Surviving Korean Summer Mold: A Foreigner's Guide to Apartment Moisture Control

Okay, so you've made it through your first Korean winter without freezing to death. Congratulations! But now it's June, the humidity is climbing, and you're noticing black spots creeping across your bathroom ceiling and closet corners. Welcome to one of the most annoying parts of living in a Korean apartment: summer mold (곰팡이, gommangyi).

I'm going to be real with you—this is something literally every foreigner I know has dealt with. But after three years here, I've figured out the tricks to minimize it. Let's talk about why it happens and how to actually fix it.

Why Korean Apartments Get So Moldy

Seoul's summer humidity regularly hits 70-85%, and older apartments (which make up a huge chunk of the rental market here) weren't designed with modern ventilation in mind. Most Korean apartments have ondol (온돌)—that underfloor heating system—which creates moisture that has nowhere to go in summer. Plus, many buildings have poor exterior insulation, so condensation forms on walls when humid outside air meets cooler interior surfaces.

Add in the fact that many foreigners don't realize you need to actively manage humidity here, and boom—mold city.

Prevention: Your First Line of Defense

Use a dehumidifier

This is non-negotiable. Grab one from Coupang (쿠팡) for 50,000-150,000 KRW. I use a 10-liter capacity model from Whirlpool that runs about 80,000 KRW. Empty it daily or get one with a drainage hose.

Ventilation is everything

Open windows for 15-20 minutes every morning, even if it feels humid outside. The outside humidity is usually lower early morning.

Turn on your bathroom exhaust fan (환기구, hwangigu) during and for 30 minutes after showers.

Keep interior doors open to allow air circulation.

Watch your closets

This is where mold loves to hide. Place silica gel packets (건조제, geonjoaje) or moisture absorbers inside. You can buy these at any convenience store (GS25, CU) for 2,000-5,000 KRW. Replace them weekly.

When It's Already There

If you already see mold, don't panic. For small patches:

Mix bleach with water (1:10 ratio) and spray directly

Alternatively, use white vinegar—less harsh and works surprisingly well

Wipe dry completely

For larger areas or if it keeps coming back in the same spot, contact your landlord immediately. In Korea, landlords are responsible for structural issues. Document everything with photos and send via KakaoTalk (most Korean landlords communicate here). Use phrases like: "곰팡이가 계속 나타나요" (The mold keeps appearing) or "환기가 안 돼요" (The ventilation isn't working).

The Nuclear Option

If your apartment is genuinely damp no matter what you do, consider renting a larger dehumidifier or asking your landlord about installing proper ventilation. Some buildings have installed exhaust fans specifically for this—it's worth asking.

My Personal Recommendation

Honestly? Invest in a good dehumidifier immediately. It sounds expensive, but it's cheaper than replacing your belongings or dealing with respiratory issues. I run mine religiously from May through September, and it's made an actual difference in my apartment's overall health.

Also, check your jeonse (전세) or monthly lease (월세) contract before signing—ask specifically about ventilation and humidity issues. Some buildings are just architecturally better suited for summer living than others.

You've got this! Summer mold is annoying but totally manageable once you know the game.