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Properties of asphalt shingles:
This article discusses the key properties of asphalt roof shingles, compares organic and fiberglass matt shingles, lists and compares types of asphalt shingles: 3-tab, laminated, etc., and discusses shingle warranties, stains, wind resistance, and fire resistance. This article series discusses best practices in the selection and installation of residential roofing.
Asphalt shingles, which cover 80 to 90% of residential
roofs, have undergone much change in the last 20 to
30 years. Until the late 1970s, all asphalt shingles were manufactured
from a heavy organic felt mat that had established
a reputation for both strength and flexibility and generally
outlasted their 15- to 20-year life expectancy.
[Click to enlarge any image]
introduction in the late 1970s, fiberglass shingles have come
to dominate the market, accounting for over 90% of shingles
However, premature failure of some fiberglass
shingles in the 1980s and 1990s tarnished the product’s reputation
and spawned a number of lawsuits and resulted
in a toughening of standards and a general improvement in
fiberglass shingle quality.
Details about these fiberglass shingle problems are atCRACKS in FIBERGLASS SHINGLES.
Shingle styles have changed as well. The common
three-tab shingles of the 1950s and 1960s are now joined
by no-cutout shingles, multitab shingles, and laminated
Table 2-1 (above left lists the types of asphalt roof shingles and the properties of each, including dimensions, weight, exposure, and wind ratings.
Laminated asphalt roof shingles
provide deep shadow lines and a heavily textured appearance,
some simulating wood or slate. These now account
for over half the shingles sold.
Asphalt Roof Shingle Quality
Shingle quality is often difficult to determine visually
since it is based largely on hidden factors such as the
strength of the reinforcing mat (organic felt or fiberglass),
the strength and flexibility of the asphalt, and the amount
and type of fillers used. In most cases, however, the guidelines outlined below can help to select shingles that
perform as promised.
Organic Felt vs. Fiberglass Asphalt Shingles
Organic shingles are
built around a thick inner mat made from wood fibers or
recycled paper saturated with soft asphalt. Fiberglass shingles,
on the other hand, use a lightweight nonwoven fiberglass
held together with phenolic resin.
Both shingles are
then coated on top with a layer of harder asphalt and fillers
and topped with colored stone to create a decorative surface
and protect against ultraviolet light.
A thin layer of
asphalt on the bottom is coated with a nonsticking dusting
that keeps the shingles from sticking in the bundle. Each
type has its pros and cons. Table 2-2 below compares the pros and cons of organic asphalt shingles (Standard ASTM D255) and fiberglass based asphalt shingles (Standard ASTM D3462).
Organic Asphalt Roof Shingles: Characteristics
In general, organic shingles have better tear resistance
and resistance to nail pull-through than fiberglass
shingles, making them less likely to blow away during a
cold weather installation when they have not yet had a
chance to seal.
Also, some roofers find that organic shingles
are more pliable and easier to work with in cold
weather. On the downside, the organic mat is neither fireproof
nor waterproof. Organic shingles therefore typically
carry only a Class C fire rating.
Although uncommon, manufacturing defects that
allow water penetration into the mat can lead to premature
curling and cupping of organic shingles.
Blistering (photo above left, for details see BLISTERS on ASPHALT SHINGLES) and
curling (see CURLING ASPHALT SHINGLES) in warm climates has also been occasionally reported.
Organic shingles cost more than comparable fiberglass
shingles, but remain popular in colder regions and
With organic shingles, shingle weight
tends to be a good predictor of performance and longevity
since the added weight usually indicates a thicker mat
saturated with more soft asphalt.
Fiberglass Based Asphalt Roof Shingles: Characteristics
Fiberglass shingles, built on a thin nonwoven
fiberglass core, were first introduced in the late 1970s
and now account for over 90% of the shingles sold. Because
they use less asphalt, they are lighter and generally
less expensive than organic shingles. Because fiberglass
mats are more fire-resistant and moisture-resistant than
felt, most fiberglass shingles carry a Class A (severe exposure)
fire rating and are less prone to cupping and curling
from moisture damage.
On the downside, fiberglass shingles
are generally not as tear-resistant as organic shingles,
making them more prone to blow-offs in cold weather
when the shingles have not properly sealed.
have sealed, they can still tear from movement in the
sheathing, since fiberglass shingles have little give, unlike
organic shingles. In this situation, if the bond strength of
the adhesive strip exceeds the tear strength on a lightweight
shingle, the shingles can crack.
Premature failure of some fiberglass shingles due to
splitting or cracking led to a number of class-action lawsuits
in the 1980s and 1990s. (Photo at left).
The problems were primarily
with lower-end shingles with lightweight mats, types that
have been largely eliminated from the market. But it still
pays to buy ASTM-rated products from a reputable company
that provides a good warranty. Details about these fiberglass shingle problems are atCRACKS in FIBERGLASS SHINGLES.
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.
Also called “architectural” or “dimensional” shingles, these have two layers laminated together at the lower half of the shingle, giving the roof a thicker textured appearance with deeper shadow lines. Our photo (above-right) is a GAF illustration of their Royal Sovereign® laminated asphalt roof shingle.
Depending on the shape and size of the cutouts, half or more of the exposed shingle area is triple thickness and the rest double.
With the added thickness and without the tabs, which typically wear out first in three-tab shingles, most laminated shingles carry longer warranties as well as
higher wind ratings, some as high as 120 mph.
While not immune to the problems of other shingles, such as premature cracking, it is reasonable to expect good performance from a reputable brand.
One problem unique to laminated shingles is the loosening of the bottom-most piece of the shingle caused, in part, by nailing above the line where the double thickness ends (Figure 2-1 above left).
On many laminated shingles, nails must be precisely placed so they are high enough to stay hidden while still penetrating both layers.
Most shingles carry a windresistance rating of 60 miles per hour as tested under ASTM 3161 or UL 997, while specialty shingles may be rated to as much as 130 miles per hour. While laboratory tests may not predict actual performance in a storm, a higher rated shingle will likely perform better than a lower rated one.
Shingles rated at over 100 mph are often special order items and typically require six rather than the usual four nails per shingle.
A wind-resistance rating is not the same as a warranty. Shingles that carry a wind-resistance warranty generally require that the shingle tabs have been adequately sealed to the adhesive strip and most limit wind coverage to five or ten years from installation. In cold, cloudy weather or on a steep north-facing slope, manual sealing with roofing cement may be necessary.
Algae Resistance of Asphalt Roof Shingles
Black streaks on shingles caused by
algae or fungal growth used to be limited to warm, humid climates, but now this can be seen on houses as far north as Canada.
Some experts attribute the spread to the increased use of crushed limestone as a filler material in asphalt shingles.
Limestone is economical and makes a durable shingle, but the calcium carbonate in the limestone supports algae growth. In algae-resistant (AR) shingles,
zinc or copper granules are mixed in with the colored stone topping.
When the shingles get wet, the zinc or copper is released, inhibiting algae growth.
Warranties for algae resistance are usually for less than 10 years since the protection ends when the mineral washes away. Some shingles have longer lasting protection than others due to a
higher percentage of AR granules.
Fire ratings for roof coverings describe how well the roof covering resists fires including the ability of the roof to resist catching fire from a lightning strike, if a spark or ember lands on it (say from a nearby chimney or from a forest fire), as well as the resistance to fire spread if the material is ignited.
Keep in mind that the purposes of roof covering fire ratings (to describe the fire resistance of a roofing material), and the intent of roof fire resistance in general are to allow building occupants more time to escape in event of a fire, not to guarantee that the building nor its occupants will be unharmed in the event of a fire. A table of roof fire ratings and details about the applicable standards is at FIRE RATINGS for ROOF SURFACES.
Class A roof covering fire rating: Highest fire resistance: the roof can withstand severe exposure to fire. See ASTM E-108 at FIRE RATINGS for ROOF SURFACES.
Class B roof covering fire rating: Moderate fire resistance
Class C roof covering fire rating: Light fire resistance
All roofing materials that carry any fire rating (A, B, or C) must:
Apply to fires originating from outside the building.
During or after a fire the roof materials will not:
Blow off or fall off of the roof deck as flaming or glowing brands (burning embers that might further spread fire)
Break, slide, crack, or warp to expose the underlying roof deck
Allow the roof deck to fall away as glowing particles
Allow sustained flaming of the underside of the roof deck
The U.S. Federal Housing Administration (FHA) and other lenders require that building roofing materials conform to these standards. Various U.S. national or model building codes & state & Canadian Provincial building codes or fire codes require that roofs must carry at least a Class C fire rating or better.
Watch out: if a roofing shingle or other roof covering material is not installed exactly according to the manufacturer's recommendations its fire rating may be compromised and reduced, as may the roof warranty too. Also, a roof that has resisted a fire successfully, and thus helped protect the building from a fire, is likely to need to be replaced after a fire or after exposure to high heat from a nearby fire. Also watch for discount-grade roof shingles that may carry no fire rating whatsoever.
Also see these roofing material articles where we describe fire ratings:
Three Key Manufacturing Standards for Asphalt Roof Shingles: ASTM D-3462, ASTM D-225, ASTM D-3018
In the past, most companies did their own
testing, but under pressure from contractors’ associations
and others, most now use independent certifiers such as
Note: See our complete list of roofing standards found at STANDARDS for ROOFING - there are a lot of them.
ASTM D3462 - Fiberglass shingles
ASTM D3462 - Fiberglass shingles are
covered by ASTM D3462, which includes a tear test as
well as a new nail-pull-through test added after fiberglass
shingle failures started occurring in the late 1980s.
ABSTRACT: This specification deals with the standards for asphalt roofing in shingle form, composed of glass felt or felts impregnated and coated on both sides with asphalt, and surface on the weather side with minerals. Physical requirements of the shingles such as behavior on melting, tear strength, wind resistance, fire resistance, softening point, and pliability shall be measured immediately after packaging or at a reasonable time. Physical and performance requirements after application and during in-service use are however beyond the scope of this specification.
ASTM D3462, "Asphalt Shingles Made From Glass Felt and Surfaced with Mineral Granules." American Society for Testing and Materials, ASTM International, West Conshohocken, PA, 2003.
A new pliability test was also added in recent years.
With fiberglass shingles, look for the UL label next to the ASTM D3462 certification.
This is not the same as a UL listing for a fire rating, which is printed on most fiberglass shingle packages. More and more jurisdictions are requiring compliance with ASTM standards, but discount
shingles are still available with no certification.
As with many consensus standards, the ASTM D3462 requirement for tear strength of fiberglass shingles is
considered by many experts to be a bare minimum rather than a guarantee of high quality. Also, once installed the shingles’ strength will likely diminish. So finding products that exceed the minimum is recommended for demanding
ASTM D225 - 07 Organic Felt Asphalt Shingles
Organic asphalt shingles are covered under their own standard, ASTM D255
ASTM D225 - 07 Standard Specification for Asphalt Shingles (Organic Felt) Surfaced With Mineral Granules
ABSTRACT: This specification covers asphalt roofing in shingle form, composed of single or multiple thicknesses of organic felt saturated and coated on both sides with asphalt and surfaced on the weather side with mineral granules.
Materials shall meet specified dimensional and physical property requirements such as mass, behavior on heating (loss of volatile matter, and sliding of granular surfacing), wind resistance, fire resistance, weight of displaced granules, pliability, and saturant/coating compatibility.
ASTM Standard D225 - 07 "Standard Specification for Asphalt Shingles (Organic Felt) Surfaced With Mineral Granules", American Society for Testing and Materials, ASTM International, West Conshohocken, PA, 2003.
Related ASTM Roofing Standards:
D1079 - Terminology Relating to Roofing and Waterproofing
D1370 - Test Method for Contact Compatibility Between Asphaltic Materials (Oliensis Test)
D3161 - Test Method for Wind-Resistance of Asphalt Shingles (Fan-Induced Method)
D4977 - Test Method for Granule Adhesion to Mineral Surfaced Roofing by Abrasion
[ASTM D255-92 referred to in the original text, Standard Method for Steam Distillation of Bituminous Protective Coatings was superceded and was withdrawn in 2000. See ASTM D225 discussed above - Ed].
ASTM D 3018 - Class A Asphalt Shingles Surfaced with Mineral Granules
ASTM D3018 / D3018M - 10a Standard Specification for Class A Asphalt Shingles Surfaced with Mineral Granules
This specification covers mineral granule-surfaced asphalt roofing shingles. Covered here are the self-sealing (Type I) and non-self-sealing (Type II) types of shingles. The shingles shall consist of organic felt or glass mat(s) saturated or impregnated, and coated on both sides with a hot asphaltic material and completely surfaced on the weather side with mineral granules embedded in the coating.
The reverse side of the shingles shall be covered with a suitable material to prevent the shingles from sticking together in the package, causing possible damage upon being unpacked at ambient temperatures. Type I shingles shall have a factory-applied adhesive that will seal the shingles together after application.
Both types shall meet the conditions for Class A fire exposure, and loss and behaviour on heating tests. Type I shingles shall pass an additional wind resistance test.
ASTM D3018 / D3018M - 10a "Standard Specification for Class A Asphalt Shingles Surfaced with Mineral Granules", American Society for Testing and Materials, ASTM International, West Conshohocken, PA, 2003.
Warranties for Asphalt Roof Shingles
Shingle warranties run from 20 to over 50 years. Although products with longer warranties are usually of higher quality, in some cases, the longer warranties
are more of a marketing strategy than an accurate predictor of shingle life. While the specific terms of the warranty are important, more important is the manufacturer’s reputation
for warranty service in the local area.
All manufacturers retain the right to void the warranty if installation instructions are not closely followed, and they can often find a way to avoid honoring a claim if so inclined. Key issues to
consider in a warranty are as follows:
Is the warranty prorated from the date of installation, or is there an introductory term of 5 to 10 years when the full value can be recovered?
How long are warranties valid against wind damage, algae growth, or other types of damage?
Does the warranty cover a portion of the labor costs of tear-off, disposal, and installation, or does it cover materials only?
Is the warranty transferable? Perhaps most importantly, does the manufacturer have a strong reputation for warranty service in the local area?
Tamko Roofing Products www.tamko.com Fiberglass and organic felt shingles
Air Vent/A Gibraltar Company www.airvent.com A complete line of roof ventilation products, including shingle-over and exposed-ridge vents with exterior wind baffles and internal weather filters. Also soffit and drip edge vents and passive and powered attic turbine-type vents.
Benjamin Obdyke www.benjaminobdyke.com Shingle-over ridge vents. Low-profile Roll Vent uses nylonmatrix.
Extractor vent is molded polypropylene with internal and external baffles.
Cor-A-Vent www.cor-a-vent.com Shingle-over low-profile ridge vents, including Cor-a-vent, Fold-a-vent, and X-5 ridge vent, designed for extreme weather. Corrugated core.
GAF Materials Corp. www.gaf.com Cobra vent: roll-out shingle-over ridge vent with a polyester-matrix core 102 CHAPTER 2 | Roofing
Mid-America Building Products www.midamericabuilding.com Ridge Master and Hip Master shingle-over molded plastic ridge vents with internal baffles and foam filter
Owens Corning www.owenscorning.com VentSure corrugated polypropylene ridge vents; also passive roof vents and soffit vents
Trimline Building Products www.trimline-products.com Shingle-over low-profile ridge vents, Flow-Thru battens for tile roofs
Elk Premium Building Products www.elkcorp.com Highpoint polypropylene shingle-over ridge vents
Tamko Roofing Products www.tamko.com Shingle-over ridge matrix–type Roll Vent and Rapid Ridge (nail gun version) and Coolridge, which is molded
polypropylene with external and internal baffles
Benjamin Obdyke www.benjaminobdyke.com Cedar Breather, a 3/8 -in.-thick matrix-type underlayment designed to provide ventilation and drainage space under wood roofing
More Information about Roofing Materials, Methods, Standards
Asphalt Roofing Manufacturers Association (ARMA) www.asphaltroofing.org
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"Which Asphalt Shingle is Better?" [Organic shingles vs Fiberglass roof shingles], Tom Bollnow, Professional Roofing, Sept. 1999 p. 70, O'Hare International Center, 10255 W. Higgins Road, Suite 600, Rosemont, IL 60018-5607, Telephone: (847) 299-9070, E-mail: firstname.lastname@example.org. Professional Roofing Magazine is a publication of NRCA, the National Roofing Contractors Association. [Permission requested 9/26/10].
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.
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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.
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