Closing Up a Sarasota Seasonal Home Without Losing the Closets

A large share of the houses on the Suncoast spend half the year empty. Sarasota County Property Appraiser records show 138,488 homestead exemptions granted in 2025 against 327,657 total parcels and accounts, which the report describes as 45 percent of parcels in the county. Much of the remainder is second homes and rentals that go quiet in April and wake up in November. The closets in those houses take the worst of it, because a closet is the one part of a conditioned house that is closed, dark, packed with organic fiber, and very often sharing at least one wall with the outdoors.

None of that is a mystery and none of it requires guessing. The University of Florida's Institute of Food and Agricultural Sciences publishes a specific procedure for closing a seasonal Florida home, the Florida Solar Energy Center publishes the humidity targets, and NOAA publishes what the weather here actually does between May and October. Put those three together and the question of what to do with the closets before you leave becomes a short list with numbers attached to every line. This guide runs through it in the order the work happens: the physics, the thermostat, the closet itself, the way the closet is built, and what to do if you get it wrong.

Why does a closed-up Suncoast house go musty when nobody is in it?

Relative humidity is a ratio rather than a quantity, so it climbs whenever air cools without losing any water. The Florida Solar Energy Center gives the arithmetic directly. Indoor air at 75 degrees and 60 percent relative humidity that cools to 70 degrees rises to about 70 percent relative humidity, even though the actual amount of moisture in the air never changed. The same document notes that indoor air at 75 degrees and 60 percent relative humidity meeting an exterior wall whose interior surface sits at 63 degrees will have a surface relative humidity of 90 percent. The back wall of a closet is very often that surface.

Then there is the outdoor load. NOAA's 1991 to 2020 climate normals for Sarasota-Bradenton International Airport put normal annual precipitation at 49.05 inches and the normal annual average temperature at 74.1 degrees, with August alone normalizing 9.11 inches of rain at an average temperature of 83.4 degrees. Adding the four monthly normals for June through September gives 29.55 of those 49.05 inches falling in one third of the year. UF/IFAS Extension Sarasota County states plainly that most molds do best at over 60 percent relative humidity. An unattended house in August is a very efficient machine for producing exactly that number in exactly the places nobody is looking.

What should the thermostat and humidistat actually be set to before you leave?

UF/IFAS publication FCS3154, Closing Your Seasonal Home, is the closest thing Florida has to an official answer. It instructs owners to leave the air conditioner set to no higher than 85 degrees Fahrenheit, on the reasoning that letting the house drift above that allows indoor humidity greater than 55 to 60 percent, which the publication calls unsafe. It also recommends having the humidistat calibrated by an air conditioning company about three weeks before departure, which is early enough that a bad reading can still be corrected while somebody is in the house to notice it.

Those numbers bracket well against the general guidance. The Florida Solar Energy Center puts the best target for indoor relative humidity between 45 and 55 percent and says that indoor relative humidity above 60 percent for several hours in a conditioned home indicates the air quality control could be improved. The EPA's guidance is to keep indoor humidity below 60 percent, ideally between 30 and 50 percent. For an occupied house, UF/IFAS Extension Sarasota County recommends a thermostat set no lower than 78 degrees in summer and no higher than 68 degrees in winter. The Florida Solar Energy Center suggests spending 20 to 30 dollars on a temperature and humidity sensor, and putting one inside the closet rather than in the hallway settles most arguments.

• Air conditioner set no higher than 85 degrees Fahrenheit while the house is empty.
• Indoor relative humidity target of 45 to 55 percent, and under 60 percent at all times.
• Humidistat calibrated by an air conditioning company roughly three weeks before departure.
• Water heater switched off for absences over a month, or turned to its lowest setting for shorter ones.
• A temperature and humidity sensor left inside the closet, not just in the hall.

What goes into the closet before you fly north, and what has to come out?

FCS3154 is unusually specific about closets, and every line of it is about airflow and contamination. Leave only clean clothes in closets, because soil and body oils feed mildew that clean fabric does not. Allow space between garments to permit circulation of air. Do not leave clothes on the floor. And do not wrap garments or other items tightly in plastic, because the publication warns that doing so may increase the likelihood of mildew, which is the exact opposite of what most owners believe a zipped garment bag is accomplishing over the summer.

Two more instructions get skipped almost universally. Metal hangers, even when covered with paper, can rust and stain clothing over a humid Florida summer, so they are worth swapping for wood or coated hangers before the door closes for the last time. And interior doors, closet doors included, are left open to permit air circulation, which runs against the instinct to shut everything tight on the way out. The same publication says to remove bedding and bath linens, clean and dry them and store them, and to strip the beds on the day you leave rather than the week before.

• Only clean garments stay behind; anything worn once goes home or gets laundered first.
• Space between hangers, and nothing left sitting on the closet floor.
• No plastic garment bags and no tightly wrapped storage.
• Wood or coated hangers in place of metal, which can rust and stain clothing.
• Closet and interior doors left standing open rather than shut.
• Bedding and bath linens removed, cleaned, dried and stored.

Which closet materials and layouts survive a house that sits empty?

Design follows the physics. If the coldest surface in the room is the interior face of an exterior wall, and the Florida Solar Energy Center's own worked example has that surface driving local relative humidity to 90 percent, then the goal is to keep fabric off it and keep air moving across it. That argues for runs held off the back wall on a hanging rail rather than cabinet boxes pressed flat against it, for ventilated shelf wherever the load allows it, and for leaving the top and the bottom of a run open so the closet does not get divided into sealed dead pockets that never see conditioned air.

Material choice matters less than edge treatment. Thermally fused laminate over a particle core is dimensionally stable in this climate as long as every cut edge is banded, because raw core is where moisture gets in and swelling starts. Solid backs against an exterior wall are the one construction detail worth arguing about before a design is signed off. Door style is the other. A louvered or slatted door means the instruction to leave the closet open is not the only thing standing between a wardrobe and a bad August. We build to whichever of those the house actually calls for rather than to a default specification.

What if you come back in November and something has already grown?

Scale decides the response. The EPA's guidance is that if the moldy area is less than about 10 square feet, roughly a three foot by three foot patch, a homeowner can handle the job in most cases, and UF/IFAS Extension Sarasota County uses the same 10 square foot threshold for calling in professional service. Both sources agree on timing as well: if wet or damp materials are dried within 24 to 48 hours after a leak or spill happens, in most cases mold will not grow at all. That window is the whole game, which is why a returning owner opens the closets before unpacking anything.

For non-porous surfaces, UF/IFAS says water with soap or detergent is enough to clean visible mold, and warns against mixing bleach with other products because of the chemical reaction it creates. Affected cabinets and closets are kept open until they have completely dried and the source of moisture has been removed. In Florida, mold remediation is a licensed activity in its own right: practitioners must hold licensure from the Department of Business and Professional Regulation and certification from NEHA, AIHA, IICRC or ACAC. Anything structural, and anything past that 10 square foot line, is a remediation job before it is ever a closet job.

• Under about 10 square feet: a homeowner cleanup in most cases, per EPA guidance.
• Over 10 square feet, or anything structural: a licensed remediator comes first.
• Dry wet material within 24 to 48 hours and in most cases mold will not start.
• Keep the closet open until it is completely dry and the moisture source is gone.