Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
Ask a Question or Search InspectAPedia
InspectAPedia ® Home
ACOUSTICAL SEALANT CHOICES
AIR BYPASS LEAKS
AIR LEAK DETECTION TOOLS
AIR LEAK MINIMIZATION
AIR LEAK SEALING PROCEDURE
AIR TEST FOR MOLD: ACCURACY
AIR TEST SAMPLING CASSETTE STUDY
ALLERGEN TESTS for buildings
ALLERGENS in BUILDINGS, RECOGNIZING
ALLERGY & MOLD IAQ PRODUCTS
ALLERGY TESTS for PEOPLE
ALLERGY TEST ACCURACY
ANIMAL ALLERGENS / PET DANDER
ANIMAL ENTRY POINTS in buildings
ANIMAL ODORS IN buildings
APPLIANCE EFFICIENCY RATINGS
ARCHITECTURE & BUILDING COMPONENT ID
ASBESTOS IDENTIFICATION IN buildings
ATTIC LEAKS, CONDENSATION & MOLD
BASEMENT CEILING VAPOR BARRIER
BASEMENT HEAT LOSS
BASEMENT LEAKS, INSPECT FOR
BATH & KITCHEN DESIGN GUIDE
BEST CONSTRUCTION PRACTICES GUIDE
Best Interior Finish Practices
BLOWER DOORS & AIR INFILTRATION
BLOWER FAN CONTINUOUS OPERATION
BOOKSTORE - INTERIORS
BRICK LINED WALLS
BRICK VENEER WALL AIR LEAKS
BRICK WALL DRAINAGE WEEP HOLES
BUCKLED FOUNDATIONS due to INSULATION?
BUILDING NOISE DIAGNOSIS & CURE
BUILDING SAFETY HAZARDS GUIDE
CABINETS & COUNTERTOPS
CAR MOLD CONTAMINATION
CARPET DUST IDENTIFICATION
CARPET MOLD CONTAMINATION
CARPET PADDING ASBESTOS, MOLD, ODORS
CARPET STAIN DIAGNOSIS
CARPET & other STAIN TESTS
CARPET TEST PROCEDURE
CARPETING & INDOOR AIR QUALITY
CARPETING, SELECTION & INSTALLATION
CASEWORK, CABINETS, SHELVING INSTALLATION
CATHEDRAL CEILING INSULATION
CATHEDRAL CEILING VENTILATION
CEILING FINISHES INTERIOR
CEILINGS, DROP or SUSPENDED PANEL
CEILINGS, PLASTER TYPES
CEILINGS, PLASTER, LOOSE HAZARDS
CEILING TILES - Asbestos-Containing
CHIMNEY INSPECTION DIAGNOSIS & REPAIR
CHINESE DRYWALL HAZARDS
COMBUSTION AIR for TIGHT buildings
CONDENSATION or SWEATING PIPES, TANKS
CONDENSATION on WINDOWS & SKYLIGHTS
CORROSION in ELECTRICAL PANELS
CORROSION & MOISTURE SOURCES in PANELS
COOLING LOAD REDUCTION by ROOF VENTS
CONDENSATION or SWEATING PIPES, TANKS
CONDENSATION on WINDOWS & SKYLIGHTS
DECK & PORCH CONSTRUCTION
DEW POINT CALCULATION for WALLS
DEW POINT TABLE - CONDENSATION POINT GUIDE
DIRECTORY of MOLD / ENVIRONMENTAL EXPERTS
DIRT FLOOR MOLD CONTAMINATION
Disinfecting Buildings with Bleach
DRYWALL HAZARDS, CHINESE
DRYWALL INSTALLATION Best Practices
DRYWALL MOLD RESISTANT
EARTHQUAKE DAMAGED FOUNDATIONS
EFFLORESCENCE, Salts & White / Brown Deposits
ELDERLY & VETERANS HOME SAFETY
ELECTRICAL INSPECTION, DIAGNOSIS, REPAIR
ENVIRONMENTAL HAZARDS - INSPECT, TEST, REMEDY
FIBERGLASS INSULATION MOLD
FLAT ROOF MOISTURE & CONDENSATION
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
FLOOD DAMAGED FOUNDATIONS
FLOOD VENTS & FLOOD PORTS
FLOODS IN buildings-mold
FLOOR DAMAGE DIAGNOSIS
FOOTING & FOUNDATION DRAINS
FOUNDATION CRACKS & DAMAGE GUIDE
FRAMING DAMAGE, INSPECTION, REPAIR
FRAMING DETAILS for BETTER INSULATION
FRAMING DETAILS for DOUBLE WALL HOUSES
FRAMING METAL STUD PERFORMANCE
FREEZE-PROOF A BUILDING
FROST HEAVES, FOUNDATION, SLAB
FUNGICIDAL SPRAY & SEALANT USE GUIDE
GAS EXPOSURE EFFECTS, TOXIC
GAS DETECTION INSTRUMENTS
GAS EXPOSURE LIMITS & STANDARDS
GLARE, Sunlight/Lighting Control
HEAT LOSS in BUILDINGS
HEAT LOSS DETECTION TOOLS
HEAT LOSS INDICATORS
HEAT LOSS PREVENTION PRIORITIES
HEAT LOSS R U & K VALUE CALCULATION
HEAT TAPES & CABLES on Roofs for Ice Dams
HEATING COST SAVINGS METHODS
HOT ROOF DESIGNS: Un-Vented Roof Solutions
HOUSEWRAP AIR & VAPOR BARRIERS
HOUSE DOCTOR, how-to be
HOUSE PARTS, DEFINITIONS
HUMIDITY LEVEL TARGET
ICE DAM PREVENTION
INDOOR AIR QUALITY & HOUSE TIGHTNESS
INDOOR AIR QUALITY IMPROVEMENT GUIDE
INDOOR HOUSE DUST & DEBRIS
INSECT INFESTATION / DAMAGE
Insulation Air & Heat Leaks
INSULATION FACT SHEET- DOE
INSULATION for GREENHOUSE or SOLARIUM
INSULATION IDENTIFICATION GUIDE
INSULATION INSPECTION & IMPROVEMENT
INSULATION LOCATION - WHERE TO PUT IT
INSULATION LOCATION for BRICK VENEER WALLS
INSULATION LOCATION for CAPES, CRAWLSPACES
INSULATION LOCATION for CATHEDRAL CEILINGS
INSULATION LOCATION for GREENHOUSE or SOLARIUM
INSULATION R-Values & Properties
KITCHEN & BATH DESIGN GUIDE
LIGHTING, EXTERIOR GUIDE
LIGHTING, INTERIOR GUIDE
LOG HOME GUIDE
METAL LATH, PLASTER & STUCCO
MOBILE HOME INSPECTIONS
MOISTURE CONTROL in BUILDINGS
MOLD: A COMPLETE GUIDE TO MOLD
MOLD ACTION GUIDE - WHAT TO DO ABOUT MOLD
MOLD APPEARANCE - WHAT MOLD LOOKS LIKE
MOLD EXPERT, WHEN TO HIRE
MVOCs & MOLDY MUSTY ODORS
NOISE / SOUND DIAGNOSIS & CURE
ODORS GASES SMELLS, DIAGNOSIS & CURE
OIL, HEATING, EXPOSURE HAZARDS, LIMITS
OIL HEAT ODORS
OIL SPILL CLEANUP / PREVENTION
OIL TANK LEAK ODORS
OIL TANKS INSPECT LEAK TEST ABANDON REGS
OUTHOUSES & LATRINES
OXYGEN - O2
OZONE for MOLD OR ODORS
PAINTS & COATINGS ODORS IN BUILDINGS
PARTICLE SIZES & IAQ
Particulates & Allergens Indoors
Pesticide Exposure Hazards
PET ALLERGENS / PET DANDER
PET STAINS on FLOORS
PET STAINS on WALLS
PLASTIC CONTAINERS, TANKS, TYPES
PLASTIC HEATER VENT
PLASTIC ODORS-SCREENS, SIDING
PLUMBING SYSTEM ODORS
PVC - VINYL BUILDING PRODUCTS
RADON HAZARD TESTS & MITIGATION
SAFETY HAZARDS GUIDE
SAFETY HAZARDS & INSPECTIONS
SEPTIC SYSTEM ODORS
SEWAGE CONTAMINATION in BUILDINGS
SEWAGE EJECTOR / GRINDER PUMPS
SEWAGE BACKUP, WHAT TO DO
SEWER GAS ODORS
SMELL PATCH TEST to Track Down Odors
SOUND CONTROL in buildings
STAIN & BIODETERIORATION AGENT CATALOG
STAINS on & in BUILDINGS, CAUSES & CURES
STAIN DIAGNOSIS on BUILDING EXTERIORS
STAIN DIAGNOSIS on BUILDING INTERIORS
STAIRS, RAILINGS, LANDINGS, RAMPS
STONE CLEANING METHODS
STONE VENEER WALLS
STRAW BALE CONSTRUCTION
STUCCO WAll FAILURES DUE TO WEATHER
STUCCO WALL METHODS & INSTALLATION
STUCCO OVER FOAM INSULATION
STUCCO PAINT FAILURES
STRUCTURAL DAMAGE PROBING
STRUCTURAL WOOD ASSESSMENT
SUMP PUMPS GUIDE
SWEATING (CONDENSATION) on PIPES, TANKS
TEST KITS for DUST, MOLD, PARTICLE TESTS
Thermal Expansion Cracking of Brick
THERMAL IMAGING, THERMOGRAPHY
THERMAL IMAGING MOLD SCANS
THERMAL MASS in BUILDINGS
THERMAL TRACKING & THERMAL BRIDGING
TRIM, INTERIOR INSTALLATION
TRAPPED MOLD BETWEEN WOOD SURFACES
TRUSS UPLIFT, ROOF
TRUSSES, Floor & Roof
VAPOR BARRIERS & CONDENSATION in BUILDINGS
VENTILATION in BUILDINGS
VINYL CHLORIDE HEALTH INFO
VINYL Siding or PLASTIC Window ODORS
Volatile Organic Compounds VOCs
WALL FINISHES INTERIOR
WALL CONSTRUCTION BARRIER vs CAVITY
WATER ENTRY in buildings
WIND WASHING INSULATION At EAVES
WINDOWS & DOORS
WINTERIZE A BUILDING
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
How to diagnose Indoor stains in buildings: This article describes & diagnoses the cause of interior stains on buildings: stains of all colors, black or dark, grown, green, red, yellow, tank, or gray can appear on interior wall, ceiling, flooring or carpeting and may be due to a variety 9of sources, some of which are dangerous, others just "cosmetic". Here we explain 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.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
In the following guide we list types of stains found on building interiors, organized by by stain color & appearance, by building location or material, and by stain cause. . Some of these types of roof stains or discoloration are only cosmetic in nature, while others may indicate growths that are likely to reduce the roof covering life.
A guide to stains on building exteriors is found at STAIN DIAGNOSIS on BUILDING EXTERIORS.
Black or dark stains on building interiors: such as on carpets, ceilings, walls, floors, drywall, or trim may be due to mold contamination but might also be soot from heating equipment, candles, fireplaces, pets, or simply soiling from use and lack of cleaning.
Dark indoor stains on walls and ceilings are often caused by thermal tracking - a deposition of house dust and debris on cooler surfaces - a stain cause we explain at THERMAL TRACKING & THERMAL BRIDGING.
Mold or fungus growing on building surfaces - See FIND MOLD in buildings, HOW TO for a guide to looking for mold contamination in or on buildings, and see WHAT MOLD LOOKS LIKE for a guide to just what mold looks like on building surfaces.
Watch out: don't assume that all black stains are toxic dangerous mold, and don't assume that mold only shows up as "black" on building surfaces. There are harmful molds that are just about any color you can imagine, there are harmless black molds, and there are plenty of building stains that are not mold at all.
Brown or other dark chimney stains on interior walls or ceilings near chimneys - See STAINS on/near CHIMNEYS where we discuss stains found on chimney exteriors or stains on building interior walls or ceilings near chimneys. Also see SOOT STAINING - Black Soot Stains on Roof Shingles Around Chimneys and see Proximate cause roof shingle stains
See Black stains from animals for details about pet stains on building floors (urine) and walls (various) and see Pet Stains on Walls for diagnosing stains such as the black marks left by pets on walls.
We discuss carpet stains related to thermal tracking, air leaks, soot deposition in detail at CARPET STAIN DIAGNOSIS and we discuss carpet and other indoor soot, dust & stain testing procedures at
Often these stains are mistaken for toxic indoor mold. 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 - 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.
These are substances that you can easily learn to recognize in buildings. Save your mold test money, and increase the accuracy of your mold contamination inspection or test for toxic or allergenic mold in buildings: review these items to learn recognize non-fungal materials or even possibly harmless cosmetic "black mold" often mistaken for "toxic fungal growth."
Rule out natural color variations: Some apparent building stains may not be an actual stain at all but rather the original color or color variations in natural materials such as the birch plywood door shown at left. Sometimes what you think is a new building stain is actually a color variation that has been in place for some time, but was not previously attended.
Identify thermal tracking stains from normal house dust: If you are able to rule out specific air leaks causing normal deposition of house dust, and if you are quite sure that you have an abnormal level of stains/soot like material showing up on various surfaces then these courses of investigation are suggested as an aid to diagnosing stains on indoor ceilings, walls, floors, carpets, cabinet interiors, closet interiors, or even house contents:
How to Separate normal "thermal tracking" dust deposition patterns from other types of indoor staining
If stains or debris are appearing on surfaces which are not cooled by their location (such as exterior walls, hollow interior walls which are entertaining internal air movement due to convection from below to above, areas near cooling air registers), then it may be possible to state with confidence that the stains appearing are due more to a high level of particulate debris in the building than to the more common thermal tracking phenomenon (THERMAL TRACKING & THERMAL BRIDGING). .
Look for the source or potential sources of abnormal levels of indoor airborne debris, soot, particles, dust, such as a malfunctioning oil or gas fired appliance, any other combustion sources, even a mal-adjusted pilot light on gas stoves or heaters can be a soot source as well as the oft cited candles, fireplaces, and even pets (for example lots of dog traffic between indoors and out brings in high levels of dust).
If/when we can identify an unusual source or a source producing an unusual level of particulate debris we have perhaps answered a key part of this question of the probable source of indoor soot, dust, or debris stains.
Measure Indoor Moisture Levels when Diagnosing Indoor Stains and Soot or Debris Deposits
OPINION: even in a relatively clean home, unusually high moisture levels may result in noticeable levels of dust deposition on indoor surfaces, regardless of the dust source, and even including normal types and sources of house dust.
If moisture levels are a factor in the home, say moisture regularly above 55% RH, we would expect to see more-stained surfaces on those building surfaces that are more likely to be a bit higher in moisture, such as cooler surfaces on walls, ceilings, or in closets or cabinets where temperatures are lower and moisture may condense at a slightly higher level.
Indoor Stain Diagnosis Using Air Movement Patterns
Sometimes we can identify particular sources of air movement, directions of air movement, which we can correlate with the areas where we see staining. A simple example is the higher amount of dust deposition that occurs around heating or air conditioning supply registers on ceilings and walls. Relating air movement patterns to dust or soot or other debris stains may be diagnostic.
Also take a look at a short paper we wrote on an analysis of suspect indoor dust, at An Investigation of Indoor House Dust Debris where we determined that indoor dust levels which had been suspected of originating in an HVAC system were actually carpet dust and fibers.
How to Use Particle Identification to Diagnose the Source of Dust, Dirt, Soot, or Debris Stains
It is often possible to collect samples of suspect dust or debris for microscopic analysis in order to suggest a source or type of source of indoor stains.
It is essential that you select a forensic laboratory whose staff includes people experienced and trained in the identification of a wide range of indoor particles. A lab specializing in mold or allergen identification, for example, may not consider much less apply methods used to identify oil burner soot, common components of ordinary house dust, mite fecals, pet dander, human skin cells, fabric fibers, or other indoor particles which, if properly identified along with a statement of relative frequency in the sample, may be diagnostic.
Frequently Asked Questions (FAQs) about Diagnosing the Cause of Stains on Interior Surfaces in Buildings
Question: What is causing black soot in my condo, who is responsible if it's the heating system, and is it dangerous?
i read an article concerning thermal tracking, ghosting, soot online. I have a major problem with that in my condo and i have a few questions that i need help with. would you mind my asking them to you, if you would answer them it would help me out quite a bit.
I live in a garden style condo that is a mess with all the soot all over my walls, windows, etc. what can i do? I asked the plumber what can i do and he said it was my responsibility, but if this has issues concerning the heating system who would be responsible for this? there is one main boiler for the whole bldg. is this a health issue? Who can I contact about this in the mass area? Or can you help me? I am worried concerning my health more than anything else. Please any information that you can send to me would be a big help right now. - D.B.
Reply: identify the source of soot, and resolve unsafe heating system problems before beginning cleanup
A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem. That said, here are some things to consider:
First establish that the soot you see is due to the heating system; if the same system is serving multiple condo units in the building, as your note indicates, then in most cases one would expect other residents to have the same problem.
A basic explanation of thermal tracking or "ghosting" is provided at THERMAL TRACKING & THERMAL BRIDGING.
Second, severe sooting traced to the boiler indicates both improper operation and possibly very unsafe conditions at the boiler, especially if it's a gas unit (carbon monoxide hazards); Be sure you have working smoke detectors and CO detectors in your home.
Now if sooting is traced to the heater, then you may have a claim for cleaning and restoration work to remove the soot from your own home, as one would expect it is due to improper system maintenance, or repair. That's something to discuss with your condo owners association and management association, not the local plumber or heating contractor. But this concern, while understandably troubling to you, should be addressed after any questions about current operating safety of the system have been addressed.
or if your system is a gas fired heater see
Soot can indeed be a respiratory or eye irritant if at high levels.
If you have extensive soot damage that will require professional cleaning, and perhaps re-painting, you should also contact your homeowner's insurance company. Soot cleanup may involve washing and re-painting walls and ceilings, professional carpet cleaning, and cleaning, laundering, or dry cleaning of curtains etc. But I wouldn't begin cleanup before the cause of the sooting is identified and cured.
Questions & answers or comments about diagnosing the causes of stains found on indoor surfaces.
Ask a Question or Enter Search Terms in the InspectApedia search box just below.
Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
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.