How to Reduce Basement Humidity

water in cement basement
  • 4-8 hours
  • Beginner
  • 350-750
What You'll Need
Brush (to clean the coils)
Extenders for downspouts
Splash blocks for downspouts
What You'll Need
Brush (to clean the coils)
Extenders for downspouts
Splash blocks for downspouts

Basements are often used as places for storage, where things like the cat litter gets put, and your laundry machines hang out. Not a lot of homeowners spend time down there because they are dark, dank, spaces that aren’t particularly welcoming.

While they can be turned into usable space, like kids play rooms or extra living quarters, homeowners don’t always have the funds to do a complete reno, and instead DIY the space to make it work for their needs.

These unfinished spaces hold a lot of moisture and extra humidity because of where they are located and how they are built. To make your space more comfortable, here are some ways to reduce basement humidity.

Why Is It Humid?

Basements are prime suspects for humidity because they are located underground, and usually surrounded by cement or other masonry materials like concrete blocks, which hold in moisture. Ground that is below grade always holds moisture, as well, so it's inevitable that it will seep in through the walls and the floor.

It also maintains a moderately cool temperature no matter what the season is, so when temps fluctuate above ground, the battle between hot and cold air will cause excess humidity. Grading issues, foundation problems, and leaks will only exacerbate the issue.

Basements are often built with lower ceilings than the rest of the house, and with minimal windows. Small, dark spaces will hold humidity more than airy, well-lit ones, where natural sunlight and airflow can naturally fend off extra moisture in the air.

Humidity Problems

You’ll know there's too much humidity if you see mold anywhere. Mildew and bacteria thrive on wet concrete walls and floors, or may be hidden underneath drywall and other wall boards.

Check the lower corners where the walls meet the floor. Mold can also get into any insulation that isn’t ventilated properly. If your concrete walls are cool to the touch, that’s normal, but if you see water droplets or feel any dampness, then humidity levels are too high. Same goes for any condensation on glass windows or plastic vapor barriers.

Smell is another giveaway that air quality is off due to dampness. You can usually pick up on mildew and excess humidity with your nose, as anything that will hold moisture like newspapers, cardboard, drywall, and other penetrable surfaces are prime breeding grounds. While bleach can kill mold and mildew, it’s merely a band-aid to a bigger problem.


dehumidifier in basement

For most homes, simply running a portable dehumidifier in the basement can solve humidity problems as they draw in excess moisture from the air. Units come in various sizes, don’t need professional installation, and cost anywhere from $50-$500, depending on the size.

The larger they are, the more cubic feet they are meant to handle. Unlike square footage which is length by width, cubic footage measures the length, width, and height to calculate the space of the entire room. Multiply these numbers to get the total cubic feet of the basement, and use a dehumidifier that will be powerful enough for that area.

If you have multiple rooms, you should place one unit in each of them. They need an electrical outlet to run, and will have to be drained once their reservoirs fill up. Some can be drained directly into a laundry sink.

They are simple, and effective ways to reduce basement humidity without breaking the bank.

Whole-Home Dehumidifiers

Whole house dehumidifiers are excellent options for homes that have extreme humidity problems. These units have to be professionally installed on your existing HVAC system where they will monitor humidity levels through a humidistat, and keep levels consistent.

They can be great solutions in very humid climates, but shouldn’t be installed to cover up for problems like leaks, floods, and other foundation issues. They can keep your home much more comfortable all season long, and take away the cumbersome need to drain portable units that also take up space in a room.

The costs are a lot higher up front, ranging from $1000-$3000 depending on your needs. Multiple portable units can add up fast, so it may be worth the cost in the long run, especially since they are more energy-efficient.

There are even models designed for crawl spaces that will be slightly less expensive, and worth the money since options for removing moisture in tight spaces like that are limited.


basement insulation

Since basements are fully enclosed in cement and concrete materials, insulating the walls and floor can be a great way to keep humidity levels down. Not any insulation will do, however, as batts and vapor barriers are breeding grounds for mold in damp environments.

Foam boards or professional spray foam is the best kind of insulation to create a thermal barrier between the warm air from the room, and the cold air from outside. If the basement space is vented with hot and cold air registers, the insulation will keep the space conditioned just like the rest of the home, naturally balancing the fluctuating temperature.

The wrong insulation or improper installation can do more harm than good, so don’t cheap out on this job. Foam boards can be DIY-installed, but spray foam should be done professionally.

Seal any gaps between windows, and where pipes and vents meet exterior walls with caulking, canned spray foam, and weather-stripping. Insulating water pipes with foam strips is another easy way to cut down on condensation in your basement.

Install and Open Windows

basement with windows

Getting some fresh air into a space can be a great way to get rid of musty, stagnant air, especially when you get a cross breeze between two windows on opposite sides of the room.

Good quality windows with screens can be an effective and relatively simple way to reduce trapped humidity on a nice day. If the air outside is overly humid, however, it would actually be better to close them, and use other ways to ventilate.

Installing windows in a windowless basement also lets in natural sunlight which reduces dampness and combats mildew, so even if you aren’t opening them, they can provide a lot of humidity-reducing benefits.

Check out local rebates for replacing old, inefficient windows in your basement.

Turn on Your Furnace or A/C

Your HVAC system is great at creating airflow and ventilation throughout the whole home. Warm air in the winter naturally dries out the room, which is why dehumidifiers aren’t run as much during the colder months.

The basement often stays cooler than the rest of the house since hot air rises, and it’s below ground. This can be great in the summer as the space stays naturally cooler, but that doesn’t mean humidity levels won’t increase. Running the air conditioner in the summer months will help reduce humidity in basement spaces even though they may be cooler than the rest of the house.

If it’s too cold for the AC, but the space feels stuffy, running the fan option for an hour can help to ventilate the space without adding hot or cold air. This is not recommended as a constant mode, but only as needed.

Check that your systems are running well, replace filters regularly, and make sure vents are run into the basement, and kept open.


plant in house by window

Here’s a great reason to buy more houseplants: they reduce humidity levels! Plants will absorb the moisture in the air through their foliage, sucking up excess moisture in basement spaces.

Some plants are better at this than others, but many of the indoor plants that you already love are excellent at balancing humidity levels. Peace lilies, spider plants, peperomias, snake plants, orchids, palms, and ferns are all recommended for humid spaces.

You don’t have to worry about only using these species, as any indoor plant will naturally help with humidity. Most houseplants are tropical and love humid spaces, so it’s a win-win for you both.

Make sure not to over-water them, as this will cause extra moisture in the air, and possibly fungal problems. While plants won’t fix major issues, they can help a humid basement feel more comfortable.

Use Ceiling and Portable Fans

A ceiling fan can be very effective at reducing humidity without costing a lot of money. They are fairly easy to install yourself, and only require some basic electrical knowledge.

Stagnant air breeds moisture and mold, and any kind of breeze or airflow will naturally make a space drier. Circulating fan blades will help moisture evaporate by increasing airflow, and dispersing it around the room.

Run them counter-clockwise when it’s warm as the fans will push cool air down, changing them to clockwise when the temp is cool. Basements are notorious for having low ceilings, so it may not be possible to install them without causing a safety issue.

If that’s the case, wall and floor fans will also work to circulate air around the room and reduce humidity. Placement is very important, as fans can draw in air from windows, or push air out of them. Window fans can be installed quite easily and inexpensively, with fans that oscillate to push or pull outside air in.

Use Exhaust Fans

drill installing exhaust fan

If a basement is being used as extra living space or apartment, activities like cooking and bathing can add a generous amount of humidity to the air. Boiling water and baking will increase the amount of heat and steam in a room, which will increase humidity.

Always use the exhaust fan above the stove and make sure it's properly vented outside. If you don't have one, get one installed or do the job yourself. The exhaust fan will reduce the extra humidity while you are cooking and also when you finish, so leave it on for an extra 30 minutes. It will also remove smells and help indoor air quality.

Same goes for bathroom exhaust fans. These should be run anytime anyone showers or takes a bath, as steam and heat will add a ton of moisture to the air.

Dishwashers, hand washing dishes or clothes, and damp towels will also add humidity. Run exhaust fans in conjunction with opening windows to reduce the effects of these everyday actions.

Inspect any exhaust vents that run outside, including the stove exhaust, bathroom fan, and the dryer vent. Seal up any gaps, and use HVAC metal tape on dryer vents that are loose or broken.

Don’t Hang Dry Your Clothes

This may seem like a no-brainer, but since the washer and dryer are often in the basement, many people choose to hang pieces of clothing on a clothes rack or hangers near the machines. While this can be convenient, the humidity released from the wet clothes will saturate an already humid basement, adding extra moisture, and taking longer to dry your items.

If you want to save on energy costs, install a clothesline in your backyard and make use of the sun and wind to naturally dry your clothes for free. They’ll last longer, and smell better, too.

If it’s too cold to dry them outside, you may want to opt for using the dryer, or find a spot upstairs where rooms may benefit from the added humidity.

Install a Fireplace

A wood burning stove installed in the basement can drastically reduce the humidity of the room that it’s in. While it’s a misconception that wood burning stoves dry out air more than a furnace, the reason they do is because of the concentration of the heat.

Furnaces distribute heat around the entire house, so while they dry out the home to the same degree, the wood burning stove dries out the area directly surrounding it. Wood stoves are always vented outside, which also increases air circulation.

Gas fireplaces that are vented outside will dry out the air in the same way as wood burning stoves, but un-vented ones may have the opposite effect, as this type of combustion actually adds moisture to the air.

Fix Foundation and Grading Issues

foundation water damage

If any concrete grading around your home slopes inward instead of outward, water will inevitably seep in. Fix the grading so that water falls away. This may be enough to solve any leaks coming in through the foundation.

If there aren’t any issues with the grading around your house, but you are noticing leaks or places where water pools, then the job becomes a bit bigger and more expensive, as it means you may have a crack somewhere in the foundation. This can be costly, but the repair is necessary to save the integrity of your home.

Leaks after heavy rainfall can damage your items, and cause other problems like mold and mildew. Installing a sump pump may be another way to deal with constant floods and leaks, but this can also be expensive and back-breaking work.

If you suspect you have foundation issues, get a professional to assess the job.

Check Downspouts and Eaves

You may not need a contractor to reduce the amount of moisture that is seeping in through your walls, as it could be as simple as drawing water away from the home. Take a walk around the perimeter of your house and see if there are spots where the ground angles into the home rather than away.

Driveways, lawns, patios, and pathways should all be built with slope in mind so that when it rains, water runs away from the foundation. You may be able to fix slope problems yourself by adding height to these areas with dirt fill, gravel, or concrete, depending on the location.

Downspouts from eaves troughs should also be checked to see that they usher rainfall towards gutters and sloping driveways, not foundations.

You can buy downspout extensions or long pipes to help guide the rain towards a slope. They can also be fed into rain barrels, or directly into rain gardens to eliminate excess water from getting into your home.

Adding a better slope to your paved spaces could be a much cheaper and more efficient way to eliminate water from entering.

Basements will naturally be humid spaces because of their construction and location, but that doesn’t mean you can’t achieve healthy levels and keep the space comfortable.

Remember that the goal for basement humidity is reducing excess amounts, not abolishing them. You'll never be able to completely remove it, nor should you want to. Invest in a humidistat and use some of these tips to keep humidity levels below 50 percent.

Learning how to reduce basement humidity may solve common issues and keep major repairs at bay, while also maintaining the health of your home and those who live in it.