Carpet Mold: Identification, Prevention and Removal

The Dangers of Mold

Molds produce allergens, which are substances that can cause allergic reactions, as well as irritants and, in some cases, potentially toxic substances known as mycotoxins.  Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals.  Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis).  Allergic reactions to mold are common.  They can be immediate or delayed.  Molds can also cause asthma attacks in people with asthma who are allergic to mold.  In addition, mold exposure can irritate the eyes, skin, nose, throat and lungs of both mold-allergic and non-allergic people.  Symptoms other than the allergic and irritant types are not commonly reported as a result of inhaling mold, but can also occur.

Carpet at Risk

Carpeting is an area of the home that can be at high risk for mold growth.  In order to grow, mold needs moisture, oxygen, a food source, and a surface to grow on.  Mold spores are commonly found naturally in the air.  If spores land on a wet or damp spot indoors that contains dust for them to feed on, mold growth will soon follow. Wall-to-wall carpeting, as well as area rugs, can provide an ample breeding ground for mold if conditions are right.  At especially high risk for mold growth are carpeting located below ground level in basements, carpet in commonly moist or damp climates, and carpet that has been wet for any period of time.

Identifying Mold in Carpeting

Just because mold is not immediately apparent or visible on a carpet’s surface does not mean that mold growth is not in progress.  In fact, mold will probably only be visible on the surface of carpets in unusually severe cases of growth, such as carpet damaged in flooding that has remained wet for some time.  The following are some examples of identifiable instances where mold growth has occurred or is likely to occur:

  • visible mold growth:  As stated above, this can be a rare case, but sometimes it may be obvious from visual inspection that mold growth is occurring.  Carpet in this condition is most likely not salvageable and should be disposed of and replaced.  Often, even if mold growth is not visible on the top of carpeting, it may be occurring underneath the carpet where it can’t be easily seen.  Carpet suspected of containing mold should always be examined on both sides.
  • carpet mildew:  Any discoloration or odor on carpeting that might be described as mildew is probably a case of mold.
  • wet or water-damaged carpet:  Any carpet that has been subjected to water damage from flooding or standing water will most likely need to be disposed of.  Conditions are ripe for mold growth, in this case.  Even if visibly apparent mold growth has not yet begun, it is highly likely to happen unless the carpet is completely removed, cleaned and dried within 24 to 48 hours.  Even then, removal and cleaning are not guaranteed to prevent mold growth.  It is more likely that the carpet will need to be replaced.
  • wet padding beneath carpet:  If padding beneath the carpet has become wet for any reason, or has become moist from condensation, the padding as well as the carpet on top are at risk for mold growth.  The padding may need to be replaced, as will the carpet, in some cases.
  • basement carpet:  Carpeting in basements below grade level is especially at risk in areas where humidity is high, or where wide temperature swings can produce condensation.
  • odors and stains:  There is a wide range of things that can cause odors and stains on carpets.  If mold is suspected, samples can be taken and sent for analysis to determine if mold growth has occurred.

Preventing Mold Growth in Carpeting

The best method for combating mold is to not allow mold growth in the first place.  The best way to do so is by ensuring that conditions conducive to growth do not exist.  Below are some ways to prevent mold growth in carpets.

  • Reduce indoor humidity.  The use of dehumidifiers will help control moisture in the air, depriving mold spores of the water they need to grow into mold.  A range of 30% to 60% humidity is acceptable for interiors.
  • Install intelligently.  Do not install carpeting in areas that are likely to be subject to frequent, high moisture.  Carpet in a bathroom, for example, will quickly turn to a breeding ground for mold growth due to the high humidity from constant water use in that area.
  • Choose high-quality carpet padding.  Solid, rubber-slab carpet padding with anti-microbial properties is available.  It is slightly more expensive than other types of padding but can be helpful for preventing the growth of mold, especially in climates prone to periods of high humidity.
  • Never allow standing water.  Carpet exposed to standing water will quickly be ruined.  If standing water ever occurs because of a leak or a spill, all carpeting exposed must be immediately cleaned and dried.  The top and bottom surfaces of the carpet, any padding, and the floor underneath must be cleaned and completely dried within a short period of time after exposure to standing water if the carpet is to be saved.  If a large flood has occurred, or if standing water has been present for any extended period of time, the carpet will probably need to be replaced.
  • Clean smart.  When carpeting needs to be cleaned, try to use a dry form of cleaning, when possible.  If any water, liquid, or other moisture has come in contact with the carpet during cleaning, be sure it is dried thoroughly afterward.

Removing Mold From Carpet

In many cases, if mold has grown on carpet, cleaning will not be possible.  If growth has occurred on more than one area of the carpet, or if there is a large area of growth, the carpet will probably need to be replaced. 

Small areas of growth that have been quickly identified can sometimes be dealt with.  Detergent and water used with a steam-cleaning machine may be enough to clean the carpet thoroughly.  It is then important to ensure that the carpet dries completely after cleaning to prevent the growth from recurring.  Stronger cleaning agents can be substituted if detergent does not work.  Anything stronger than detergent or common rug-cleaning products should first be tested on an inconspicuous area of the carpet to ensure that the rug will not be damaged during cleaning.  About 24 hours is a reasonable amount of time to wait after testing to be sure that wider cleaning will not discolor or damage the carpet.

Another option in instances where mold growth is not widespread is to remove the ruined section of the carpet.  If cleaning has been attempted unsuccessfully, the area of mold growth may be removed and replaced with a patch of similar carpet.  Of course, this will only work in situations where aesthetics are not a big concern, since exactly matching the patch to the original carpet may be difficult and the seam may be visible.  If mold has grown in more than one area of the carpet, or if the area of growth is larger than a couple of feet, this will probably not be an effective method of mold removal.
As with all areas of the interior at risk for mold growth, prevention is the best method of control for carpet mold.  Eliminating high-moisture conditions and preventing the risk of flooding or standing water will reduce the possibility of growth.  Inspectors will want to know where to look for and how to identify mold growth in carpeting.  It is also helpful to know how to determine if carpet should be replaced, or whether there is a possibility of cleaning and saving it.
by Nick Gromicko and Ethan Ward

Abrasive Blasting for Mold Remediation

 Mold in the Home

Health concerns related to the growth of mold in the home have been featured heavily in the news.  Problems ranging from itchy eyes, coughing and sneezing to serious allergic reactions, asthma attacks, and even the possibility of permanent lung damage can all be caused by mold, which can be found growing in the home, given the right conditions.

All that is needed for mold to grow is moisture, oxygen, a food source, and a surface to grow on.  Mold spores are commonly found naturally in the air.  If spores land on a wet or damp spot indoors and begin growing, they will lead to problems.

Molds produce allergens, irritants and, in some cases, potentially toxic substances called mycotoxins.  Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals.

Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis).  Allergic reactions to mold are common.  They can be immediate or delayed.  Molds can also trigger asthma attacks in people with asthma who are allergic to mold.

In addition, mold exposure can irritate the eyes, skin, nose, throat and lungs of both mold-allergic and non-allergic people.

As more is understood about the health issues related to mold growth in interior environments, new methods for mold assessment and remediation are being put into practice.  Mold assessment and mold remediation are techniques used in occupational health.  Mold assessment is the process of identifying the location and extent of the mold hazard in a structure.

Mold remediation is the process of cleanup and/or removal of mold from an indoor environment.  Mold remediation is usually conducted by a company with experience in construction, demolition, cleaning, airborne-particle containment-control, and the use of special equipment to protect workers and building occupants from contaminated or irritating dust and organic debris.  A new method that is gaining traction in this area is abrasive blasting.

Abrasive Blasting

The first step in combating mold growth is not to allow for an environment that is conducive to its growth in the first place.  Controlling moisture and assuring that standing water from leaks or floods is eliminated are the most important places to start.  If mold growth has already begun, the mold must be removed completely, and any affected surfaces must be cleaned or repaired.

Traditional methods for remediation have been slow and tedious, often involving copious amounts of hand-scrubbing and sanding.  Abrasive blasting is a new technique that is proving to be less tedious and time-consuming, while maintaining a high level of effectiveness.

Abrasive blasting is a process for cleaning or finishing objects by using an air-blast or centrifugal wheel that throws abrasive particles against the surface of the work pieces. Sand, dry ice and corncobs are just some of the different types of media used in blasting.  For the purposes of mold remediation, sodium bicarbonate (baking soda) and dry ice are the media commonly used.

Benefits of Abrasive Blasting

Abrasive (or “media”) blasting provides some distinct advantages over traditional techniques of mold remediation.  In addition to eliminating much of the tedious labor involved in scrubbing and sanding by hand, abrasive blasting is extremely useful for cleaning irregular and hard-to-reach surfaces.

Surfaces that have cross-bracing or bridging can be cleaned more easily, as well as areas such as the bottom of a deck, where nails may be protruding.  Areas that are difficult to access, such as attics and crawlspaces, can also be cleaned more easily with abrasive blasting than by traditional methods.

The time saved is also an advantage, and the typical timeframe for completion of a mold remediation project can often be greatly reduced by utilizing abrasive blasting.

Soda-Blasting

Soda-blasting is a type of abrasive blasting that utilizes sodium bicarbonate as the medium propelled by compressed air.  One of the earliest and most widely publicized uses of soda-blasting was on the restoration of the Statue of Liberty.
In May of 1982, President Ronald Reagan appointed Lee Iacocca to head up a private-sector effort for the project.  Fundraising began for the $87 million restoration under a public-private partnership between the National Park Service and The Statue of Liberty-Ellis Island Foundation, Inc.  After extensive work that included the use of soda-blasting, the restored monument re-opened to the public on July 5, 1986, during Liberty Weekend, which celebrated the statue’s  centennial.

The baking soda used in soda-blasting is soft but angular, appearing knife-like under a microscope.  The crystals are manufactured in state-of-the-art facilities to ensure that the right size and shape are consistently produced.

Baking soda is water-soluble, with a pH near neutral. Baking-soda abrasive blasting effectively removes mold while minimizing damage to the underlying surface (i.e., wood, PVC, modern wiring, ductwork, etc.).  When using the proper equipment setup (correct nozzles, media regulators, hoses, etc.) and technique (proper air flow, pressure, angle of attack, etc.), the process allows for fast and efficient removal of mold, with a minimum of damage, waste and cleanup.  By using a soda blaster with the correct-size nozzle, the amount of baking soda used is minimized. Minimal baking soda means better visibility while working, and less cleanup afterward.

Dry-Ice Blasting

Dry ice is solidified carbon dioxide that, at -78.5° C and ambient pressure, changes directly into a gas as it absorbs heat.  Dry ice pellets are made by taking liquid carbon dioxide (CO2) from a pressurized storage tank and expanding it at ambient pressure to produce snow.  The snow is then compressed through a die to make hard pellets.  The pellets are readily available from most dry ice suppliers nationwide.  For dry-ice blasting, the standard size used is 1/8-inch, high-density dry ice pellets.

The dry-ice blasting process includes three phases, the first of which is energy transfer.  Energy transfer works when dry ice pellets are propelled out of the blasting gun at supersonic speed and impact the surface. The energy transfer helps to knock mold off the surface being cleaned, with little or no damage.

The freezing effect of the dry ice pellets hitting the mold creates the second phase, which is micro-thermal shock, caused by the dry ice’s temperature of -79º C, between the mold and the contaminated surface.  This phase isn’t as much a factor in the removal of mold as it is for removing resins, oils, waxes, food particles, and other contaminants and debris.  For these types of substances, the thermal shock causes cracking and delaminating of the contaminant, furthering the elimination process.

The final phase is gas pressure, which happens when the dry ice pellets explode on impact.  As the pellets warm, they convert to CO2 gas, generating a volume expansion of 400 to 800 times.  The rapid gas expansion underneath the mold forces it off the surface.

HEPA Vacuuming

A HEPA vacuum is a vacuum cleaner with a high-efficiency particulate air (or HEPA) filter through which the contaminated air flows.  HEPA filters, as defined by the U.S. Department of Energy’s standard adopted by most American industries, remove at least 99.97% of airborne particles that are as small as 0.3 micrometers (µm) in diameter.  HEPA vacuuming is necessary in conjunction with blasting for complete mold removal.

While abrasive blasting with either baking soda or dry ice is an effective technique, remediation will not be complete until HEPA filtering or vacuuming has been done.  Abrasive blasting removes mold from contaminated surfaces, but it also causes the mold spores to become airborne again.  The spores can cover the ground and the surfaces that have already been cleaned.  So, the mold spores need to be removed by HEPA filters.

Additionally, while some remediation companies claim that there will be no blasting media to remove after cleaning, especially with the dry-ice method, there will be at least a small amount of visible debris left by the blasting that must be removed before HEPA vacuuming can occur.  HEPA vacuuming removes all invisible contaminants from surfaces and the surrounding air.  When HEPA vacuuming is completed, samples at the previously contaminated areas should be re-tested to ensure that no mold or mold spores remain.

by Nick Gromicko and Ethan Ward

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