Organic Felt Asphalt Roof Shingle Defects

ORGANIC FELT SHINGLE DEFECTS - CONTENTS: Types & photographs of organic felt asphalt roof shingle defects & failures. Asphalt roof shingle granule loss, photographs. Asphalt roof shingle cupping, curling, fishmouthing, photographs. Asphalt roof shingle blisters and splices, photographs
POST a QUESTION or READ FAQs about the life expectancy & defects found on organic felt asphalt shingle roofs
REFERENCES

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Guide to asphalt shingle roofing:

This article series explains 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.

Common shingle failure factors 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.

ORGANIC FELT SHINGLE DEFECTS - Organic-mat-based Asphalt Roof Shingle Wear & Failures

Normal organic shingle edge curling with age - end of life condition shown here (C) Daniel Friedman

"Organic felt" roof shingles refers to using cellulose (paper) as the substrate on which the shingle is constructed. The cardboard or cellulose shingle mat is impregnated with hot asphalt and coated with mineral granules to form a sunlight and weather resistant upper surface. Shown above: normal end-of-life curling at the edges of an organic shingle. This roof is fragile, should not be walked-on, and is ready for replacement. Below we describe other types of wear or damage found on this type of roof shingle.

By contrast, at CRACKS in FIBERGLASS SHINGLES we discuss a previous history of thermal splitting of fiberglass-mat-based asphalt roof shingles.

Storm damage from wind and hail occur and need to be distinguished from defective asphalt shingle product or asphalt shingle installation errors.

By listing common causes of asphalt roof shingle failures and how to recognize them, building owners and roofing contractors may also be able to reduce the occurrence of asphalt roof shingle storage, handling, and installation errors that affect roof life. Readers are also invited contribute roof failure information to the web author for research purposes.

Mineral granule loss from asphalt roof shingles

Below are summary remarks, full details about asphalt shingle granule loss are at GRANULE LOSS from SHINGLES

This photograph shows severe loss of mineral granules from an asphalt shingle roof. This roof is way past needing replacement and is almost certainly leaking. Even a roof with less dramatic granule loss is showing signs of wear and reduced future life. Anywhere that a shingle has lost the protection of its mineral granules that shingle has a reduced life expectancy.

In all climates the loss of granules from an asphalt shingle or mineral-covered roll roofing roof means that area of the roof shingle has lost its protection from sunlight. In freezing climates, shingle wear may accelerate in the area of lost granules as the roof ages and is exposed to freeze thaw cycles.

Once the shingle substrate is exposed by mineral granule loss, that area of the shingle will absorb more water than its neighbors. While in this photo the roof is "worn out", there are several other conditions that can produce mineral loss on asphalt shingle roofs:

Cracking of old organic asphalt shingle roofs is a common, normal wear sign; roof wear accelerates as fine cracks (due to loss of volatiles in the asphalt and increasingly brittle shingles) permit water to enter the shingle substrate.
See ORGANIC FELT SHINGLE NORMAL WEAR

Granule loss on a new asphalt roof, loose mineral granules wash down the roof and will appear in gutters and at the ends of downspouts. This is a normal condition unless it continues and begins to show black exposed roof shingle substrate.
Granule loss on roof shingles due to blister rash damage or wear: blistered asphalt shingles, normally an artifact of the manufacturing process, can be a point of wear due to foot traffic, hail damage, or aging and wear. If you see granule loss at the tops of shingle blisters this is probably what's going on on your roof. Details are
at BLISTERS on ASPHALT SHINGLES
Granule loss 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. 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.

Granule loss on old asphalt shingle roofs: when an asphalt shingle roof is nearing the end of its life (or is at end of live as in the photo just above) we may see that granules have begun to wash off of the shingles so as to leave large "bald" or nearly bald areas showing black shingle substrate. These shingles have more porosity than those where their mineral granules remain in place and may already be leaking even if leaks are not quite visible in the building interior. Such a roof is ready for replacement.
See GRANULE LOSS from SHINGLES
Granule loss on asphalt shingles due to storms: it is possible that severe weather, such as hailstorms, may damage shingles producing pitting and granule loss. Such roofs have a reduced remaining life, depending on the severity of damage.
See HAIL DAMAGED SHINGLES
and
see WIND DAMAGE to ROOFS
Granule loss due to blistering: blisters or "pimple-like" protrusions from a shingle surface may be a "cosmetic" manufacturing defect (at least in the opinion of the manufacturers). On at least some roofs we find that these blisters ultimately become the first wear points on the shingle when their upper surface wears away (perhaps from foot traffic or weather) exposing small round dots of missing granules on the shingle. We discuss this defect and how to distinguish between defective shingle product and storm damage
at ASPHALT SHINGLE BLISTERS,

Normal Age & Wear Cracking in Organic Mat Asphalt Roof Shingles

Organic mat asphalt shingles also may show cracking and accompanying granule loss. Defective asphalt shingle products of either organic or fiberglass based shingles may experience several failures including cracking, tearing, granule loss, blistering, etc. So, splits or cracks can occur in both organic-mat based and fiberglass-mat based asphalt roof shingles.

But thermal splitting is particularly a problem with fiberglass mat based asphalt roof shingles.

Normal Asphalt Single Wear Cracking & Granule Loss

Our photos (left and below) show a badly worn organic mat asphalt roof shingle with multiple fine cracks throughout its surface. This shingle is worn-out, but the wear pattern is homogenous over the roof slope and in our opinion is a normal wear condition.

Hairline cracks appear in the (generally thicker) organic mat based asphalt roof shingles as a normal sign of aging, and normally late in the life of the roof shingles.

Our OPINION is that a variegated cracking in a somewhat random pattern over the exposed shingle surface is a common age and wear indicator found on older organic based (paper) substrate asphalt shingle roofs.

See ORGANIC FELT SHINGLE DEFECTS for other wear signs on organic mat asphalt shingles.

Nevertheless, fine cracks through roof shingles, regardless of cause, mean accelerating wear rate and on a roof like the one shown at left, the roof needs replacement.

But catastrophic early shingle splitting failures like the ones illustrated earlier in this article were principally a problem of lightweight, fiberglass-mat based asphalt roof shingles made during the period discussed above. Roughly, from 1992 - 1997.

Cracking due to cold weather installation & bending ridge or hip cap shingles: see RIDGE & HIP CAP SHINGLES for additional discussion of distinguishing cracking wear failures from other types of shingle failures.

Also see ASPHALT SHINGLE PROPERTIES and see Choosing an Asphalt Shingle: Organic vs. Fiberglass, Ted Cushman, The Journal of Light Construction, May 1993 for more about the debate around the advantages and disadvantages of organic mat asphalt shingles vs. fiberglass mat-based asphalt roof shingles.

Readers are also invited contribute roof failure information to the web author for research purposes. web author for research purposes.

Roof shingle fragility and damage risks

We recommend that inspectors stay off of cupped-asphalt shingle roofs, particularly in cold weather (shingles are more likely to break).

If we absolutely have to walk on a cupped shingle roof, we would tiptoe carefully, avoiding stepping on the raised or cupped shingle sections, or if doing repairs, we would prop a ladder up off of the roof surface and work from that scaffold as is sometimes done with slate or other fragile roof surface repairs.

Is Roofing Felt Underlayment Needed Under Asphalt Roof Shingles?

While the requirement for felt underlayment beneath asphalt roof shingles seems to be a topic of almost timeless argument subject to much arm-waving and little reading of manufacturer's instructions and warranties, various sources recommend or require installation of a felt underlayment over the roof deck before asphalt roof shingles are installed.

The short answer is that underlayment should be installed beneath asphalt shingles.

See UNDERLAYMENT REQUIREMENTS, ROOF - home, for complete information on this question.

Also see Choosing an Asphalt Shingle: Organic vs. Fiberglass, [PDF] Ted Cushman, The Journal of Light Construction, May 1993 for more about the debate around the advantages and disadvantages of organic mat asphalt shingles vs. fiberglass mat-based asphalt roof shingles.

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Continue reading at ASPHALT SHINGLE FAILURE TYPES or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see ASPHALT SHINGLE LIFE / WEAR FACTORS

Or see ASPHALT ROOF SHINGLES - home, for all articles about asphalt roof shingles

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ORGANIC FELT SHINGLE DEFECTS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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Technical Reviewers & References

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Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. (727) 595-4211 mark@BestTampaInspector.com
Hankey and Brown home inspectors, Eden Prairie, MN, technical review by Roger Hankey, prior chairman, Standards Committee, American Society of Home Inspectors - ASHI. 952 829-0044 - hankeyandbrown.com
Arlene Puentes, a licensed home inspector, educator, and building failures researcher in Kingston, NY.
Carl Gerosa, New Rochelle, NY.
"The Uses and Performance Requirements of Steep-Slope Roof Underlays in North America and the United Kingdom", Robert J. Booth, Keith Roberts, Proceedings of the North American Conference on Roofing Technology, p. 112-118 - Web Search 07/12/2010. This scholarly article cites 33 research articles on the role of roofing underlayments.
"Unvented Roofs, Hot- Humid Climates, and Asphalt Roofing Shingles Research Report - 0306 Feb-2003 Building Science Corporation", Building Science Corporation, 30 Forest Street, Somerville, MA 02143
Quoting from the article abstract: "When constructing unvented roofs with asphalt shingles in hot-humid climates, a vapor barrier must be installed between the asphalt shingles and the roof deck." - Web Search 5/21/2010
NRCA Roofing & Waterproofing Manual, 5th Edition, National Roofing Contractors Association, 10255 W. Higgins Road Suite 600 Rosemont, IL 60018-5607 Telephone: (847) 299-9070 Toll Free: (866) ASK-NRCA (275-6722), e-mail: info@nrca.net. - http://www.nrca.net/rp/pubstore/details.aspx?id=243&c=9
"Choosing an Asphalt Shingle: Organic vs. Fiberglass", Ted Cushman, The Journal of Light Construction, May 1993, pp. 11-14. Used with Permission from the Journal of Light Construction.
The Journal of Light Construction has generously given reprint permission to InspectAPedia.com for adaptations, quotations, or reproductions used at this website. All rights and contents of the JLC material are ©Journal of Light Construction and may not be reproduced in any form.
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

Cupping Asphalt Shingle Explanation & Photos

Please see CUPPING ASPHALT SHINGLES for the full text of this article.

Asphalt roof shingles often show cupping (a concave center), curling (raised edges which curl downwards), and fishmouthing (raised edge of a shingle tab at its center with little curling). Each of these is discussed below.

Cupping asphalt roof shingles (see photos below), particularly on organic or felt-based asphalt shingles, are a normal wear pattern that shows up with shingle age.

This "normal" cupping or curling pattern will display shingles which are concave in their center, with the corners and possibly the three exposed shingle tab edges curled such that the very edge of the shingle curls downwards.

Shingles in this condition are fragile and nearing end of life. In this condition, if someone walks on cupped shingles the raised cupped sections will break and can lead to early failure and leaks.

Curling Asphalt Shingle Explanation & Photos

Please see CURLING ASPHALT SHINGLES for the full text of this article.

Curling roof shingles (see photos below) will show a curling-under at the edges of the shingle tab, first at the lower edge and sometimes also at the two sides of the shingle tab.

In fact we have seen a "failed" roof that was not leaking until the fellow who was asked to inspect it walked across this fragile surface.

From a ladder at the roof edge one could clearly see the virtual footprints of broken shingle edges where the "inspector" had walked. It's best to stay off fragile roof surfaces to avoid converting a "near end of life" condition to a "failed, leaking" condition.

Curling and cupping may occur together on the same roof, or shingles may appear to be curled-only (or fishmouth-curled-only as you'll read next). We don't see cupping without some curling.

Fishmouthing Asphalt Shingle Explanation & Photos

Please see the full text of this article at Fishmouthing Asphalt Shingles.

You may not realize it but asphalt roof shingles are not quite waterproof and in particular the back side of asphalt shingles is much less water resistant than the upper or exposed side.

The exposed side of an asphalt shingle is protected from sun damage by a coating of mineral granules.

These shingles rely on the pitch of the roof and mechanical drainage combined with proper placement or pattern of shingling on the roof to avoid leaks. [Photo: Carl Gerosa]

Fishmouthed asphalt roof shingles: An example of the less-waterproof back of asphalt roof shingles is seen below in our photo of "fishmouthed" roof shingles. In these cases a specific "curling" pattern of shingles called "fishmouthing" is not simple age and wear. This pattern displays a raised shingle edge (it's not cupped over at the very edge) which, if inspected closely, will typically occur first and worst over the shingle butt joints where shingle sides abut one another.

Fishmouthed cupping of asphalt roof shingles is caused by excessive under-roof moisture such as by a poorly or un-vented attic or roof cavity.

Moisture escaping through the roof sheathing and up through the bottom of the shingles contacts the uppermost shingle which spans the butt joint of shingles below, placing more moisture at that point on the shingle tab than elsewhere. This uneven moisture, probably combined with weather exposure, leads to a raised, cupped "fishmouth" look on those shingles.

Laddering and stair-stepping of roof shingles

Please see LADDERING vs STAIR STEPPING SHINGLES for the full text of this article.

The photograph shows a sloppy "ladder pattern" installation of strip-type asphalt shingles. While opinions (and expertise) vary among roofers, this ladder pattern shingle application may not be as durable a roof installation as one which staggered the shingle offsets more than a single six inches (or in this case only 3") left and right with each shingle course.

On other asphalt shingle roofs, particularly older ones, you may notice that the pattern of fishmouth occurrence on an asphalt shingle roof follows a fairly regular or stair-stepped pattern, or it may follow a regular "ladder" like pattern up the roof such as is shown in these photographs.

That's because the fishmouthing is occurring at the butt joints of the shingles where more moisture is passing out of the roof structure into the back side of the shingle above each butt joint.

You can thus determine the actual pattern in which the shingles were applied to the roof.

"Laddering," while permitted by some manufacturers and standards, is a less workmanlike shingle installation and may result in a localized early wear area on a roof. Ladder-pattern shingle application shows that the roofer liked to work up the roof from one position for as long as possible before moving.

Like cupped and curled asphalt shingles, fishmouthed shingles are also fragile and near end of life and are, as with ordinary cupping, damaged if walked-on.

In some other cases a defective product might cup or curl But we don't have authoritative data on the frequency of that defect. [Photo of fishmouthed shingles courtesy of Carl Gerosa, New Rochelle, NY.]

Workmanship: Fasteners/Nailing Problems, Wind Damage appeared to have led wind blow-off of these Atlas shingles, though an investigation of whether or not the shingles had self-sealed was also needed.

Workmanship: Fasteners/Nailing Problems lead to holes or wind blow-off

Workmanship: Fasteners/Nailing Problems lead to holes or wind blow-off. Notice that not only has one shingle already fallen or been blown off of the roof, but its neighbors are sliding down. Diagnosis from a photograph is questionable but there appears to be a nailing problem here.

Workmanship: Installation Pattern Problems:Laddering [Photo: Carl Gerosa, New Rochelle, NY.]

Workmanship: Flashing and underlayment problems
Workmanship: Improper materials/roof-slope problems
Holes and nail-pops in shingle roofs

In discussing wind damage to roofing with your insurance adjuster or roofing contractor, be sure to review the details of original and replacement shingle installation as this can give evidence about the underlying cause of roof failure as well as informing you of how to avoid roof shingle blow-off in the future.

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.
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.
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
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.)
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