BLACK ROOF STAIN CAUSES- CONTENTS: Guide to the causes & cures of all types of black, brown, green, and other stains on building roof surfaces. Diagnostic Guide to Types of Stains and Staining Materials Found on Roof Surfaces. Causes, cure, and prevention of black stains on roof shingles
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Black stains on roofs: here is our catalog listing the types of black stains that are found on roofs, using asphalt shingle roofs as the prime example. This article series 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.
Aesthetic or Cosmetic Roofing Issues - Black Stains on Asphalt Shingles
Some consumers have concerns with how their shingles look on the roof as much
as with how long the roof will last. Roofing manufacturers offer a wide
variety of products which give different "looks" and shadings.
that in addition to site and installation conditions, variations in
manufacturing process (granule adhesion, bleed-through) can affect how the
roof looks from the ground.
We've also investigated client concerns with
shadows appearing in early morning or late afternoon which show variations in
the roof surface.
Some shadows which are only of cosmetic nature may be
caused by slight buckling or unevenness in the roof decking and may not
indicate a structural or durability concern.
If you have particular concerns about roof appearance ask your roofer if
s/he can direct you to a house where the product which interests you is
Remember that site differences (orientation to sun, shade
trees, height above ground, roof pitch, and probably other factors) may make
shingles look a bit different on your house.
Bleed-Through Shingle Stains
Black Bleed-Through or Extractive Bleeding Black Stains on Asphalt Shingles
Extractive bleeding - bleed-through asphalt shingle stains may be mistaken for but are
not black algae or black "fungus", nor are they soot. Extractive bleeding stains on asphalt shingles are caused by loss of black pigment in the asphalt mix intended to impregnate the shingle mat itself.
Extractive bleeding or "bleed through" stains leaving black streaks running down an asphalt
shingle roof is an indication of a defective roofing product.
Typically bleed-through on asphalt shingles appears as black streaks running down shingles.
see black streaks of varying length and width (photo at left).
Really? Some experts claim that extractive bleeding of roof shingles is a fantasy - that it never occurs, and that all black roof stains are due to algae growth or other causes. Having found some expert citations describing extractive bleeding of asphalt roof shingles as a product defect, while we agree that it's not common, we don't agree that it's a fantasly.
See EXTRACTIVE BLEEDING on SHINGLES for our full discussion of extractive bleeding stains on asphalt shingles.
Black Algae Roof Staining
Black Algae Stains on Asphalt Shingles, Roll Roofing & Many Other Kinds of Roof Surfaces
Black algae stains on roofs is in many areas the most common explanation for black blotches, streaks, or discoloration on asphalt roofing products as well as on some other roofing materials.
Misnamed as "mildew" or "fungus" by some writers, algae staining on asphalt shingles usually in
shaded areas or on the more-shaded roof slopes (photo at left) characterized by black staining fairly uniform over shingles,
but appearing specifically in areas of the roof shaded by nearby trees.
The black stains on the roof at above left are probably an algal growth.
Debris-Staining on Roofs
Black Debris Can Cause Stains on Asphalt Shingle Roofs & Other Roof Materials Too
Debris staining on roofs produces fairly uniform black or brown staining in areas where due to
low-slope or presence of overhanging trees, organic debris collects on the roof slope.
Decaying debris may encourage fungal or algal growth (cited above). Debris staining often incorporates fungal or algal growth in the shaded, longer-wet areas of a roof as well as staining caused by the actual roof debris itself.
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Roger Hankey is principal of Hankey and Brown home inspectors, Eden Prairie, MN. Mr. Hankey is a past chairman of the ASHI Standards Committee. Mr. Hankey has served in other ASHI professional and leadership roles. Contact Roger Hankey at: 952 829-0044 - firstname.lastname@example.org. Mr. Hankey is a frequent contributor to InspectAPedia.com.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Green Roof Plants: A Resource and Planting Guide, Edmund C. Snodgrass, Lucie L. Snodgrass, Timber Press, Incorporated, 2006, ISBN-10: 0881927872, ISBN-13: 978-0881927870. The text covers moisture needs, heat tolerance, hardiness, bloom color, foliage characteristics, and height of 350 species and cultivars.
Green Roof Construction and Maintenance, Kelley Luckett, McGraw-Hill Professional, 2009, ISBN-10: 007160880X, ISBN-13: 978-0071608800, quoting: Key questions to ask at each stage of the green building process Tested tips and techniques for successful structural design
Construction methods for new and existing buildings
Information on insulation, drainage, detailing, irrigation, and plant selection
Details on optimal soil formulation
Illustrations featuring various stages of construction
Best practices for green roof maintenance
A survey of environmental benefits, including evapo-transpiration, storm-water management, habitat restoration, and improvement of air quality
Tips on the LEED design and certification process
Considerations for assessing return on investment
Color photographs of successfully installed green roofs
Useful checklists, tables, and charts
Roofing The Right Way, Steven Bolt, McGraw-Hill Professional; 3rd Ed (1996), ISBN-10: 0070066507, ISBN-13: 978-0070066502
Slate Roofs, National Slate Association, 1926, reprinted 1977
by Vermont Structural Slate Co., Inc., Fair Haven, VT 05743, 802-265-4933/34. (We recommend this book if you can find it. It
has gone in and out of print on occasion.)
Roof Tiling & Slating, a Practical Guide, Kevin Taylor, Crowood Press (2008), ISBN 978-1847970237, If you have never fixed a roof tile or slate before but have wondered how to go about repairing or replacing them, then this is the book for you. Many of the technical books about roof tiling and slating are rather vague and conveniently ignore some of the trickier problems and how they can be resolved. In Roof Tiling and Slating, the author rejects this cautious approach. Kevin Taylor uses both his extensive knowledge of the trade and his ability to explain the subject in easily understandable terms, to demonstrate how to carry out the work safely to a high standard, using tried and tested methods.
This clay roof tile guide considers the various types of tiles, slates, and roofing materials on the market as well as their uses, how to estimate the required quantities, and where to buy them. It also discusses how to check and assess a roof and how to identify and rectify problems; describes how to efficiently "set out" roofs from small, simple jobs to larger and more complicated projects, thus making the work quicker, simpler, and neater; examines the correct and the incorrect ways of installing background materials such as underlay, battens, and valley liners; explains how to install interlocking tiles, plain tiles, and artificial and natural slates; covers both modern and traditional methods and skills, including cutting materials by hand without the assistance of power tools; and provides invaluable guidance on repairs and maintenance issues, and highlights common mistakes and how they can be avoided.
The author, Kevin Taylor, works for the National Federation of Roofing Contractors as a technical manager presenting technical advice and providing education and training for young roofers.
The Slate Roof Bible, Joseph Jenkins, www.jenkinsslate.com,
143 Forest Lane, PO Box 607, Grove City, PA 16127 - 866-641-7141 (We recommend this book).
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: email@example.com. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones