How to Get Rid of Mold in Your Basement

by on September 30, 2012Karie Fay

You’ll know it when you smell it: that damp, musty smell that reminds you of a medieval dungeon, and an earthy scent much like the dirt, deep in the forest, underneath a layer of rotting leaves. You’ll probably recognize it: colonies of invading fungi, growing in ever-spreading clusters of white, black, brown, or even gray, yellow or green. When mold rears its ugly, smelly head in your basement, it’s only a matter of time before it spreads and claims the rest of your home for its own. Don’t let it. Get rid of the mold – and take steps to make sure it stays away.

The Problem With Mold

how to get rid of mold in basementIt’s not that mold is completely bad. Not only does one species of mold save lives as penicillin, but in nature, molds decompose tons of organic matter daily. With over 100,000 types of mold worldwide and around 1,000 of those here in the U.S., mold is virtually everywhere. It grows outside and only comes inside as it is able. In fact, at times the mold count outdoors is higher than inside many homes.

Growing mold releases microscopic spores – tiny little seeds – that drift in the air. It’s almost unavoidable that some will come inside your house. The problem begins when they find the conditions they need to develop into mold. Dark, damp, stagnant or mostly still air and temperatures above freezing (but somewhere below boiling) spells home to mold. Kind of sounds like your basement, right?

The good new is that most species of mold are relatively harmless. In fact, only an “estimated 6 to 10 percent of the general population” are sensitive to mold allergens, according to the Centers for Disease Control and Prevention. For these people, higher exposure levels may lead to rashes, watering eyes and runny nose, coughing, sinus congestion, and even difficulty breathing. There’s also a higher incidence of mold allergies in asthmatics, although whether mold causes the asthma has not been established. People with compromised immune systems and those with established lung disease may experience a higher risk of infection from molds, suggests the Washington State Department of Health.

What’s worse, some molds are considered “toxic,” even to healthy people. Toxic molds produce chemicals called mycotoxins, which may cause serious illness, infections, and possibly even fatal conditions. Commonly called “black mold,” many of these, such as the greenish-black Stachybotrys mold and its cousin, Memnoniella, grow on popular building materials such as sheetrock, wood and paper.

Not to say that you should panic over any mold you encounter – even if it appears black. You should, however, make an immediate plan of action to remove the mold and follow sensible safety procedures during the clean up. Most basement mold cleanups are something you can DIY, as long as you feel capable of tearing up materials and performing the repairs yourself. If the mold covers the entire basement or if you suspect it’s growing in areas you feel uncomfortable handling, such as inside air conditioning vents, consult a mold remediation professional instead.

Mold Removal Tools

  • Plastic sheeting, 4-millimeter thickness minimum.
  • A respirator.
  • Spray bottles.
  • Disposable rags or paper towels.
  • Large garbage bags.
  • 5-gallon buckets.
  • Rubber or latex gloves.
  • Measuring cup.
  • Borax or vinegar.
  • Dehumidifier.
  • Commercial-grade HEPA vacuum, if possible.
  • Full clothing, such as coveralls.
  • Goggles or similar eye protection.
  • Scrub brush or broom.

Mold Removal Preparation and Safety

It’s too late, once you’ve entered your moldy basement, to realize you forgot things you need and then make endless trips back and forth to the rest of your home. Proper preparations and gathering the things you need before you attack are critical. Permit yourself one inspection trip, armed with personal safety equipment, to determine the scope of the problem and to eliminate the source of moisture if possible.

If the basement is wet from a flood, the source is obvious. Other possibilities include gutters ending too close to the house, improperly graded soil around the house, leaks in the foundation, a dryer that isn’t vented to the outside, and leaking pipes, among others. Closely examining the area of mold should quickly reveal where the water is coming from. Then, take steps to eliminate the source. Call in a professional for foundation issues or other repairs as needed. Only after the problem is resolved will you be successful in eradicating the mold. All it takes, after all, is a single spore to grow into a colony again.

Once you’ve stopped the moisture, hang sections of plastic sheeting over door openings and heating or air conditioning vents to isolate the infected areas from the remainder of the basement or house. At this point, there’s less mold outside than indoors, so open a window, if possible, to provide ventilation and fresh air circulation. A fan, set in the window and pointed outside, or aimed at the ceiling, will also help circulate the air. Avoid blowing it directly at the mold or turning it on high, which will stir up the mold and encourage it to release spores.

Consider running a heater or dehumidifier at this point to aid in drying out the basement. If you do, wipe the appliance down with a disinfecting mold cleaner when you are done with the removal to prevent recontaminating your home.

Mold Removal Solutions: Borax and Vinegar vs. Bleach

Here’s the truth about expensive mold removal solutions and bleach: You don’t need them. If the mold is growing on removable items such as drywall or boxes stacked on the floor, much of it is removed simply by discarding contaminated objects and replacing them with fresh material. Then, scrubbing the surroundings with detergent and water or a natural product removes the mold residue. It’s cheaper than commercial fungicides and doesn’t burn your eyes, lungs and skin like bleach.

If your basement flooded, it’s still a good idea to use bleach to sanitize it. Bleach reduces the mold count – it doesn’t completely kill it – and neutralizes harmful bacteria. Mix chlorine bleach with warm water in a bucket at a ratio of one cup (8 ounces) of bleach per gallon of water. As you use the bleach water and it becomes dirty, flush the remainder and mix fresh solution.

A better choice for removal is either straight vinegar for smaller areas or borax and water for larger areas. Sure, vinegar has strong fumes, but they will dissipate within a few hours. Borax, another completely natural product, leaves a powdery residue behind as it dries, which will repel mold spores before they begin to grow. Mix about 1 cup of borax per gallon of warm water in a bucket and refill a spray bottle as necessary.

Getting Rid of the Mold

So you’ve found the source of moisture, fixed the problem and dried out the basement. You’ve gathered your tools, chosen a mold removal solution and donned your protective wear. It’s time to give the mold in your basement eviction papers.

Look for mold not only on exposed surfaces, but also in cracks and crevices surrounding the source of moisture. Whenever you find mold, spread your search farther than the original spot. In many cases, visible mold turns into invisible or hidden spots of contamination.

An unfinished basement is likely the easiest cleanup. Remove boxes, bags and other items stored in the area. Place them in garbage bags to contain the mold until you can remove them after you are done cleaning the basement itself. Finished basements are a little more complicated. You may need to tear away wall sheathing – drywall, paneling or similar – to expose the wall interior. Throw away sheathing or insulation that comes in contact with mold. There’s no good way to clean it.

Rip up carpets and other flooring material if you suspect mold underneath. Mold growing in hidden spots under you walls, in your ceilings or under your floors will only continue to grow. If you tear it up and find it’s okay, often you can reuse the material after wiping it down with solution or steam cleaning the carpet. If you do find mold, however, just throw it away. The cost to replace it is insignificant in comparison to your family’s health.

After removing and bagging all furniture, decorations, boxes, stored items as well as any building materials, it’s time to treat the surfaces to kill what remains. Fill a spray bottle with vinegar or borax and water. Spray the walls, pipes, windows or other permanent fixtures until they are thoroughly coated with the solution and allow it to set, penetrating the mold and basement surface, for an hour or two. Once the mold is damp, it’s unlikely to release any spores. Take advantage of the break to slip out of the basement, removing your protective wear before you walk through the rest of the house, and carry the bagged items outside.

In your driveway or backyard – well away from windows or doors – sort the bagged items. Contaminated building materials should go immediately to the trash. Cardboard, paper and other absorbent materials are best thrown away as well, with the exception of clothes, which may be washed in hot water with bleach or borax added. Plastic, metal and other moisture-resistant materials are often safe to simply wash down with fresh solution and air dry in the sun. Use your best judgment to decide what can be saved and what cannot.

When you return to your basement, spray the surfaces down again to refresh the mold-killing properties. Spray past the contaminated surfaces – overdoing it is better than leaving spores to grow again. Use a brush on vertical surfaces such as walls, wood framing and windows to scrub the moldy surface. Rinse brushes frequently in fresh solution to prevent re-contamination. Scrubbing physically removes much of the now-dead mold. Try a broom on floors or hard-to-reach spots and switch to cloths as needed.

Now that the mold is dead and scraped from the surfaces, you must remove it from the property. Scrubbing and wiping with fresh water is tedious, but effective. Go over the area repeatedly, changing your rinse water every few minutes. Experts also recommend using a HEPA vacuum, spending about one minute per foot of contaminated area, according to the Wisconsin Department of Health Services, to ensure that every trace of mold is gone. Again, while tiresome, cleaning the mold properly will ensure it is completely gone. In the long run, this will save both time and money, and possibly your health.

If you used borax to clean the mold, lightly spray the surfaces one final time. Then, when you are satisfied that every contaminated item and area has been removed, cleaned and thoroughly rinsed, you must allow your basement to dry. It can’t be stressed enough: You can’t allow moisture in your basement. Wipe down treated surfaces with clean rags to start. Ideally, purchase a dehumidifier, if you don’t already have one, and set it up in the middle of the area.

After the basement is dry, repair and redecorate it. Install new insulation, sheathing and flooring if necessary. Replace items removed from your basement during cleanup (provided they are mold-free). Just take your time in treating, rinsing, drying, and repairing your basement at all costs. The best job comes when you take the time to do it right, and with mold, rushing generally results in an unwelcome, permanent guest.

Preventing Mold’s Return

You’ve evicted the mold, but that’s not enough. More is sure to come if you don’t take steps to keep it away. Remember, mold needs a source (spores), food (anything from biodegradable building products to simply dead insect parts and skin particles drifting in the air and settling on surfaces), water, hospitable temperatures and darkness. So your job is to eliminate as many of these factors as you can.

Modern buildings are often energy-efficient and relatively airtight. Any source of moisture, from over-watering plants to leaks, should be eliminated. This is especially true in the basement, where temperature differences between the upstairs and downstairs encourage the formation of humidity and condensation. Running a dehumidifier year round and installing vents, especially in the bathroom, helps significantly.

It might seem unrelated, but even proper insulation helps control moisture. Insulation always pays for itself in several ways. Vapor barriers are also essential, even in a dirt-floor area. Run unbroken sheets of plastic across the dirt floor and cover with more dirt to prevent moisture migrating up from the soil.

Install a hygrometer to monitor your relative humidity in the basement. Humidity levels above 50 percent indicate the environment is ripe to grow mold. When used in combination with a dehumidifier, it can also tell you when you may have a moisture problem. That is, in a temperature-controlled environment with a dehumidifier running, your RH levels should remain fairly stable. If the level suddenly rises, you should suspect you have a leak or other moisture source and investigate.

Speaking of controlling the temperature in your basement, it’s true. While you may not want to heat it to the same temperature as the rest of the house, heating it to about 60 degrees during the winter months is a smart move. Below-ground structures – especially concrete or masonry – easily stay musty and damp as they are more absorbent and transfer temperature differences through their thickness. Heating your basement helps to maintain consistent relative humidity levels.

At this point, your basement is now mold free and unlikely to host any more. Not only should it look much better, but it’s healthier and you saved a lot of money by doing it yourself.

{ 66 comments… read them below or add one }

Roselyn Saab July 17, 2014 at 6:14 pm

I live in a 37 year-old, one-story townhouse with a concrete basement. Half of the basement is finished with wood paneling and carpeting on the floor. The carpeting is old and I am thinking about replacing it, but I have a problem I may have to face before doing so. In the back, uncarpeted part of the basement, the floor has been developing light cracks and the concrete has a marbleized appearance that it didn’t have before. Because I live at the top of a hill, I’ve never had a water problem, but I’m wondering if there now is mold growing underneath the basement floor. I have no odor problems such a mustiness or anything unusual, but the vinyl-covered floor in the downstairs bathroom started developing dark stains when it was discovered that the shower leaked. I had it fixed and after mold treatment, thought it was fixed — but it isn’t. Once again, I have dark spots under the tile in bathroom, even though we quit using the shower. Do you think this black/gray marbleing under the concrete in the back of the basement is caused by mold? I’m very concerned, because I am allergic to mold.

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Chris July 13, 2014 at 1:28 am

Hi Karie Fay,
We had a flood and extensive remediation in our finished basement. Two boxes of important papers and photos that were sitting on the floor have moderate to heavy black mold growth in the contents. Is there any way to rescue some of the irreplaceable papers and photos? E.g. thoroughly dry or expose to sunlight individual papers that were not destroyed but that do have visible black mold growth? Or must every paper item with visible mold growth be discarded, even important documents and photos??
Thanks,
Chris

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Dorothy July 2, 2014 at 6:26 pm

HOw long would it take for black mold to dry from basement if you remove drywall from the walls and ceiling? Would it take 18 months? Would you just leave it bare to dry out naturally or would you have to clean and then coat it ? I f you are removing black mold in your basement , would you hav e to remove your basement floor or parts of it?

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DLewisD May 22, 2014 at 8:09 pm

We have knotty pine panelling entirely covering every wall in our basement. The walls are large, hollow red clay bricks. Water has damaged the bottom 6 to 10 inches of the panelling, rotted out with lots of dark brown wood decay. I’m going to have to assume that the walls underneath the panelling are probably inundated with mold. This will not be an easy job it I have to remove all the paneling. The house was built incorrectly to begin with. I really don’t want to remove all the knotty pine. Are there any suggestions anyone might have??? What if I can find a way to ventilate all the paneling, and run a dehumidifier at the problem spots as much as possible?

A major part of the problem with rain-water is that the driveway cement slabs are sloping toward the house rather that away from it.

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DLewisD May 22, 2014 at 8:13 pm

Oh, I might be able to raise the driveway slabs to make them slope away front the house again, and then use a driveway sealer caulk to caulk between the drive and the house.

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DLewisD May 22, 2014 at 8:16 pm

P.S.
Our paneling is somewhat like the image at the start of this topic; knotty pine with rotted bottom where it meets the cement slab floor.

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tanya May 20, 2014 at 4:16 pm

We had a flood in the basement from the rain..we had to rip up the carpet.We wipe the drywalls down with bleach, after a couple of days we notice mold growing along the wall, is there anything esle we should use to keep it from coming back

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Maija-Liisa Downing May 6, 2014 at 11:10 am

We have found black mold in our washing machine, which I tried cleaning out with bleach. It still looks like it is there however, and my husband and I are feeling weird symptoms which we are afraid are due to toxic mold ( fatigue, dizzy, tingling, memory/brain fog, etc) Should we call a mold expert for hundreds of dollars, or just get a new washing machine. I guess my question really is, could the mold from the washing machine have spread to other areas, or will getting rid of the washer likely also get rid of our problem?

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Karie Fay May 15, 2014 at 4:04 pm

Hi Maija-Liisa,

What a pretty name!

If it was me and I could afford to do so, I would probably throw the washer away. It’s a small expense compared to professional mold remediation.

Now, what you see inside it is probably NOT toxic black mold. However, consider having air samples taken and tested. I am wondering if there might be another explanation for how you and your hubby feel. Start with testing and go from there. Meanwhile, see how you feel with a new washer in your home.

Good luck!
Karie

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Angelo May 1, 2014 at 4:49 pm

Hi.
I just found out we have mold on the drywall .side wall of the furnace room inside ..
We called professionals but the prices were extremely hi.
but the good news are that the mold is at the beginning of its spreading so is removable .
Any advice what should I do and what should I use to remove the mold …
thank you.

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Karie Fay May 15, 2014 at 4:00 pm

Hi Angelo,

Follow the steps in this article. First spray every surface to wet and weigh down mold and mold spores. Carefully remove the drywall. Clean anything else exposed to the mold (everything in that room) and redrywall it. It isn’t hard but you will save a TON of money.

Hope that helps!
Karie

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Brenda April 28, 2014 at 9:48 pm

Is it safe for an infant to reside in home in which has been treated for recent mld

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Karie Fay May 15, 2014 at 3:58 pm

Hi Brenda,

I wouldn’t have a problem with that, unless the infant has special health problems (like an immune compromised system). Once the home has been treated no mold should remain. The only thing I would look closely at are the products used to clean up the mold.

Hope that helps!
Karie

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Linda April 26, 2014 at 3:22 pm

Hello. My elderly mother has had a chronic cough for 5 months; doctors can’t diagnose. My parents recently had a mold inspection and some air samples taken. Some visible mold was found on 2 items in the basement; no visible mold on walls, etc. The basement air sample came back in the high range, with Pen/Asp and Cladosporium leading the pack.

We received an estimate from a professional remediation company to remediate the mold in the basement, as well as fog/cold-mist the middle and upper floors. However, I believe my father seems to think that removing the ‘moldy’ items may be enough to correct the situation.

Could you provide an opinion? Many thanks for your valuable input.

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Karie Fay May 15, 2014 at 3:56 pm

Hi Linda,

Your father sounds reluctant to spend the money, and at his age, it’s kind of understandable. He simply doesn’t understand how mold works. Now, I am not well versed on the fog/ cold mist application. I would research that process completely before deciding if it is warranted. Remediation IS a good idea in my opinion. Removing moldy items helps, but doesn’t remove the spores left behind (as evinced by the air sample). As for the cough… Does your mother have any acid reflux problems? I have a tendency to think they are unrelated.. But I could be wrong.
Please write back if I can help more.
Karie

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Sheila April 24, 2014 at 4:49 pm

I have an old house with a field stone basement. I need to clean the mold before I can repair due to the leaking is coming in between some of the stones, this is also where the mold is growing. You mentioned above about repairing before cleaning the mold, what are your suggestions in this situation?

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Karie Fay May 15, 2014 at 3:51 pm

Hi Sheila,

Sorry for the delay in responding to you. I would recommend, in your situation, cleaning your field stone and then applying a sealer to the entire basement. They make special sealers designed for stone. Read up on the product before purchasing and applying.

Hope that helps!
Karie

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Don April 23, 2014 at 12:55 pm

What are the chances of getting mold out of a BASEMENT and it not returning?

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Karie Fay April 24, 2014 at 5:17 pm

Hi Don,

That’s kind of a trick question ;) Mold — at least mold spores — is everywhere. You will never eliminate every last trace of it in your home. Growing mold, on the other hand, CAN be killed. Just follow the steps in the article and keep a close eye on the area. Just like plants, humans or any other living thing, if you make the conditions hostile to life, it will die.

Thanks,
Karie Fay

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Chris I April 27, 2014 at 6:00 am

We have a finished basement with a walk out. In the summer we run a dehumidifier as well as fans to keep humidity down. I have had black mold in the corners of the rooms and have bleached it to kill mold, but still returns. My granddaughters cannot sleep their because the start coughing after spending one nite. We have a wood furnace and electric furnace. Wood furnace is 12 years old, electric is 37 years old. Got prices for new electric furnace and central air. It’s a lot of money and am wondering if the central air will help with air circulation in basement. I think it’s a humidity problem. I don’t think it’s in walls, I think it’s from the floor. It’s laminate floor with an ünder lay underneath. I’m planning to talk off baseboard to see I’d mold is growing from floor or just humidity. I have cupboards in storage room and they will get a whitish film on them. Is this mold too?

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Ricky April 18, 2014 at 4:44 pm

i’m trying to re do a persons house for them I ran into a problem the dirt floor in the basement is covered in mold all kinds of colors what is the best way to get rid of it and to not let it come back people have given a lot of ideas but I don’t know witch one I can trust please help thank you!!!

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Karie Fay April 24, 2014 at 5:31 pm

Hi Ricky,

I will tell you what I suggest. First, there has to be something in or on the soil that the mold is feeding on. Second, mold moves easily from the basement up, possibly contaminating the floor joists overhead and other areas of the house. I would inspect everywhere very carefully, especially in the basement. Next, I would take a borax solution and mist the floor and the basement framing. Finally, I would get thick plastic sheeting, like what is used for vapor barriers, and line the dirt floor with it. Extend the edges up the side walls slightly and tape any seams or edges. (Overlap seams as well to ensure you don’t leave a gap through which vapor can flow.) Cover the plastic with gravel, sand or a few boards to prevent walking on it. The plastic will keep ground moisture from invading the basement, thus preventing mold growth.

Let me know if you have any other questions,
Karie Fay

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jack April 12, 2014 at 10:12 am

recently have found actual mushroom looking growths on carpet in finished basement. water got in thru foundation carpet wasnt wet anymore but could tell that it had been. removed carpet and pad, pulled off paneling in that area ran dehumidifier and fan treated area with bleach and water mix. now letting area breath for a while and waiting to see if water leaks in again or if it was extreme winter ice melt off that was too much for gutter to handle. anyway, wondering what these growths are and how dangerous they are as i have tenants with babies living in the house. no pics buts mushroom looking kind of waxy look to them.

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Karie Fay April 15, 2014 at 6:06 pm

Hi Jack,

Great question! I applaud you for being a landlord who cares about the property and the tenant’s health.

Believe it or not, it may indeed be just mushrooms. I have heard of this happening before in damp basements. Food (carpet and other biological items in the home environment such as dead skin cells, small crumbs and such), water and — with mushrooms — dark or dim lighting is all it takes. Remember that mushrooms are cousins to mold as well.

If you want to make sure exactly what it is, you could consult a mold removal specialist — they’ve probably seen various mushrooms growing in local homes. I know there are also home mold and fungus kits, but I think that’s more to identify the presence. Other than that, I think you took the proper steps. Did you remove items carefully to avoid spreading the spores?

If you have foundation problems you will want to have them fixed immediately. Waterproofing the wall may help as well — not sure if it was done to the wall exterior before it was backfilled?

I would invest in a moisture meter and run a dehumidifier regularly. I don’t think you will find the mushrooms caused any health problems — and with proper cleanup and moisture control, the risk should be over now. Just keep an eye on things and consider testing or identification if you suspect an issue.

What color were the mushrooms?

Good Luck!
Karie Fay

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Cindy May 20, 2014 at 6:10 pm

At my mothers house, water came up through any crack in the basement floor. I thought there was a leak in the cinder block walls. Turns out we needed a sump pump, which worked. Water accumulates under the cement floor and comes up through the cracks. Have not had a problem since we put in the sump pump

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Rachel March 16, 2014 at 10:46 am

I had some black mold on the walls in my basement that my friend painted over in an effort to help “fix” it. Now I don’t know how to remove the mold, since I want I refinish my basement, and I think that is the first step! What can I do?

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Karie Fay March 22, 2014 at 1:08 am

Hi Rachel,

Ouch! I am glad you are aware that painting over it isn’t a cure. Now the solution. Is fresh mold growing on the wall? If so, your first step is to kill and remove it, as I outlined in the article. After that, you will want to strip the paint. Do you have cement walls or drywall? If cement, use a chemical paint stripper (with lots of ventilation) and clean the walls afterward. If it’s drywall, however, you may want to remove it.

Hope this helps,
Karie Fay

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Dixie March 1, 2014 at 10:28 pm

I have a question we have noticed some black mold on the cement wall and the holes in the cement walls are getting bigger holes what is causing this.

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Karie Fay March 8, 2014 at 2:48 am

Hi Dixie,

Good question! Here’s what I know. Mold can’t eat concrete — there’s no biological matter in the concrete on which the mold can eat. It can feed on bio-film, however — dead skin cells, dust, oils etc. that float in the air and attach to the walls. And since concrete is porous, it can hold the moisture the mold needs as well.

I suppose it is possible that a heavy mold population could deteriorate the concrete similar to how roots of a tree will crumble a foundation. Still, I think the most important thing is removing the mold — save what’s causing the holes for later. Run a dehumidifer, remove the mold and then examine your wall closely. If it’s in bad shape, you will want to hire a contractor or other professional to repair it.

Hope this helps,
Karie Fay

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Elgin February 12, 2014 at 2:43 pm

Hello Karie,

Our realtor just called to inform us there is mold on a wall of our finished basement. The house currently unoccupied and we reside overseas. Its somewaht difficult to fully assess the the problem. I think its because there is no one living in the house and the heater is running to keep the temp from freezing the pipes. Would installing a dehumidify help along with increasing the temperature?

Thanks

Elgin

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Karie Fay February 17, 2014 at 11:24 pm

Hi Elgin,

I am curious what the realtor noticed specifically. If it’s rather limited, it will be much easier to tackle.

Increasing the temperature should help, and a dehumidifier is really a must. I assume it’s likely a concrete basement, and they seem to stay somewhat damp unless you run a dehumidifier.

Do you have someone you can trust to go in and evaluate and clean up the problem? My concern is that there could be mold the realtor doesn’t notice. If it’s limited, however, if you can get someone to go in and remove it, set up a dehumidifier and keep an eye on things, that would be ideal. Running a dehumidifer alone will not remove the mold that’s already there, just keep conditions from encouraging new (fresh) growth once the existing is gone.

That said, I would think a temperature of 60 degrees is sufficient. Circulating air will also help somewhat. Please remove what’s already there first. You don’t want it to get out of control.

Hope that helps!
Karie Fay

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Susie February 7, 2014 at 8:38 pm

We just found mold in our basement in the kids playroom. Are all the toys infected? We haven’t cut into the wall yet because we wanted to do some research first. We cannot find any source of waster, the mold is on (and probably inside) an interior wall. Any suggestions?

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Karie Fay February 18, 2014 at 12:07 am

Hi Susie,

Good question! Here’s my thoughts: Any concrete basement tends to be high in humidity. Mold needs food, air and water — rather moisture — to survive. If your basement has high humidity, that’s enough to supply the mold. It is, of course, possible to have a moisture problem inside your wall. A leaking pipe, a roofing problem and similar issues can cause mold growth inside the wall. I am thinking your problem is possibly simply high humidity however.

Try running a dehumidifier to lower your air moisture. Keep good air movement in the basement and think about increasing the temperature a little as well.

If it was me, I would wipe down every toy I could with a bleach water solution and allow it to air dry in a mold-free area. Things that can’t be cleaned, consider throwing away or isolating so you can check it later if you can’t bear to throw it away.

After removing and cleaning toys I would remove the surface mold. Clean the entire area while you’re at it — you really can’t be too cautious when it’s your children, I know. You can cut out a section of the interior wall and look inside with lights and mirrors rather than tearing it all away.

Good Luck and hope this helps!!!
Karie Fay

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jessica January 18, 2014 at 7:07 am

My basement is unfinished, and always has water in the spring when snow melts and ground thaws. Also when there is heavy rain. There is no way for me to afford to fix the water coming in. If power goes out, it is a given I have a foot or more of water. Think- a wading pool up to my knees. Anyhow, mold is a given. I’m wondering though if there is a way to prevent/block it from coming up through the floor into the house. I’ve had a lot more respitory issues since I moved my bedroom to first floor. If I leave anything on my floor it starts to smell musty. Overall the living area doesn’t seem too bad because our house has such low humidity (besides bathroom). It is a really old house and will always have some problems but I’m trying to make it healthier for us. Thank you for any suggestions or feed back!

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Karie Fay January 24, 2014 at 12:46 am

Hi Jessica,

I am so sorry to hear about the condition of your basement. What you describe isn’t good at all. It’s a given, as you said, that your situation will lead to mold. I am kind of afraid of worse than that. You can easily end up with rot in your wood framing, and simply sealing off the floor — even if there’s a way to do it — isn’t going to prevent structural damage. You mention respiratory problems — my bet it’s from the mold. And as small and airborne as mold is, it’s going to spread.

Here’s what I would try to do:

Install a A “French drain” around your home foundation. A French drain is an 8- or 10-inch perforated pipe placed in a trench dug as deep as the basement footers. Gravel surrounds and covers the pipe, and when it rains or floods, the water seeps into the gravel and is captured in the pipe, which routes it away from your home. They also have interior french drains which are installed by digging a channel into the outside edges of your basement floor and sinking a pipe similarly. A French drain has 1 inch of slope per 8 feet of run for effectiveness.

Have a sump pump installed. Water flooding the basement will enter a sump basin where it can be pumped out of the basement rather than accumulating.

Run a dehumidifier. It will help keep moisture to a minimum.

Waterproof your basement walls. I assume they are concrete. Have you checked for cracks and damage? Try applying a sealer to the inside or black tar on the outside.

Do you have eaves troughs to carry away water? Have you checked your yard slope? Try to get to the bottom of why you are having this problem — though I suspect the water table may be high in your area or some other similar cause.

Yes, all of these cost money — but your health is important. You can’t really sell the house in this shape and the situation will only get worse.

Good Luck!
Karie Fay

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Holly January 14, 2014 at 1:11 pm

We have a mold problem in our basement. We have a concrete slab in our back yard that is pitched toward our house. We do not have the money and its the middle of winter to tear out and replace it, but the mold downstairs is getting worse. Should I still clean it and try to prevent it from getting worse until the problem can be fixed outside. I know mold will come back but its gotta be better than waiting and letting it get out of control. Right?

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Karie Fay January 23, 2014 at 11:47 pm

Hi Holly,

Gosh that’s such a judgement call that I hate to say do one thing or another and have it on my shoulders. I will give you my thoughts.

First, tearing out that slab is important — why in the world was it placed there tilted toward the house? Until you can do so, I am wondering if you can rig something up to help the problem. How big is the slab? A sheet or two of plywood placed on top of the slab and propped up on the low end of the slab so it catches water and snow and drains it away from your house might help. Just an idea…

If the mold in your basement is bad, it’s only going to get worse. However, each time you mess with it, you’re disturbing the spores and increasing your exposure. I would go with instinct, personally. If there’s removable items I would definitely clean and remove them. Perhaps I would spray the mold down as covered in the article and let it set for a while until I can remove the slab. More likely, I would personally clean it now, and again later.

Have you waterproofed your basement walls? How far from the house is the slab? I am wondering if you can dig a small trench to divert water from the home foundation. Try everything you can to help keep the mold down until you can completely fix the problem.

Hope the information helps!
Karie Fay

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Eric Rieman December 18, 2013 at 3:25 pm

We found mold in our basement this morning. I knew it had to be there as I lived in this house from age 5 till I was 30, and then bought it from my parents estate when they passed away. The house always had water in the basement and the year plus it sat empty didn’t help. Had a company come out and evaluate and they took an air sample. W’ell see how that turns out but there are a few rough spots to repair. I’ve had allergies for as long as I could remember but it’s been the worst ever in the past year since we’ve moved in. I’ll let them give me an estimate for repair but just hoping it’s not going to bankrupt us. No black mold was found, just peniscillium of some sort, in which I am allergic to. Praying for an easy and not so expensive fix.

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C elizabeth November 11, 2013 at 6:21 pm

Recently discovered some patches of mold on our concrete basement walls. My dad thinks we should pressure wash the walls to remove it. Im worried that my basement wont really ever dry out and make the problem wworse. Is he right or should we just scrub it off?

thanks

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Rick December 5, 2013 at 2:23 pm

Hi Elizabeth;

I wash basements all the time before I apply Hydro-Seal 75 waterproof coating and your basement will dry out after washing. The only time we use pressure washers is when we have a stone and mortar foundation rehab project and you will need a wet vac to vac up the water as you pressure wash. My normal method is to wash basement walls and floors with TSP and then neutralize with clear water by working out of a plastic 5 gallon pail with a stiff bristle brush changing the water as it gets dirty. This will control how much water you are using. We typically wash and apply two coats of Hydro-Seal 75 to the walls in one day because by the time we are done washing the walls the water has started to evaporate(darker in areas that are wet and lighter where water has started to evaporate) I also like to use bleach on surfaces with mold before washing with TSP. So wash working from a pail to control amount of water released into basement and walls will dry out. Also very important to find the source of the moisture and water by checking gutters, drainage, grading, cracks in foundation, ect.

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fred rodriguez, CMRS, CSDS November 10, 2013 at 7:11 am

i made a typo, i meant to write $15,000 in professional remediation equipment not 150K.

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fred rodriguez, CMRS, CSDS November 10, 2013 at 7:08 am

I tend to disagree with the above blogs claims that most mold problems can by performed as a DIY project for the everyday homeowner. I guess we need to ask a few questions prior to delving into such comments. If you have a mold problem that is obvious and visible: 1) Are you concerned about the spreading and aerosolizing of mold spores during your DIY attempt? 2) How will you remove the mold spores from the air, this requires the use of large commercial grade HEPA filtration air scrubbers. 3) if visible mold is growing on framing, does the homeowner have the means, equipment to properly and effectively abrasively “sand” down the framing – which is required in order to remove the mold spore and its root system which has grown into the first few layers of the wood framing. 4) Is it important for remediation whether it be DIY or professional remediation, is it important that the work area pass third party testing/post remediation verification (includes mold testing, moisture content readings and a visual inspection of the remediation areas building materials). The average mold remediation project is b/w $3000-$10,000. As a professional remediation firm, we typically bring in over $150000 in professional equipment (scrubbers, dehumidifiers, HEPA vacuums etc…) in order to perform a remediation project which will hold up to third party clearance testing scrutiny. If you are not interested in passing third party clearance testing and are not interested in having documented clearance/post remediation verification report stating that your home is free of elevated mold (usually required for home resale and sale disclosures) then a DIY attempt may be worth it. I will tell you that the chances of a DIY remediation passing any level of third party IAQ testing and assessment is highly unlikely. Remember we’re dealing with a microscopic organism which requires laboratory analysis to determine if the mold levels are acceptable or not. Its not remediation unless you’ve passed a qualified third party Post Remediation Verification sampling and assessment. So if you are going to attempt a DIY mold remediation, find a qualified and local IAQ professional that will verify your DIY attempt was successful and Good Luck. Also, i would highly recommend pre testing / or DIY screening the property by using a qualified Indoor Environmental Professional or a professional grade air sampling DIY mold testing kit.

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Andy Coston February 28, 2014 at 7:54 pm

Fred,

I absolutely agree! This is a very informative article for the most part. Unfortunately there are some common misconceptions that have been reinforced here. Bleach is almost never a good idea to use in mold remediation. Unless it is a non porous surface (i.e. tub, shower, concrete etc.) it is ineffective. When mold grows on porous surfaces like drywall, subfloor, studs, the majority of the mold growth is under the surface. The hyphe, or root, of the mold grows inside of these materials. Depending on the mold species it can actually start inside and work its way out. When you use various biocides or bleach you are only killing the surface. Since these chemicals all have a high concentration of water it actually encourages mold growth! The EPA advises against using bleach in mold remediation and this fact is also listed on OSHA’s website. I would also argue the statistic for mold allergies is irrelevant when you’re dealing with toxic molds like Aspergillus (very very common) or the dreaded Stachybotrys. I do agree some mold remediation firms are unscrupulous and there are some jobs that can easily be tackled by the average homeowner. However, a large amount of the time when a homeowner or an uninformed mold remediation company tackles a small issue they simply make it much worse. Also mold testing is ALWAYS a good idea before and after a remediation project. It’s easy to discredit mold remediation firms as just being greedy, but from my personal experience they are actually providing a much needed service that could otherwise not be successfully completed.

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Kris November 7, 2013 at 10:30 am

I am finding mold growing on items (luggage, leather coat, boxes) in my basement storage room. We have not had any water leakage into the basement but were without air conditioning for most of the hot/humid summer and did not run a dehumidifier. I suspect this is the cause of the mold growth because the mold is not contained to one area but throughout the space. I am in the process of discarding items and wiping down everything I would like to keep with bleach. What else can I do to prevent the mold from coming back? Is there some kind of disinfectant or mold preventer?

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Karie Fay November 10, 2013 at 1:43 am

Hi Kris,

Yuck… not a pleasant situation, is it? I think you are spot on about the cause. The fact that it’s widespread makes me think humidity is a large factor. I take it that you have a concrete basement — the concrete by nature creates a damp environment. That’s what I personally like about a wood foundation. The basement is so nice.

Anyway, I know they mold-preventatives on the market. However, I would consider a wash with borax, personally. If you leave a light residue behind, it should help. Vinegar may as well.

The most important thing, in my opinion, is to get rid of all the mold you have now. Sounds like you are on the right track there. Then, two important steps regardless of the time of year: Ventilate. Run a dehumidifier.

Even a fan helps for ventilation. A dehumidifier will make a world of difference. Plus, if you have plants, you can use the water for them.

If you have any other questions, just ask.

Thanks!
Karie Fay

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Victoria Torres November 12, 2013 at 6:27 pm

Does it matter what kind of vinegar?

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Karie Fay January 23, 2014 at 10:07 pm

Hi Victoria,

The standard in most home applications is white vinegar, but personally, I use white or cider vinegar almost interchangeably. They will both work just as well when dealing with mold in my opinion. The only real consideration is that cider vinegar is a darker color, so it may stain things that white vinegar won’t.
Good Luck!
Karie Fay

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Angel October 31, 2013 at 5:50 am

We found the source of the water and fixed it but the floor boards that the paneling is nailed to are black. Do I need to remove those boards or can I just clean them according to your instructions? Is the damage too deep into the wood? So I’ve developed a horrible allergy and can’t get rid of it. Could it be the mold?

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Karie Fay November 10, 2013 at 1:35 am

Hi Angel,

Sorry to hear about your mess! I am not quite picturing what you mean by the floor boards are nailed to the paneling… but in either case, I do understand that you have wood flooring and it is black. Correct?

Mold can damage the wood by causing stains — usually green or black. However sometimes a discoloration is caused by another fungi and creates brown rot. This causes the wood to darken and shrink, eventually crumbling.

If your wood is very soft and seems like it’s rotting, I would go ahead and throw it away. Otherwise, personally I would try a borax solution. The good thing about borax is the residue remains and helps fight off mold (if you leave residue on without rinsing the final wash away). If the wood remains discolored, you might try sanding it or bleaching it. It really depends on what you see as you work, however.

I wouldn’t be surprised if you do have problems from the mold — especially if it’s the ‘wrong’ kind or widespread. Getting rid of it is the best idea, and kudos for fixing the moisture problem first! If you have any questions, just ask.

Good luck!
Karie Fay

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Erin October 15, 2013 at 6:24 pm

My husband and I started noticing a smell at the top of our basement stairs this summer, and now the smell has crept across the living room, which is in the room next to those stairs. At first it was kind of on and off, but since we both have terrible allergies, we couldn’t smell it and therefore we don’t really know how long it’s been going on. It smells kind of like dirty socks, for lack of a better description. I guess I always associate “musty” with the way the inside of and old wooden chest smells, but I suppose that mold or mildew could smell like dirty socks as well, yeah?

Anyway, we have fiberglass insulation above a drop ceiling throughout most of the basement. A lot of the insulation looks ratty in spots, and I’m tempted to just rip everything out. At this point I am just so sick of the smell and I’m sure the rest of the insulation is holding that odor.

After we do some of our own investigating, what kind of professional do we hire try to point out our problem areas?

By the way, thanks for your article- it was very helpful.

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Karie Fay October 20, 2013 at 5:14 pm

Hi Erin,

I am glad you enjoyed the article. I like thinking I help people help themselves.

I tend to think you are smelling mold growth. A musty smell may be like dirty socks, or rotting leaves, or earth. An old wooden chest to me would be more stagnant air and the smell of dead wood…

Anyway. I am not convinced you need to hire a professional. First thing I would do, personally, is rip that insulation away. If it’s ratty, it’s not doing a great job anyway. Same if it’s compressed, water damaged, or anything other than perfectly installed and undisturbed.

Do you heat and cool your basement? If you do, you might consider leaving the insulation out — the most important insulation in that situation is the wall insulation. If you heat and cool upstairs only, the ceiling insulation is more important.

There’s nothing there that should produce an odor unless you have mold/mildew growing, or if you somehow have a dead mouse, squirrel, snake, etc. caught in there. And if the smell is growing, the problem is growing as well.

It’s impossible for me to say what kind of professional to get since it could be something else causing it. How handy are you and your husband? Do you feel comfortable ripping insulation away and investigating? If it’s a water leak, you might be able to pinpoint where — if you can’t, get a plumber. If there’s no sign of moisture, look for something dead. If you find neither, think about getting a carpenter or contractor — possibly a handyman even, as long as you KNOW their reputation and quality of work. As for reinsulating — you should be able to do that yourself as well, it’s not difficult. You will save a lot of money that way too.

Feel free to ask if you have any other questions.
Thanks!
Karie Fay

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Marsha October 5, 2013 at 6:23 pm

Thanks so much for the info! Can u suggest what to do with wood furniture in the basement? Can it b saved? Ours is unfinished and never got water til this year. We have a greenish powder convering on some stuff which I thought was harmless mildew but now looks like it may b mold after reading this. We also have a mattress stored down there. Should we trash it? Thanks for any help!

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Karie Fay October 12, 2013 at 3:59 am

Hi Marsha!

Unfortunately, I have to agree with you, it sounds like mold. In fact, it might very well be aspergillus or penicillium. Of course, I can’t be certain. Mold tends to be powdery, while mildew tends to be slimy.

As for your contents. I would throw the mattress away if there’s any way it could be contaminated. Did it get wet? Does it smell musty? If it didn’t get wet, but smelled a little musty, I might be tempted to drag it outside and air it out, then see what I thought. Either way, however, even though mattresses aren’t cheap, it simply isn’t worth keeping one that’s damaged. Sorry.

The unfinished wood furniture. Yes, it can be saved. You will want to take a lot of care making sure you get the mold permanently eliminated, however.

You’ll find conflicting advice and various helpful suggestions everywhere. Many wood lovers will cringe at exposing their wood furniture to bleach, but FEMA recommends using 1/4 cup bleach to about a gallon of water to treat mold. I know you can also use trisodium phosphate (TSP) at a weak solution. Or use borax as I suggested in the article.

Personally, I would be tempted to use vinegar — about half water and half vinegar. It will kill mold but it’s not hazardous, since it’s all-natural (which I love). It’s not as likely to bleach the wood or raise the grain, either. Although, if the mold itself stains the wood — particularly as you say it’s unfinished — that’s another story.

If you bleach the wood with your solution or the mold leaves marks, I would suggest sanding it down slightly and applying a finish (once the mold is gone).

Thanks for the question!
Karie Fay

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ingrid roubicek September 27, 2013 at 1:13 am

i have 1 room in the house which since app3 weeks has a potent moldy small. the plaster walls have no damage .it cant come from the ground as the garage is underneath. so it can only be in the walls. a person came to check with an instrument could not find any damp showing up. what can i do.
would be a miracle and thanks for a good suggestion.

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Karie Fay October 5, 2013 at 9:01 pm

Hi Ingrid,

I am not sure what is going on with your house. I guess if it was me, I would first say to myself suspend my disbelief and look underneath the floors and behind the plaster. Still, if a professional used a tool to measure the moisture and didn’t find any — well mold can’t grow without a source of moisture.

Have you looked under and around your sinks, your toilets and tub? Do you have washing machine? Any water-using appliance could cause a water leak that allows mold to grow. Even a broken pipe — and all it takes is a slight trickle.

So I would start there — inspecting water fixtures, looking at plumbing lines, etc. At the same time, try airing out your home to see if you can eliminate the moldy smell.

Good luck!
Karie Fay

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Kurt Anderson September 26, 2013 at 3:24 am

My son is looking to buy a house that is quite obvious of mold contamination. The mold is in every corner of the somewhat finished basement. You are correct in where the moisture problem came from. Poor drainage from improper rain gutter and purely bad slopping to the landscape. Without the knowledge of proper sealing on the outside of the foundation the work expense is tuff to estimate. Removal of at least the first two feet of all the completed walls is a must. In the corners probably floor to ceiling. With never attacking a problem of this size what would you suggest before making an offer? The house appears to have been closed up for a few months with the mold problem most likely years. It looks like they finished the basement to hide the mold.

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Karie Fay October 5, 2013 at 8:56 pm

Hi Kurt,

The answer to your question is really a personal thing. First reading your query, the thing that jumps to my mind is what else are they hiding? Finishing the basement to hide mold isn’t exactly illegal — but it is unethical. It would make me wary of the whole deal.

That said, if this is the house your son really wants, it’s not the end of the world. It will take work — and that will be cheaper if he DIYs.

I would excavate the entire foundation. Concrete is porous and will absorb any moisture in the ground. Dig it out, then choose from a wide variety of concrete waterproofing materials available at your home store: asphalt, rubber, urethane-based products and physical barriers such as polyethylene (sheet plastic). Do a little research, ask lots of questions and choose what works best for him.

Once it’s sealed fill in around the foundation again. Dig for the mold — make sure you look for any hiding places.

I would definitely offer a lower price for the house. Point out the problem — maybe get a professional estimate of repairs — and go from there.

Hope this helps –
Karie Fay

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Mark September 2, 2013 at 8:34 pm

We treated exposed lumber surfaces in our basement with 20 Mule Team Borax 1 Cup dissolved in a Gal. of hot water. We found that an LED headlamp causes the mold to fluoresce making it easy to see.

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Caleb August 26, 2013 at 9:24 am

I believe that the best thing to do to get rid of mold damage is to hire a professional. This way you know that the job is done right and the damage has been taken care of.

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Kenneeth C, Floyd August 25, 2013 at 3:43 pm

I ‘m intrested in more articles about removing mold from walls in your basement, after removing part of the sheet rock and before replacing it what other solution do you sugest for cleaning.

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Karie Fay September 12, 2013 at 11:41 pm

Hi Kenneeth,

What kind of walls are you talking about? You say you remove the sheet rock — is this a case of furring out concrete walls and mounting drywall to the furring strips, or do you have wood-stud walls instead? In either case, vinegar or borax will take care of the mold… bleach will as well, but I like the thought of natural products. Other than that you could buy commercial products — but I don’t see a need. Just scrub the surfaces well and retreat if that puts your mind at rest.

If I can be of further assistance, let me know.

Thanks!
Karie Fay

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Mark August 17, 2013 at 1:12 pm

I agree with Eric. This is well-written and informative. I wanted to know the writer so I saw the link at the top of the article. Karie Fay has written some articles on other topics as good as this one. See especially the article “After a Flood…”, which for many of us looking after mold problems began with this problem.

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Eric Rajchel August 11, 2013 at 11:30 am

This is one of most informative articles on indoor mold growth I have ever read, and I have read alot of them. Whoever wrote this is definitely experienced in the field or did extensive homework. One thing though… the author mentions that 6 to 10% of the population are sensitive to mold allergens. While this is true, just about anyone can find themselves suffering if they are consistently in an environment with abnormally elevated levels of mold, even if the species “black mold” is not present.

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Chris @ Mold Removal Products April 12, 2013 at 9:48 am

If mold removal products and mold remediation products are used safely and properly with the proper eye, skin and breathing protection, anyone can clean up mold or make affected areas clean and safe again. You don’t have to be a professional with a little training and some practice.

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Tony December 21, 2012 at 4:09 am

I prefer installing insulating screens on such molds which totally solves such problems. Moisture seeping inside the walls does not just give a stingy smell but also weakens the foundation. Thus, proper measures should be taken.

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Eric Salonga October 2, 2012 at 9:44 pm

Mold is a big issue for any home owners especially if they are trying to sell their home. This is a great article on how to address this serious problem. Here in the Central Valley, there aren’t a lot of houses with basements but mold is still a problem. For the most part it’s due to poor ventilation in the bathrooms. There are a lot of local resources to help get rid of mold but the best way is to be proactive. Just don’t let moisture build up in any room and you should be fine.

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