I typed this up for myself/another forum since I'm getting ready to move again. Thought I'd pass it along here.
So, it's your second or third year in Korea - you're not a lifer yet who can afford 20+ million key money, but you'd like to get a better place.
Having lived in Korea a whopping 3 years and during that time inhabited 2 crappy places, one decent one, and seen dozens more I thought I'd offer my thoughts about apartment hunting here. Aside from a few exceptions, western cities don't have the same population density nor the same issues. Also, having asisted my father on numerous suburban house projects growing up I shake in disbelief at how many code violations Korean buildings often fail - even new ones.
A year ago I went looking for about 3 weeks to different 부동산s and must have seen about 80 places before settling on my current place which I must leave, for hopefully greener pastures. It's best to go on foot; I found that Korean real estate sites are a real pain in the ass to navigate; plus you've gotta register for half of them and get phone calls later. You can try searching for (town/city) 원룸/투룸 on naver or check out a PC Bang in the neighborhood you want to live in; there are usually shortcuts on the desktop to all kinds of things.
1) Location: Is the room _________? I detest noise.
On a busy street?
Are 24 hour businesses nearby?
Are there delivery motorcycles coming and going? Do the delivery bikes have obnoxious ghetto blaster rigs on them?
Is there a tiny 100 square meter park outside begging for assholes to hold soju drinking contests at 3am?
Are there smelly restaurants, mountains of garbage, or open sewers nearby? Is there a busy car maintenance shop nearby?
Is it a university neighborhood?
Are there annoying LED signboards everywhere?
Are there 안마s up and down the block?
Things I haven't contended with in the last year: The god squad hasn't knocked on my door! Protip: save those "You must call the gas company to check to make sure you aren't going to die from a leak" papers, repost them after you get checked... makes your apartment look vacant.
Make sure to walk around the neighborhood at different times of day. Find out when trash day is.
Two final things that'll probably get me in trouble: I'd stay away from South East Asian worker quarters, my white guilt kicks in when I learn 5 guys are living in a one room. However, I've had a lot of female friends get harassed by them. Finally, if you pick a university neighborhood and are female be ready to encounter stalkers, flashers, and less desirable things. This isn't exclusive to western women. A lot of exchange students and Korean women have to contend with this too.
2) Building: How ________ is it?
Dilapadated? Does it have many cracks in the cement? Is the sidewalk deteriorating? Is there sinking brick or cracked concrete? Are there power lines strung haphazardly everywhere?
How noisy is the stairwell/center stairwell? Is it the smokers lounge?
Is it clean? Full of spit stains? Bugs? Cats? Rats?
Which floor is the apartment on?
Is it an officetel with businesses on the first floor?
Is there a public restroom in the building?
Is there a place to stash the bike which you paid less than 60k won for that no one wants to steal?
What is the likelyhood of getting a headache/cancer/dying from fumes/fire/earthquake from brake cleaner, glue, or CO2 poisoning from the elderly neighbors whose children forgot about them?
Tip: look for a building that is camouflaged - my current place used to be a hagwon maybe 4 years ago; the signs are still up and the second floor still has a large glass door which most of the flier stickers think is just a single apartment, not three. Also, don't live in a building with children. If you see a school uniform of any kind, mark the place off your list - you don't want students knowing where you live.
3) Apartment: Does the apartment ________?
Have a strong door which isolates hallway noise and provides an airtight seal? Does it have a myriad of locks?
Have a separate kitchen and bathroom? Smells travel.
Have windows with damaged screens - note how difficult it will be to plug holes to prevent mosquito and bug ingress.
Have windows which can be easily covered with wallpaper or wrapping paper to reduce sunlight and streetlight?
Have floors in good shape?
Have dirty is the wall paper? Have mold? Have dirty cabinets and greasy fume hoods?
Is there a decent large mirror in the apartment?
Have decent shoe storage? If there is built in clothing storage, is it in a sensible place, ie doesn't require walking in the dirty entryway.
Are the windows clean or have old decals/signs on them?
Do you have privacy?
Do the neighbors get busy at 3am?
How is the ambient noise?
Is there a place to dry clothes?
How many hours of scrubbing will it take to make the place livable?
Have a really smelly bathroom?
How poor is the plumbing - no trap(the u shaped tube which is supposed to keep sewer gas from seeping into your apartment), are the pipes unsealed?
A common shower and sink drain? Do the drains actually work?
Have cracked tile and caulk?
Does the showerhead have strong pressure?
Is there a splashguard on the bathroom door?
Will the toilet paper holder get soaked?
Are the bathroom light fixtures bright enough?
Is the mirror large enough?
What is the likelyhood of electrocution - are power outlets in the bathroom protected?
Are the washing machine hookups in the bathroom?
Have working lights?
How difficult is it to disable the motion activated light?
How difficult is it to change the light bulbs?
How obnoxiously cheap are the CFL lights?
Are there enough power outlets?
Is there a good CATV/internet outlet? Does 100mbps internet come through those 15 year old wires or will a new punched through a hole and stapled across the room?
How is cell phone reception?
Is the wifi spectrum crowded?
Does the apartment have separate and easily identified power and gas meters?
Have decent heat (non-electric, new boiler, thermostat from this century?)?
Have air conditioning? Is it moldy or clean? Does it drain outside or into a 2 liter bottle? Are the holes around those tubes plugged?
Is there counter space in the kitchen for a toaster, rice cooker, microwave, or whatever else you can't live without?
Is the gas range completely caked in grease?
Tips: ask for an electric lock to be installed. It's 40k won and will help to sell the place in the future - realators hate looking for keys.
If the wallpaper is dirty ask to have it replaced; if it's moldy stay away.
Buy a smoke alarm - one should be included with every public school teacher's care package.
Pink plastic bathroom fixtures and vanity might be ugly and insult your masculine sensibility, but it beats rusty metal any day. The same goes for wallpaper: Pink flowers are unavoidable.
4) Furniture: Do you need a full option situation?
Take photos. Lots of photos. Bring a tape measure.
Measure the stuff that you have, think about where you'll sleep, where your huge fridge will go, where you can put your plants.
5) Moving out: / Renewal
Pay your gas and electric bills. Don't pay them twice. Get your deposit back. Leave on good terms.
If you'd like to stay longer, contact your landlord asap - not your real estate agent. You will need a Korean friend for this. Real estate agents may charge you again...
월새, 전새, 보징금, and how Korean housing contracts work have been covered elsewhere on the internet. I paid my real estate agent 100,000 for their services. For reference I'm paying 350k/month with 2mil down. A friend living 2 kilometers away only paid 30k but is paying like 400k/month for a new apartment and 2 mil down.
Ask the price of every place you look at. All of the above can be done without a Korean friend's help. Bring one along to translate during the contract signing. Buy them dinner or a nice thank you gift. Try not to get ripped off.