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Tests for Black Algae Stains on Asphalt Roof Shingles InspectAPedia®  -     How to test for black algae growth and stains on roof surfaces Algae stains and black marks on asphalt roof shingles: causes, effects on roof life, cure & prevention Types & photographs of organic felt asphalt roof shingle defects & failures

Here we discuss methods used to test for and confirm black roof stains due to algae or "black fungal growth" on roof shingles. We provide a list of type of stains and colors that appear on roof shingles and on other roofing materials. Also see Black Algae for more photos of black algae stains on roofs. And see ALGAE, FUNGUS, LICHENS, MOSS on SHINGLES and see STAINS on ROOF SHINGLES. To remove and prevent black algae stains on roofs, see BLACK STAIN REMOVAL & PREVENTION.

This website tells readers how to identify & explain the most-common asphalt roof shingle failures and how to obtain asphalt roofing shingle failure claims assistance. These defects occur on organic-mat or fiberglass-mat asphalt roof shingles. Readers are also invited contribute roof failure information to the web author for research purposes. web author for research purposes.

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use the links at page left to navigate this document or to go to Other Website Topics. Green links show where you are in our document & website.

Free Testing Offered to Identify Roof Stain Material

See Bleed-Through for more on extractive bleeding; some roofing consultants, including Mr. Norman (above) assert that all of the black stains on asphalt shingle roofs are due to algae growth. To test black roof debris for a determination of whether the black stains are due to soot, algae, fungus, or asphalt bleed-through our forensic lab will accept tape samples for processing at no fee between April 2009 and June 2009.

Use the tape sampling procedure and mailing instructions found at MOLD TEST KITS for DIY MOLD TESTS to send us samples for testing. (No more than two samples per roof, please.) Include a note referring to this article or just a printout of the first page of this web article along with your sample so that we won't be looking for a payment. Be sure to press your tape firmly into the black stain material.

Testing Black Roof Stain Material in the Forensic Lab

In our forensic laboratory (not on a roof itself) we prepare a microscope slide of black roof debris particles for direct examination at low and high magnification. Algae is identifyable by physical characteristics.

If the black material does not appear to be an organic structure we use a solvent on the microscope slide. Xylene or Hexane will cause asphalt products to bleed and stream on a microscope slide.

Our photos above show black stains on a roof and an initial lab photo of the black roof debris at 400x. Sample material from the stained area on this roof was prepared on a microscope slice and mounted in lactic acid. Lactic acid does not dissolve asphalt but that will hydrate and expand algae and mold spores. The debris in our photo (above left) looks like brownish black something that is not organic. But take a look at the photographs just below.

Here is what that same sample looks like under the microscope at 1000x, oil immersion, after allowing five minutes for hydration (expansion of the cells of material.) We see a dark algae on the left and green algae on the right, both found in the same sample material. The black stains on the roof above are definitely algae, not bituminous material.

Testing Black Roof Stains On the Roof

Mr. Norman proposes a simple test of applying a light spray of a diluted mixture of trisodium phosphate [use a TSP substitute, not TSP which is an environmental contaminant] and chlorine (with water) in the proper proportion will determine weather or not this is algae quite readily. If it is asphalt pigment, it will not lighten.

If the residue is bitumen, a petroleum product would be necessary to remove it, but cleaning the roof with any solvent would of course be unwise as you will also damage the shingles as well as risk a fire, explosion, and environmental contamination.

To remove and prevent black algae stains on roofs, see BLACK STAIN REMOVAL & PREVENTION.

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ASPHALT ROOF SHINGLES
  ASPHALT SHINGLE DEFINITIONS
  ASPHALT SHINGLE FAILURE TYPES
  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

• Shingle Shield™ are zinc strips that are inserted under the shingle tabs of individual shingles to reduce moss, lichens, and algae growth on asphalt roofing - see shingleshield.com
• StainhandleR are zinc strips that are inserted under the shingle tabs of individual shingles to reduce moss, lichens, and algae growth on asphalt roofing- see stainhandler.com
• Zinc-Shield® - zincshield.com and Z-stop™ zinc roofing strips - z-stop.com, are roll-out zinc strips intended for installation near the ridge of a roof to reduce moss, lichens, and algae growth on roofs
• 04/09: thanks to William M. Norman, P.E., S.E., Keeler-Webb Associates, 486 Gradle Drive, Carmel, IN 46032 for opening discussion regarding the legitimacy of extractive bleeding as a term to apply to asphalt roofing material. Mr. Norman suggests that many (not all) black stains on asphalt roofing may be due to algal growth. We will report progress in this discussion as updates to this web article.

List of All Types of Stains on Building Roofs, Surfaces, Walls

In the following guide we list types of stains by stain color & appearance, by building location or material, and by stain cause. We distinguish among the following stuff that may stain or be found growing building roofs, walls, or other surfaces, with extra focus on asphalt shingle roofs as well as other roofing materials such as wood shingles, wood shakes, roll roofing, and even slate or tile roofs. 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 more detailed, illustrated version of the list below is given at Stain Diagnosis on Building Exteriors.

• Algae caused black stains on roof surfaces - Some photos of black algae stains are at Black Algae Stains on Asphalt Shingles. For details see ALGAE STAINS ON ASPHALT ROOF SHINGLES. Algae can produce black stains on asphalt roofing products. Also see  ALGAE, FUNGUS, LICHENS, MOSS COMPARED.
  
• Black stains on asphalt roofing products such as asphalt shingles or roll roofing, caused by extractive bleeding (product defects) - see Bleed-Through and see Roofing material defect / environmentally-caused roof shingle stains.
• Black, brown, or gray stains on roofing products due to debris left on the roof surface, such as piles of leaves and organic waste from nearby trees. See Debris Staining and see Proximate cause roof shingle stains
• Black or other colored stains on roof surfaces may be caused by soot from chimneys, both wood-fired and oil-fired devices. Black or other colored stains may also appear on roof surfaces from nearby industrial activities. See Soot Staining.
• Black stains on building interiors: such as on carpets, drywall, or trim: see STAIN DIAGNOSIS on Indoor Surfaces and then STAIN DIAGNOSIS on Indoor Surfaces and also see STAINS on Indoor Surfaces: PHOTO GUIDE
  
• Brown or red stains on roof surfaces are often caused by rust from wearing steel flashing or other on-roof metal products. See Rust Stains on Shingles.
• Chimney stains on roofs - see see SOOT STAINING - Black Soot Stains on Roof Shingles Around Chimneys and see Proximate cause roof shingle stains
• Debris stains on roof shingles - see Debris Staining - Black Debris Stains on Asphalt Shingle Roofs
• Extractive bleeding stains on asphalt roofs - see Bleed-Through and see Roofing material defect
• Lichens growing on roof surfaces - Lichens are not the same growths as moss or algae, and are difficult to remove without damaging the roof surface. See Lichens on Roofs for details about how lichens can cause roof damage, see ALGAE, FUNGUS, LICHENS, MOSS on SHINGLES for a guide to preventing these roof growths and stains. Also see   ALGAE, FUNGUS, LICHENS, MOSS COMPARED.
• Mold or fungus growing on roof surfaces or on other building surfaces - see ALGAE STAINS ON ASPHALT ROOF SHINGLES. 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. Be sure also to see Stuff that is Mistaken for Mold to avoid becoming excited about harmless substances that people think are toxic mold. If you know your building has a mold problem, see ACTION GUIDE - WHAT TO DO ABOUT INDOOR MOLD.
• Moss on roof surfaces - see ALGAE, FUNGUS, LICHENS, MOSS on SHINGLES. Green or other colored mosses are a bit easier to remove than lichens on roofing surfaces, but both can carry away mineral granules and damage the roof surface. Moss tends to hold more water and moisture on the roof surface. So in our opinion moss is more likely to damage a roof surface than lichens or algae. Also see   ALGAE, FUNGUS, LICHENS, MOSS COMPARED.
  
• Rust Stains on buildings - see Rust Staining - Red or Brown Rust Stains (on shingles)
• Soot or Creosote black or brown stains on roof surfaces near or below chimneys - see SOOT STAINING - Black Soot Stains on Roof Shingles Around Chimneys and see Proximate cause roof shingle stains
• Tree-caused stains on roofs - see Proximate cause roof shingle stains
• White stains on roof surfaces may be from wash-down of pigments in paint on surfaces above the roof such as a gable end or dormer wall; white or less-black roof surfaces may also be found below copper or aluminum flashing whose salts run down the roof surface in wet weather, preventing algae or moss growth and leaving a white area on an otherwise stained roof surface. Our article at ALGAE, FUNGUS, LICHENS, MOSS on SHINGLES includes a photograph of this condition on a wood shingle roof.

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