Pictures help diagnose types & causes of stains on indoor surfaces & materials:

This article describes, provides photographs, & diagnoses the causes of interior wall, ceiling, flooring or carpeting stains and explains how to recognize their probable cause and source, including soot stains, house dust stains, pet or animal stains, and thermal tracking or thermal bridging stains associated with building air leaks, and building insulation defects.

A Photographic Guide to Help Diagnose the Causes of Indoor Stains on Carpet, Cabinet Doors, HVAC Registers

Often dark indoor ceiling, wall, carpet or floor stains are mistaken for toxic indoor mold when they come from other causes instead.

When investigating a building for a mold problem, you can save mold test costs by learning how to recognize

MOLD APPEARANCE - STUFF THAT IS NOT MOLD or is only Harmless Mold but may be mistaken for more serious contamination - save your money.

Because some clients have on occasion sent samples to our mold test lab that really should not have been collected, much less looked-at, we provide this library of photographs of things that are "not mold" and don't need to be tested.

"Black mold" often mistaken for "toxic fungal growth." Photos of HVAC and carpet stains (excluding the moldy carpet photos) were provided courtesy of Pat Belkin, Charlotte, NC.

Here are some examples of troubling indoor surface stains with some preliminary opinions about what these stains may be about. We emphasize preliminary opinion because here we comment on these photos before an expert diagnostic building inspection has been performed and before any lab samples have been collected and analyzed from these surfaces.

Whether or not such sampling and analysis are justified depends on the experience of the building occupants (health complaints or health vulnerability), the history of the building (exposure to leaks, damage, pets, contaminants), and other site investigative results.

See MOLD / ENVIRONMENTAL EXPERT, HIRE ? for help in deciding when to go further.

How to Recognize & Diagnose Phantom Stains on Indoor Surfaces

Often when people become concerned about indoor air quality, mold, or stains, they begin to study their building surfaces more carefully than ever before.

When this happens we sometimes find people reporting as "new" stains that were there from original construction, but where simply not noticed, or were not so particularly noticed before other concerns increased their level of attention.

This interesting photograph of a large yellowish stain on the surface of what appears to be a birch kitchen cabinet door surface (probably the door's interior surface) could be an example of this phenomenon.

What would support the "phantom stain" hypothesis for an item such as this cabinet door?

Stain pattern: If the stain appears in a regular pattern on companion surfaces such as other cabinet doors it may be an artifact of the door's manufacture

Stain location: If examination of other cabinet surfaces shows similar stains in varying locations

Manufacturing artifacts: If examination of sample cabinets from the same supplier or manufacturer, new, say in a showroom, show similar markings

Ability to remove surface staining material: If a tape sample cannot remove any debris from this are of darkened color

Stain particulate or chemical components: If a tape sample of surface debris removed particles which are determined to be finish coatings or wood fibers without fungal or chemical modification,

Presence of common causes of stains: If there are no moisture, food, air movement, or other suspect sources that have affected some of these cabinets but not others

Time of occurrence of stain: If the stain is under the finish-coating of the wood cabinet surface rather than something which was deposited on top of the coating (though indeed moisture can in some circumstances affect surfaces below their coating)

then this may be the case with this example photo of a yellowish stain on a birch ply cabinet door interior

How to Diagnose Stains & Discoloration on Heating or Cooling Supply or Return Registers or Plenums

Supply Register debris: The left photo above shows typical house dust deposition on a heating or cooling ceiling air supply register, where you can see brown debris adhered to the metal register surface. A second example is in our photo below.

These particles adhere to the register surface due to either moisture from condensation or in this location, more likely due to static electricity as particles are moving across a normally dry surface.

See STAINS at HVAC Supply Registers for more examples.

What to do about supply register debris: House dust, normally composed primarily of human skin cells and fabric fibers, is not usually an environmental or air quality issue, though at high levels on surfaces it can be diagnostic of building conditions such as high moisture or poor HVAC system maintenance.

We can reduce this debris deposition by duct and air handler cleaning and by better and constant maintenance of filters at the return air registers. If other information disclosed by the building investigation warrants, one have this debris screened for mold, allergens or other problematic particles by using a forensic laboratory whose technicians are expert in house dust analysis.

Return register & return air plenum debris: The right hand photo shows a combination of paint overspray (white particles on the black return plenum insulation liner), and house dust (brown debris on the metal frame intended to hold a return air filter).

What to do about return plenum debris: The brown dust and debris indicates that the air filter used at this location has been leaky.

See AN ANALYSIS OF THE EFFECTIVENESS OF AIR FILTERS ON HVAC SYSTEMS for further advice on air filters that do not leak in this location.

How to Diagnose Stains & Discoloration on Heating or Air Conditioning Filters

Air filter debris: This home air filter was taken from the central return air plenum and register cover shown in the photograph just above.

The brownish stains on the filter are a typical color (brown to gray) of debris found on any indoor air filter. Such "stains' indicate that the filter is doing its job of reducing the level of airborne debris in the building.

What to do about air filter debris heating and air conditioning filters should be changed at least monthly whenever this equipment is in operation. In a dusty environment more frequent changes may be needed.

Also see An Analysis of the EFFECTIVENESS of AIR FILTERS on HVAC Systems for further advice on air filters that do not leak in this location and

also see WHEN TO HIRE a PROFESSIONAL to investigate a building for help in deciding when to go further in inspecting, diagnosing, and testing particles and debris on a building air filter. In many circumstances further testing would not be justified.

How to Diagnose Mold Stains & Mold Growth on Floor Carpeting

These photographs show two common patterns of mold growth on the upper surface of a carpet that was left wet in a building. In the left photograph a brown mold is growing in a rather uniform pattern without definite edges on carpet in a closet.

The black mold visible in the upper left and right portions of the photograph will probably be a different mold genera and species - this is an example of the dangers of careless sampling of mold in buildings since a lot of what people think is present in a building depends on exactly how mold samples are collected.

The right hand photo above shows two rather round black patterns of mold growth on floor carpeting in the same building.

Even if no mold was visibleOn other carpet surfaces in this building it is likely that the carpeting, if it was wet, has become mold contaminated - a condition that might be confirmed by inspection of the carpet backing, padding, or other building surfaces.

Carpets or furniture that have been wet or had mold growth: Wall-to-wall carpets and upholstered furniture that have been soaked and/or have had mold growth on their surfaces, most likely cannot be adequately cleaned and should be replaced.

See CARPET MOLD / ODOR TESTS.

Also see CARPET STAIN ID TESTS

and CARPET CONTAMINATION TEST PROCEDURE.

Carpet padding and subfloor: And where carpeting has been wet, don't forget that the padding below the carpeting and even the floor and subfloor below may be damaged or moldy.

See CARPET PADDING ASBESTOS, MOLD, ODORS.

Even carpeting which has not been wet may be a significant problem mold reservoir in a building if the carpeting has been exposed to a high level of airborne mold or other allergens. This condition occurs, for example, when a water-damaged moldy building has been remediated without proper dust and debris control.

The difference is that carpeting or upholstered furniture that has never been wet and that has not had mold growth on its surface, that is, it has been subjected to settled dust only, may often be adequately cleaned using HEPA vacuuming methods.

See CARPET DUST IDENTIFICATION

Screening samples of carpeting and other building surfaces taken outside of the remediation work area both before and after a mold remediation project can protect both the remediation company and the building owner from unanticipated additional mold cleanup work after the initial mold remediation project has been completed.

Another case of severe carpet staining [photo] due to furniture left on wet carpeting, accompanied by mold growth, is shown in this photograph.

How to Diagnose Stains & Discoloration on Rugs or Wall to Wall Carpeting

Possible thermal tracking stains are shown by the darkened debris on the floor carpet in the left photo above, where a grayish line appears to follow the point where the wall to wall carpeting abuts the building wall or wall baseboard trim.

See THERMAL TRACKING STAINS for detailed discussion of this phenomenon and how to diagnose it.

Possible furniture footprint stains on carpeting are suggested by the right hand photo above. Sometimes a stain like this, particularly where it follows the same shape as an object which has been placed on the carpet, suggests that the stain was deposited from the object itself, or dirt on its surface, or bleed-out if the object was placed on a carpet left damp after carpet shampooing.

A Severe carpet staining [image] due to furniture left on wet carpeting, accompanied by mold growth, is shown in this photograph.

How to Diagnose "Clean" Areas of Carpet Surrounded by Stains or Discoloration

"Clean" areas of carpet under furniture can also tell us what's been going on in a building. In the right hand photo above, the carpet appears darker inside the stain perimeter which suggests that the mark we see is either from a spill on the carpet or from the footprint of an object which was placed on the carpeting.

But if a mark on carpeting outlines an area of carpet which is lighter or cleaner than the surrounding carpeting, we usually find that an object which had been placed on the carpet was actually protecting that surface from settling dust, soot, or other debris in the building.

In this case we'd look further for an indoor source of high levels of airborne soot or other debris, such as a malfunctioning gas or oil fired heating system.

Because such heating systems could be unsafe (for example, risk of fatal carbon monoxide poisoning), the inspector should be one who is quite familiar with inspection methods and indicators of an unsafe or improperly-functioning heating or cooling system.

Usually soot marks, thermal bridging, or thermal tracking stains appear, if at all, in the building interior locations listed just below discussed in the remaining sections of this article.

Photos & Diagnosing Stains on Building Walls and Ceilings

Common stains on painted inteior walls and ceilings include

• Black smudges and streaks on walls and ceilings -
  
  see THERMAL TRACKING & THERMAL BRIDGING where we describe indoor dust deposition patterns, soot stains, and other dark indoor stains often mistaken for mold (photo at left). In our thermal tracking stain article series we also distinguish candle and fireplace soot staining
  
  Stains from Candles, Woodstoves, Fireplaces from other indoor stain sources.
• Dirt and soiling including from pets or other animals -
  
  See PET STAINS & MARKS in BUILDINGS
  
  and  PET STAINS on WALLS 
• HUMAN OCCUPANT STAINS ON WALLS
  
  Human occupant stains may also be from smoking. In rooms occupied by heavy smokers we have found brown stains on walls and ceilings. If there are occasions of high indoor moisture and condensation on walls you may see concentrations of brown stains running down walls in a water pattern or droplets or small brown spots where moisture accumulated on ceilings.
• Mold growth on building interior walls occurs on visible surfaces in buildings that have been wet or subject to high humidity, particularly on mold-friendly materials such as drywall and wood paneling. Watch out for hidden mold reservoirs in wallor ceiling cavities that have been wet - investigation may be justified.
  
  See MOLD APPEARANCE - WHAT MOLD LOOKS LIKE for photos of mold growing on indoor building surfaces of various materials.
• Also see Other Stains on Indoor Walls & Ceilings
• Red Stains on Walls or ceilings may be due to mineral salts and efflorescence if the wall is masonry, particularly brick masonry, or the red stains may be a species of mold or even a red yeast such as Rhodotorula often found indoors in wet moldy conditions. Photo below: red stains on an interior wall, possibly wallpaper, that may be a red mold or yeast.
  
  See RED MOLD PHOTOS
  
  and compare those images with
  
  EFFLORESCENCE & BROWN DEPOSITS

The contributor of this photo, C.R. (1/27/2016) commented:

... [I have ] often seen mold *behind” objects close to cold walls (due to the decreased airflow stopping condensate from evaporating, I assume) but it just seems weird to get it on a surface that should actually be *drier* than behind the pictures. Just goes to show all these different molds have their own specific preferred conditions, eh?

Photos & Diagnosing Stains on Building Floors other than Carpets

Common sources of stains on building floors include:

• Rust marks left on vinyl tile or sheet vinyl where floors were wet below metal objects
• Pet urine stains on wood flooring (photo at left).
• We discussed and illustrated carpet stains above.
• See PET STAINS & MARKS in BUILDINGS
  
  and  PET STAINS on WALLS for details.

Stains on Plumbing Fixtures, Sinks, Showers, Toilets

Stains on plumbing fixtures may be due to simply poor housekeeping or to contaminants in the water supply, or as shown on the porcelain-coated cast iron sink above, a combination of the two.

See WATER SOFTENER OUTPUT COLORS DEBRIS STAINS ODORS

and
See WATER STAINING CONTAMINANTS

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2021-12-10 by Inspectapedia Com Moderator

@Mw,

Encouraging news.

On 2021-12-10 by Mw

@Inspectapedia Com Moderator,

ok, environmental specialist out today thinks that since i have the windows open often & lots of mulch around the house that some spores have settled on the walls.

He thought because the paint is flat throughout the house that they have stuck to walls more readily. There are no signs of mold growth behind trim, in carpet padding, etc.

On 2021-12-07 by Inspectapedia Com Moderator

@Mw,

Mold doesn't usually grow uniformly throughout a building except in extreme conditions.

Diagnostic would be to review the history of building leaks and renovations.

Rather than cutting willy-nilly, I would go to the most-suspect or worst-looking areas and make a few strategic 2x4" test cuts to look into the wall or ceiling.

I describe test cuts and what to look for in the article link I gave at my earlier comment.

Do keep us posted.

On 2021-12-07 by Mw

@Inspectapedia Com Moderator, oh I definitely think there is. I am trying to confirm it. I was shocked when the tests came back negative.

I’ve pulled back trim & ifted up carpet. Other than a few obvious areas in the bathroom, so far nothing except these spots. Which are again in just about every room so far & at random heights along the wall.

They are definitely multiplying. The worst area is that cluster which is in the kitchen above a south facing window.

I am not afraid to go cutting in the walls to get to the bottom of it. We have 2 little kids.

I guess my question would be if it is in fact mold, were there spores that landed throughout the house from hopefully one contaminated area? I understand you can’t say one way or the other, just thinking here.

I also can’t help but think its related to the fishy trim paint... thank you for your time

On 2021-12-07 by Inspectapedia Com Moderator

@Mw

About your reply:

Mold tests alone as a building screen for mold contamination are simply not reliable.

Details are at MOLD TESTING METHOD VALIDITY

I am certainly not asserting that there is for sure a mold problem, I'm alerting you to that possibility. Don't go chopping out walls.

On 2021-12-07 21:15:55.795480 by Mw

@Inspectapedia Com Moderator,

Thank you for your response. We own. House was empty for 3 months before be purchased. We had a mold test in 3 rooms & all came back negative but now these are popping up & not in areas where anything could have been splattered previously.

On 2021-12-07 by Inspectapedia Com Moderator

@Mw,

You're not going like part 2 but here goes:

Part 1: Spots on a wall: cosmetic issues alone:

If you're pretty confident that nothing has splashed onto those walls, I suspect you're seeing little spots of bleed-through of something that was on the wall before it was painted.

That can happen particularly if a property is being re-sold by a real-estate flipper who focuses on cosmetics

If that's nothing serious you can dab on a bit of lacquer primer sealer on those spots to stop bleed-through when re-painting feels (to you) justified .

If that's all we've got, then this is only a cosmetic issue.

Part 2: Spots on a Wall Hiding Bigger Trouble:

I've been (OPINION) nauseated by coming across cases of painting-over extensive and harmful indoor mold contaminated drywall on walls and ceillings. The result looks great - for a while. But "killing" mold by spraying it and / or painting over it on drywall is a serious error that leaves hidden, mold-contaminated materials in place where sooner or later you're going to be saying .... it's BACK!

The proper repair for moldy drywall is to remove all of the moldy material, remove any wet or moldy insulation behind the drywall, then find and fix the leaks, and dry out the building before completing its restoration.

IF a building was in that condition and simply painted it's likely that there are mold reservoirs not only on the painted-over drywall surfaces but on the wall cavity-side of the drywall. IF extensive in size (more than 30 sqft) then that becomes a health hazard for building occupants, more-so if occupants include people at extra risk: elderly, infant, immune impaired, allergic, asthmatic.

So what now:

• Are you an owner or renter?
• What was the building's history of leaks or water entry?
• What are the building's construction and materials? Frame and drywall?
  

At the very least you'll be alert for

• mold odors
• allergic reactions indoors
• signs that more and more "spots" are bleeding through the wall

and

if the level of indicators and worry justify it, then it would be appropriate to do some destructive / invasive inspecting of the most-suspect wall or ceiling cavities.

Details are at

HIDDEN MOLD in CEILING / WALL CAVITY

On 2021-12-07 by Mw

Multiple in one area

On 2021-12-07 by Mw

Additional picture of a streak

On 2021-12-07 by Mw

Moved into a home that was freshly painted all white. After a month starting to notice small, 3 to 5 mm, brown spots surfacing up from under the paint. Various places throughout the house

On 2021-12-06 by Danjoefriedman (mod)

@Greeneyes43040,

Those look like splash-spots - something splashed on the cabinet door and was liquid enough that there was some further droplet movement, as indictated by the yellow arrows I've annotated.

On 2021-12-06 by Greeneyes43040

@Danjoefriedman, I thought so too but it’s random… the furniture is the opposite side of my closet doors… the stairwell is downstairs.

I think I’ll scrub all that I see and if they reappear. If they do, I’ll call someone.

On 2021-12-05 by Danjoefriedman (mod)

@Greeneyes43040,

Those little spots could be mold - you'd need a much closer look, or try sending a tape sample to a lab for testing, especially if they increase in size or number.

On 2021-12-05 by Danjoefriedman (mod)

@Greeneyes43040,

Those spots look as if something splashed on the surface.

On 2021-12-05 by Greeneyes43040

This is my entertainment center

On 2021-12-05 by Greeneyes43040

This is my closet doors

On 2021-12-05 by Greeneyes43040

I moved into my condo first of September (still warm outside). I had the carpet and condo professionally cleaned prior to moving in.

At the end of the month, I started noticing faint, tan-like spots on both my stairwells. Now I'm starting to notice them on my furniture.

I am now starting to freak out. Can anyone help? Picture below is stairwell closest to main floor.

On 2021-11-22 by Michelle

@Inspectapedia Com Moderator,

I looked behind the frame but there’s no corresponding stain. It’s so weird. Bug juice - like something was smashed and the insides leaked out. I’ll take your advice though ‘cause I can’t think of anything else. Appreciate the help!

On 2021-11-22 by (mod)

@Michelle,

It does look as if something leaked out of the back of the frame or painting or whatever it is that's hung on the wall. It's worth a closer look.

If a stain material leaked into the surface of the drywall it's not going to scrape off. You may need to paint the stain with a lacquer primer sealer before repainting that part of the room.

On 2021-11-22 by Michelle

@Inspectapedia Com Moderator, wow! That was fast! I didn’t expect a reply until tomorrow. Here is a better photo. You can see it has a slightly glossy appearance. But, I’ve scrubbed and can’t get it off. It’s about a foot long. Thank you!

On 2021-11-21 by (mod)

@Michelle:

Often a termite mud tube looks like what we see in your photo, but that would be soft and easily broken, not something that needs to be sanded.

I'd remove the picture and pinpont the exact location of the start of that run-down or rivulet type stain on your wall.

Then look at the corresponding location on the back of the framed picture to see if there is any clue such as a moisture-induced drip that dissolved something in the frame or its materials.

On 2021-11-21 by Michelle

I am about to take a sander to the wall here. I have tried every cleaning product i can buy to get this off.

I think it might be bug-related, but I’ve only seen this one other time in my grandma’s house - also starting behind a picture.

It seems fused to the paint. Behind the picture, it just starts, then a few inches behind the dresser it just stops. Nothing on the back of the picture.

Thankfully, it’s in the spare bedroom, but I have to get it off before anyone can stay. It looks gross. Please help if you can. Thank you.

On 2021-11-09 by (mod)

@Mary,

are those dark "marks" only on one side of the corner?

are they visible in all lighting conditions?

are we sure they are not shadows?

On 2021-11-09 by Mary

Hello, Just today I noticed these two discolored spots on the corner of my wall. There are no pipes behind it and it has not rained recently at all. Any ideas on why these two spots could be discolored?

On 2021-10-21 by (mod)

@Anonymous, [Ralph]

sorry, as we want to help, but from just your text we're baffled about what's going on.

Under house, over house at a utility pole, leakage of what, where from what source etc.

Perhaps you need an onsite inspector; try the page top EXPERTS directory.

On 2021-10-16 4 by Anonymous

Under house leakage above house-utility pole leakage. Ralph Teasley home. 256-238-8435.

On 2021-09-22 by (mod)

@Loeslr1,

Not without more information. What's in the wall cavity in that location?

On 2021-09-22 by Loeslr1

A softball size round spot on wall above toilet in the bathroom. It lacks the paint sheen and is warmer than the typical wall when I run my hand over the spot. It was repainted but returned. It looks like a round shadow and the paint sheen disappears in that spot Any ideas what could cause this?

On 2021-07-03 by (mod)

@Anne,


That looks like surface mold, perhaps from dampness/condensation;

See

MOLD CLEANUP, DO IT YOURSELF https://inspectapedia.com/mold/DIY_Mold_Cleanup_Guide.php

for what to do

On 2021-07-03 by Anne

I have these brownish spots/areas on the walls of a couple closets. Probably haven't had the best of air movement in them over the years. Are they mold? If so, what's the best way to get rid of them and prevent them returning?

Thanks!

On 2021-03-26 by (mod)

@Jennifer Young, no attic insulation means a LOT of heat loss, possible condensation or even frost in the attic, possibly of that runs down into walls,

OR the wall insulation is wet.

That's only a guess, based on the pattern of dark areas that seems to map stud bays.

I would explore the wall cavity from the inside in one of those wet-looking bays to check for wet insulation, water stains, mold.

Let me know what you find.

On 2021-03-26 by Jennifer Young

Hello, can you please help me understand what’s going on with my house? We had an ice dam/frozen condensation in our attic that caused pretty significant water damage in our home.

Since the incident, I notice our house looks like this on cold nights. Can you help me understand what’s happening here? Is there moisture in our insulation?

I should note we do it have any insulation in our attic at this time. It was wet, removed and yet to be replaced.

On 2021-03-11 by (mod)

@P robinson, I'm not sure, which surface is the ceiling?

On 2021-03-11 by P robinson

Could you advise me what is causing this mark on my ceiling

On 2021-02-20 - by (mod) -

@Mary Schwartz,

I agree that there are numerous small soot stain marks on your ceilings and walls, each where there appears to be a source of thermal or air movement.

I can't say for sure that the soot source is scented candles - the cost of an actual forensic lab analysis of the soot is probably prohibitive and would not be as well-spent as a thorough inspection of your building to address safety concerns first, such as proper operation of a gas or oil fired furnace.

See THERMAL TRACKING STAINS for detailed discussion of this phenomenon and how to diagnose it.

On 2021-02-20 by Mary Schwartz

Light fixture burn marks. Is it LED light bulbs? We have several light fixtures with this issue. Lights are burning out very quickly even when the “wattage rating” is much lower than rating allows.

[Watch out: if a light fixture component or wiring is burned or damaged from overheating - as may be caused by using a bulb at higher wattage than the fixture permits - then the fixture is unsafe and is a fire hazard - Ed. ]

On 2021-02-20 by Mary Schwartz

Scented candle ashing?

On 2021-02-20 by Mary Schwartz

HVAC airflow ghosting?

[Below: house dust or soot stains at an HVAC ceiling air supply register - check the safety of the heating equipment - Ed. ]

On 2021-02-20 by Mary Schwartz

Dear Sir, I will post four images with four different “ghosting issues”. Please assist us if these are more dangerous than: 1. LED bulbs. 2. Dust from HVAC air flow. 3. Scented Candles. Thank you and God bless you.

Below: Smoke detector “ghosting”. Is it airflow issues?

[Below: Dark stains on wall above a smoke detector, probably ghosting due to air currents caused by heat from the smoke detector's own electronics - Ed. -]

On 2021-01-27 - by (mod) -

RD

Check for leaks into the wall cavity; if there are no leaks you can paint the wall with a lacquer primer sealer before painting with a finish coat; in that procedure the stains won't keep bleeding through.

If there have been leaks then it's worth checking the wall cavity for mold after the leak source is found and fixed.

On 2021-01-27 by R Dattani

Yellow stains keeps reappearing after wiping on the wall just above the bed.

On 2021-01-21 - by (mod) -

Have you tried a lacquer primer sealer like Bin or Enamelac?

On 2021-01-20 by Toby Witte

I have a inside wall that has brown coloured running streaks that will not clean off coming from light switch and about 12 inches to the right there is a bubble that has just formed with the same streaks coming from it.

The bubble has not broken but still these streaks. Nothing is removing the runs. I have applied primer to the runs as I am painting this room and the streaks have come right through the 2 coats of primer which now the colour of the streaks have now turned to a pinkish colour. Any help would be great

On 2020-09-10 by Anonymous

Dianne

There has been a leak above the point where those run-down stains appear. The leak could be from plumbing or from a roof leak, either of which entered the building wall above this point, OR there has been a leak nearby that ran across the ceiling to find its way out at the wall-ceiling trim.

On 2020-09-10 by Dianne

This was found on our Grandmother's house which has sat empty for a year. There is a second story above this room..no evidence on walls, floor or ceiling in second story above area. Just in this area...it is wet and more red than brown. No leaks in attic that we have found. Is this mold? Has no smell. Thank you for any help in identifying.
cooke1and2@aol.com

Our Grandmother's house has sat empty for about a year. We found this on the interior wall....just in this area. There is a second floor above this wall and no evidence on floor, ceiling or walls upstairs.

On 2020-07-03 - by (mod) -

It certainly sounds as if your vent system isn't working, and that could certainly be a major contributor to high levels of condensation. Vents can work horizontally or vertically depending on the length of run, the duct diameter, termination and other installation details. Identify your fan brand and model and take a look at the manufacturer's installation specifications.

Sometimes condensate will even leach chemicals or materials out of the drywall or out of under layers of paint. That seems more likely to me than iron in the water but you certainly could, at very low cost, have a water sample tested for iron level.

On 2020-07-03 by LYNND

Correction: The exhaust duct is running horizontal (accidentally said vertical).

Thank you for the reply.

No smokers or wood burning going on yet the spots reappear after they are washed away (they look exactly like the color of earwax!). Now that you point it out, I do see that it looks like it has been deposited by the fact that the condensation has formed drips.

The water is rather hard and while it runs clear at the tap it tasted like iron when we moved in, so we filter our drinking water using an Aquasana under-the-sink unit (not RO type). In talking to the water company, they deny it's anything on their end — but part of the community water is drawn from local wells. Is it possible we're seeing rust stains?

With respect to the ventilation, the Delta exhaust fan/heater unit was installed along with a duct that is running vertical to vent outside a gable. (It was installed this way because the original home build had the bathroom's venting into the attic space. Rather than cut a hole in the roof the contractor ran a duct about 9' to a gable.

Is the fact that it's not venting vertically to the roof responsible for the poor performance of the exhaust fan?

Or does the sheer amount of water collecting on everything and running down the walls after a ~12 minute shower have more to do with the fact that the exhaust fan is poorly designed (if I hold up a tissue there is no suction, not even momentarily, while the exhaust fan is running). I even tried contacting Delta for a replacement exhaust fan but the new fan works the same way — it doesn't seem to evacuate much of the moisture.)

What's the better bet — replace the exhaust fan/heater unit, replace the textured paint that seems to be allowing the water to pool in the crevices or install a whole-house water filter of some kind?

Thank you Dan!

On 2020-07-03 - by (mod) -

Lynn

Thank you for the photo and interesting orange stain question. I can't say for certain but from zooming in on your photo and from experience these may be resulting from condensation on the bath walls and ceiling.

The stain mechanism, if this is the case as I suspect, is the following:

- condensation collects on a wall or ceiling, wetting the area

- as the condensate sits on the area it dissolves deposits on the surface such as house dust, skin cells, fibres, and in a house where there were smokers or a wood or coal stove, smoke particles (often brown or orange)

- The condensate forms drops that concentrate the stain

- The condensate droplets later dry out, leaving the stain as a spot on the surface

If you look very carefully at these stains on a ceiling or wall but especially where they appear on a wall, you might see a rivulet or droplet track where some droplets move or on a wall actually run a fraction of an inch or so down the wall in the collection, concentration, and dryout process.

On 2020-07-03 by LYNND - Delta Breeze ventilator vs orange spots?

The orange stains, pictured, accumulate on my bathroom walls and ceilings. (I have yet to notice them in tiled shower/tub stall but they're continue to reappear on the painted walls in my bathroom.)

I bought a new exhaust fan/heating unit, triple the CFM I should need for a bathroom that is under 70sq ft, and paid a hefty sum to have it installed within a year of moving into my home.

The exhaust fan, unfortunately, is anemic and does not prevent the walls from being coated with steam from use of the shower, nor does it prevent the vanity mirror from being so saturated that water runs down and pools on my vanity after a 12-15 minute use of the shower.

The question is twofold: What are these orange spots?

And was I on the right track to try to improve the exhaust ventilation in my bathroom? (The manufacturer is Delta Breeze.

I bought their largest model two years ago and can't find anything comparable in size to replace the larger hole that was cut in my ceiling to install it.)

These orange spots are difficult to reach as they end up on the entirety of the bathroom walls. Since I only notice them on the painted surfaces, would it help to repaint the bathroom without the texture — or will they reappear anyway?

I guess what I'm trying to figure out is whether I'm better off trying to revisit the ventilation issue or whether a whole house water filter is in order?

The community I live in uses a mix of local well water and State-supplied water. The piping in the house is copper. Any feedback would be much appreciated.

Thank you.

On 2020-01-01 - by (mod) -

Mike: notice that the stain appears to have run down the wall and behind the (now removed) floor-wall trim; perhaps this is dog urine. If this is drywall or wallpapered drywall then I would clean the surface repair any holes in the wall, seal with a lacquer primer/sealer like Bin or Enamelac, and then re-paint;

I note also that the bottom of the electrical receptacle is broken off in both plug-in's;

See also

• ANIMAL STAINS & MARKS in BUILDINGS
• ANIMAL or URINE ODOR SOURCE DETECTION
• ANIMAL or URINE ODOR REMOVAL
  

On 2020-01-01 by Mike

I'm a contractor working at a veterinary clinic. There is a yellow staining happening in the building on floors, walls countertops ect. They cleaned with alcohol but it came back. I cleaned an area with bleach , it seemed to work . here is a photo. It seems to be air bourn .Please help.

On 2018-04-27 - by (mod) - strange reddish brown stains

Hari I'd like to help but with not a shred of information about the building or its mechanical systems nor the stain nor building conditions, age, materials, I can't guess at just what is the cause of a red stain. You could try attaching a photo of the stain and another giving a more-distant view of the wall (use the picture frame icon adjacent to the Comment button.

It seems unlikely that red stains on a basin and red stains on the wall would be from the same cause, unless, for EXAMPLE, iron content in water, or mud in water is both staining the basin and for some reason running down and staining a wall.

See also BROWN or REDDISH BROWN RUST STAINS

On 2018-04-26 by Hari Kesava

Dear Sir,
I am Hari. I am staying in a room. I used to clean total room including bathroom which is attached in bedroom. I have seen some suspicious stains (reddish brown stains) on the walls of the bathroom and also on the basin. It's second time that I have seen that stains.

Can you please tell me what might be the reason behind it.
I am afraid to go bathroom in my room as I have seen that stains.

...

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