Roof damage assessment (C) D Friedman R LeBlanc

Mechanical Damage to Asphalt Shingles - cuts, punctures, tears, granule loss

MECHANICAL DAMAGE of SHINGLES - Photo guide to mechanically-damaged roof shingles & mineral granule loss
- Shingle granule loss due to foot traffic or other shingle damage; roof damage during inspection in hot weather?
- Shingle damage due to cuts, tears, misaligned roofing staples, or application errors
- Types of roof shingle stains, causes, cures, prevention
- Case study examines causes of damaged roof shingles and granule loss
Questions & answers about damage to roof surfaces or shingles caused by mechanical means, not natural wear or weather
References

Click to Show or Hide Related Topics

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

This roof shingle damage diagnosis article describes the causes and effects of mechanical damage to shingles from a variety of sources: foot traffic, tears, punctures, tool cuts, or damage during shingle installation. The results of mechanical damage to asphalt shingles includes mineral granule loss from the shingles, leaks, or simply shorter roof life. Other common asphalt shingle failure factors discussed in this article series include improper storage and handling of the asphalt shingles before installation, improper nailing, improper flashing (which pertains to any roofing material), and defective asphalt shingle product material leading to thermal splitting, cracking, blistering, staining, and in some cases curling or cupping shingles.

Mechanical Damage to Roof Surfaces

A roof surface can be damaged resulting in leaks, reduced life, or other troubles by events other than normal sun, wind, and weather exposure. Examples include walking on fragile roof surfaces, walking or twisting and turning while stepping on hot asphalt or modified bitumen roof surfaces, stomping around on slates, wood shakes, wood shingles, cement asbestos or fibe cement shingles, and chopping ice to try to stop an ice dam leak.

Case Study of Damaged Asphalt Roof Shingles

Here we present a series of photographs of asphalt roof damage. A professional investigator documented these conditions and joined in a discussion of the apparent cause of damage shown in each photo. All of these pictures were taken on the North slope of an asphalt shingle Firehalt brand roof.

A windstorm adjuster for TWIA (Texas) inspected an insured's roof with a large amount of granular loss. The roof is in these photos is 10/12 pitch (hip with build ups) and was 11 years old at the time of inspection. The roof is vented by turtle vents (4) and (1) turbine vent only (no ridge vent). The shingles are Firehalt Brand (Certain Teed®) - 30 year shingles. In our opinion the damage was not, however, related to the brand. Roof consultants, manufacturers, suppliers, and building inspectors are invited to Contact Us to offer further diagnostic comments about this case.

Damage due to improper installation - staple exposed, askew, not flush, wrong location & mis-nailed.

Looks like same type of damage as the prior shingle photo, due to improper installation - staple exposed, askew, not flush, wrong location & mis-nailed, but in this photo the staple itself is not visible.

Damage due to blown off hip shingle, improper nailing is most likely, possibly wind and failure to seal.

See WORKMANSHIP & WIND DAMAGE for details.

Damage due to improper installation - surface nailed broken shingle over excessive bend fracture - maybe installed in cold weather; granule loss on exposed top of hip/ridge intersection, weather or foot traffic.

Damage due to cracked hip shingle, weather-damage granule loss around fracture - moisture penetration of shingle contributes to granule loss due to the fracture

Damage due to same as the previous photograph: people often step right on this spot on roofs.

Photo not sharp, but this looks like a cracked shingle tab, defective product or mechanical damage (someone tried to lift the tab after it was sealed??

Damage due to diagonal tear in single, mechanical damage is most likely. See my article on thermal splitting but as this tear is not over a butt joint it is more likely due to tear during installation or tear if someone tried to lift the tab (less likely)

Damage due to vertical tear in shingle tab - IF this tear is over a butt joint (which it appears) this could be thermal splitting - if so the number and extent of these will increase on the roof; COULD be also torn due to application over a raised staple - you need to investigate this further

Damage due to shingle edge injury due to walking on the roof - note the wear on the very edge of most of the shingle tabs - looks like foot traffic wear

Damage due to torn shingle tab, appears depressed as if broken by foot traffic at low temp; if left side of tear originates at a butt joint, could be thermal splitting.

Damage due to what appears to be classic defective product, curling and thermal splitting, split runs through at least 3 shingle tabs in the photo.

Damage due to diagonal tar near wall flashing, foot traffic or damage during installation.

Also the wall flashing may be improper and leak prone - single long counter flashing caulked to brick is unreliable, and step flashing may be absent (investigate further - possible clue of improper workmanship, look for step flashing at every shingle along this juncture by carefully lifting the counter flashing, or by carefully lifting some shingle tabs) - a second cracking torn shingle may be present at lower left of photo.

Damage due to cracked or torn shingle, note evidence of mechanical damage including the very straight cut to the left of the diagonal tear. Some granule loss to left of the straight cut at photo lower left - foot traffic looks likely as well as possible tool damage)

Damage due lifting, torn shingle tab at photo center, not over a butt joint, looks like mechanical damage or tear during installation

Damage due horizontal weathered tear across center of two laminated single tabs, exposed substrate, appears to be defective product or mechanical damage in storage, transport, or installation that later appears as a cut or tear. This does not look like a splice shingle but the wear is similar. See SPLICE DEFECTS on ASPHALT SHINGLES.

Conclusions About These Contributors to Asphalt Shingle Damage & Mineral Granule Loss on This Roof

Primarily, questionable or perhaps even poor workmanship, use of staples, mis-located, staples askew, high raised-corner staples, mis-stapled on top of shingles, foot traffic, mechanical damage, possibly excessive bending in cold weather at the hip/ridge appear to be the problems on this roof. We also saw some minor mis-nailing or inadequate nailing leading to a single blow off at the roof hip.
Secondarily: a few of the cuts and damage could be defective product - see CRACKS in FIBERGLASS SHINGLES. At least one cut was made by a tool or implement.
Weather does not appear to be a root cause of this roof damage, though once a shingle has been worn by walking or mechanical damage the exposure of the shingle substrate accelerates wear and granule loss.
We would not characterize the prime problem of this roof as "granule loss" which was the original owner's concern. GRANULE LOSS from SHINGLES provides more details.

In our opinion the roof damage was not, however, related to the brand. Roof consultants, manufacturers, suppliers, and building inspectors are invited to Contact Us to offer further diagnostic comments about this case.

Walking on an Asphalt Shingle or Roll Roofing Roof can Cause Damage to the Roof

Walking on a roof can damage shingles in several conditions.

Asphalt Shingle Roof Damage from Walking on Fragile Roof Surface

Granule loss or actual shingle damage may occur on a roof being walked-on: walking on any asphalt shingle roof loosens some of the mineral granules from their attachment embedded in the asphalt used to impregnate and coat the shingle.

Walking on shingles that are brittle, cupped, curled, can damage them at any time, perhaps more so if the inspector steps on a raised, curled, or otherwise damaged portion of the shingle, or if the asphalt shingles are simply old, brittle, and fragile, even if flat.

We investigated a complaint against a home inspector charged with damaging a roof that we learned he had been smart enough to stay off of - inspecting from the roof edge by ladder. But a contractor, called to bid on roofing repairs, stomped around inspecting the roof to make his repair bid. The result was conversion from a roof that needed replacement soon to one that needed immediate replacement. We could virtually see the footprints of the contractor, in a trail of broken shingles across the roof.

Asphalt Shingle Roof Damage during Other Repair Work

On roof repair work of other components, for example around a chimney, involving standing, moving, turning, placing repair materials on the roof surface without first protecting that surface from damage.

If there is a lot of roof traffic, such as when work is being done on a chimney, you may see "bald" areas of shingles with lost granules where people have been walking. This is damage caused by workers and is not a product defect.

Walking on fragile roof shingles. See CUPPING ASPHALT SHINGLES and CURLING ASPHALT SHINGLES.

Roof Damage from Walking on very Hot, soft Asphalt Roofing

We think it's subjective, and we don't have a specific number, but the variables underlying roof damage during an on-roof walking inspection include:

outdoor air temperature at the time of the roof inspection
sun exposure on different roof slopes - a shaded slope may be cooler and safe to walk-on even on a hot day
number of hours the roof has been exposed at various temperatures - longer roof exposure to sun and high temperature on a given day, walking on a roof in the last half of a very hot day, for example, is more likely to lead to damage
the nature of the foot traffic - walking carefully vs. standing in one place and spinning on your heels - the latter will certainly damage a hot soft asphalt shingle or roll roofing.

Alone no single number answers the questions raised by these factors. But certainly we've both seen damage to roofs when walked on during a hot day - when someone was careless.

Thanks to home inspector Charlie Gallagher for suggesting this added detail.

Frequently Asked Questions (FAQs) about causes of damage to roof shingles from mechanical events: walking, punctures, tree limbs, chopping ice, brushing off moss, etc.

...

Ask a Question or Search InspectApedia

Questions & answers or comments about how roof shingles may be damaged, leak, or wear out not from natural means but from events or misuse or abuse..

Ask a Question or Enter Search Terms in the InspectApedia search box just below.

Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

Randy LeBlanc, a Windstorm Adjuster for TWIA (Texas), provided photographs and assisted in technical assessment of this material 4/12/09.
Charlie Gallagher is a professional home inspector in Lawton, OK and can be contacted at CAGFISHING@aol.com

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

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

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.

Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.

Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
Decks and Porches, the JLC Guide to, Best Practices for Outdoor Spaces, Steve Bliss (Editor), The Journal of Light Construction, Williston VT, 2010 ISBN 10: 1-928580-42-4, ISBN 13: 978-1-928580-42-3, available from Amazon.com
The Journal of Light Construction has generously given reprint permission to InspectAPedia.com for this article. All rights and contents are ©Journal of Light Construction and may not be reproduced in any form.
Architectural elements: the technological revolution: Galvanized iron roof plates and corrugated sheets; cast iron facades, columns, door and window caps, ... (American historical catalog collection), Diana S Waite, available used out of Amazon.
Asphalt Roofing Residential Manual,
Building Pathology, Deterioration, Diagnostics, and Intervention, Samuel Y. Harris, P.E., AIA, Esq., ISBN 0-471-33172-4, John Wiley & Sons, 2001 [General building science-DF] ISBN-10: 0471331724 ISBN-13: 978-0471331728
Building Pathology: Principles and Practice, David Watt, Wiley-Blackwell; 2 edition (March 7, 2008) ISBN-10: 1405161035 ISBN-13: 978-1405161039
Built-Up Roof Systems, Manual, C.W. Griffin, Mcgraw-Hill (Tx); 2nd edition (July 1982), ISBN-10: 0070247838, ISBN-13: 978-0070247833
Concrete Folded Plate Roofs, C. Wilby PhD BSc CEng FICE FIStructE (Author), Butterworth-Heinemann, 1998, ISBN-10: 0340662662, ISBN-13: 978-0340662663
Concrete Shell Roofs, C. Wilby PhD BSc CEng FICE FIStructE (Author),
Concrete Dome Roofs (Longman Concrete Design and Construction Series),
Concrete Roofing Tile, History of the, Batsford, 1959, AISN B000HLLOUC (availble used)
Copper Roofing, by CDA
Copper Roofing, Master specifications for copper roofing and sheet metal work in building construction: Institutional, commercial, industrial, I.E. Anderson, 1961 (hard to find)
Corrugated Iron, Building on the Frontier, Simon Holloway
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
Handbook of Building Crafts in Conservation, Jack Bower, Ed., Van Nostrand Reinhold Company, NY 1981 ISBN 0-442-2135-3 Library of Congress Catalog Card Nr. 81-50643.
Historic Preservation Technology: A Primer, Robert A. Young, Wiley (March 21, 2008) ISBN-10: 0471788368 ISBN-13: 978-0471788362
Historic Slate Roofs : With How-to Info and Specifications, Tina Skinner (Ed), Schiffer Publishing, 2008, ISBN-10: 0764330012 , ISBN-13: 978-0764330018
Low Slope Roofing, Manual of, 4th Ed., C.W. Griffin, Richard Fricklas, McGraw-Hill Professional; 4 edition, 2006, ISBN-10: 007145828X, ISBN-13: 978-0071458283
- Roof failure causes in depth (and specific methods for avoiding them)
- Roof design fundamentals and flourishes, based on voluminous industry research and experience
- New technologies and materials -- using them safely and correctly
- Comprehensive coverage of all major roofing systems pecifications, inspection, and maintenance tools for roofing work
Metal Roofing, an Illustrated Guide, R.A. Knowlton , [metal shingle roofs],
Patio Roofs, how to build, Sunset Books
Problems in Roofing Design, B. Harrison McCampbell, Butterworth Heineman, 1991 ISBN 0-7506-9162-X (available used)
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).
Slate Roofing in Canada (Studi4es in archaeology, architecture, and history),
Smart Guide: Roofing: Step-by-Step Projects, Creative Homeowner (Ed), 2004, ISBN-10: 1580111491, ISBN-13: 978-1580111492
Solar heating, radiative cooling and thermal movement: Their effects on built-up roofing (United States. National Bureau of Standards. Technical note), William C Cullen, Superintendent of Documents, U.S. Govt. Print. Off (1963), ASIN: B0007FTV2Q
Tile Roofs of Alfred: A Clay Tradition in Alfred NY
"Weather-Resistive Barriers [copy on file as /interiors/Weather_Resistant_Barriers_DOE.pdf ] - ", how to select and install housewrap and other types of weather resistive barriers, U.S. DOE
Wood Shingle Roofs, Care and Maintenance of wood shingle and shake roofs (EC), Stanley S. Niemiec (out of print)
...


	InspectAPedia^®	Question? Just ask us!	InspectAPedia
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair

Question? Just ask us!

Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair