InspectAPedia ^®

This article describes How to Recognize & Diagnose Thermal Tracking, Soot Stains on Building Walls - Diagnosing Causes of High Heating Costs and discusses other various interior wall and ceiling stains and explains how to recognize thermal tracking, thermal bridging stains, building air leaks, and building insulation defects. 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.

These are substances that cause black sooty marks on building interior ceilings or walls and sometimes also on carpets are from sources and causes 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."

Readers should see HEAT LOSS in BUILDINGS. Also see AIR SEALING STRATEGIES and AIR LEAK DETECTION TOOLS as well as AIR LEAK MINIMIZATION. For photos of snow melt on rooftops that also show points of building heat transfer and loss, see STAIN DIAGNOSIS on Building Exteriors.

© Copyright 2010 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Air Leaks Causing Thermal Tracking Stains on Building Walls

Thermal tracking stains may appear on the building walls themselves, in a pattern of vertical "stripes" which may be roughly 16" or 24" on center, marking the (cooler) location of wall studs or ceiling joists. In this case the exterior wall surface (see that window at right in the photo) are cooler where the wall studs are located and warmer between the wall studs. Probably the wall cavity is insulated, and the insulated areas have a higher "R" value than the solid wood studs themselves. So the wall is cooler where the studs are located, increasing condensation on those surface areas, and picking up a greater share of house dust in air moving across those surfaces. Thermal tracking stains may appear as dark black/brown wall stains appearing close to floor level, above heating baseboards mounted on exterior walls are probably due to thermal tracking.

Wall Stains over Heat Sources such as Hot Water Baseboards

Why Black Stains May Appear on Building Interior Walls as Well as on Building Exterior Walls

Our photo at below left shows wide black rectangular stains on a wall where insulation was omitted. The photo at below right shows long narrow black stains on a wall where thermal tracking marked the location of wall studs, but where insulation was present. Why did both of these patterns appear in the same building?

High interior moisture (air handlers in wet crawl spaces, a wet basement) was most likely the determining factor in the extent of staining that occurred in this home. Moisture condensed (and caused adhesion of house dust particles) on cooler surfaces. In some areas the un-insulated wall was coolest and got stained (below left) while in other areas the wall studs were cooler than the insulated wall cavity, so the stud-areas got stained (below right).

Black, roughly rectangular stains on building interior or exterior walls: may be present wherever insulation has been omitted. While usually these stains are going to appear on the building exterior walls (which get colder) they may appear on interior walls as well. These stains on interior walls, which may be completely un insulated, may appear with greater severity where other construction details increase the flow of air and/or moisture in certain sections of wall cavity.

An example of the cause of this stain pattern is air movement up through the wall cavity from a cool, damp basement or crawl space. The heated building living space warms the open interior wall cavity, causing air in that cavity to rise by natural convection towards the building attic or roof cavity.

Air movement upwards in the wall cavity draws cooler air from the basement or crawl space. Where some wall sections have more air movement, less insulation, or greater moisture exposure, they may become more darkly stained than their neighbors or more darkly stained than other walls in the building interior.

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

Share this Article      

...

Technical Reviewers & References

• InspectAPedia.com^® - Daniel Friedman
• InspectAPedia Bookstore lists recommended books, organized by topic & available for purchase. Most of our articles also include a list of recommended books for the specific article topic as well as other references, and information sources.
• Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
• Additional technical contributors & reference sources for this article are listed below.

Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

• Thanks to Alan Carson, Carson Dunlop, Associates, Toronto, for technical critique and content suggestions regarding thermal tracking.
• 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.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• ...

More Information on Building Diagnostic Inspections and Repairs

• Attic Condensation and Ice Dam Leaks - Detection and Correcting Venting and Condensation Problems in Buildings
• INSULATION INSPECTION & IMPROVEMENT: Insulation in Buildings: Identification, R-values, Heat loss, Insulation Types, Insulation Characteristics
• Asbestos pipe insulation in buildings
• Brick "Insulation" in Building Walls
• HEAT LOSS CALCULATIONS, Insulation Properties, Definitions of R, K, U values, Insulation Design
• How to Detect and Correct Attic Condensation & Prevent Ice Dam Leaks in Buildings
• Insulation Materials as Indicators of Building Age
• Indoor Air Quality Investigations: Fiberglass in Indoor Air, HVAC ducts, and Building Insulation
• Insulation Identification Photographs - Fiberglass insulation photos, yellow, pink, green, white fiberglass identification in building attics, walls, ducts, other locations
• Insulation Identification Photographs - Cellulose insulation photos, Mineral wool insulation photos, rock wool insulation photos, cotton insulation photos, balsam wool insulation photos
• Insulation Identification Photographs - Vermiculite insulation photos
• Insulation Properties, Table of R-Values, density, moisture permeability, fire safety, aging effects on various insulation materials
• Mold in Fiberglass in Insulation
• Radiant Heat Floor Mistakes to Avoid case history of improper placement of slab insulation and radiant heat tubing
• Thermal Tracking thermal bridging & air leak stains in buildings or on building insulation
• Un-Vented Roof Solutions - How to Prevent Attic Condensation, Ice Dam Leaks, Roof Mold, & Roof Structural Damage in Buildings with Un-vented Roof Cavities
• Vermiculite Building Insulation & Asbestos
• Ice Dam Leaks in building attics and roof cavities, how to inspect for evidence of leaks, identify causes, and correct bad attic ventilation, improper roof venting, and these causes of attic mold or roof structure damage
• Looking for Mold what mold is often found where in buildings - simple technical presentation
• Mold spores in the Home - a Photo ID Library for detection and identification of mold allergens
• Recognizing Allergens: What various indoor allergens look like - identification photos to help identify pollen, dust mites, animal dander, toxic or allergenic mold - Common Mold and other Allergens, Irritants, Remedies & Advice
• Stuff that is not mold but is often mistaken for it - things you may not want to test. Also, not all "black mold" is toxic - here are examples of harmless black mold.
• Animal Allergens: Dog, Cat, and Other Animal Dander - Cleanup & Prevention Information for Asthmatics and regarding Indoor Air Quality.

InspectAPedia® Home & Site Map - Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Advice: In-depth research & advice on diagnosing, testing, correcting, & preventing building defects & indoor environmental hazards. Unbiased information, no conflicts of interest.

The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems

Use this simple, economical mold test kit by following our instructions on how to collect and mail mold samples to our lab

Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.

Building Inspection, Problem Diagnosis, Forensic Investigation & Testing, Repair Consulting

Contact Daniel Friedman for website content suggestions or for fee-paid consulting