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How & when to clean off or remove roof debris:
This article explains debris on building roofs as a source of dark stains on the roof surface and possible reduced roof life or actual roof damage.
We provide at Diagnostic Guide to Types of Stains and Staining Materials Found on Roof Surfaces. Causes, cure, and prevention of black stains on roof shingles.
We also illustrate use of gentle sweeping to remove accumulated debris from a rooftop to extend the life of the roof.
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.
ROOF DEBRIS STAINING - Black & Brown Debris Stains on Asphalt Shingle Roofs
Debris staining on roofs produces fairly uniform black or brown staining in areas where due to
low-slope or presence of overhanging trees, leaves, or organic debris collects on the roof slope.
Decaying debris may encourage fungal or algal growth (cited above).
Lichens or even thick moss may also grow on such roof areas.
Debris, lichens, or moss on a roof will shorten its life
by holding water on the roof surface, preventing drying, and (in cold climates) adding wear and tear on the roof
surface by freeze-thaw cycling.
In contrast, debris from an upper roof gutter that spills onto lower roof slopes may result in tan, white, or other stains depending on the metal of the gutter and the length of time that leaves and debris rest in it.
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The decision to permit the upper roof gutter to spill down the lower slope (photo above/left) also risks creating an early wear-area and thus leaks on the lower slope roof.
Remedies for black or brown or gray debris staining on asphalt shingles:
As cited above, cleaning off debris
(gentle sweeping or washing, watch out for damaging the roof during cleaning),
or cutting unnecessary overhanging tree branches may help.
See PROXIMATE CAUSE roof shingle stains for
details about these growths on buildings.
There are other sources of roof staining, from cosmetic to harmful to the roof and as we discuss at WHITE ROOF COLOR BENEFITS (live link just below) stains also affect the roof's solar or heat reflectance.
Gentle Sweeping Off of Roof Debris
Above I'm about to gently sweep away accumulated hemlock needles and leaves that accumulate on the up-roof side of skylights on the roof of this Two Harbors MN home. What you see is about a decade's worth of accumulated organic waste.
Watch out: Leaving this debris on the roof can risk more than stained shingles. Organic debris on the roof surface holds water, wind-blown soil, and decaying material that can cause early wear and failure of the shingles below, as a result of:
Holding moisture or water on the roof surface
Permitting actual plant growth; roots damage the shingles
Permitting freeze-thaw cycle damage of wet roof debris (in a freezing climate).
Watch out: this roof was just low-enough in slope that I could walk on it, but even on a low-slope roof the presence of loose debris can act like a coating of ball bearings, sending you skidding and screaming down the roof and onto the rocky Minnesota ground below.
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Really? Now for a look at real world conditions: climbing onto this roof placed me smack into an area where there was already an accumulation of hemlock needles just hoping they could send me back down to earth in a hurry. Walk carefully and use your broom!
I took care to stand above the debris and to sweep carefully and gently (so as to avoid damaging the shingles by scouring off mineral granules). I swept down towards the roof eaves, standing always and only in the swept-clean space.
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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