How to Get Rid of Mold in Your Basement or Crawlspace

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SANY0020-1You'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

SANY0009-1It'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.

SANY0012-2Once 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.

SANY0016Look 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.

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