How to Inspect for Mold, Pests, and Odors During Apartment Viewings — A Complete Pre-Inspection Checklist
During apartment viewings, attention often focuses on layout and natural light, but problems like mold, pests, and unpleasant odors—which frequently cause regret after moving in—require specific locations and inspection procedures to identify during the viewing stage. This guide explains concrete checkpoints and assessment criteria.
Why Check for Mold, Pests, and Odors During Apartment Viewings
Apartment viewings typically take place in a limited timeframe of 30 minutes to 1 hour. While concentrating on checking brightness, size, distance to stations, and floor plan, many people overlook less obvious issues like "mold," "pest evidence," and "unpleasant odors."
After moving in, problems like spreading mold, frequent cockroaches, or persistent pet or cigarette odors from the previous tenant can emerge, requiring repair claims to the landlord or hiring deodorization services. In the worst case, you may be forced to move again within a short period, which may involve paying cancellation penalties.
A few minutes of inspection during the viewing can reveal most of these risks beforehand. This article focuses on inspection techniques specialized in three areas: "mold," "pests," and "odors."
Mold often hides not only in visible places but in concealed areas. Focus your inspection on the following 7 locations.
1. Bathroom and Washbasin Ceiling and Corners: The caulking on the bathroom ceiling (silicon-based joints) is where black mold most commonly develops. Turn on the light and check the four corners of the ceiling. If the caulking is discolored, mold infiltration is suspected.
2. Window Frames (Grooves in Aluminum Sashes): Black stains or white powdery mold may form inside the aluminum sash frame or in the grooves. Run your finger over it or gently wipe with a handkerchief you've brought to check.
3. North-Facing Walls and Inside Closets: North-facing walls receive poor sunlight and are prone to condensation, creating an environment where mold thrives. Also inspect the walls and floors inside closets and storage areas. Be cautious if there are black spots or water stains on the wall.
4. Under-Sink Storage (Below Floor Level): Open the cabinet doors under the sink and check the bottom and back wall. Water leaks from drain pipe connections can cause mold to grow. If the bottom is wet or the wood appears swollen, it indicates past water damage.
5. Area Around the Washing Machine Location: Check inside the washing machine pan and the wallpaper and flooring on the back wall. Washing machines are prone to wet floors from disconnected hoses or condensation, and prolonged neglect can become a mold breeding ground.
6. Wallpaper Seams and Lifting: If wallpaper seams are lifting, discolored, or feel sunken when touched, moisture may be trapped under the surface.
7. Air Conditioner Outlet: Shine a light on the air conditioner outlet (fin section) to inspect. Discoloration or white powdery deposits are signs of mold growth. Since mold that has reached inside the unit is difficult for anyone but a sanitization specialist to address, request that the landlord perform pre-move-in cleaning if you discover it.
Pest Evidence Inspection — Cockroaches, Dust Mites, and Mice
Pest evidence often remains as "traces" rather than being directly visible.
Cockroaches: Check whether feces (black particles about 2–3 mm) are present under the sink, behind shelves, or on the floor near the refrigerator. Also, if there's a distinctive oily smell from cockroaches (an oxidized oil-like odor), it may indicate the presence of a long-established nest. Always inspect under-sink storage when checking for mold.
Mice: Confirm whether feces (small black elongated particles about 1 cm), gnaw marks on walls or flooring materials, or lifting floor sections are present. In older wooden properties in particular, mouse entry from below the floorboards can be a problem. You can also check by lightly tapping the ceiling to listen for a hollow sound (if there's an inspection port in the property, you may ask permission to check).
Dust Mites and Fleas: If the previous tenant had pets, dust mites and fleas may linger in flooring grooves, carpets, or tatami mats. If your ankles itch when walking barefoot during the viewing, this may indicate lingering infestation. During the viewing, ask the staff whether it was a pet-friendly property and about the previous tenant's pet-keeping situation.
Odor Inspection — 4 Types of Odors to Check During Viewings
Cigarette and Nicotine Odor: Even in a vacant unit, cigarette odor absorbed into wallpaper can linger for months or longer. Bringing your nose close to the wallpaper is the most reliable way to confirm. Even if a property is marked as "non-smoking," if the previous tenant smoked, odor may remain in the wallpaper.
Pet Odor: Sharp ammonia-like odors (cat urine odor) or dog body odor may be absorbed into wallpaper or flooring. Check for odors along the grain of the flooring, or be cautious if the smell intensifies when the air conditioner is turned on and air flows out.
Mold and Moisture Odor: Earthy or moldy odors can indicate mold in unseen areas. Especially if you're viewing during the period just after the rainy season or during winter's dry season, ventilation may have cleared the odor, so also check around ventilation ports and inside closets.
Sewer or Garbage Odor: If sewer odor rises from kitchen or bathroom drains, the drain trap is often dry (from the property being vacant for a long time), and this usually resolves once you run water after moving in. However, the drainage pipe itself may have issues, so ask the staff if similar odors were present before.
Assessment Criteria and Solutions
If you discover problems during a viewing, you don't need to immediately decline—you can negotiate for improvements.
If Mold is Found: Negotiate for the landlord to cover professional mold removal and anti-mold treatment before move-in. If refused, you can propose a rent discount of ¥1,000–3,000 per month.
If Pest Evidence is Present: Have the landlord provide a written commitment to pest extermination (cockroaches, mice, etc.) before move-in. Requesting a "pest control certificate" clarifies post-move-in responsibility.
If Odor is Strong: Deodorization treatment or complete wallpaper replacement can solve the issue. If the landlord cannot cover the cost, request a "re-inspection after treatment." There is no need to sign a contract without a re-inspection.
A thorough pre-inspection during the viewing is the most effective investment in minimizing problems after move-in. Share any concerns with the staff and use this checklist to choose a property where you can live comfortably.
