

1. Musty or moldy odors

A damp or musty smell often indicates the presence of mold or mildew. These fungi thrive in damp environments and can cause respiratory issues and allergies. Mold is especially common in areas with poor ventilation or water leaks.

In addition to the nasty smell, mold is definitely not something to mess around with as long-term exposure has a negative effect on indoor air quality and can lead to lung infections and chronic bronchitis. 

What to do:

Use a digital hygrometer (available online for less than $10) to measure humidity levels and run a dehumidifier in rooms with high humidity. Spray antimicrobial sprays on fabrics in these high humidity areas. Look for leaks that could be causing wet spots. If the problem persists, call in an expert. Home insurance may cover mold remediation if is occurs from a covered peril. Cost to repair will depend on how widespread the issue is.

2. Fishy smell

If you’ve just made a fish dinner and haven’t cleaned up, that’s probably your culprit. But what if you haven’t? A fishy smell can actually be caused by an electrical wiring issue. Sometimes this will also present as a burning smell or specifically burning rubber.

When a wire or electrical mechanism overheats and melts its insulating plastic or rubber, it can produce these smells. And without that insulating plastic or rubber, you’re at risk for a house fire. In fact, electric malfunction is one of the top three causes of house fires each year. 

What to do:

Check all your appliances while they are running to see if one is overheating. If you find the culprit, immediately turn it off, until it can be rewired or otherwise replaced or repaired.  If the smell seems to be emanating from an outlet, switch off the circuit breaker and call an electrician. Home insurance will often cover house fire damage from electrical fires, but potentially not if there's proof you didn't properly maintain your electric systems.

3. Sweet, syrupy smell

A sweet, syrupy smell could be a sign of a coolant leak from your HVAC system or refrigerator. Coolants used in air conditioning such as ethylene glycol can be toxic if inhaled or ingested.

And of course, a well-functioning HVAC system requires all the fluids being in proper working order, so a leak can cause issues with your system.

What to do:

It's essential to address the leak and ventilate the area. Bring in an HVAC repair person to repair the leak. This is not something home insurance will likely cover unless damage to the HVAC system is caused by a covered peril. If you have a home warranty plan, that might cover the cost of HVAC repair. 

4. Ammonia smell

If you detect the smell of ammonia when you haven’t recently been cleaning, it could be the smell of a decaying animal. A mouse, squirrel or raccoon may have found its final resting place in your attic, basement or inside your home’s walls behind the drywall.

Dead animals can attract insects and pose health risks, but the biggest issue of a dead animal in your walls is just the awful smell itself. 

What to do:

Locate the corpse to remove it. Follow your nose to see if you can pinpoint where the smell is coming from. Also look for entry points where the rodent might have gotten in so you can seal off your home from becoming an animal graveyard in the future. 

Animal damage is a covered peril for most home insurance policies, so its possible if the animal did damage before it died, that would be covered. The death and smell alone would not qualify. 

5. Sewage smell

If you notice a sewer smell coming from a bathtub or sink drain, it could mean you have a clogged pipe.

It could also mean you don’t have enough water in the train’s P trap. The P trap is a curved pipe that is full of water and blocks offensive odor of sewer gas from your sewer line or septic tank. In a tub or toilet that is seldom used, this water may have evaporated. This water needs to be replaced in order to get rid of the smell. 

What to do:

Flushing the toilet or running the water may solve the problem if the issue is the drain is seldom used. If it’s a clog in your plumbing system, do your best to unclog it with drain cleaner or, if the the clog is too far down in the pipe, you may need to get a plumber to come with a snake or auger. Home insurance likely won't come into play here unless there are substantial plumbing issues caused by a covered peril.  

6. Rotten-egg smell

Anyone who has ever been to a natural hot spring, knows the unmistakable smell of rotten eggs that indicates sulfur is present. A rotten-egg smell in your home is a warning to you that you have a natural gas leak. This is an immediate safety concern. Gas is volatile and can cause an explosion. 

What to do:

Get everyone out of the house now. Leave doors and windows open and immediately call your gas company. Minor gas leaks aren't often covered by home insurance, but if your leak is caused by a covered peril (like a lightning strike or a fire), it could potentially be covered. 

7. Chemical or paint smells

If you haven't recently used chemicals or paint, a strong chemical smell could indicate a gas leak, particularly from carbon monoxide. A distinctly chemical odor can result from a crack in the heat exchanger component of your furnace. This component cycles heat out of the combustion chamber. In addition to be being smelly, a broken heat exchanger increases the risk of fire and can distribute carbon monoxide fumes throughout your home.

Carbon monoxide itself is odorless and colorless, making it especially dangerous. 

What to do:

Get everyone out of the house and seek medical attention if needed. Call an HVAC expert. Install carbon monoxide detectors in your home. As explained above, home insurance likely won't cover HVAC repair unless its damaged from a covered peril. 

8. Chemical smell from new furniture

If you’ve recently built new flat-packed furniture or installed new carpets, you might notice a chemical smell emanating from them. Pressed-board furniture and carpets can release what are known as volatile organic compounds (VOCs). These can impact your indoor air quality, and of course the bad smell itself is off-putting.

What to do:

Ideally, air out new furniture outside before bringing it in the house. Otherwise, open the windows to ventilate the affected area.

Wrapping up

As a homeowner, strange house smells shouldn’t be ignored, as they can sometimes indicate serious issues. If you encounter a persistent or unusual odor in your home, it's best to investigate and address it promptly to ensure the safety and well-being of your household.