The short answer
What Causes the Smell
A musty odor is almost always a sign of moisture. In a duplex, the smell can come from a leak in a shared wall, a dripping pipe, or condensation in a crawl space. Even a small, slow leak can keep materials damp enough to produce that earthy smell.
Poor airflow makes it worse. When air cannot move through a space, humidity builds up and moisture lingers on surfaces. In a semi-arid climate, you might not expect this, but indoor humidity from cooking, showers, and drying clothes can still create damp spots.
The source may not be visible. Water can travel along pipes or framing and collect in a low spot. A musty smell in one unit can actually come from the other unit, especially if the two share a heating or cooling system.
How to Find the Moisture Source
Start with a careful visual check. Look for water stains on ceilings, walls, and floors, especially near plumbing fixtures, water heaters, and washing machines. Check under sinks and around toilets for signs of drips or dampness.
Pay attention to the building's shared areas. In a duplex, the crawl space, attic, or basement may be the culprit. A leak in one unit can soak insulation or drywall in a shared wall, and the smell will travel.
If you cannot find the source, consider a professional leak detection service. They use tools to locate hidden moisture without tearing open walls. Early detection can prevent more damage and reduce the chance of mold taking hold.
- Check under sinks and around toilets for dampness.
- Look for water stains on ceilings and walls.
- Inspect the area around the water heater and washing machine.
- Feel the floor near baseboards for soft spots or moisture.
- Use your nose to trace the strongest smell to its source.
- Consider a leak detection service if you cannot find it.
Drying and Dehumidifying
Once you find the moisture, dry the area thoroughly. Remove any wet carpet, padding, or drywall that cannot be saved. This helps stop mold from spreading and reduces the musty smell at its source.
Use fans and dehumidifiers to speed up drying. Open windows when the weather allows, and keep air moving in the affected space. In a duplex, you might need to run a dehumidifier for several days, depending on how much moisture is present.
For larger areas, structural drying and dehumidification may be needed. This involves professional-grade equipment that pulls moisture from walls, floors, and framing. It is often the fastest way to get a space fully dry and remove the odor.
When to Call the Pros
If the musty smell persists after you have dried the area, or if you suspect mold, call local water damage pros. They can inspect the property, map moisture levels, and identify hidden dampness. Their job is to find the problem and help you decide on the next steps.
You should also call the pros if the leak is large, if you cannot locate the source, or if the water has soaked into walls or flooring. They have the equipment to extract water and dry the structure properly. This reduces the risk of long-term damage.
In some cases, the pros may need to remove water-damaged materials like drywall or flooring. This is not always necessary, but it is sometimes the only way to stop mold and eliminate the smell. They will explain what they find and what the work involves.
- You cannot find the source of the moisture.
- The smell is strong and does not go away.
- You see visible mold growth on surfaces.
- The leak has soaked into walls or floors.
- You need help drying a large area.
- You want a professional moisture assessment.
Preventing Future Mustiness
Once the moisture is gone, focus on preventing a repeat. Fix any plumbing leaks right away, and check for condensation on pipes and windows. Improve ventilation in bathrooms, kitchens, and laundry areas to keep humidity down.
In a duplex, talk to your neighbor about shared issues like roof leaks or drainage problems. Keeping gutters clean and grading soil away from the foundation helps keep water out. Regular checks of the crawl space and attic can catch problems early.
If you live in Layton, keep a written record of your shutoff valve location. This can help you act quickly if a pipe bursts and minimize water damage. A little maintenance now can save you from a musty, moldy problem later.
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Call Now (801) 383-0232Frequently asked questions
Can a musty smell be harmful?
A musty smell itself is not necessarily harmful, but it often indicates mold or bacteria, which can trigger allergies or breathing issues. If you feel unwell, see a doctor. It is wise to find and fix the moisture source promptly.
Will the smell go away on its own?
Not usually. The smell comes from moisture, and that moisture will remain unless you dry the area. Simply masking it with air fresheners does not solve the problem. You need to remove the source of dampness and dry the affected materials.
Should I check the other unit?
Yes. In a duplex, a leak in one unit can affect the other, especially through shared walls or floors. Talk to your neighbor and coordinate a check of both sides. If you cannot find the source, a professional inspection can help locate hidden moisture.