How Do I Get Rid of a Musty Smell Before Listing My Home?

Find and fix the root cause first. A musty smell almost always traces back to moisture. Common sources include hidden water leaks, mold behind drywall, HVAC condensation, or furniture saturated by years of Florida humidity. Once the source is eliminated, an ozone treatment neutralizes whatever odor lingers in the walls, carpet, and soft surfaces. 

Why Musty Odors Kill Home Sales Faster Than Almost Any Other Condition Issue

A buyer forms an opinion within seconds of stepping inside. Price, photos, and location got them through the door. The smell decides whether they stay. A musty odor triggers an immediate association with mold, water damage, and deferred maintenance. Even if none of those problems exist, the perception alone is enough to send a buyer back to their car.

On the Discover South Florida Podcast, Larry Mastropieri noted that this issue shows up across every price point:

"We've sold $4 million homes that had these issues. We've sold $100,000 homes that obviously have these issues. There's a number of strategies. It's going to be deal-by-deal solutions."

In South Florida, humidity is a constant aggressor. Homes that sit vacant absorb moisture through every porous surface. Seasonal residents who close up a property for five months return to what Larry calls "dead air smell." Occupied homes develop musty pockets too, especially in closets and laundry rooms where airflow is limited.

Step One: Diagnose the Root Cause Before Treating the Symptom

This is where most sellers and most agents get it wrong. They spray something, light a candle, plug in a diffuser, and hope the buyer does not notice. That approach fails every time because the source of the odor is still active.

Larry was clear about the order of operations:

"First, you got to find out the root cause. Why does a house have a musty smell? Is it the couches? Is it water damage? Is there mold in there? You got to address root cause. You got to get rid of whatever's causing the issue."

The Most Common Sources of Musty Odors in South Florida Homes

Florida's climate makes certain problems more likely than what sellers in other states deal with. Here are the culprits Larry's team encounters most frequently:

• Hidden water leaks inside walls, under sinks, or beneath slab foundations that create sustained moisture and mold growth.
• HVAC systems with dirty evaporator coils, wet ductwork condensation, or bathroom exhaust fans venting into the attic instead of outside.
• Mold colonies growing behind drywall, under flooring, or inside closets where airflow is restricted and humidity accumulates.
• Upholstered furniture, carpet, and drapes that have absorbed years of moisture and organic compounds in a humid climate.
• Vacant or seasonally occupied homes where stagnant air allows microbial growth to take hold unchecked for months.

Each source requires a different fix. A water leak needs a plumber and drywall repair. Mold behind a wall needs professional remediation. A dirty HVAC system needs cleaning and potentially duct sealing. The listing agent's job is to help identify which problem exists. Then connect the seller with the right contractor to fix it.

Why Larry's Team Can Diagnose These Issues Better Than Most Agents

Larry brings a background most real estate agents simply do not have. He holds a degree in mechanical and chemical engineering. Before real estate, he spent years in environments where air quality and chemical processes were part of daily work.

On top of that, his team operates a parallel business. They own 150 apartments and regularly purchase foreclosure properties. That portfolio exposes them to every conceivable condition issue. Cast iron plumbing failures. Full mold infestations in homes that sat vacant for years.

Larry connected this experience directly to the listing side:

"We have an immense skill set at construction and what fun issues can be found in any house or apartment or condo. Together we would identify what the issue is, whether we need to bring in people to solve it or we can identify it quickly as a team."

Step Two: Use Ozone Treatment to Neutralize Lingering Odors After the Fix

Once the root cause is resolved, the smell often persists. Mold spores embed in drywall. Smoke compounds soak into carpet fibers. Moisture residue clings to soft surfaces. Standard cleaning gets the visible problem. Ozone gets the invisible one.

Larry shared this as a direct pro tip on the podcast:

"Ozone. You can buy machines. We have multiple machines at our office that the realtors on the team can grab at any time. The ozone machine is very effective at neutralizing odors."

How Ozone Treatment Works and Why It Succeeds Where Air Fresheners Fail

Ozone (O3) is a highly reactive gas. When released into an enclosed space, it oxidizes organic compounds that cause odor. It penetrates carpet, drywall, fabric, and ductwork, reaching areas that no surface cleaner can touch. Professional remediation companies use high-output ozone generators as a final step after mold removal for exactly this reason.

Air fresheners mask odor with fragrance. Ozone destroys the molecules causing it. The difference is permanent removal versus temporary cover-up.

Critical Safety Rules for Running an Ozone Machine in Your Home

Larry was emphatic about the safety requirement:

"You can't stay in the house while you have ozone running in it. This will kill you. It'll kill your animals. If you're committed to solving the problem, you have to leave the house for 24 hours."

That is not an exaggeration. Ozone at treatment concentrations is toxic to all living things. The space must be completely vacated. Pets, plants, and people all need to be out. After the treatment cycle completes, the home needs at least an hour of ventilation before anyone re-enters. Running the HVAC fan during treatment helps circulate ozone through the ductwork, which is often where musty odors hide.

When Ozone Alone Is Not Enough

Larry was careful to set expectations on the podcast:

"If you have a location where the odor is emitting from and you're not solving that root cause, the ozone's only going to do so much. It'll solve it and then it'll come back."

Ozone is the second step, never the first. Running an ozone machine without fixing the leaking pipe or removing the mold colony produces temporary results. The smell returns within days. The treatment works as a finishing tool after remediation, not as a substitute for it.

Why the Agent You Hire Determines Whether Odor Problems Get Solved or Ignored

Most listing agents have no construction background and no access to specialized equipment. When they encounter a musty home, their advice tops out at scented candles and open windows. Larry had a sharp take on this gap:

"Most realtors probably don't even know about ozone or other techniques. They probably just say, 'Oh yeah, use a Glade plugin.'"

Larry's team carries multiple ozone machines at the office. Agents on the team can check one out any time a client needs it. Roughly 10% of the team's 300 annual transactions involve ozone treatment, which works out to about 30 homes per year. That is not a niche case. It is routine preparation for homes across Boca Raton, Delray Beach, West Palm Beach, and Palm Beach County.

As Larry framed it on the podcast:

"Preparing the home for sale means us helping and working with you and having solutions ready. This is why you hire us."

Get a Pre-Listing Walkthrough That Catches Odor and Condition Issues Early

We do not wait until a buyer complains about the smell. We catch it at the first walkthrough, diagnose it, and fix it before the listing goes live. That is part of what it means to get the condition pillar right. Reach out to The Mastropieri Group, Realtors®. Call (561) 544-7000. We will walk your property, identify what needs attention, and handle it before a single buyer crosses the threshold.