Garage Mold in Florida: Causes and Fixes
The garage is usually the only part of a Florida home that is enclosed but not air-conditioned. It takes in humid outdoor air every time the door opens, heats up during the day, cools at night, and often holds a wet car, a water heater, a washer and stacks of cardboard boxes. Mold in a garage is common for those reasons, and in many cases it is a manageable problem. It becomes a bigger one when it reaches the wall or ceiling shared with the living space.
Why garages grow mold
- Humidity with no dehumidification. Indoors, the AC removes moisture. In the garage nothing does, so relative humidity often stays well above the 60 percent level where mold growth becomes likely.
- Condensation. The slab and block walls stay cooler than the humid air, and moisture condenses on them. A sweating floor on a muggy morning is this effect. The wall shared with the air-conditioned house is cooler still.
- Water under the garage door. A worn bottom seal, a driveway that slopes toward the garage, or heavy sideways rain lets water run in along the floor and soak the base of the walls.
- Wet vehicles. A car parked after a storm brings in a surprising amount of water, which evaporates into a closed space.
- Appliances. Water heaters, washers, utility sinks, water softeners and AC air handlers located in the garage all have connections that can leak or drain lines that can clog.
- Roof and attic issues. Garage ceilings are often the first place a roof leak shows, because the attic above is less insulated and less often checked.
- Stored materials. Cardboard, paper, fabric, wood and leather absorb moisture from the air and supply food for mold.
Where to look
- The bottom foot of every wall, particularly near the garage door corners and behind shelving.
- The wall and ceiling shared with the house.
- The ceiling below any roof penetration and around the attic access hatch.
- Around and behind the water heater, washer and air handler.
- The backs and bottoms of cardboard boxes and anything stored directly on the slab.
What you can clean yourself
Small areas of surface growth on hard, non-porous or durable surfaces are reasonable to handle on your own. That includes bare or painted concrete block, sealed concrete floors, metal shelving and plastic bins.
- Wear gloves, eye protection and an N95 respirator, and open the garage door for ventilation.
- Scrub with detergent and water using a stiff brush, then dry the surface with fans.
- Wipe down hard-surfaced stored items outdoors before putting them back.
- Discard moldy cardboard, paper and other cheap porous items. They are not worth cleaning.
Drywall is a different matter. If the garage has finished walls or a drywall ceiling and the board is soft, stained through, swollen at the bottom or growing mold again after you wipe it, the material needs to be removed, not scrubbed.
Fixes that actually keep it away
- Stop liquid water first. Replace the garage door bottom seal and side weatherstripping, add a threshold seal if water runs under the door, and correct drainage so water moves away from the opening. Repair any roof or plumbing leak.
- Get things off the floor and off the walls. Use metal or plastic shelving with a few inches of clearance behind it. Switch from cardboard boxes to lidded plastic bins.
- Dehumidify. A dehumidifier sized for the space, set up to drain continuously so you do not have to empty a bucket, is the most effective single step in a closed garage.
- Be careful with ventilation. Opening windows or running a fan that pulls in outdoor air helps in dry weather. During a humid summer it brings in more moisture than it removes.
- Seal the door to the house. Good weatherstripping on that door keeps humid garage air, and anything growing in it, from being drawn into the living space.
- Do not park wet and close up. Leave the garage door open for a while after pulling in a soaked car, when it is practical to do so.
- Check the appliances. Look at hoses, pans and drain lines every couple of months.
When the garage is a sign of a bigger problem
Pay closer attention if you notice a musty smell inside the house near the garage door, staining on the interior side of the shared wall, mold on a garage ceiling that has a bedroom or bonus room above it, or growth that covers a large section of drywall. Those situations suggest moisture inside the wall or ceiling assembly, and disturbing that material without containment can spread spores into the home. If you want sampling or a formal report, that is the job of an independent licensed mold assessor, a separate company from the remediator under Florida rules.
Next step
If your garage has moldy drywall, a stained ceiling or growth that keeps coming back after cleaning, request an on-site remediation estimate at drymiami.com or call (954) 778-7999. The visit is $79, credited in full toward the job if you hire DryMiami.
Mold problem at home?
We come out, find the moisture source and give you a written remediation estimate. The visit is $79, credited in full toward your job if you hire us.
