Woman plugging her nose because of a musty smell in her house

Why Does My House Smell Musty?

Many factors can cause musty odors including, but not limited to, mold, mildew, cigarette, and pet odors. Whether your home is eight years old or 80, these smells don’t discriminate. Read on to learn more about the potential causes and how to combat them.

Musty Smell Sources

So, just what is the source of that offensive old house smell? Musty smells in houses may be attributed to several causes, including:

  • Mold and mildew: Leaky pipes, a damaged roof, high humidity, and exposed dirt in the crawlspace may all contribute to moisture buildup. This moisture combined with the stagnant air and dark corners can lead to the growth of mold and mildew. Mold and mildew can hide behind walls or in other unseen places. Worse, long after the mold dies, its odor lingers, having permeated the carpet, curtains, and upholstery, making the whole house smell like mildew.
  • Musty odors trapped in the HVAC system: If you haven’t cleaned your ducts recently, they are likely grimy, dusty, and smelly resulting in a musty odor. In addition to your ducts, your heating and cooling equipment itself may be introducing musty odors.
  • Cigarette and cigar smoke: Smoking indoors, even occasionally, leaves a lasting impression on a home. Drywall and other soft surfaces like carpeting soak in the scent of smoke and nicotine. If the previous homeowner smoked, the walls will emit that odor for decades without proper mitigation.
  • Spills and messes: Pet accidents and drink spills that are not properly cleaned will seep deep into carpet padding and even the subfloor of a room. These odors can linger for years if never properly cleaned.
  • Poor Airflow: Homes that have poor air circulation can result in a musty smell. Good airflow is vital to keeping a home smelling fresh.

How to Get Rid of Musty House Smells

Eliminating an unpleasant musty odor in your home can be difficult, even with deep cleaning. To get to the root of the problem, you often need to make some home upgrades.

  • Air out the house: Encourage airflow throughout the home by opening windows and doors (equipped with screens) and turning on any fans. Be mindful to encourage cross-breezes throughout the house.
  • Change the air filter: A clean air filter will trap airborne contaminants that contribute to old house smells. Change the air filter in any HVAC appliance you’re currently using (furnace, stand-alone HEPA filter) and make a schedule for changing the filter in the coming months and years.
  • Clean the air ducts: When were your ducts last cleaned? Professional air duct cleaning is an effective way to eliminate odors that manifest when you turn on the furnace or air conditioner.
  • Repair leaks: Leaks in your home can cause problems with mold and mildew. A little home improvement—including fixing the roof, sealing windows and doors, and replacing damaged pipes—can go a long way.
  • Paint the walls: Paint the walls: Drywall and wallpaper are notorious for soaking up smells. Strip old wallpaper and paint all the drywall surfaces in the home with an oil-based, mold-resistant paint to seal the walls.
  • Clean or replace the carpet: Clean or replace the carpet: A quick sniff will tell you if the carpet is compromised by pet stains or mildew. Professional carpet cleaning may do the trick, but you may need to replace the carpet. If you remove the carpet, inspect the subfloor. If the subfloor is stained, replace it or seal it with an oil-based paint.

When you or your contractor remove the carpet, be sure to inspect the subfloor. If the subfloor is stained, replace it or seal it with an oil-based paint.

  1. Seal exposed dirt floor with concrete: If you have an unpaved area in the crawlspace, it could make the house smell musty after rain, or earthy during hot, humid weather. Hire a contractor to pour concrete over the dirt floor and seal the area for good.

Test Your Home’s Air Quality 

Although the above steps might remove the musty smell, your air quality may still be poor. Air quality testing lets you know whether your air is contaminated, and if so, what actions to take. The professionals at Aire Serv can help. Read more about our Indoor Air Quality service.