Last Updated on October 24, 2026 by Umar Farooq
How to reduce humidity in an apartment: measure it with a cheap hygrometer, then cut the moisture you add (steam from cooking, showers and indoor laundry), vent what you can, and keep the reading under 60% RH, ideally 30-50%. Anything the building itself causes, such as leaks or a dead extractor fan, is a job for your landlord, not for you.
Most humidity advice is written for people who own the loft. This is the version for the person with a lease and a sofa.
Why a flat holds on to moisture
Three things set an apartment apart from a house, and none of them is your fault.
- Little air. Four people breathing, showering and cooking in 55 square metres (about 590 sq ft) share one small volume of air. Nothing dilutes the steam.
- Little control. You often cannot choose the fan, vents or heating, and noise or security may keep windows shut.
- Nowhere for steam to go. If the bathroom fan is weak or blocked, the steam moves to the bedroom.
I cannot give you a typical apartment figure, because no source I could open measures one. Measure yours.
Get a hygrometer before you change a single habit
A hygrometer is a small gauge that reads relative humidity. I think it is the only purchase worth making before you change anything else, because it tells you which of the fixes below is worth the effort. How humidity is measured explains what the numbers mean.
Put it where you notice the problem, away from the bathroom door, and read it morning and evening for a week. The EPA’s guide to moisture in the home says to keep indoor humidity below 60%, ideally between 30 and 50%, and that an inexpensive meter from a hardware shop will do.
Run the fan, then check it is doing anything
EPA advice is to run the bathroom fan or open a window when showering, and to use an exhaust fan or window when cooking.
Here is the test most people never do: switch the fan on, hold a single sheet of toilet paper up to the grille, and see whether it sticks. If it falls off, the fan is not moving air. That is a repair for the landlord. The GOV.UK damp and mould guidance says landlords should check that kitchen and bathroom extractor fans work and are powerful enough, and that fans with an overrun, which keep running after you leave, are one option.
Three habits cost nothing: lids on pans, the bathroom door shut while the shower runs, and the fan left on for a while afterwards. A cooler shower makes less steam too.
Dry washing where the damp can leave
An airer of wet washing is the most common hidden source in a small flat, because the water has to go somewhere. Dry in one room with the door shut and a window open a crack, or use a vented or heat-pump dryer if the building allows one. Drying clothes indoors without mould has the full routine, including what to do on the day you cannot open a window.
GOV.UK lists drying laundry as a source of indoor moisture, so if your building has a covered outdoor drying area or a shared laundry, use it.
Summer is a different problem
In summer the moisture comes in from outside. Damp warm air through an open window is not going to dry anything, and the guidance I trust on this comes from building scientist Allison Bailes at Green Building Advisor: keep windows closed when the outdoor dew point is above 60°F (15°C), and set the air conditioner’s fan to “auto” so it does not blow moisture from a wet coil back into the room.
An air conditioner takes some moisture out as a side effect of cooling; does air conditioning remove humidity? covers where that helps.
Is a portable dehumidifier worth it in an apartment?
Sometimes, and it is the last fix rather than the first. I would add one when the hygrometer stays above 60% after the habits above, or when you have a small room, such as a windowless bathroom or a bedroom with a damp external wall, that you cannot ventilate.
Size it to the room: what size dehumidifier do I need? takes you through it. For diagnosis across a whole home, see how to lower humidity in a house.
A dehumidifier treats the air, not the cause. If water is coming through a wall, ceiling or window frame, running a machine will not fix it, and you should tell your landlord rather than mask it.
Tell the landlord what you found, in writing
This is the bit I most want tenants to hear. The GOV.UK guidance on damp and mould in the home (England) says landlords should not blame damp and mould on tenants’ lifestyle choices, because cooking, washing and drying laundry are unavoidable. It treats changes in tenant behaviour as an addition to fixing the building or ventilation, not a substitute.
That makes your evidence useful. I would send:
- the hygrometer readings, with dates
- photos of any condensation, mould or stains
- whether the extractor fans work and the trickle vents are open
- any leaks, drips or damp patches, and where
The same page encourages tenants to report quickly and says you can go through a tenant advocate or your local council if you do not want to approach the landlord directly. Rules differ between countries, so check the guidance where you live.
A small flat needs fewer sources, not a bigger machine
To reduce humidity in an apartment, change the moisture you make before you buy anything that makes noise, and ask the landlord to fix what you cannot. The hygrometer tells you which step worked.
FAQ
How to reduce humidity in an apartment without a dehumidifier?
Cut the moisture you add: lids on pans, fans on for showers and cooking, one shut room for drying laundry, and windows closed on humid days. If a hygrometer still reads above 60%, a portable unit is next.
What humidity should an apartment be?
The EPA says keep it below 60%, ideally 30 to 50%.
Why is my apartment so humid?
Small volume, daily steam, indoor laundry and weak ventilation are the usual causes. Blocked extractors and leaks are the landlord’s to fix.
Who is responsible for damp in a rented flat?
In England, GOV.UK guidance says landlords are expected to address the underlying causes of damp and mould and not blame tenants’ lifestyle. Rules differ elsewhere, so read your local tenant guidance.
