Humidity and mold are common issues in many homes, especially during colder months when windows stay closed, heating is reduced, and moisture builds up indoors.
In Zagreb, this can happen in apartments, houses, rooms, studios, and older buildings, but also in newer properties if the space is not used properly. The good news is that many humidity and mold problems can be prevented with regular ventilation, proper heating, and responsible daily habits.
This guide explains what tenants should do to keep the property healthy, comfortable, and protected during their stay.
Why Humidity Happens
Everyday activities create moisture inside the property.
Moisture comes from:
- showering
- cooking
- drying clothes indoors
- sleeping with windows closed
- keeping rooms cold during winter
- not ventilating regularly
- blocking airflow behind furniture
- ignoring leaks or water stains
When moisture stays trapped inside, it can create condensation on windows, walls, ceilings, corners, furniture, and around poorly ventilated areas. Over time, this may lead to mold.
Why Ventilation Is Important
Ventilation is one of the simplest and most important ways to prevent humidity.
Opening the windows allows moist indoor air to leave and fresh air to enter. This is especially important after sleeping, cooking, showering, cleaning, or drying clothes.
A short, strong ventilation several times per day is usually better than leaving a window slightly open for many hours during cold weather. In winter, leaving windows tilted for too long can cool down the walls and increase the risk of condensation.
A practical routine is:
Open windows fully for a few minutes in the morning, after showering, after cooking, and before sleeping if needed.
The goal is to refresh the air without cooling the whole property too much.
Heating Matters Too
Ventilation alone is not enough if the property is kept too cold.
During colder months, rooms should be heated reasonably and consistently. If a room stays cold for a long time, walls and corners become colder, and moisture from the air can turn into condensation more easily.
This is especially important in bedrooms, bathrooms, kitchens, and rooms with outside walls.
Tenants should avoid turning off heating completely for long periods during winter if the apartment is occupied. Saving a small amount on heating can later create a much bigger problem if humidity or mold appears.
Good heating and good ventilation work together.
Heating keeps the space warm enough.
Ventilation removes excess moisture.
Both are necessary.
Daily Habits That Help Prevent Mold
Small habits make a big difference.
Tenants should:
- ventilate every day
- heat the property reasonably during colder months
- use the kitchen hood when cooking, if available
- open a window after showering
- dry bathroom surfaces if there is too much water
- avoid drying large amounts of laundry indoors without ventilation
- keep furniture slightly away from cold outside walls
- avoid blocking radiators or heating sources
- report leaks, water stains, dripping, or damp areas immediately
- clean small condensation spots early before they become a bigger problem
If you see water on windows in the morning, that is usually a sign that the room needs more ventilation and/or better heating.
Drying Clothes Indoors
Drying clothes indoors can create a lot of humidity.
If there is no balcony, dryer, or laundry room, tenants should dry clothes carefully. Use a drying rack in a ventilated space, keep some distance from walls, and open the windows regularly.
Do not dry wet clothes in a closed, cold room. This can quickly increase moisture and may contribute to mold.
If a dehumidifier is available, use it according to the instructions.
Bathrooms and Kitchens Need Extra Care
Bathrooms and kitchens create the most moisture.
After showering, tenants should ventilate the bathroom or use the fan if there is one. If there is no window or fan, leave the bathroom door open after use so the air can circulate.
In the kitchen, use the hood if available, cover pots when possible, and ventilate after cooking. Boiling water, long cooking sessions, and steam can quickly increase humidity.
Report Problems Early
Some humidity or mold problems can be caused by leaks, roof issues, pipe problems, poor building insulation, window defects, or other technical issues.
That is why tenants should report problems early.
Report immediately if you notice:
- water stains
- leaks
- dripping
- wet walls
- damp corners
- mold spots
- unusual smells
- condensation that does not improve
- windows or walls that stay wet
- problems with heating or ventilation systems
Send photos, videos, and a clear explanation of where the issue is located and when you first noticed it.
Early reporting helps the landlord understand whether the cause is technical, building-related, or connected to daily use.
Tenant Responsibility
Tenants are responsible for using the property responsibly during their stay.
If mold or humidity damage appears because the property was not ventilated, not heated properly, used carelessly, or because obvious signs were ignored and not reported, the tenant may be held responsible for the resulting damage, cleaning, repairs, or related costs according to the rental agreement and applicable documentation.
This does not mean every mold issue is automatically the tenant’s fault.
Sometimes the cause may be a leak, structural issue, poor insulation, broken ventilation, or another technical problem. Responsibility should be based on the cause of the issue, available evidence, photos, communication records, and, where needed, professional assessment.
However, tenants should understand that lack of ventilation, lack of heating, drying clothes indoors without airflow, and ignoring early warning signs can create or worsen mold problems.
What to Do If You Notice Mold
If you notice mold, do not ignore it.
Take clear photos, note the date, describe the location, and report it to the landlord or the responsible contact person as soon as possible.
Do not cover the area with furniture, posters, paint, or decorations. This can make the problem worse and hide important evidence.
Continue ventilating and heating the property properly while the issue is being reviewed.
For small surface spots caused by condensation, regular cleaning and improved ventilation may help. For larger or recurring mold, the cause should be checked properly.
Final Reminder
A healthy apartment needs regular airflow and reasonable heating.
To prevent humidity and mold:
Ventilate daily.
Heat properly in winter.
Use the kitchen hood and bathroom fan where available.
Dry clothes carefully.
Keep airflow around walls and furniture.
Report leaks, dampness, or mold early.
Good habits protect your health, your comfort, the property, and your security deposit.