Mold doesn’t need much to get started. Give it a damp surface, something to feed on like wood, drywall or even dust, and a day or two, and it’ll move right in. In Eastern North Carolina, where summers are long and sticky and plenty of homes sit over crawl spaces, that damp surface is never far away.
The good news is that mold has one weakness you can control. It can’t grow without moisture. Every tip below comes back to that idea, and most of them cost little or nothing.
1. Keep indoor humidity under 50 percent
Mold spores are already floating around in every home. What turns them into a problem is moist air that keeps surfaces damp. The EPA suggests keeping indoor humidity below 60 percent, and ideally somewhere between 30 and 50 percent.
A cheap digital hygrometer will tell you where you stand. Check a few rooms, including bedrooms and any room over the crawl space. If the numbers keep creeping toward 60 percent in summer, a dehumidifier and a look at your air conditioning are good next steps. We cover more ways to do that in our post on how to reduce indoor humidity.
2. Send steam and cooking moisture outside
Showers, boiling pots and clothes dryers all put water into the air. Run the bathroom fan while you shower and leave it on until the mirror clears, then a little longer. Use the range hood when you cook.
It’s also worth checking where those fans actually go. Bath fans and dryer vents should end outdoors, not in the attic or crawl space. A fan that dumps warm, wet air into the attic just moves the mold problem upstairs, and it’s one of the things we look for during a home inspection.
3. Fix leaks fast and dry things out within 48 hours
Wet drywall, carpet pad and wood can start growing mold within a day or two, so speed matters more than almost anything else after a leak. Stop the water, pull out soaked materials that can’t be dried, and run fans and a dehumidifier until everything is dry to the touch and stays that way.
Slow leaks are sneakier than big ones. Every so often, look under sinks, behind toilets, around the water heater and under the dishwasher. A drip you can’t hear can soak a subfloor for months.
4. Keep rainwater away from the house
A lot of indoor mold starts outside. Overflowing gutters, downspouts that empty right at the foundation and soil that slopes toward the house all push water into crawl spaces and against walls. Clean the gutters, extend the downspouts so water lands several feet out, and make sure the ground falls away from the foundation. Our guide to improving drainage walks through the details.
5. Don’t forget the crawl space
In homes built over a crawl space, that’s often where moisture problems start, and it’s the part of the house most people never see. Damp soil, standing water, a torn or missing vapor barrier and sweating ductwork can keep the wood under your floors wet for months at a time. Air from a crawl space also tends to drift up into the living space, so what grows down there doesn’t always stay down there.
Damp wood draws termites too, since they need moisture to survive. If your crawl space smells musty or nobody has looked at it in years, our moisture control service is a good place to start.
6. Let air move through the house
Mold likes still, stagnant corners. Closets on outside walls, the space behind a dresser pushed tight against an exterior wall and rooms that always have the door shut are common trouble spots. Leave a few inches between big furniture and exterior walls, open closet doors now and then, and don’t block supply vents or return grilles.
Your air conditioner plays a part as well. A clean filter, a clear condensate drain line and a drain pan that isn’t holding water help the system pull moisture out of the air the way it should. A clogged condensate line can overflow and soak the floor or ceiling near the air handler without anyone noticing.
7. Watch for condensation on cold surfaces
When warm, humid air hits something cold, water forms. In summer that can mean sweating windows, dripping cold water pipes and ductwork in the attic or crawl space beaded with water. Over time, that steady moisture is enough to grow mold on window sills, insulation and nearby wood.
Wipe up condensation when you see it, and treat it as a clue. Constant sweating usually points to high humidity indoors, missing or damaged insulation on pipes or ducts, or air leaks letting humid outdoor air in where it shouldn’t be.
If you already see mold
Small spots on hard surfaces, like a patch on a bathroom ceiling, can usually be scrubbed off with detergent and water and then dried well. Wear gloves and try not to stir up dust. The EPA suggests getting professional help when the moldy area is bigger than about 10 square feet.
Mold that keeps coming back, or a musty smell you can’t trace, means there’s a moisture problem cleaning won’t fix. That’s where an inspection helps. We offer mold inspections along with our home inspections, and every inspection includes moisture readings and infrared scanning to help find where water is getting in. Find the water, fix it, and the mold has nothing left to grow on.
