Unexplained Sweet Smell in House? 16 Common Causes

There are many issues that can occur in a house, from improper surface grading/drainage, improper electrical wiring, roof damage, problems with heating systems, plumbing issues, poor ventilation, or overall poor maintenance of the house. 

All of these have some sort of smell associated with them, and that’s when homeowners begin to suspect that something doesn’t quite add up with their house performance. 

One of the most common smells associated with problems in a house is a sweet pungent smell, which is often earthy.  

In this guide, we’ll identify some of the most common causes of a sweet smell in a house; why these issues arise; the risks associated with them; how you can diagnose the issue in the first place, and how you can resolve it.

1. Mold 

When mold grows indoors, it poses a threat to the longevity of a home and is a health hazard to the occupants.

There are various types of mold, but some of the most common ones that grow indoors are: 

  • Cladosporium: this type of mold is either brown, green, or black in colour and tends to grow in both warm and cold areas. It can be found on wood, fabrics, or carpets, as well as in heating/cooling ducts.
  • Penicillium: this type of mold is fuzzy blue, green, or yellow and is found underneath carpets, in basements, and inside insulation.
  • Aspergillus: Aspergillus is either green, white, or gray scattered with dark spots and often a powdery look. This common type of mold grows in fabrics, inside walls, in attics and basements, as well as dry food items.

Mold requires water and moisture to grow, and the growth of mold may begin indoors if mold spores land on wet surfaces, like near leaky pipes, wet carpeting, bathroom walls, around windows, basements, attics, etc. 

So, what are some of the risks associated with mold? 

The issue here is twofold: mold has the potential to cause health problems as it potentially releases toxic substances. Some reactions include: sneezing, runny nose, red eyes, and skin rashes. Exposure to growing mold is a health hazard, so seek professional help if you have mold in your house. 

Second, if left untreated, mold decreases the longevity and value of your home

Mold remediation can be quite expensive, so be sure to address any repairs as soon as you notice any signs of mold growth. 

Signs of Mold Growth in Your House

  • Leaks/water damage issues: mold easily grows in areas where water damage has occurred, especially if the clean up hasn’t been done properly after the water damage 
  • If you notice a sweet pungent smell in the house, chances are mold is growing. Black mold (Stachybotrys Chartarum) is the type of mold that smells sweet, and is potentially deadly as it releases airborne spores
  • If you notice a lot of condensation in glass or metal surfaces around your house, this may be a sign of mold growth as well

How To Prevent Mold Growth

  • If you notice any signs of mold growth in your home, it’s best to seek professional help as soon as possible. They are better equipped to safely remove mold from any affected areas, and will effectively deal with the water damage cleanup to mitigate further issues
  • Properly ventilate areas in your home where moisture-related issues are most susceptible
  • Using a dehumidifier to keep the humidity levels in your home at bay. The less humid your home, the less likely it is for mold to grow
  • Make sure that your home’s roof gutters and downspouts are in good working condition, ensuring that the groundwater flows away from your property (and not towards it)

2. Sewer Problems

Your home’s sewer line comprises of the largest drain, and is often exposed to potential issues, some of which are:

  • Pipes that are broken, collapsed, or cracked, which occur due to any shift in the structure of soil or due to frozen ground in the winter season
  • Tree roots that intertwine with your sewer line can damage the structure of the sewer line, causing problems
  • Old pipes that have deteriorated – newer builds use PVC piping, which is more long-lasting
  • Leaky joints: any broken seals between the pipers will cause water to escape into the area surrounding the pipe 

When it comes to fixing sewer line problems, be sure to constantly check any signs of blockage from time to time. It’s a good idea to have your septic tank inspected every three to five years, ensuring that the system works well without any breaks or cracks.

3. Dead Rat / Mice in Walls 

It may be difficult to diagnose exactly whether or not a dead rat/mouse is present inside your house walls, but a sweet rotten smell is often a clear indicator. 

How to get rid of that dead rat/mouse smell 

  • Wear protective clothes, gloves, and a face mask 
  • Apply odor-neutralizing chemicals to get rid of the smell 
  • Dispose everything in a plastic bag, and bleach the area well
  • Ventilate the area well 
  • Mouse-proof all food storage areas

4. Wild Animal Infestation (Bats, Squirrels, or Raccoons)

Animal infestation is more common in the cooler season, as they look for warm places to hide. Wildlife like squirrels, raccoons, and skunks find their way into homes at times. 

Oftentimes, the presence of wildlife inside homes will lead to a sweet pungent smell. 

Below are some common signs of animal infestation in homes:

  • Squeaking or scratching noises coming from your walls or attic
  • Rustling noises coming from under your home or deck
  • Garbage cans turned over and trash scattered around
  • Urine stains on ceilings or floors that are brown and have a strong odor
  • Feces droppings around your home that are small and brown

How can you avoid an animal infestation in your home? 

  • Ensure that your kitchen and living spaces are free of food/crumbs
  • Cover your garbage! Letting garbage sit around (both indoor/outdoor) can attract wildlife into your home
  • Repair any holes/cracks in your home
  • Deep clean your home on a regular basis

5. Insect Infestation

If insects infest a living space, it’s because they’ve found their way through a house’s front door for instance, or through tears in the window screens.

A few insects here and there is no issue, but if you find that your house has an insect infestation, which often has a sweet stinky smell associated with it, then you’re going to want to address the issue.

How to avoid an insect infestation?

  • Seal up any cracks or openings that are visible
  • Regularly deep clean your kitchen, since most insects go where the food is! Also be sure to properly cover and store leftovers
  • Be sure to dry up any damp areas. Insects not only seek food, but water as well – and  some home invading pests, such as silverfish, springtails and house centipedes, prefer damp spaces

6. Excess Humidity

High humidity levels in a home can potentially lead to moisture-related issues in your home. 

Mold and mildew begin to grow, which may lead to rot – damaging your home and the value of it. 

Often, issues related to excess humidity have an odor that’s sweet and even rotten if mold is present.

Here are some tips to preventing high humidity in your home:

  • Make sure that your home is well-ventilated 
  • Avoid drying clothes indoors – this creates humidity when the moisture evaporates
  • Install an indoor air quality monitor

7. Wet Carpets 

There are a number of causes of water damage on carpets, like: rainfall/snowfall leaks in your home, home appliances that use water, and issues with drainage and plumbing pipes for instance. 

Often, wet carpets create a nasty odor, one that’s associated with a sweet earthy smell.

How can you resolve the issue of wet carpets?

  • Locate the source of the water damage 
  • Dry your carpets immediately (using wet vacuums)
  • Sanitize and deodorize your carpets
  • Call a professional carpet cleaner

8. Something Melting that Can Cause Electrical Fire

Electrical fires in homes have a number of causes. If something is melting it’ll have a sweet chemical smell associated with it.

Some of the most common causes of electrical fires in homes:

  • Faulty electrical outlets
  • Outdated/worn out electrical wiring
  • Cords and electrical circuit overloads
  • Old appliances that have frayed cords or loose or faulty wiring can catch fire
  • Portable heaters

9. Pet Smells

Pet odors in homes often linger to the point where they become normal to smell around a house! These odors are often the reason you smell an unexplained sweet smell.

Getting rid of pet odors in your home:

  • Vacuum up pet hair constantly
  • Wash and dry all items that your pet uses on a regular basis
  • Clean pet toys, collars, and leashes
  • Regularly bathe your pets 
  • Use baking soda and vinegar to deep clean 
  • Use a HEPA mechanical air-purifying filter to tackle any odors

10. AC Leak or Heating System Trouble 

Air conditioning problems occur when rooms are closed off and air flow through the home is disrupted.

Some other problems with existing air conditioners can result from things like: faulty installation, poor service procedures, and inadequate maintenance

Improper installation of a central air conditioner can result in leaky ducts and low airflow, which can explain that honey-like smell coming out of your AC.

Problems associated with AC leaks/heating systems:

  • If your air conditioner is low on refrigerant, either it was undercharged at installation or it leaks
  • Inadequate maintenance
  • Electric control failure
  • Sensor problems
  • Drainage problems

Hiring a professional to help diagnose issues related to your AC/heating system is your best bet to mitigating these issues.

11. Dust on Radiators

Warm air rises and cool air falls – so when the air sinks, it takes the dust with it – which is then drawn up through the radiator. 

This dust begins to collect at the back and across the fins of your radiator – if left for a long time, the dust odor will start to linger, which can have a sweet smell associated with it.

Steps to clean your radiator and get rid of that sweet smell in your house:

  • Use a vacuum cleaner or duster 
  • Deep clean the radiator with some soapy water using sponges/cloths

Regularly dusting and cleaning your radiator will help ensure that your radiator works as efficiently as it should, without emitting any smell along the way. 

12. Furnace Leak 

There are a few reasons behind why your home furnace may be leaking water. While some naturally produce water, if the amount leaking is larger-than-usual, be sure to inspect the issue to prevent water-related damages.

Why is my furnace leaking?

  • Condensation from furnace/internal drain system clog
  • Secondary heat exchanger that’s faulty
  • Problems with the furnace humidifier
  • Clogged furnace filter that’s causing a coil leak

What to do if you notice your furnace leaking?

  • Turn off your furnace 
  • Clean up the area to avoid water-related damages
  • Replace your filter
  • Call a professional who’s best suited to diagnose the leak and fix the problem

13. Gas Leak

A gas leak inside a home is very dangerous, and is usually confirmed by a certified inspector using a device called an adjusted electronic gas analyzer.

How do you know if there’s a gas leak in your home? 

A strong smell will be your cue here – hydrogen sulfide is a flammable gas that smells like rotten eggs at low concentration levels in the air. At high concentration levels, gas has a sickening sweet odor to it.

Hydrogen sulfide is a colorless, flammable gas that smells like rotten eggs at low concentration levels in the air. At high concentration levels, it has a sickening sweet odor.

Carbon monoxide on the other hand is odorless, and is a byproduct of combustion. This can leak from your gas furnace, stove, dryer, or water heater. Also installing carbon monoxide alarms is key.

If you suspect a gas leak in your home, it’s important to leave the premises immediately and call for professional help.

14. Garbage Disposal

If you have a garbage disposal installed in your sink, it may often troubleshoot/not work properly. You’ll notice an obvious stinky/garbage smell surrounding your kitchen in this case. 

Signs that your garbage disposal doesn’t work properly:

  • The unit seems to be making a humming noise
  • The garbage disposal is not turning off
  • Puddles of water begin forming
  • The garbage disposal slowly drains/doesn’t drain at all

Steps you can take if you have issues with your garbage disposal:

  • Check all electrical connections and push the reset button
  • Make sure that garbage disposal cord is plugged in
  • Clear any jam by inserting a ¼-inch hex wrench into the hex-shaped hole

If the above steps don’t cause the garbage disposal to resume working, your best bet is to call for professional help.

15. Building Materials in Your House

Construction smell often lingers around a house that’s just been experiencing some repairs/renovations – or that’s being newly built. 

Here’s how you can detox your home of that sweet smell associated with building materials:

  • Be sure to replace the furnace filter following any construction/repairs/renovations in your house
  • Run your furnace fan at all times
  • Open the windows to ensure proper ventilation
  • Runt the kitchen and exhaust fans
  • Using an air purifier will come in handy as well
  • Using cleaning products that are effective in deep cleaning your living space – it’ll help if they smell good too!

16. New Furniture  

There’s always a strong chemical odor that emits from new furniture. Some chemicals are sprayed on new furniture to help protect the material, but the smell can be off putting. 

How can you get rid of that new furniture smell in your house?

  • Keep your living spaces dry and humid-free. Damp or humid conditions sometimes contribute to the levels of chemical odor emitted from furniture
  • Use a vinegar/water mixture to spray onto fabrics to kill of that chemical odor

Sweet Smell in Your House After in Rains?

Ever noticed a sweet smell surrounding your house after it rains? That scent is called petrichor, and is a combination of oils which come from plants along with the bacteria that live in the soil.

Properly ventilating your home will help get rid of that smell, which is sometimes too much especially after heavy rainfall. Consider using air purifiers as well to help get rid of that sweet smell.

Sweet Smell in Your Bathroom?

If there’s a sweet smell lingering in your bathroom, chances are there’s a clogged drain. When items get stuck in a drain, like soap, conditioner, detergent, etc. they’ll eventually decompose – leaving off a sticky sweet smell. 

To mitigate this, you’ll want to regularly unclog and maintain your bathroom drains.

Sweet Smell in Your Basement?

A sweet pungent smell in your basement indicated mold growth. Since basements are naturally humid/damp, they often become a breeding ground for mold and mildew. 

To avoid the growth of mold and mildew, you’ll want to make sure that the basement area is constantly ventilated – and if you suspect any water-damage issues have it inspected. 

Scroll to Top