How to identify musty odor?

Question

Hi all,

I've had a property in a Class C neighborhood for about 5 years in Parramore, downtown Orlando. The last tenants were so filthy, with tons of cockroaches, food crumbs, and sewage smells. I've had massey pest control get rid of the cockroaches and I've had a professional cleaning company clean the place. I've also painted all the walls and yet there's a musty odor in the air. I just can't figure it out.

I have a property manager who is semi-experienced and he's trying his best getting contractors out to figure it out. The place has been empty for 2 months since no one wants to rent with that smell.

Does anyone know if there are any legitimate companies that can identify smells? Or even better, is there an investor in downtown Orlando, specifically the Paramore Avenue area, who would take a whiff for me and identify the issue? That'd be the ultimate solution. I don't know what else to do at this moment.

Any help would be greatly appreciated!

Richard F. · Answer

Obviously there is a water leak somewhere, likely behind the walls. Could be from a roof leak making its way down to the foundation. Could be supply lines, could be waste lines. Do you have cast iron and galvanized waste lines? They can have hairline cracks the length of a full section of pipe, seeping just enough to "feed" the mold that is now growing. Could also be window frames leaking from the exterior to inside of your walls. Could be an icemaker line with kink or bad connection. Highly likely could be the tub/shower and surround, with water penetrating cracks in the tile grout. It does not take much water to create an odor when allowed to go unchecked. I'd bet that anyone with 20/20 vision could spot most likely areas to begin your investigation, except for the fact you have now painted over a substantial amount of evidence. One way or another, you need to look for the signs. White mineral deposits on rafters or structural members, any staining or discoloration of ceilings, walls, baseboard areas especially near plumbing and in corners. Soft or bubbling paint/drywall. Use a bright flashlight to check visible connections, valves, pipes inside of cabinets, crawl spaces, attics, and other accessible areas. Inspect the roof at seams, penetrations, and flashing, as well as entire surface for signs of aging or damage. And find a PM that has a lot more experience if they have been unable to point to source. Also, who placed the tenants? They need to be fired too, allowing the tenants to create such conditions.

Leo Stein · Answer

Musty smells after a rough tenancy are often hiding in the places paint can't reach, like the subfloor or carpet pad, the HVAC ducts and drain pan, or moisture in a wall or crawl space. If the carpet or pad is still in, pulling a corner to smell underneath is a cheap first test. A moisture meter and a duct inspection can narrow it down before you spend on bigger fixes.

Clever Mukori · Answer

Since you said the furnace still looks filthy after the duct cleaning, I'd have the air handler itself opened up next: a dirty evaporator coil or a drain pan holding standing water will push a musty smell through every vent, and duct cleaning usually doesn't touch either. Also, with the place sitting empty for two months, pour water down every drain, tub, floor drain and seldom-used sink, because dry P-traps let sewer gas in and that can read as "musty" more than "sewage." If neither fixes it, a mold inspector with a moisture meter and thermal camera is the legit "smell detective" you're looking for, and they can check behind the fresh paint and under the flooring without tearing things open. Run the HVAC fan for an hour with the windows shut and sniff at the returns versus the far rooms, which tells you fast whether it's the system or a spot in the house.

Divin Kanyama · Answer

@David Smith That sounds frustrating, especially after two months vacant. At this point, I’d spend on finding the source rather than more cleaning or paint. A musty smell warrants a moisture investigation, but it doesn’t prove mold—or that the previous tenants caused it.

I’d start with an independent indoor-environmental professional or Florida-licensed mold assessor who investigates moisture, not just sells air tests.

Because you also mentioned sewage smells, I’d have a licensed plumber check drain traps, toilet seals, and venting, plus an HVAC technician inspect the coil, drain pan, and condensate line. Ask your manager to coordinate one documented investigation rather than more trial-and-error treatments. If moisture or mold is found, fixing the water source is essential. Another investor’s nose might offer a clue, but it’s no substitute for identifying and correcting the underlying problem before renting.

Randy Schell · Answer

Two months empty with a smell nobody can pin down is so draining, I'm sorry. After 20+ years of inspections I'll say one cheap thing people forget is running water in every drain, including the floor drains and tub, because dried out traps after sewage trouble can keep that odor coming even when everything looks clean.

Randy, Bunklow

BJ Everson · Answer

David, have the PM run every faucet, tub, and floor drain weekly while the unit is empty. Dry traps alone can make a place smell like sewer. Swap the HVAC filter and run the system on fan after each fix, so you can tell which change actually made a difference. Get the cause and the fix in writing, with dated photos. Once the source is gone, an ozone or hydroxyl treatment can clear what’s left in the soft surfaces.

David Smith · Answer

Thank you for this incredibly detailed answer. I'm going to go through your list and see if I can get a moisture meter. The property manager was myself for these tenants. That's one of the reasons why I hired a property manager for future tenants 😞

David Smith · Answer

We had a duct cleaning but the furnace looks filthy. Thanks for the pointers!

How to identify musty odor?

How to identify musty odor?

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