What to do with wet or mold-contaminated carpets or rugs.

Can wet or moldy carpeting and carpet padding be cleaned and retained? Area-rugs, maybe. Wall-to-wall: small-areas, maybe. Usually not.

Inspection & test procedures for wet, contaminated, moldy or smelly indoor carpeting & rugs.

This article describes how we inspect, test, and cure wet, smelly, or moldy carpeting or rugs. We discuss the risk of hidden mold under carpeting and in carpet padding and in walls around such floors.

Daniel Friedman is retired a mold/indoor air quality investigator, forensic microscopist, and home inspector who continues to work as journalist in Poughkeepsie, New York. He is a member of ASHRAE, and was of AHIA, the American Industrial Hygiene Association and was Standards, Exam & Technical Committee chair of ASHI, the American Society of Home Inspectors.

How to Handle Wet, Sewage- or Mold-Contaminated Carpeting & Rugs

While you may see mold on carpeting in unusually severe cases, carpet, especially wall-to-wall carpeting can be a reservoir for hidden mold, mite fecal, pet dander, rodent dander, fecals, and dust, bacteria, and other allergens, pathogens, and irritants even though you cannot see anything suspicious on the carpet.

Warning signs that carpeting may be an IAQ problem source in a building:

• Carpets that are visibly moldy 
  
  such as in the photo above - these need to be discarded.
  
  If only a section of carpeting has been wet and mold contaminated it might be possible to cut out the wet or moldy carpet and padding material and replace that section, seaming the replacement in place if it can be color matched, or changing it if the area is small, such as the interior of a closet.
• Carpets that have been wet 
  
  such as by basement water entry, a plumbing leak, roof leak, sewer line backup.
  
  If wall-to-wall carpeting has been wet it should be removed and disposed-of along with its padding.
  
  Small exceptions might involve a small corner are of a square foot or two that was wet by clean water and that can be pulled-back and, along with the padding and surfaces below, be completely dried in 24-48 hours.
  
  There are services which will remove wet area rugs or carpets and clean them for reinstallation. If non-permanently-installed wet area rugs or wet area carpets are removed and cleaned and dried in 24-48 hours those might be salvageable.

If any rug or carpet was wet and stayed wet for days, regardless of whether the carpet was permanently-installed (eg tack strips or adhesive), it's history. Area rugs can often be professionally cleaned and salvaged.

If in a room where the entire floor is covered with a large area of wall to wall carpeting, and just a very small area of your carpeting has become wet or moldy, it may be more practical to cut out the damaged, wet, moldy section, plus 12" past all visible wet or damaged area, replacing or patching that section.

If you can live with the cosmetic defect of imperfectly matched carpeting the cost will be much less than a complete replacement.

Be careful: don't forget to check the entire room to be sure you're not leaving other areas of wet moldy carpeting in place. - Thanks to reader Eva for these suggestions.

• Carpets over wet padding or carpets, carpet padding, or carpet tack strips which are water stained 
  
  or moldy indicating that water or condensation has been present below the carpet.
  
  The photo shown here is an example of a moldy carpet tack strip which offers a clue of a limited area of water entry in a basement although no staining was visible on the exposed top of the carpet.
  
  Notice the small brown stain spots on the back side of this carpet?
  
  These are rust marks from the carpet tack strip - another indicator of wet conditions below this carpeting.
• Carpets in basements or located on floors below grade
  
   such as in split level homes, particularly in areas where there are periods of high humidity or wide temperature swings in a building likely to produce condensation.
• Carpets exposed to high pet traffic 
  
  are likely to have a high level of animal dander and, depending on the building humidity history, almost always have a high level of mite fecals and other allergens - this is not a mold problem but is likely to be an IAQ problem especially for people who are asthmatic or allergic to pets.
  
  I have tested carpets before and after home vacuuming, home HEPA vacuuming, and professional dry and wet process cleaning.

None of these methods can completely clean a carpet, though they might temporarily reduce the level of particles in the very top of the carpet nap.

Watch out: conditions that have wet a carpet or area rug may also have sent water into building wall or floor cavities. If so the risk of a significant hidden mold or bacterial hazard can justify further investigation. We discuss this concern below.

• Carpet mildew diagnosis:
  
  carpeting that has light mold or smells like mold might be described by an inexperienced inspector or a building owner as mildewed carpeting. It's moldy.
  
  Our photo of moldy carpet (left) was taken from a sample of carpeting that was the final target of a building "mildew odor" diagnosis procedure.
  
  See MILDEW in BUILDINGS ?
  and
  
  see MILDEW ERRORS, IT's MOLD for details.
• Carpet odors: 
  
  carpeting that smells can be caused by a wide range of problems.
  
  See ODORS GASES SMELLS, DIAGNOSIS & CURE
• Carpet stains:
  
  can also be caused by a wide range of sources, some of which are harmless, others may diagnose other building problems such as a heating system that is not working properly, or building air leaks.
  
  See CARPET STAIN DIAGNOSIS to identify the cause of stains on carpets and rugs.

How to Look for Hidden bacteria, pathogens, or mold in or underneath wall to wall carpeting and carpet padding

If you see carpet stains of any color, black, brown, green, yellow, in areas where there may have been water leaks from any source, you should suspect a mold growth problem, and further investigation of the carpet, the padding below the carpet, and the subfloor below that are all in order.

Mold stains on carpeting such as those in our photo at left are discussed in more detail in this article.

More photographs of thermal tracking and other stains on carpeting can be seen

at PHOTO GUIDE TO STAINS on Indoor Surfaces

We welcome more thermal tracking, soot tracking, air bypass leaks, and similar photos of indoor stains as well as text suggestions to expand this detail and would be glad to credit contributors.

Watch out: in our experience [DF] when a building has been wet enough to allow water to enter even just the very bottom of a wall cavity, there is a high risk of harmful and costly mold contamination of both the interior wall cavity surfaces as well as wall insulation.

More advice on handling wall and floor cavities where the floors have been wet is

at Step 6. FLOOD DAMAGED BUILDING CLEAN-UP for carpeting and rugs that have been wet by area or building flooding

Advice for Testing Indoor Carpeting for Mold, Bacteria, or other Pathogen Contamination

If carpeting has been wet and was not dried within about 24 hours after that event, it is likely to be moldy. If carpeting smells or looks moldy it also will almost certainly need to be replaced. But what if we don't know a carpet's history, we don't see mold on the carpet nor on it's underside, but we need to test the carpeting for mold?

If carpeting or rugs were wet by drain water or sewage backup they should be disposed-of along with their padding.

Details of our advice on testing carpeting for mold or other contaminants can be read

at CARPET CONTAMINATION TEST PROCEDURE.

In addition to taking a careful case history of the leak exposure 

to which carpeting has been exposed, and in addition to making a thorough olfactory (subjective smell test) and visual (by eye) inspection, we on occasion test carpeting using a vacuum method, combining a vacuum pump with a sampling cassette.

Selection of the area of carpet to be tested is important:

choose the most-suspect area of carpeting such as where leaks or water are likely to have been present or where there may have been cross-contamination from mold remediation in other areas of the building.

We advise against use of tape samples of a carpet upper surface to screen carpeting for mold

since there is a significant risk that such methods will fail to detect problem mold that is in the carpet but not on its uppermost surface. This condition occurs, for example, when moldy carpeting has been HEPA vacuumed or cleaned.

However, if there is mold already visible on a carpet (such as is shown in the next section of this article) it may be appropriate to collect a surface sample using tape in order to identify the type of mold present when that data is needed for medical or post-remediation clearance test purposes.

How to Recognize Mold Visible on Exposed Carpeting Surfaces

Mold visible on carpeting surfaces:

As we also mentioned

at CARPET PADDING ASBESTOS, MOLD, ODORS,

carpets or even area rugs may not actually be mold contaminated but can smell moldy if the carpeting or padding have absorbed Mold-related Volatile Organic Compounds
( MVOCs).

In the case of the moldy carpet photo at left, we suspected that the visible carpet mold was the "tip of an iceberg" of hidden mold below.

Details about types of stains on carpeting, their cause, significance, and cure, are

at CARPET STAIN DIAGNOSIS.

Watch out: carpets can absorb other odors besides mold.

And watch out for over-using ozone treatments that may oxidize building components and lead to a new and horrible chemical like smell.

See OZONE MOLD / ODOR TREATMENT WARNINGS.

Should I Test my Moldy Wall to Wall Carpeting?

Is a tape sample of my mold-suspect carpeting surface useful?

I took a clear tape sample of some mold on the carpet in my baby's bedroom, but I don't see any visible mold on the sample, even though I pressed fairly hard. Is that ok to send to you, or must I see the mold on the tape? I just don't want to waste anyone's time by sending an insufficient sample. S.P.

Answer: Testing a Moldy Carpet is Usually Not Needed

Thanks for asking. Our suggestions below, basically recommending that you do not have this carpet mold sample processed, are opinions based on ethics (don't perform unnecessary lab tests), and common sense, not out of a reluctance to be of service:

• If the carpet is visibly moldy, smells moldy, got soaked, it almost certainly needs to be removed and disposed-of along with the padding. It is near impossible to completely clean mold from wall to wall carpeting, and trying to do so risks health issues as well as wasting money.
  
  Toss out moldy carpet, being careful not to spread moldy dust throughout the building in the process, and clean the exposed surfaces, and of course, fix the cause of mold.
• A carpet surface tape sample, unless there was visible mold, is too unlikely to represent the actual mold-condition of the carpet.
  
  If we have a technical reason to actually determine what kinds of mold are present in carpeting, for example to allow a client to inform their doctor to what molds they've been exposed at high level, we use a vacuuming method that pulls particles from the carpet interior, under-side, top side, and carpet padding as well as checking the conditions of the subfloor below.
  
  Details are at CARPET CONTAMINATION TEST PROCEDURE.
• And if there is mold visible on the carpet surface, our first point pertains. Despite claims to wash and restore carpets, that approach has not done well in the field and lab tests we've conducted.

Some exceptions to this no-carpet-test advice / opinion

• If there was only very small moldy spot
  
  caused by a limited-scope, well understood event - such as a child left a piece of apple wet-side down on the carpet- that's such a localized problem that ordinary cleaning should suffice, and replacing the carpet ought not be necessary.
  
  That's because we know the cause, we know there was no extensive wetting nor mold growth, and we are not facing conditions that make further mold growth likely - at least not from the apple.
• If occupants of the building are ill, 
  
  where moldy carpeting is or has been installed the occupants will need to inform their physician, pulmonologist, or allergist about the molds to which they have been exposed - in which case other building screening samples (such as settled dust) and a more thorough inspection may be in order, lest we focus on the "wrong mold" reservoir or miss something else important.
• Carpeting that is not permanently installed -
  
  better called area rugs - can be removed and sent out for professional cleaning and drying and if appropriate, tested before it is reinstalled in the building.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Small amounts of mold on plush carpet but in many spots - Thank you. Wonderful website.

My question is regarding plush wall to wall carpeting in a home with small amounts of mold in numerous locations. The mold event was initially triggered by HVAC problems that caused several days of high humidity. A lot of cleaning has been done, and the carpet was never wet or showed mold. Does it need to be replaced? Thank you. Wonderful website. - On 2019-11-12 by Judy -

Reply by (mod) - maybe

Judy:

RE: Can our moldy carpet be cleaned if it was never actually wet?

Answer: Maybe

I cannot say with certainty whether or not your carpet really needs to be replaced, but in experience, NO carpet cleaning I've ever tried, done myself, hired carpet cleaner companies to do, or that I've tested and measured by collecting tape, vacuum or other samples to later process in our forensic lab - NONE of these ever was able to remove all of the mold contamination from a carpet IF

1. the carpet was wet (not your case)

2. the carpet had mold actually growing on the carpet

Where cleaning has been successful by simple surface HEPA vacuuming was when the carpet surface had been dusted with airborne mold and moldy dust from another mold problem (or perhaps poorly-contained mold remediation) in the building. Only if the mold was superficial rather than imbedded into or growing in the carpet has such cleaning been successful.

You say "a lot of cleaning has been done" ...

If by that you mean that you've had your carpet professionally cleaned and it's still moldy by odor or appearance or test result, then that seems to answer the question. It's time to remove the carpet and carpet padding, clean the exposed surfaces, and proceed from there.

Culture mold test of my oriental rug means what?

What about an oriental area rug that has been in a house with a somewhat high mold concentration in the air (4-8 colonies after 1 hour exposure of petri dish) but has not gotten wet and does not have any visible mold? Can we move this rug into our new (mold-free, we hope) home after a HEPA vacuuming? - On 2019-10-31 by Jeff -

Reply by (mod) - Nothing

Jeff

Culture tests are not a reliable test for indoor mold because many , in fact most mold genera/species won't grow in any culture and also because what falls on the culture does grows on it may not represent what's in the building.

But if you suspect an area rug has been in a moldy environment, have it professionally cleaned before bringing it into your new location.

Concerned about significant symptoms of mold allergy in carpeted rooms of our school

I'm concerned about significant symptoms of mold allergy in carpeted rooms of our school. The district did air sampling and said the spores outside were higher, so no mold.

They also said they looked for heat signatures, or something like that, so again said no mold (this is CA, they did the testing end of July when it hadn't rained in five months). Some parents have complained of mold smells and several have complained of symptoms.

I strongly suspect the often-shampooed carpeting on poorly insulated slab foundation is growing mold because of condensation and collecting indoor air pollutants because of it, but the district believes it's consultant and refused to go by the CDPH release that these air tests are useless.

If I'm concerned about mold from condensation on the carpet on poorly insulated slab, what's the best way to diagnose that? - On 2012-09-07 by Mom -

Reply by (mod) - symptoms of mold allergy in carpeted rooms of our school.

Comparing outdoor air to indoor air is often comparing apples to oranges.

Also looking for heat signatures alone as a "mold test" is more junk science.

After all, heat signatures mean areas of heat loss, not areas of mold. Indeed there MIGHT be condensation in such cool areas, but consider a different example: a building could have had major leaks into a ceiling or wall cavity that are now dry - as the leak occurred a long time ago.

No heat signature will detect that condition, but the leak could have inaugurated a large mold contamination problem hidden therein.

A competent and reliable examination of a building for evidence of mold contamination won't rely on an air test and a thermal scan alone.

On 2011-08-09 by Jill - flooded apartment, wet wall to wall carpeting

About three weeks ago the entry portion of my apartment flooded, and it soaked some of the wall-to-wall carpet to the point where I had to use numerous towels just to sop up the water.

I suggested to my landlords that the carpet should be professionally cleaned and dried, but instead they opted to use fans to draw moisture out the apartment.

The carpet dried to the touch in 2 days or so after this.

I don't really think I smell a musty odor however I am concerned that the carpet padding didn't dry out as fast as the actual carpet. I don't see any visible signs of mold around the baseboards or on the carpet, but from what I have read here it seems probable that mold could be growing underneath. Would you agree?

Would the next step be to pull up a corner of the carpet and inspect? Or should I already be seeing signs of mold growth on the baseboards and along the carpet edge?

I am running a dehumidifier at night, and for the first two weeks after the flooding incident the dehumidifier was running all day and night.

On 2011-08-09 - by (mod) - Carpet that has been wet by flooding and just let air dry is likely to develop a mold problem

Carpet that has been wet by flooding and just let air dry is likely to develop a mold problem; furthermore, those wet floor conditions mean it's likely that water entered the bottom of wall cavities. Leaving all of those materials in place is inviting trouble.

At a minimum I'd do some more thorough inspecting to define exactly where water went in the building and if wall cavities were wet, I'd make at least one test opening, perhaps behind baseboard trim, in the area of most-suspect water entry - look for mold not just in carpet but carpet padding, floors below that area, and on the wall cavity side of drywall at the test cut.

What is the most identifiable way to describe the SMELL of moldy carpet + padding?

What is the most identifiable way to describe the SMELL of moldy carpet + padding?

I need to convince my boss that the carpet in my department smells of mold.

He denies ever having any flooding or anything similar in the department in the past. I think the smell I sense every day is indeed mold but I'm no expert! Please help! On 2011-08-03 by Mario -

Reply by (mod) - the smell of mold is distinctive enough that most people can recognize it

Mario for most people and cases the smell of mold is distinctive enough that most people can recognize it correctly - a wide range of mold genera and species make a moldy or musty smell (under some conditions, not always) that most people recognize. It smells ... "moldy".

But to pinpoint a source of a moldy smell, especially in carpet or carpet padding, other than lying on the floor and sniffing up-close, here's what you can do:

at page left click on the article link titled

ODORS & SMELLS DIAGNOSIS & CURE

and among that topic's sub articles, when you see that page, click on

SMELL PATCH TEST to Track Down Odors

use the smell patch test to collect and demonstrate odors from a specific surface - it works well and is not expensive.

Or just search our website for SMELL PATCH TEST and you'll find the "how to" article.

If this were a legal matter there are other more durable methods - vacuum canisters that can be used to collect gases for laboratory testing - doesn't sound like you need that procedure.

 

Thank you to our readers for their generous comments

Thank you. Wonderful website - On 2019-11-12 by Judy -

...

Continue reading at CARPET FUNGICIDAL SPRAY or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see CARPET MOLD / ODOR TESTS FAQs - questions & answers posted originally at this page

Or see these

Recommended Articles

• CAR SMELL - MOLD DEODORIZING
• CARPET STAIN DIAGNOSIS - home
• CARPET AIR LEAK STAINS at WALLS
• CARPET CONTAMINATION TEST PROCEDURE
• CARPET DUST IDENTIFICATION
• CARPET FUNGICIDAL SPRAY
• CARPET MOLD / ODOR TESTS
• CARPET OZONE MOLD / ODOR TREATMENT WARNINGS
• CARPET PADDING ASBESTOS, MOLD, ODORS
• CARPET STAIN ID TESTS
• CARPET STAINS by AIR LEAKS
• CARPET TACK STRIPS & FLOODS
• CARPETING & INDOOR AIR QUALITY - home
• CARPETING, SELECTION & INSTALLATION
• DUST SAMPLING PROCEDURE
• SEWAGE CLEANUP PROCEDURES & STANDARDS
• SMELL PATCH TEST to FIND ODOR SOURCE
• STAINS on INDOOR SURFACES, PHOTO GUIDE
• VOCs VOLATILE ORGANIC COMPOUNDS

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CARPET MOLD / ODOR TESTS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to MOLD CONTAMINATION & REMEDIATION

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