How to Lower Humidity in Your House: 12 Methods That Work

We may earn a commission from links on this page. How this works.

The twelve methods below are deliberately ordered by cost, cheapest first. That is not a gimmick. Moisture problems are almost always a supply problem, and a dehumidifier is a bucket under a leak — useful, but it never stops the leak. Work down the list in order and stop when your readings sit in range.

Before anything else, measure. A cheap digital hygrometer in the room that bothers you, left an hour to settle, tells you whether you have a real problem and later tells you whether you fixed it. A basic hygrometer costs less than a takeout lunch and is the only honest way to judge this — your phone does not have a humidity sensor, and weather apps report outdoor conditions.

The free fixes

Eight of these cost nothing but attention. Do them all before you spend a cent.

1. Run the bathroom fan properly — and leave it running

A shower can put a pint of water into the air in ten minutes. Most people turn the fan on when they get in and off when they get out, which is exactly the wrong window: the room is still saturated, and the walls and ceiling are still wet.

Turn the fan on before the shower and leave it running for at least 20 minutes afterwards, with the door closed so the fan is pulling from the bathroom rather than the hallway. If your fan has no timer, a cheap wind-up or electronic timer switch is one of the better small upgrades in a damp house. And check the fan actually moves air: hold a square of toilet paper against the grille, and if it does not stick, the fan is decorative.

Shower habits matter too. Water vapor released scales with temperature and time. Dropping a 15-minute steaming shower to eight minutes and a few degrees cooler measurably reduces the load, particularly in a small bathroom with a marginal fan. Less enthusiastically received than the other advice on this page, but it works.

2. Use the range hood, and check where it goes

Boiling a pot of pasta releases a startling amount of water. Cooking with the range hood on, and the lid on the pot, cuts that dramatically. Covering pots alone reduces the moisture released and cooks faster.

The catch: a lot of range hoods are recirculating, not ducted. They pull air through a grease filter and blow it straight back into the kitchen. That does nothing for humidity. If yours has no duct to the outside, treat kitchen moisture as something you have to vent by other means — a window, or the bathroom fan with interior doors open.

3. Stop drying laundry indoors

This is the single biggest avoidable indoor moisture source in most homes. Every load of wet laundry hung on an airer holds roughly a couple of quarts of water, and all of it ends up in your air, in your walls and on your windows.

If you have no choice, dry it in one room with the door shut and a window cracked or an extraction fan running, so the moisture leaves rather than distributing itself through the house.

4. Check the dryer is actually vented outside — and connected

This is worth crawling behind the machine for, because it is common and it is dramatic. A tumble dryer moves several quarts of water per load. If the flexible duct has vibrated off the machine’s outlet or off the wall port, every bit of that goes into your laundry room.

• Run the dryer and put your hand behind it. If it is warm and damp back there, the duct is disconnected or split.
• Check the exterior vent hood actually opens when the dryer runs. A flap painted shut, blocked by lint, or screened over with insect mesh backs the moisture up.
• Never vent a dryer into a crawl space, garage, attic or basement. Ventless heat pump and condenser dryers are a different case — they do not need a duct, but they do need their condensate tank emptied or drained.

5. Deal with firewood, plants and aquariums

Freshly cut firewood releases a lot of water as it dries indoors — keep it outside under cover and bring in only what you will burn that day. Houseplants transpire continuously, so a large collection grouped in one room is a real contributor; spread them out or move some. An uncovered aquarium evaporates steadily, and a lid stops most of it. None of these floods a house on its own, but in a tight home they add up.

6. Open interior doors and get air moving

Still air is what turns a damp room into a moldy one. Moisture accumulates in the pockets nothing reaches: behind furniture on exterior walls, inside closets, in corners.

• Pull furniture a few inches off exterior walls so air can circulate behind it.
• Leave closet doors ajar, especially closets on outside walls.
• Open interior doors so the whole house shares one air mass rather than one room becoming a moisture trap.
• A ceiling fan or a box fan on low does more for surface condensation than its size suggests. It does not remove any water, but it stops cold surfaces sitting in a stagnant humid film.

7. Ventilate at the right time of day

Opening windows helps only when the outdoor air is drier than the indoor air. In a humid climate in August, opening the windows at 6 pm makes the house wetter, not drier. Compare dew points rather than relative humidity figures, because dew point tells you the actual water content of the air. If the outdoor dew point is lower than the indoor one, bringing that air in dries the house; if it is higher, you are importing moisture. As a rough guide, an outdoor dew point in the 50s°F or below is drying for most homes, and one in the 60s or 70s is not.

The reliable exception is winter. Cold air holds very little water, so ventilating in cold weather always dries a house, which is why a 10-minute cross-draft on a January morning clears steamed-up windows so effectively.

8. Clear the gutters and extend the downspouts

Outside work, but free, and it is the fix for a huge share of damp basements. Water dumped at the foundation soaks the soil against the wall and comes through as vapor for weeks.

• Clear gutters so they actually carry water to the downspouts.
• Extend downspouts at least 4 to 6 feet from the foundation. Splash blocks alone are rarely enough.
• Check the ground slopes away from the house for the first several feet. Soil settles over the years and quietly reverses the grade.
• Keep a cover on the sump pit. An open pit is an evaporating pond in your basement.

The cheap fixes

Small money, and each of these solves a specific mechanism rather than just moving air around.

9. Repair, upgrade or seal your extraction

A bathroom fan that is 20 years old, clogged with dust, or vented into the attic instead of outside is worse than no fan — it is putting your shower into your roof structure. Pull the cover off and look. Replacement fans are inexpensive, and a quiet one with a humidity sensor and a run-on timer is the version people actually leave switched on.

While you are at it, seal the dryer duct joints with foil tape rather than cloth duct tape, which dries out and falls off. Short, straight and rigid beats long, crushed and flexible every time.

10. Insulate cold surfaces so they stop condensing

Condensation is a surface temperature problem as much as a humidity problem. Where a surface sits below the dew point of the room air, water forms on it, feeds mold, and evaporates back into the room later.

• Cold water pipes. Foam pipe sleeves cost a few dollars per length and stop the summer dripping that makes basements damp.
• Uninsulated ductwork running through a humid basement or crawl space sweats for the same reason.
• The crawl space hatch and band joist. An uninsulated, unsealed hatch is a direct connection between a damp crawl space and your floor.
• Exterior wall corners and closets that grow mold repeatedly are usually cold spots. Insulation there fixes what a dehumidifier cannot.

11. Run your air conditioning the right way

Your AC is already a dehumidifier — it condenses water on the evaporator coil and drains it away. Most people cost themselves that benefit through one setting.

Set the thermostat fan to AUTO, not ON. This is the most useful little-known point on this page. In ON mode, the blower keeps running after the compressor stops. The evaporator coil is still wet with the condensate it just pulled out of your air, and blowing house air across a wet coil evaporates that water straight back into your home. You get moved air and re-humidified rooms. In AUTO, the fan stops with the compressor, the coil drains, and the water goes down the condensate line where it belongs.

Two more AC points worth knowing:

• Long, gentle cycles dry better than short blasts. The coil needs several minutes of runtime before it is pulling meaningful moisture. An oversized system that satisfies the thermostat in six minutes cools without ever drying, which is why some homes feel clammy at 72°F. Why is my house so humid covers that diagnosis.
• Check the condensate drain. A blocked line or full pan means the water your AC collected is sitting indoors evaporating again.

When you actually need equipment

If you have done the above and your readings still sit above 55–60%, you have a moisture load your building cannot shed on its own. That is what a dehumidifier is for, and at that point it is the right purchase rather than a shortcut.

12. Get the size right, then run it sensibly

Undersizing is the standard mistake, and it has a specific cause: US capacity ratings changed in 2019. Units are now tested at 65°F rather than 80°F, which puts the same machine roughly 25–30% lower on paper. An old 70-pint is about today’s 50-pint. Most sizing charts still floating around the internet were written against the old numbers and are therefore around 30% undersized.

Work out what your space needs with the dehumidifier size calculator, which uses current figures. If the space is a basement, the basement dehumidifier guide covers drainage and placement, both of which matter more than brand.

• Set it to 45–50%, or 50% in a basement. Setting 30% costs a great deal more electricity and protects nothing extra.
• Treat one space with the door closed. One basement unit does not dehumidify a whole house.
• Use continuous drainage if there is a floor drain or a suitable route. Nobody empties a bucket twice a day for long.
• Budget for the running cost before you buy — see what a dehumidifier costs to run.

Ventilation systems in tight houses

If your house is new or recently air-sealed, it may simply no longer breathe. Older houses leaked their moisture away through drafts; a tight one needs deliberate ventilation. The usual answer is a balanced system — an HRV or ERV, which exchanges stale indoor air for filtered outdoor air while recovering most of the heat. An ERV also transfers some moisture, generally the preference in humid climates.

Both are HVAC contractor territory rather than a weekend project, and worth pricing against a whole-house dehumidifier tied into your ductwork if the problem is the whole building rather than one damp room.

How to stop condensation on windows

This is the symptom people notice first, and it is telling you something specific. Glass is by far the coldest surface in a heated room, so when room air touches it and is chilled below its dew point, water comes out onto the pane. Condensation therefore means one of two things: too much moisture in the air, or a window surface that is too cold. Usually both.

What to do, in order:

• Lower the indoor humidity for the outdoor temperature. In a cold snap the ceiling is far lower than the usual 50% — often 30–40%, and lower still below 10°F. The full table is in ideal indoor humidity levels. Drop by 5 points and check the next cold morning.
• Get air moving across the glass. Open the blinds and curtains during the day; a closed curtain traps a cold, still, humid layer against the pane, which is why condensation is usually worst behind them.
• Ventilate briefly in the morning. Ten minutes of cross-draft in cold weather removes a lot of overnight moisture cheaply.
• Attack the sources overnight. Bedrooms are the classic case — two sleeping adults release a meaningful amount of water into a closed room. Leaving the bedroom door ajar usually solves morning window sweat on its own.
• Warm the glass. Storm windows, insulating film, thermal curtains left open by day, or eventually better glazing. A warmer inner surface can hold a higher room humidity without dripping.

Wipe up what forms, every time. Standing water on a sill soaks into paint, wood and drywall and produces the black spots at the bottom of the frame that are the real damage.

One distinction worth making: condensation between the panes of a double-glazed unit is not a humidity problem at all. The seal has failed and the unit needs replacing. Nothing you do to your indoor air will change it.

Frequently asked questions

How can I lower humidity without a dehumidifier?

Cut the moisture you are producing and vent what remains. Run bathroom and kitchen extraction properly and for 20 minutes after use, stop drying laundry indoors, confirm the tumble dryer is vented outside with the duct connected, cover pots when cooking, and open interior doors so air moves. Outside, clear gutters and extend downspouts away from the foundation. In cold weather, brief cross-ventilation dries a house quickly.

Does opening windows reduce humidity?

Only if the outside air is drier than the inside air. In winter that is almost always true, so airing out works well. On a humid summer day it does the opposite — you are inviting moisture in. Compare the outdoor dew point rather than the outdoor relative humidity, since dew point tells you the actual water content of the air.

Does air conditioning lower humidity?

Yes, as a byproduct of cooling — water condenses on the cold evaporator coil and drains away. Two things stop it working: setting the thermostat fan to ON rather than AUTO, which re-evaporates coil water back into the house, and an oversized system that satisfies the thermostat too fast to dry anything. Set the fan to AUTO and check the condensate drain is clear.

How do I stop condensation on my windows overnight?

Lower the bedroom’s moisture and improve air movement. Leave the bedroom door ajar so the room is not a sealed box holding the water two sleeping people release. Leave curtains and blinds open, since a closed curtain traps a cold humid layer against the glass. If it persists, drop your whole-house humidity by 5 points and reassess after the next cold night.

What humidity level should I aim for?

30–50% relative humidity, targeting 45–50% in living space and 50% in a basement. The EPA advises staying below 60%. In cold weather the practical ceiling drops further because window glass condenses long before the air feels damp — if your windows sweat, you are too high for that day regardless of what a chart says.

Next steps

• Work out the cause first: why is my house so humid?
• The targets, room by room: ideal indoor humidity levels
• What the number means for mold risk: what humidity level prevents mold
• If you need a machine: the dehumidifier size calculator
• Damp downstairs specifically: the basement dehumidifier guide
• What it will add to the bill: dehumidifier running costs