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Here we discuss the identification and diagnosis of black roof stains caused by soot or creosote washing off of building chimneys and we discuss possible safety and fire hazards associated with this condition. This series of articles tells readers how to identify & explain the most-common causes of black, brown, red, gray, green, or white stains appearing on roof shingles and on other building surfaces. Roof shingle stains are often caused by black algae, bleed-through or extractive bleeding of asphalt, dirt, soot, or organic debris.

See Causes of Roof Stains and  Catalog of All Roof Stains for the causes and types of stains that occur on building roofs. There are other sources of roof staining, from cosmetic to harmful to the roof. For the diagnosis and cure of other building stains, see STAIN DIAGNOSIS on Building Exteriors and STAIN DIAGNOSIS on Indoor Surfaces.

© Copyright 2009 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. s on Roof Shingles

SOOT STAINING - Black Soot Stains on Roof Shingles Around Chimneys

Soot from fireplace flues washing down onto the roof - characterized by staining appearing below and in line with the chimney Similarly, soot from oil-fired heating flues washing down onto the roof, characterized by the same pattern of staining around and below the chimney; also probably an indicator of an operating problem with the heating system. That was clearly the case in the photograph shown at page top. At left our photo shows soot stains running down a masonry chimney and onto the roof surface. Incidentally, this chimney needed to be re-lined but evidence of that is not presented in this photo. Gas Flue Safety Warning: If this same sooting appears on and around a gas-fired appliance flue, there is a very unsafe condition present and risk of fatal carbon monoxide production inside the building. Immediate action is be needed. [Photograph of a soot-stained roof top at page top was courtesy of Roger Hankey a Minnesota home inspector.

Unlike other roof shingle stain patterns shown in this article, black stains caused by soot staining from a chimney will be prominent in a wide swath along the sides and below the chimney and will be little in evidence elsewhere on the roof.

• For a detailed guide to chimney inspection, diagnosis, and repairs, see CHIMNEY INSPECTION & REPAIR GUIDE

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ASPHALT ROOF SHINGLES
  ASPHALT SHINGLE DEFINITIONS
  ASPHALT SHINGLE FAILURE TYPES
  ALGAE, FUNGUS, LICHENS, MOSS COMPARED
  ALGAE STAINS ON ASPHALT ROOF SHINGLES
  ALGAE STAIN TEST METHODS
  ALGAE, FUNGUS, LICHENS, MOSS on SHINGLES
  BLACK STAIN REMOVAL & PREVENTION
  BLISTERS on ASPHALT SHINGLES
  CRACKS in FIBERGLASS SHINGLES
  CUPPING ASPHALT SHINGLES
  CURLING ASPHALT SHINGLES
  FISHMOUTHING ASPHALT SHINGLES
  GRANULE LOSS from SHINGLES
  HAIL DAMAGED SHINGLES
  LADDERING & STAIR STEPPING SHINGLES
  LIFE / WEAR FACTORS in SHINGLES
  MECHANICAL DAMAGE of SHINGLES
  MOSS & LICHENS on SHINGLES
  ORGANIC FELT SHINGLE DEFECTS
  SPLICE DEFECTS on ASPHALT SHINGLES
  STAINS on ROOF SHINGLES
  WHAT ARE ASPHALT SHINGLES
BUILT UP ROOFS
CERTIFICATIONS for ROOFING CONTRACTORS
CHIMNEY INSPECTION & REPAIRS
CHOOSING A ROOFING CONTRACTOR
CLAY TILE ROOFING
FIRE RETARDANT PLYWOOD
LOW SLOPE ROOFING MATERIALS
MEMBRANE ROOFS
METAL ROOFING TYPES
MODIFIED BITUMEN ROOFING
ROOF INSPECTION SAFETY & LIMITS
ROOF VENTILATION SPECIFICATIONS
ROOF VENTING ENERGY SAVING DETAILS
SLATE ROOF INSPECTION & REPAIR
SOD ROOFING
SIDING WOOD
STAIN DIAGNOSIS on Building Exteriors
STAIN DIAGNOSIS on Roofs
  Causes of Roof Stains
  Catalog of All Roof Stains
  Catalog of Black Roof Stains
  Black Algae
  ALGAE STAIN TEST METHODS
  Black Stain Removal & Prevention
  Bleed-Through
  Chimney-Caused Roof Stains
  Debris Staining on Roofs
  Lichens on Roofs
  Moss on Roofs
  Rust Stains on Shingles
  Soot Staining

• 7/07: thanks to Roger Hankey & Cheryll Brown, ASHI home inspectors in Minnesota, for the rooftop soot staining photograph. Mr. Hankey is a past chairman of the ASHI Technical Committee, serves as co-chairmain of ASHI legislative committee, and has served in other ASHI professional and leadership roles.

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• Roofing
• ASPHALT ROOF SHINGLES

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