Q&A on our photo guide that help diagnose types & causes of stains on indoor surfaces & materials:

This article series 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.

FAQs on the Causes of Indoor Stains on Carpet, Cabinet Doors, HVAC Registers, Ceilings, Walls

These questions and answers about diagnosing stains on indoor surfaces or materials were posted originally

at STAINS on INDOOR SURFACES, PHOTO GUIDE - you definitely want to check out that photo guide.

 

Diagnose these discolored spots on the wall

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? 2021-11-09 by Mary

Reply: are we seeing stains or shadows?

@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?

These brownish spots keep appearing on closet walls - are they mold?

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! 021-07-03 by Anne

Reply: yes, that's mold

@Anne,

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

See

MOLD CLEANUP, DO IT YOURSELF for what to do.

 

Stains from ice dams, leaks, no or wet insulation

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. 2021-03-26 by Jennifer Young

Reply:

@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 ceiling joistb ays.

If your photo is of a ceiling, then I would explore the space above from the inside in one of those wet-looking bays to check for wet insulation, water stains, mold.

Then read

ICE DAM LEAKS - home

Let me know what you find.

Why are these yellow stains appearing on our bedroom wall?

Yellow stains keeps reappearing after wiping on the wall just above the bed. - On 2021-01-27 by R Dattani

Reply:

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.

See more help at STAIN DIAGNOSIS on BUILDING INTERIORS 

What kind of sealant paint works as a primer to cover stains?

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 2021-01-20 by Toby Witte

Reply:

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

We discuss using those paints

at THERMAL TRACKING REMEDIES 

How to clean off yellow-orange stains in a veterinary clinic

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 airborne .

Please help. 2020-01-01 by Mike

Reply:

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
  

I need help diagnosing reddish brown stains on the bathroom walls and basin

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. 2018-04-26 by Hari Kesava

Reply: 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

Just cleaning alone won't stop thermal tracking stains

I have pretty severe indoor tracking on a third floor bedroom with vaulted ceilings.

if i repaint using the stain resistant paint will that prevent
me from seeing the stains which i assume will return in a matter of months. 2018-03-20 by jill

Reply:

just cleaning and painting will not prevent the occurrence of thermal tracking stains. You would want to look for underlying causes such as a source of high levels of indoor dust or soot in the indoor air or incomplete insulation or abnormal moisture conditions indoors.

See details about the cause and cure of the stains you might be describing

at THERMAL TRACKING BRIDGING GHOSTING

After looking into the stain causes or sources, and then after cleaning, use a lacquer-primer sealant over the stained areas before re-painting. I find that some of the other (non-lacquer based) "stain killer" paints will still bleed through some stain substances.

Cleaning alone won't cure a mold problem

Hi. Yesterday I noticed a stinky smell in our living room. Come to find out thier are black small circular spots on the brick wall behind my wood burner.

I believe it's mold. I went to Lowe's and brought a spray for surfaces that contain mold. It has seem to stopped the smell but the spots are still their. Any suggestions on what this could be?

The wood burner haven't been used for many years 5+.... I was told by a friend I should paint over the brick with special paint.. will that solve the problem or make it worse?

Also the black spots are on different parts of the brick. Left side, right side, even on the floor of the brick. 2017-08-26 by Anonymous

Reply:

Anon

Mold "sprays" might help clean up mold but are not a proper remedy. The remedy is to

1. clean or remove the mold

2. find and fix the leak that caused the mold to grow.

It would be unusual but not impossible for mold to grow on brick. Molds generally want to grow on an organic material where there is mold-food. On brick behind a wood burner, where surfaces are normally heated and dry, mold would be unusual.

Greasy oily circular spots

Greasy oily circular spots on bedroom wall. Growing in number. 2016-10-20 by Anonymous

Reply:

Greasy oily spots on a bedroom wall growing in number are worth investigating, including a look into the wall cavity for leaks. I can't guess in more detail as I can't see what's going on at your home by etext

Problem with ghosting on our 70 year old church walls

The church I attend is 70 years old. Over the last 20 years or so a problem with the walls and ceilings discoloring or ghosting has developed.

These don't look like stains with defined edges such as those that may be following a beam or joint. They appear more cloud like with irregular softer borders. Do you have any idea what would cause this problem when it hadn't existed for the first 50 years? 2016-01-24 by Dale Laravee

Reply:

Dale I can't diagnose the stains from just your e-text. I'd be looking for a leak or an interior soot or debris source; You can send photos if you like, using our page bottom CONTACT link.

 

How can I remove rust?

How do you get the rust off of a hot water register in a bathroom caused by urine? 2015-12-15 by Alison

Reply:

Sorry I don't know what a hot water register is.

If you are referring to a hot water heating baseboard cover, I recommend replacing the cover as the most quick and economical approach.

If you can't do that, you're going to need to use normal metal surface cleaning and repainting methods: wire brush, sand, clean thoroughly, prime, paint.

 

Question: diagnose oval marks the size of a man's thumb on ceilings

I have two outside walls in my living room, with vaulted ceiling, that started to get oval-shaped marks about the size of a man's thumb in the same places for the last six or seven years.

They appear to be oily but are not to the touch. They are worse in the summer and sometimes they actually weep and run.

This room only has one coat of paint plus the contractors coat. I tried washing them off but although they lessen, they don't ever go away.I asked a professional painter for his opinion and he had no idea what could cause this.

He checked my walk-in crawlspace and it is completely dry.

This summer I have probably twenty to twenty-five on each wall. They are smaller this year but each has a center that looks wet.

Some are running. I listened for bees...no sound and there's hardly any bees left anymore anyway. Any idea what is causing this? I'd really like to repaint but not if it's just going to happen again. Thank you. (July 21, 2014) Donna Shaw

Reply:

Donna,

take a look at the article titled THERMAL TRACKING BRIDGING GHOSTING

you may be seeing ghosting at drywall nails and condensation on those points, particularly if the spots are at regular intervals and map the location of wall studs or other building framing members.

Try painting the stains with a lacquer primer sealer before re-painting the surface.

 

Question: black stains on wood floor

I got a wooden floor and it gone black I think my cat wee there how do I know if it wee or damp help me please. (Aug 1, 2014) Ann

Reply:

Ann, this article will help you recognize the stain type on your floors: STAINS PETS, FLOORS

 

Question: dark spots on carpeting

My hall and landing carpet get dark spots on it which have no odour and feel greasy to touch. When I pull the carpet up the boards and underlay aren't wet. The stains seem to spread more during the winter (could it be to do with rainwater?).

I'm at a bit of a loss. Thinking of pulling the hall carpet up and seeing what happens on the floorboards for a bit.

Don't know hat kind of 'expert' to call out. Builder? Drains? Flooring? We've lived here a year and the previous occupants did have 2 small dogs but as I say the marks don't smell and they do fade and then reappear intermittently. Thanks. (Aug 31, 2014) Helen Booth

Reply:

Helen

Do you think the stains could be due to air movement and leaks? - see the notes in the article above about thermal tracking.

Stuart Weston said [OPINION]

Some carpet cleaners can damage our carpets . Chemicals can damage the carpets . You can use some household tricks such as using a solution of vinegar and baking powder.

 

Question: how to remove severe ghosting stains on walls

I have severe ghosting stains on all of my walls. getting insulation looked at but what do i clean it with. it is severe! (Jan 9, 2015) pam gallagher

Reply:

Pam

Any household cleaner, such as a TSP substitute or non-sudsing detergent works well; you'll probably have to re-paint.

But if you don't address the cause of these stains they will reappear anew.

See THERMAL TRACKING BRIDGING GHOSTING

...

Continue reading at STAINS on INDOOR SURFACES, PHOTO GUIDE - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• STAIN DIAGNOSIS on BUILDING INTERIORS - home
• THERMAL TRACKING BRIDGING GHOSTING

Suggested citation for this web page

STAINS on INDOOR SURFACES, PHOTO GUIDE FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING STAINS

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Questions & answers or comments about identifying the cause and finding the cure for indoor stains on ceilings, walls, floors, carpeting, furniture, and other indoor surfaces and materials

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.

---

IF above you see "Comment Form is loading comments..." then COMMENT BOX - countable.ca / bawkbox.com IS NOT WORKING.

In any case you are welcome to send an email directly to us at InspectApedia.com at editor@inspectApedia.com

We'll reply to you directly. Please help us help you by noting, in your email, the URL of the InspectApedia page where you wanted to comment.

Citations & References

In addition to any citations in the article above, a full list is available on request.

---

ADVERTISEMENT

---