How to Prevent (& Deal With) Mold in Your Rental Properties

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Mold is everywhere, especially if you live in a wet climate; there is simply no way to escape it. Mold spores drift through the air and settle on the couch, on your face, on the floor, everywhere! The problem, however, is when mold spores are given an environment where they thrive and begin to grow on surfaces. This is when the dreaded “black mold” shows up, something that strikes more fear into the hearts of tenants than anthrax or Ebola. The truth is, black mold is just a naturally occurring fungus that, when highly concentrated, can cause allergic reactions for those with weak immune systems. That said, if your tenant sees a small amount of mold on their bathroom wall, you can bet they’ll be calling you telling you about their leg pain, their headaches, their sleepless nights, and their hepatitis — all caused, of course, by that dreaded “black mold.”

All joking aside, the presence of visible mold is a serious issue landlords need to deal with swiftly. As stated by, “across the country, tenants have won multimillion-dollar cases against landlords for significant health problems — such as rashes, chronic fatigue, nausea, cognitive losses, hemorrhaging, and asthma — allegedly caused by exposure to ‘toxic molds’ in their building.” Some states, like Washington and California, actually have laws that require certain disclosures be given to all tenants when they sign a new lease. Besides the health concerns for those with weak immune systems and hypochondriacs, mold will also cause significant damage if left untreated (and many times, because of the stigma behind mold, tenant’s won’t go near it with a ten foot pole, even when it’s an easy fix). Therefore, mold IS your problem, whether or not it is caused by the tenant or your building. If it’s caused by your tenant and they fail to remedy the problem, deal with it swiftly, hold your tenant responsible for the damages, then educate your tenant on how to prevent future occurrences.


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Why Mold Grows (& How to Deal With It)

Mold tends to grow where there is poor air flow and moisture. This is why bathrooms are the worst culprits for mold, usually due to the lack of a window and the continuous steam from hot showers. Mold also can grow easily behind furniture that is pushed too close to a wall, if there is a heavy level of moisture in the room air. Notice that in both of these cases, the mold is NOT a disease, mischievously planted by the landlord, despite what tenants might think. Mold is commonly caused by the tenant, but as the quote above by NOLO shows, this doesn’t mean it’s not your responsibility to deal with it.

Step one in dealing with mold is making sure you and your tenant are properly educated on what causes mold and how to clean it. We would recommend printing out the PDF produced by the United States EPA titled, “A Brief Guide to Mold, Moisture, and Your Home,” which you can download for free at Make sure your tenant gets a copy of this document when they move into their unit. Also, explain to the tenant that mold is most commonly caused by three things:

  1. Steamy showers
  2. Furniture against walls
  3. Leaky pipes, ceilings, faucets, etc.

Explain to them that numbers one and two are their responsibility, and number three is yours IF they report issues. If they don’t report a leak that results in mold growth, this falls under the category of avoidable damage, most likely making them liable for the expense of the remediation. Encourage your tenant to run the bathroom fan at least one hour after every bath or shower and run their kitchen fan while cooking. This is probably the number one reason why tenants have mold; if they do not use proper ventilation during these activities, all that warm, moist air will settle throughout the house, creating a prime environment for mold and mildew. If the tenant’s bathroom or kitchen does not have a vent, install one. Be sure they understand the need to properly ventilate their home by opening windows and airing it out on nice days, make sure they keep their couches, their beds, and their clothes away from walls, and they don’t cram items into corners or against walls in non-ventilated areas (such as closets, cabinets, or attics). And of course, be sure leaks are fixed immediately.


The 5-Step Process to Clean Up Mold

According to the EPA, mold that covers less than 10 square feet (an area about three feet by three feet) can be easily cleaned up by a non-professional. Therefore, if the mold already exists in small amounts (on windowsills, behind a bed, on the shower tile), the following five-step process, as given by the EPA, should take care of the problem:

  1. Act Quickly: The faster you deal with mold, the less damage it can cause.
  2. Fix the Cause: If the cause is a leak, get that fixed as soon as possible. If the cause is heavy moisture, encourage the tenant to open windows more often or run their fan(s) more often. Also make sure the tenant’s furniture is moved away from the walls.
  3. Clean It: Scrub mold off hard surfaces with detergent and water, and dry completely. Be sure to wear gloves, goggles, and possibly a respirator if you are concerned about breathing in spores.
  4. Toss Porous Stuff: Porous materials, like ceiling tiles or carpet, may need to be thrown away if they are moldy.
  5. Paint: Never paint over mold (it’ll just grow over the new paint), BUT after it is cleaned and dry, you may paint it if desired.

Remember, mold is not a disease or a chemical that is likely going to kill you or your tenants. However, it is a serious enough issue that you need to understand how to deal with it to keep your tenants safe and happy, and to prevent damage to your property. It’s also important to understand mold and mildew so you don’t get stuck footing the bill for tenants whose living conditions are the result of the problem.

[This article is an excerpt from Brandon Turner’s The Book on Managing Rental Properties. For the full read, click here.]

Have you ever encountered a bad case of mold in your rentals? How did you handle it?

Let me know your experiences with a comment!

About Author

Brandon Turner

Brandon Turner is an active real estate investor, entrepreneur, writer, and co-host of the BiggerPockets Podcast. He began buying rental properties and flipping houses at age 21, discovering he didn’t need to work 40 years at a corporate job to have “the good life.” Today, with nearly 100 rental units and dozens of rehabs under his belt, he continues to invest in real estate while also showing others the power, and impact, of financial freedom. His writings have been featured on,,, Money Magazine, and numerous other publications across the web and in print media. He is the author of The Book on Investing in Real Estate with No (and Low) Money Down, The Book on Rental Property Investing, and co-author of The Book on Managing Rental Properties, which he wrote alongside his wife, Heather. A life-long adventurer, Brandon (along with his wife Heather and daughter Rosie) splits his time between his home in Washington State and various destinations around the globe.


  1. So! I had a tenant who had mold on the bathroom ceiling after I bought this 4-unit. I explained to him that I was going to renovate the bathroom in a couple of months. So he decides to pull the I’m not paying rent until you fix the issue game, later to find out his wife lost her job and they afraid I was going to raise rent due to the up and coming renovation. Anyhow, they called the health department on me and little did they know, I beat them to it as well as having provided the health inspector with a couple of quotes from my contractor. CYA-Lesson#1 and mostly, because it is the right thing to do! Here’s what I did to make sure its done right!

    1.) Had my contractor open the walls (even so the mold was on the outside)
    2.) Called my own mold inspector who deemed the inside mold free, took pictures along with a report
    3.) Had my contractor renovate which included dropping the ceiling and installing a high power vent, with new exhaust.
    4.) Had my electrician wire the light switch to the fan (I do this in all of my units), so that when the light is turned on, so is the fan–so there should be no question in the future!
    5.) After renovation, walls painted with a mold resistant paint.
    6.) Visit from health inspection for occupancy certification. He was impressed!

    Note: For removing mold, DO NOT USE BLEACH! Bleach promotes mold growth. Use a product such as Mold-X, which not only cleans it off, but stops future growth from happening.

    Cheers and Happy Holidays!


    • Bernie Neyer

      Where did you get the idea that bleach (chlorine) doesn’t kill mold? Not only does it kil mold, the county ag agent instructs people to use bleach to kill and clean small areas of mold, which is what we are dealing with here.

      As stated in the blog, keeping moisture to a minimum and air circulation good will stop mold. I have found tenants shutting the heat off to a room and closing the door to that room is one of the greatest causes of mold. They will open the door to enter then leave. Warm moist air seeks cold and the contents of the room will sweat and without warmth or air circulation mold will start.

      Now here is a jewel. In speaking with someone that cleans mold up, the dreaded back mold only occurs in areas that don’t freeze or doesn’t get cold for long periods of time. He said the mold is actually fragile and can’t survive the cold. He said what we call black mold up north, isn’t the bad mold.

      Some time ago I heard about someone who developed a cleaner to clean up after anthrax discovered it killed mold too. I guess anthrax is mold too. However, I’ve never been able to find the stuff online. I did find something call a mold bomb fogger at They also show cleaners. I’ve never used the stuff and if someone does, please post your results for the rest of us.

  2. Christopher Smith

    Bleach kills mold. Bleach will kill nearly anything organic. What it can’t do is fully permeate porus materials such as wood and wall board and as such would not necessarily be effective in cleaning those surfaces. However it’s completely effective if properly applies to non porus surfaces e.g., tile.

  3. Tina Peters

    Brandon, excellent article . As a landlord in California for over 25 years I have definitely dealt with the issues of mold, more than 90% of the time it is tenants lack of housekeeping for lack of notification . How I have handled this with great success is to have mandatory semi annual inspections of all units. In California you cannot inspect a unit “just because” so your reasoning for the notice is to check safety devices such as the smoke detectors and for plumbing leaks. You’re only required to give it our 24 hour notice in California, however I try to build a relationship with the tenant so I give them a full seven day notice . During this inspection were checking the common items such as the smoke detector and then under the sinks for leaks etc. where I find the most damage though is not in the bathroom as suspected, but rather behind the couches and in warm harboring places such as the closets. Both of these areas are places that tenants just never check.

    I cannot tell you how many thousands of dollars I have saved and further damage as well as the ability to back charge the tenant for their lack of notification. Probably most important is that I have a rock solid paper trail of my handling of my units.
    1. I tell the tenant up front with the disclosure that we very proactively inspect the units for the mentioned items semi annually and lack of notification of item in between inspections could result in them being charged.
    2. One week prior to the scheduled semi annual inspection I provide the tenant with notification that we will be entering to check for safety items and plumbing and moisture concerns. At the same time there is an additional form included where I require them to update their vehicles, tenants and pets.(side tip). With the standard notice to enter I have a section on the bottom where they tell us known items they need checked. Well we’re going to check everything anyway, this signed document that they get back to us is an acknowledge meant from them that they do not believe they have any issues with their unit (huge hidden benefit as you build a paper trail when they two months later claim issues! My lawyer has told me this is the best thing that he has seen to negate any future claim

    3. Once we have performed the inspection we give them back a letter stating I did that everything was clear or generally there are some minor items that fall on the tenant as proactive approach for the future. If there is any damage that we know whether it is the tenants damage for Management. If it’s management then we schedule a work order. If it’s tenant damage we highly educated them and may or may not charge. If I do charge I make easy payments for them. Any money that I can collect during the tenancy is far easier than when I find the damage upon exiting when they I might be able to collect due to lack of funds and the security.

    4. Tidbit on the extra form that I mentioned above. When I give them the form to acknowledge their documents, vehicles and Pitts semi annually I find it much easier to find violations in the lease. They are either going to list them not thinking that pets/occupants etc are in violation and you have means to discuss or they’re not going to list them. You’ll then serve notice when you find them and have recent proof, coupled with your lease, where they signed stating the pets, occupants Do not Occupy the unit. Hard lie to back themselves out of

  4. Concrobium moldx is the best product on the market I’ve found. It works by encapsulating and crushing the mold spores. Home depot rents a fogger to use for larger spaces affected by mold IE basements. I use this in every basement prior to finishing as a safeguard to remove all traces of mold. Great product!

  5. Joan Defenbaugh

    Does anyone have experience with crawl space dampness? My daughter rents a home that has a very stinky crawl space. It has an opening to the family room level that is closed up, but inside the crawl space there are vents to the outside that are letting in hot, humid air in the summer and cold, damp air in the winter. It smells so bad in there!

  6. Fred Weinkauff

    Bleach will kill mold but only on non-porous surfaces (bathroom tile), it will no kill it on caulk or grout. So for the most part bleach is a waste of time to use. Mold-X and Concrobium Mold Control are both inexpensive products that work, I have used them both. When mold grows it attaches with a root structure that grows into wood , Sheetrock , paint etc and bleach will only kill the mold on the surface for a short period of time and then it will grow back bigger and better. So always use a real mold killing product that will kill it on both porous and non-porous surfaces. Crawl spaces can be fogged with Concrobium Mold Control and that will keep the Mold at bay.

  7. margaret smith on

    I seem to be encountering this tenant-caused moisture problem for the first time now. Here in SW Florida, I have Mitsubishi mini-split AC units, including in my tenant suite– and it turns out if you keep any unit going too long at too cold a temp, it will sweat until it drips down the wall- each day! Very hard to clean inside, but clearly FILLED with black mold. Love all these really helpful comments- and Tina- You rock, Girl! THANK YOU ALL!

  8. Julie Marquez

    From another Washington State landlord, my dad put moldicide in all the paints that he uses in the bathrooms. He even asks for the twice the amount of moldicide to be added, and tells them it is not going to be used in an occupied space (like the bedroom) so he can get that extra protection. With this special paint, he paints right over the existing mold.

  9. I encountered a house which had green and black discoloration covering walls in bathroom, one bedroom and attic of course I immediately called a mold remediation service. The technician explained to me that what I described was not actually mold but mildew. He instructed me to get a spray bottle and bleach and spray the walls down. He also explained – as mentioned in this article – that only people who have an allergy to mold will have any sort of reaction to it.
    There are also a few mold resistant paints sold in home supply stores (Lowes, Home Depot, Menards, Ace).

    Thanks everyone for the article and comments!

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