Signs of Mold in An Apartment – Experts Reveal How to Be Sure

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Whether you’re currently apartment-hunting or just moved in, mold is certainly one of the last things in the world you want to find! Nevertheless, if you’re still seeking out how to check an apartment for mold, congratulations! You’re a very intelligent, wise, and astute apartment hunter. Most people don’t even consider looking.

In this article, our experienced mold experts here at Cleaner Guys break down important signs of mold in an apartment, list all the places you should check for it, and answer all your most pressing questions about mold. Let’s dive in!

Table of Contents

Signs That There May Be Mold in An Apartment

The signs that point to mold can be subtle, and take very careful observation. However, it is crucial to pay attention to them! Hidden mold could be the cause of your neverending headaches, or the reason you can’t make that one room smell nice. Read on to learn what signs you should be looking for.

  1. Musty, unpleasant odors. In our experience, this is the strongest indication of the presence of mold. Most mold has a pungent smell, similar to rancid food or very old books.
  2. Persistent cold or allergy symptoms. Many people have allergic reactions to mold, and they usually present as cold symptoms like a runny nose, a cough, and more. However, you will notice that the symptoms last much longer than they did before you moved in to this apartment. Learn more about mold sickness here.
  3. Headaches. By the same token, headaches are a particularly strong sign of mold in your new apartment if you did not normally get headaches before moving in.
  4. Previous water damage. Always ask the landlord if the unit you’re looking at has ever had previous water damage, like an overflowed toilet or a pipe leak. If there was, ask how it was dealt with. If the landlord did not specifically inspect and clean for mold after a water damage incident, then there is almost certainly mold somewhere.
  5. Discolored portions of walls. Use the list below of places to check for mold, and keep an eye out for any discoloration or dark dots on any area of wall or ceiling. Brown or grey stains are sure signs of water damage, and therefore probably mold.

Check out this informational video from the CDC to learn more about mold sickness. The video was made during a flooding season, but the information can be applied to any time.

Top 9 Places to Check for Mold in An Apartment (Plus a Bonus)

Now you know what some of the symptoms are of mold in an apartment. If you recognize any of them in your apartment, you most likely now want to know all the places you should check. Here is our list of the most important places in your apartment to inspect for mold. Our mold remediation experts here at Cleaner Guys compiled it based on our 50+ years of collective experience with mold.

Check These Places for Mold:

  1. Under-sink cabinets. The most forgotten place to check for mold, in our experience, is in the very back of the cabinets under the sinks in your kitchen and bathroom(s).
  2. Baseboard trim. Another overlooked place is the trim where your walls and floors meet. Now, we are not recommending that you pull it off — you’d probably get in trouble for that! But if there is discoloration, swelling and warping, or black spots anywhere along your apartment’s trim, it’s a sure sign of water damage and/or mold.
  3. Discoloration. As previously suggested, carefully inspect the walls and ceilings of the apartment for any brown or grey discoloration, or any small dark dot clusters. This is a sure sign of the beginnings of mold in the wall.
  4. Behind appliances and large furniture. Pull out the refrigerator and washing machine from the wall. They are rarely moved, so they are prime breeding grounds for mold. If the apartment is pre-furnished with a bed, be sure to check behind that too.
  5. Ventilation shafts. Remove the grates covering all ventilation shafts in your apartment, and check for any black, grey, or green spots or smears. This is mold.
  6. Windows. Is there any black, brown, or green stuff anywhere around the windows? This may be mold, which probably means the windows aren’t properly sealed.
  7. Discolored carpet. Check for discoloration or stains along the edges of all carpet. This is a sign of a liquid spill, which, if not cleaned up properly, may well have left behind mold inside the wall or under the carpet.
  8. Closets. Be extra careful about checking the backs of closets. Especially if one of the apartment’s closets houses the water heater.
  9. Bathroom caulk and grout. Carefully inspect the caulk and grout of the bathroom(s). Is there any staining, discoloration, blackness, or spots? This may be mold. You should get it inspected, cleaned, and resealed by the landlord; preferably before you move in.


Attics and crawlspaces. Finally, if you are renting a house and not an apartment, you absolutely must check the attic and the crawlspace — or hire someone to check them for you. In single-family homes, the attics and crawlspaces are the top places we find mold.

Frequently Asked Questions

  • How do you clean mold? If there area of mold is very small, you can safely try cleaning it yourself. Do this only while protected by gloves and a mask. However, if the area is larger than certain parameters, let professional mold cleaners handle it. Learn everything you need to know about mold cleaning here.
  • Can you live in a moldy apartment? Staying in a moldy apartment is generally not advised. However, if you cannot afford to go anywhere else, and no one living in the apartment is exhibiting any strong mold sickness symptoms, you may be fine to remain in the mold-infested apartment. On the other hand, you should still get it removed and cleaned as quickly as possible. Learn more here.
  • How long does it take to get sick from mold? It can take less than 24 hours to experience mold sickness symptoms. However, it can sometimes take days to show up.

When To Hire a Mold Inspection Company

If you detect any of the signs of mold in an apartment that we have listed, it is wise to either walk away from the apartment (if you’re apartment hunting), or to get a professional mold inspection (if you already live there).

If this article helped you identify visible mold in your apartment, and the area is larger than 1 square foot, call a professional mold removal company immediately. Learn how to find a trustworthy service company here.

In addition, if you’re unsure whether you or your landlord should have to pay for professional mold inspection and removal, read this section of our Ultimate Guide for Dealing With Apartment Mold. Keep in mind, this is NOT legal advice. If you have to figure out whether you or your landlord has to pay for mold removal in your apartment, we highly recommend that you consult a legal professional.

Residents Of Western Washington State

If you are anywhere north of Seattle in Western Washington State, consider Cleaner Guys as one of the wisest choices for a mold inspection and mold removal company. We’ve risen to be one of the most popular and well-loved in the area! This is because of our award-winning customer service, our commitment to better prices than the other companies, and our high standards.

If you need mold inspection or mold removal in Mount Vernon WA, hit the phone number in the menu at the top of your screen, and we’ll answer all your questions right now!

Disclaimer: This article is for informational purposes only. No part of this article is medical or legal advice, and may not be used as such. For all serious medical matters, consult your doctor. For all serious legal matters, consult your legal advisor. This article contains Cleaner Guys’ experience and opinions only.

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    Hello would you mind stating which blog platform you’re working with?
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    1. Melanie Ortegon

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