This article describes how to use indoor wall or ceiling thermal tracking & other indoor stains to diagnose building air leaks, missing insulation, and indoor air quality problem.

We also discuss other interior wall and ceiling stains, building air leaks, and building insulation defects. Often these stains are mistaken for toxic indoor mold. The black stains in the photo at page top are not mold, they were caused by candle soot from the two candle sconces shown in the image.

How to Use Indoor Stains Like Thermal Tracking to Diagnose Building Air Leaks, Insulation Defects, and Indoor Air Quality Problems

Significance of Other Indoor Stains and Marks for Building Framing Location or Defects in Heating & Cooling System Operation

The short explanation: thermal tracking and soot stains are not mold. But indoor stains may still indicate indoor health or air quality problems.

Many building stains, thermal tracking, thermal bridging, ghosting, stains at heating or air conditioning registers, and even mineral salts left behind by evaporating water at a foundation wall are all very easily recognized as "not mold". Review the stain patterns shown in these articles before ordering a costly building mold test or investigation.

While mold growth in buildings indeed follows the location of leaks or moisture, mold growth does not usually occur on building surfaces in the same regular pattern described by thermal tracking.

When investigating a building for a mold problem, you can save mold test costs by learning how to recognize Stuff that is Not Mold or is only Harmless Mold but may be mistaken for more serious contamination. In addition to a study of the stain patterns of Thermal Tracking (this series of articles) readers should also see both  

WHAT MOLD LOOKS LIKE

and STUFF THAT IS NOT MOLD.

Mold, Safety, & Health Warning:

Your building might have a separate mold problem:

However, because indoor moisture is an important factor in the cause of thermal tracking or soot ghosting, the same building that has lots of thermal tracking stains might also have a serious mold problem due to leaks, water entry, or high indoor moisture.

But where we find this to be the case, the location of the most serious building mold is often not at all the same as the location of the thermal tracking stains.

See MOLD / ENVIRONMENTAL EXPERT, HIRE ? for help in deciding when it is appropriate to hire a mold inspector.

Your building might have unsafe heating equipment:

Watch out: Both oil and gas fired equipment can produce soot when they are not working properly. (In particualr, gas-fired heating equipment produces dangerous CO easily if there are combustion air or venting defects.)

Soot from a gas fired appliance is a very dangerous sign, often indicating that dangerous carbon monoxide (CO) gas is being produced - which can be fatal. Be sure your home has working smoke detectors and CO detectors.

See CARBON MONOXIDE WARNINGS: HOME HEATERS.

This black stuff is not mold. Since thermal tracking, or soot marking, or "thermal bridging" always tell us about missing or openings in building insulation or about air leaks, we can learn other facts about a building such as those listed in this article on thermal tracking, soot stains, and other indoor building stains.

But don't assume that any stain on a building wall is due to poor insulation, moisture, mold, or thermal tracking. In the page top photograph we see candle soot - sometimes a source of indoor air quality complaints or even lead poisoning if a poor quality or perfumed candle is used to excess.

In the photo at left we see thermal tracking soot or house dust or cigarette smoke stains on a ceiling - but high building moisture that was a factor in this staining could also have been a factor in development of a mold problem somewhere in the home.

Indoor stains can also tell us of other conditions that should not be confused with mold or indoor air quality complaints:

How "Read" Indoor Stains to Identify Indoor Air Quality Concerns

A careful examination of the location of indoor stains permits the observer to use thermal tracking or soot marks on building walls or ceilings as an indicator of possible excessive (seasonal) interior moisture or other potential indoor air quality concerns.

Dark stains on building interior walls may appear in other patterns and could be from other causes - we provide photographs, description, diagnosis, and advice for many of these indoor stains in this article series. Let's start with another example

of THERMAL TRACKING BRIDGING GHOSTING so that we an distinguish these stains from others listed below.

Reader Question: These are some of the pictures from our living room.

It seems like this year its getting darker. My husb. went up to the attic and he does notice that insulation seems to need work but i want to make sure i have 2 small boys and everyone keeps saying it cant be healthy and now im worried. - K.C. 4/4/2014

Reply: how to recognize thermal tracking or ghosting stains in buildings

A competent onsite inspection by an expert usually finds additional clues that would permit a more accurate, complete, and authoritative answer than we can give by email alone. You will find additional depth and detail in articles at our website. That said I offer these comments:

There is no doubt that we are looking at thermal tracking or "ghosting" - deposits of dust and soot on cooler, more humid areas of ceilings in your home.

These are not themselves a particular health concern but the conditions that cause thermal tracking, if they involve high indoor moisture levels, particularly if that moisture comes from a damp or wet basement or crawl space, could be a subtle clue that there is a hidden mold problem in the building.

I emphasize that the stains themselves are not mold nor likely to be hazardous

We explain this phenomenon beginning

at THERMAL TRACKING BRIDGING GHOSTING

and we offer some remedies at THERMAL TRACKING REMEDIES.

An easy way to recognize thermal tracking (synonyms: ghosting, bridging, thermal bridging) is to notice where they appear and their patterns. These stains appear on ceilings below attics or cathedral ceilings and on exterior walls, and less often on interior partition walls that may suffer cooling from internal air movement or air leaks. The stains appear in rather regular and uniform streaks on intervals that map building ceiling joists or wall studs.

In some of youur photo details the shorter black ceiling stains between the longer ones (mapping ceiling joists) are perhaps areas of heat loss between gaps in the end butt-joints of poorly-laid ceiling insulation.

• Location & spacing of building framing members. Indoor stains can help find the location and spacing of wall studs or ceiling joists: use thermal tracking marks on building interior surfaces to spot the location of wall studs or ceiling joists when we need to find those members (for placing a picture nail, for example).
  
  Observing the spacing between these stains can tell us how a building has been framed.
• Location of areas of missing building insulation or areas where more air is moving across a surface
• Building areas where high moisture is present - which could be the cause or contributor to a mold or other indoor air quality issue

How to Diagnose Stains and Debris at Ceiling and Wall Heating or Cooling Air Supply Registers

Dirty HVAC duct work, lack of air filter maintenance, or furnace malfunctions can all be indicated by black stains that appear around warm or cool air delivery registers in building ceilings or walls. (This is usually a deposition of house dust, rarely is it mold, and rarely is it related to thermal tracking.

Details about these stains at registers are given

at STAINS at HVAC REGISTERS

An investigation of what was at first

called KILLER HOUSE DUST from an HVAC SYSTEM [web article] showed that the dust of concern turned out to be cotton and other carpet fibers having nothing to do with the Heating or Cooling equipment was discussed at

our FEAR OF MOLD - MYCOPHOBIA WebLog or "Blog" where we periodically post results of interesting forensic investigations.

• Watch Out: Potentially dangerous problems with heating equipment may be indicated by stains around HVAC air supply registers.
  
  See STAINS at HVAC SUPPLY REGISTERS for details.

Indoor stains may identify unsafe heating equipment or poorly-functioning fireplaces: use thermal tracking marks on interior building walls and ceilings, particularly where they vary from room to room, to diagnose poorly-vented chimneys such as fireplaces that do not work well (also look for soot stains at the hearth face).

Such marks may also indicate poor and even unsafe operation of central heating systems since a poorly maintained oil burner will often leak soot into a building interior, and a dangerously un-vented gas appliance may also produce both soot and potentially fatal carbon monoxide gas.

And our photo at left shows a floor "stain" that tells us that the building could catch on fire due to an improperly-built fireplace: there is no hearth extension. An astute inspector would worry what other safety mistakes were made by this builder.

How to Recognize Pet Stains on Building Walls

Evidence of pets in buildings: In buildings where pets are or have been housed, smudge marks on walls and at doors and door trim are sometimes mistaken for thermal tracking.

These are not thermal tracking, but these marks, along with others (scratches, urine stains) can tell us the history of pet occupancy in a building, information of use when investigating indoor air quality concerns, especially in spaces occupied by asthmatics or people with pet allergies.

Black marks on interior walls such as painted drywall might be just be where the dog [image] lay on the floor against the wall (as shown in this photograph).

Notice that the stain patterns tend to be round or oblate, not mapping building framing nor HVAC duct air movement. Notice that the stain to the left of the oor is close to the floor by the door and that the same stain blotch extends to the the floor baseboard trim and the door jamb trim.

See STAINS ANIMAL / PETS in BUILDINGS

How to Recognize Wall Stains from Human Occupants

Black marks on interior walls such as painted drywall might be also be dark wall stains where people rested their heads [image] in bed (as shown in this photo).

Look at the location of these stains and imagine a bed having been placed with its head against the wall shown in the photograph. Notice the two wall lights.

This is where a bed was almost certainly placed, and we can easily explain these black stains on the drywall. No further testing would be appropriate in normal circumstances.

How to Recognize Wall or Ceiling Stains due to use of Candles, Woodstoves, or Fireplaces

Smokers or scented candle hazards: In buildings where occupants are or have been smokers, or where occupants burn candles, especially scented candles, thermal tracking will often be still more distinctly visible as soot stains in the thermal tracking patterns we've already discussed. Since scented candles can be a source of indoor air quality problems including toxic lead deposition and perfumes which are respiratory irritants to some people.

Thermal tracking on buildings combined with this evidence can also be a clue useful in diagnosing indoor air quality complaints. In these photographs, all of the stains visible appear due to use of candles. Note the absence of framing-interval staining (16" or 24" on center) which would have been characteristic of thermal tracking, even of the candle soot, had the building surfaces been cool due to poor insulation.

Excessive indoor humidity: If indoor humidity is too high we may be encouraging mold growth in a building or we may be inviting excessive levels of dust mite activity which in turn increases the level of allergens in the building.

Other Sources of Dark Stains on Indoor Walls & Ceilings

If you have frequent fireplace fires, cooking, or if you burn scented candles, if people smoke in your home, or if your oil-fired or gas-fired heating system is not working properly, the added soot particle load in the building air is not only a health concern (soot and potentially lead), it also will mark the building surfaces in this characteristic pattern.

• Some floor stains may indicate contamination by animal urine, feces, or mold on carpet or floors.
  
  See STAINS ANIMAL / PETS in BUILDINGS
  and also
  
  see CARPET MOLD / ODOR TESTS.
• Identify sources of irritating or harmful indoor particles and soot, such as excessive use of scented candles.

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

...

Continue reading at AIR LEAK DETECTION TOOLS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• AIR LEAK MINIMIZATION
• AIR MOVEMENT in BUILDINGS - When, where, how & why air moves in buildings
• MOLD APPEARANCE - WHAT MOLD LOOKS LIKE
• OIL BURNER SOOT & PUFFBACKS
• STAIN DIAGNOSIS on BUILDING INTERIORS - home
• STAINS CANDLES FIREPLACE WOODSTOVE
• THERMAL TRACKING BRIDGING GHOSTING - home
  • DEFINITION of THERMAL TRACKING
  • EIGHT INTERACTING FACTORS CAUSE GHOSTING
  • AIR VELOCITY & MOVEMENT PATTERNS
  • COMPOSITION of DARK GHOSTING STAIN PARTICLES
  • GHOSTING STAIN INSPECTION
  • GHOSTING DARK STREAKS or LINES: CAUSES
  • GHOSTING DARK RECTANGULAR STAINS: CAUSES
  • GHOSTING DARK STAINS from AIR LEAKS
  • GHOSTING DARK STAINS on INSULATION, AIR BYPASS LEAKS
  • GHOSTING STAINS on WALLS
  • STAINS CANDLES FIREPLACE WOODSTOVE
  • STAINS DIAGNOSE IAQ PROBLEMS
  • STAINS INDICATE SAFETY CONCERNS
  • STAINS MISTAKEN for GHOSTING
  • THERMAL TRACKING REMEDIES
  • WALL THERMAL TRACKING STAINS - diagnosing ghosting stains on walls

Suggested citation for this web page

IAQ DIAGNOSIS via THERMAL TRACKING STAINS 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

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