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Photograph: Mold under carpeting on tack strips indicate history of water entry, suspect moldy carpet - Daniel Friedman Wet Moldy Carpet Contamination Response
Find, identify, test, remove or salvage rugs vs carpets

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.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

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

Photograph: Moldy carpeting - Daniel FriedmanWhile 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:

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.

Photograph: Moldy carpeting - Daniel Friedman

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.

Smelly carpet mildew (C) Daniel Friedman

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

 

Moldy carpet stains © Daniel Friedman

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

Moldy carpet stains (C) Daniel Friedman


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?

Question: 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.

Reply: 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:

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

 




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2019-11-12 - by (mod) -

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.

On 2019-11-12 by Judy

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 2019-10-31 - by (mod) -

Jeff

Culture tests are not a reliable test for indoor mold because many genera/species won't grow in any culture and also because what falls on the culture and 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.

On 2019-10-31 by Jeff

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 2019-05-04 - by (mod) -

Beka

The photos of big blurry I can't quite tell what we're seeing, but in any event if sewage or waste water overflowed onto a carpet there is a bacterial Hazard as well as a mold Hazard. The carpet needs to be removed and disposed of and the exposed floor surfaces cleaned and sanitized.

If water also flowed into the bottom of the wall cavities those need to be opened and inspected and if necessary cleaned and sanitize

On 2018-06-17 by Beka

Under the wet carpet and pads I found this located from a bad drainage and waste water over flow. Is it mold or toxic waste?
IMAGE LOST

On 2012-10-07 1 - 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 2012-09-07 by Mom

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 2012-03-18 by Lou Smith

Hi - We just had the carpet in our synagogue dining hall steam cleaned (and sanitized). After a few days there is smell best described as like a wet dog. Any suggestions? Thanks

On 2011-09-16 by Gaetahaus

We had a recent mild flooding in our guest room in the basement. We immediately pulled up the carpet, threw out the padding and put fans to dry out the area, as well as a 2' x 3' area in the adjoining room.

However 2 days later we realized behind the wall separating the two rooms there is a 6" strip of carpet that is behind the wall that we can not pull out---the wall was constructed on the carpet!

We pulled off the base board and cut a few holes in the dry wall to dry out the area. Do you think we need to take down the wall, and remove that strip of carpet to prevent mold? The area seems dry now and we do not see any mold at the moment behind the dry wall.

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.

On 2011-08-09 by Jill

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 2011-08-03 - 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.

On 2011-08-03 by Mario

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!


...

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