Signs of Mold in A House – Experts Reveal How to Be Sure

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Whether you’re currently house-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 a house for mold, congratulations! You’re a very intelligent, wise, and astute house hunter or homeowner. 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 a house, list all the places you should check for it, and answer all your most pressing questions about mold.

Table of Contents

Signs That There May Be Mold In A House

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 into this house. Learn more about the dangers of mold sickness here.
  3. Headaches. By the same token, headaches are a particularly strong sign of mold in your house if you did not normally get headaches before moving in.
  4. Previous water damage. If you’re renting a house, always ask the landlord if the house 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. If you’re looking to buy a house, ask the same questions of the seller.
  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 A House (Plus a Bonus)

Now you know what some of the signs are of mold in a house. If you recognize any of them in your house, you most likely now want to know all the places you should check. Here is our list of the most important places in your house 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 — it’s a pain to put back on! But if there is discoloration, swelling and warping, or black spots anywhere along your house’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 house 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 house is pre-furnished with any furniture, be sure to check behind all of it too.
  5. Ventilation shafts. Remove the grates covering all ventilation shafts in your house, 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 house’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, 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 house? Staying in a moldy house is generally not advised. However, if you cannot afford to go anywhere else, and no one living in the house is exhibiting any strong mold sickness symptoms, you may be fine to remain in the mold-infested house. It’s still not healthy, but you can do it if you have to. 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 a house that we have listed, it is wise to either walk away from the house (if you’re house hunting), or to get a professional mold inspection (if you already live there).

If this article helped you identify visible mold in your house, 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 renting a house, and 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 house, 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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This Post Has One Comment

  1. Zachary Tomlinson

    I find it alarming that molds are contaminants that could cause headaches and other illnesses. I can see how having someone inspect and remove these contaminants from your property is a good investment. I’ll keep this in mind if I need something similar in my home once I move out.

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